Patent Publication Number: US-7584511-B2

Title: Data processing apparatus, data processing method, program, program recording medium, data recording medium, and data structure

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a data processing apparatus, a data processing method, a program, a program recording medium, a data recording medium, and a data structure. In particular, the present invention relates to those that allow data to be highly conveniently processed. 
   2. Description of the Related Art 
   In recent years, as a recording medium that has a large storage capacity and that can be randomly accessed, for example a digital versatile disc (DVD) has been outspread. In addition, a DVD device that performs various processes with a DVD has been also outspread. 
   As DVD devices, there are a DVD recorder that records and reproduces data of television broadcast programs and so forth to and from a DVD, a car navigation system that uses a DVD on which map information and so forth have been recorded, reproduces the map information therefrom, and displays it, a game device that uses a DVD on which a game program and so forth have been recorded, reads the program therefrom, and executes it, and other devices. 
   The details of the DVD are described for example in the following non-patent document. [Non-Patent Document 1] DVD Specifications for Read-Only Disc Part 3; Version 1.1 December 1997 
   A recording medium such as a DVD on which a large amount of data is recorded and a DVD device that uses it need to allow such a large amount of data to be highly conveniently processed. 
   SUMMARY OF THE INVENTION 
   The present invention is made from the foregoing point of view and an object of the present invention is to highly conveniently process data. 
   The present invention is a data processing apparatus comprising obtainment means for obtaining permission information about video data that are being reproduced from permission information representing whether video data corresponding to encoded video data equal to or larger than an access unit are permitted to be secondarily used; determination means for determining whether the video data that are being reproduced have been permitted to be secondarily used corresponding to the permission information; and capture means for capturing the video data that are being reproduced when the determination means has determined that the video data that are being reproduced have been permitted to be secondarily used. 
   The present invention is a data processing method comprising the steps of obtaining permission information about the video data that are being reproduced from permission information representing whether video data corresponding to encoded video data equal to or larger than an access unit are permitted to be secondarily used; determining whether the video data that are being reproduced have been permitted to be secondarily used corresponding to the permission information; and capturing the video data that are being reproduced when it has been determined at the determination step that the video data that are being reproduced have been permitted to be secondarily used. 
   The present invention is a program comprising the steps of obtaining permission information about the video data that are being reproduced from permission information representing whether video data corresponding to encoded video data equal to or larger than an access unit are permitted to be secondarily used; determining whether the video data that are being reproduced have been permitted to be secondarily used corresponding to the permission information; and capturing the video data that are being reproduced when it has been determined at the determination step that the video data that are being reproduced have been permitted to be secondarily used. 
   The present invention is a program recording medium on which a program has been recorded, the program comprising the steps of obtaining permission information about the video data that are being reproduced from permission information representing whether video data corresponding to encoded video data equal to or larger than an access unit are permitted to be secondarily used; determining whether the video data that are being reproduced have been permitted to be secondarily used corresponding to the permission information; and capturing the video data that are being reproduced when it has been determined at the determination step that the video data that are being reproduced have been permitted to be secondarily used. 
   The present invention is a data recording medium on which record data have been recorded, the record data containing encoded video data composed of video data that have been encoded every a predetermined unit that is an access unit, and permission information representing whether video data corresponding to encoded video data equal to or larger than the access unit are permitted to be secondarily used in the data processing apparatus. 
   The present invention is a data structure of the data being processed by a data processing apparatus, the data containing encoded video data, composed of video data that have been encoded every a predetermined unit that is an access unit and permission information representing whether video data corresponding to encoded video data equal to or larger than the access unit are permitted to be secondarily used in the data processing apparatus. 
   In the data processing apparatus, the data processing method, the program, and the program recorded on the program recording medium of the present invention, permission information about video data that are being reproduced is obtained from permission information representing whether video data corresponding to encoded video data equal to or larger than an access unit are permitted to be secondarily used. It is determined whether the video data that are being reproduced have been permitted to be secondarily used corresponding to the permission information. The video data that are being reproduced are captured when it has been determined that the video data that are being reproduced have been permitted to be secondarily used. 
   On the data recording medium of the present invention, record data that contains encoded video data composed of video data that have been encoded every a predetermined unit that is an access unit and permission information representing whether video data corresponding to encoded video data equal to or larger than the access unit are permitted to be secondarily used in the data processing apparatus have been recorded. 
   In the data structure of the present invention, data contains encoded video data composed of video data that have been encoded every a predetermined unit that is an access unit and permission information representing whether video data corresponding to encoded video data equal to or larger than the access unit are permitted to be secondarily used in the data processing apparatus. 
   According to the present invention, data can be highly conveniently processed. In particular, secondary use of video data can be controlled. 
   Next, embodiments of the present invention will be described. The relationship between elements of claims and embodiments is as follows. The relationship represents that specific examples that support the invention set forth in claims are described in embodiments. Thus, even if some specific examples are not described in elements of claims, it is not implied that the specific examples do not correspond to the elements of the claims. Conversely, even if specific examples are described as counterparts of elements of claims in this section, it is not implied that these specific examples do not correspond to other than the elements of the claims. 
   In this section, it is not implied that all aspects of the invention corresponding to specific examples described in the embodiments of the present invention are set forth in the claims. In other words, the description in this section corresponds to specific examples described in the embodiments of the present invention. Thus, the description in this section does not deny that there are aspects of the present invention that are not set forth in the claims of the present patent application and that divisional patent applications may be made and/or additional aspects of the present invention may be added as amendments. 
   A data processing apparatus as set forth in claim  1  is a data processing apparatus (for example, a disc device shown in  FIG. 1 ) that processes record data recorded on a data recording medium, 
   the record data containing: 
   encoded video data composed of video data that have been encoded every a predetermined unit that is an access unit, and 
   permission information (for example, capture_enable_flag_PlayList shown in  FIG. 5 , capture_enable_flag_Clip shown in  FIG. 10 , capture_enable_ps2 shown in  FIG. 45 , or capture_enable_flag_AU shown in  FIG. 46 ) representing whether video data corresponding to encoded video data equal to or larger than the access unit are permitted to be secondarily used in the data processing apparatus, the data processing apparatus comprising: 
   obtainment means (for example, a player control module  212 , shown in  FIG. 2A  and  FIG. 2B , that performs a process at step S 372  shown in  FIG. 44 ) for obtaining the permission information about the video data that are being reproduced; 
   determination means (for example, a player control module  212 , shown in  FIG. 2A  and  FIG. 2B , that performs a process at step S 373  shown in  FIG. 44 ) for determining whether the video data that are being reproduced have been permitted to be secondarily used corresponding to the permission information; and 
   capture means (for example, a graphics process module  219 , shown in  FIG. 2A  and  FIG. 2B , that performs a process at step S 376  shown in  FIG. 44 ) for capturing the video data that are being reproduced when the determination means has determined that the video data that are being reproduced have been permitted to be secondarily used. 
   In a data processing apparatus as set forth in claim  2 , 
   the record data further contains a play list (for example, PlayList( ) shown in  FIG. 5 ) that represents a reproduction procedure of the video data. 
   The permission information (for example, capture_enable_flag_PlayList shown in  FIG. 5 ) is described in the play list, the play list representing whether the video data that are reproduced are permitted to be secondarily used. 
   In a data processing apparatus as set forth in claim  3 , 
   the record data contains: 
   multiplexed data (for example, a program stream stored in a file 00001.PS, shown in  FIG. 4 , with which a plurality of elementary streams have been Multiplexed) of which at least the encoded video data have been multiplexed; 
   meta data (for example, Clip( ), shown in  FIG. 10 , stored in a file 00001.CLP shown in  FIG. 4 ) about the multiplexed data. 
   The meta data contains: 
   the permission information (for example, capture_enable_flag_Clip shown in  FIG. 10 ) representing whether the video data corresponding to the encoded video data multiplexed with the multiplexed data are permitted to be secondarily used. 
   In a data processing apparatus as set forth in claim  4 , 
   the record data further contains use information (for example, private_stream_ 2 _PES_payload( ) shown in  FIG. 45 ) immediately preceded by each of at least one decodable start point of the encoded video data of every access unit and used to decode the encoded video data. 
   The use information contains 
   the permission information (for example, capture_enable_ps2 shown in  FIG. 45 ) representing whether the video data corresponding to the encoded video data positioned between the use information itself and the next use information are permitted to be secondarily used. 
   In a data processing apparatus as set forth in claim  5 , 
   the record data further contains use information (for example, private_stream_ 2 _PES_payload( ) shown in  FIG. 45 ) immediately preceded by each of at least one decodable start point of encoded video data of every access unit and used to decode the encoded video data. 
   The use information contains the permission information (for example, capture_enable_flag_AU shown in  FIG. 46 ) representing whether the video data corresponding to the encoded video data positioned between the use information itself and the next use information are permitted to be secondarily used every access unit. 
   In a data processing apparatuses set forth in claim  6 , 
   the record data contain as the permission information: 
   first permission information (for example, capture_enable_flag_PlayList shown in  FIG. 5 ) representing whether the video data corresponding to the encoded video data having a first unit that is equal to or larger than the access unit are permitted to be secondarily used, and 
   second permission information (for example, capture_enable_flag_Clip shown in  FIG. 10 ) representing whether the video data corresponding to the encoded video data having a second unit that is equal to or larger than the access unit are permitted to be secondarily used. 
   A data processing apparatus as set forth in claim  7 , further comprising: 
   execution means (for example, a graphics process module  219 , shown in  FIG. 2A  and  FIG. 2B , that performs a process at step S 381  shown in  FIG. 44 ) for executing a process that displays a background or a screen saver using the video data captured by the capture means. 
   A data processing method as set forth in claim  8  is a data processing method for a data processing apparatus that processes record data recorded on a data recording medium, 
   the record data containing: 
   encoded video data composed of video data that have been encoded every a predetermined unit that is an access unit, and 
   permission information (for example, capture_enable_flag_PlayList shown in  FIG. 5 , capture_enable_flag_Clip shown in  FIG. 10 , capture_enable_ps2 shown in  FIG. 45 , or capture_enable_flag_AU shown in  FIG. 46 ) representing whether video data corresponding to encoded video data equal to or larger than the access unit are permitted to be secondarily used in the data processing apparatus, 
   the data processing method comprising the steps of: 
   obtaining the permission information about the video data that are being reproduced (for example, at step S 372  shown in  FIG. 44 ); 
   determining whether the video data that are being reproduced have been permitted to be secondarily used corresponding to the permission information (for example, at step S 373  shown in  FIG. 44 ); and 
   capturing the video data that are being reproduced when it has been determined at the determination step that the video data that are being reproduced have been permitted to be secondarily used; (for example, at step S 376  shown in  FIG. 44 ). 
   A program as set forth in claim  9  and a program recorded on a program recording medium as set forth in claim  10  are a program that causes a computer to perform a data process for record data recorded on a data recording medium, 
   the record data containing: 
   encoded video data composed of video data that have been encoded every a predetermined unit that is an access unit, and 
   permission information (for example, capture_enable_flag_PlayList shown in  FIG. 5 , capture_enable_flag_Clip shown in  FIG. 10 , capture_enable_ps2 shown in  FIG. 45 , or capture_enable_flag_AU shown in  FIG. 46 ) representing whether video data corresponding to encoded video data equal to or larger than the access unit are permitted to be secondarily used in the computer, 
   the program comprising the steps of: 
   obtaining the permission information about the video data that are being reproduced (for example, at step S 372  shown in  FIG. 44 ); 
   determining whether the video data that are being reproduced have been permitted to be secondarily used corresponding to the permission information (for example, at step S 373  shown in  FIG. 44 ); and 
   capturing the video data that are being reproduced when it has been determined at the determination step that the video data that are being reproduced have been permitted to be secondarily used (for example, at step S 376  shown in  FIG. 44 ). 
   A data recording medium as set forth in claim  11  is a data recording medium on which record data have been recorded, the record data being processed by a data processing apparatus, 
   the record data containing: 
   encoded video data composed of video data that have been encoded every a predetermined unit that is an access unit, and 
   permission information (for example, capture_enable_flag_PlayList shown in  FIG. 5 , capture_enable_flag_Clip shown in  FIG. 10 , capture_enable_ps2 shown in  FIG. 45 , or capture_enable_flag_AU shown in  FIG. 46 ) representing whether video data corresponding to encoded video data equal to or larger than the access unit are permitted to be secondarily used in the data processing apparatus. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a block diagram showing an example of the structure of hardware of a disc device according to an embodiment of the present invention; 
       FIG. 2A  and  FIG. 2B  are block diagrams showing an example of the structure of a software module group that a CPU  112  executes; 
       FIG. 3  is a block diagram showing an example of the structure of a buffer control module  215 ; 
       FIG. 4  is a schematic diagram showing an example of the structure of directories of a disc  101 ; 
       FIG. 5  is a schematic diagram showing the syntax of a file “PLAYLIST.DAT”; 
       FIG. 6  is a schematic diagram showing the syntax of PlayItem( ); 
       FIG. 7  is a schematic diagram showing the syntax of PlayListMark( ); 
       FIG. 8  is a schematic diagram showing the relationship of the value of mark_type and the type of Mark( ); 
       FIG. 9  is a schematic diagram showing the relationship of PlayList( ), PlayItem( ), clips, and program streams stored in a clip stream file; 
       FIG. 10  is a schematic diagram showing the syntax of a clip information file Clip( ); 
       FIG. 11  is a schematic diagram showing the relationship of stream_id, private_stream_id, and elementary streams identified thereby; 
       FIG. 12  is a schematic diagram showing the syntax of StaticInfo( ); 
       FIG. 13  is a schematic diagram showing the syntax of DynamicInfo( ); 
       FIG. 14  is a schematic diagram showing the syntax of EP_map( ); 
       FIG. 15A  and  FIG. 15B  are schematic diagrams showing the syntax of a program stream, a program stream pack, and a program stream pack header of the MPEG-2 system; 
       FIG. 16A  and  FIG. 16B  are schematic diagrams showing the syntax of a PES packet of the MPEG-2 system; 
       FIG. 17A ,  FIG. 17B  and  FIG. 17C  are schematic diagrams showing the continued part of the syntax of the PES packet of the MPEG-2 system; 
       FIG. 18A  and  FIG. 18B  are schematic diagrams showing the continued part of the syntax of the PES packet of the MPEG-2 system; 
       FIG. 19A  and  FIG. 19B  are schematic diagrams showing the relationship of the value of stream_id of PES_packet( ) and the attribute (type) of an elementary stream of the MPEG-2 system; 
       FIG. 20  is a schematic diagram showing stream_id that the disc device uses; 
       FIG. 21  is a schematic diagram showing the syntax of private_stream 1 _PES_payload( ); 
       FIG. 22  is a schematic diagram showing the relationship of the value of private_stream_id and the attribute of an elementary stream stored in private_payload( ); 
       FIG. 23  is a schematic diagram showing the syntax of private_stream 2 _PES_payload( ); 
       FIG. 24  is a schematic diagram showing the syntax of au_information( ); 
       FIG. 25  is a schematic diagram showing a specific example of a file “PLAYLIST.DAT”; 
       FIG. 26A  and  FIG. 26B  are schematic diagrams showing specific examples of clip information files “00001.CLP,” “00002.CLP,” and “00003.CLP”; 
       FIG. 27  is a schematic diagram showing a specific example of EP_map( ) of a clip information file “00001.CLP”: 
       FIG. 28  is a schematic diagram showing specific examples of PlayListMark( )&#39;s of PlayList#0 and PlayList#1; 
       FIG. 29  is a flow chart describing a pre-reproduction process; 
       FIG. 30  is a flow chart describing a reproduction process; 
       FIG. 31  is a flow chart describing a PlayItem change process; 
       FIG. 32  is a flow chart describing a time code display process; 
       FIG. 33  is a flow chart describing a stream change process; 
       FIG. 34  is a flow chart describing a process of a buffer control module  215 ; 
       FIG. 35  is a flow chart describing the process of the buffer control module  215 ; 
       FIG. 36  is a flow chart describing a video stream read process; 
       FIG. 37  is a flow chart describing an audio stream read process; 
       FIG. 38  is a flow chart describing a subtitle stream read process; 
       FIG. 39  is a flow chart describing a re-synchronization process; 
       FIG. 40  is a flow chart describing a mark process; 
       FIG. 41  is a flow chart describing an output attribute control process; 
       FIG. 42  is a schematic diagram showing a specific example of a set of pts_change_point and DynamicInfo( ) described in a clip information file “00003.CLP”; 
       FIG. 43  is a flow chart describing a subtitle display control process; 
       FIG. 44  is a flow chart describing a capture control process and a background/screen saver process; 
       FIG. 45  is a schematic diagram showing other syntax of private_stream 2 _PES_payload( ); and 
       FIG. 46  is a schematic diagram showing other syntax of au_information( ). 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Next, with reference to the accompanying drawings, embodiments of the present invention will be described. 
   [Hardware Structure] 
     FIG. 1  is a block diagram showing an example of the structure of hardware of a disc device according to an embodiment of the present invention. 
   The disc device shown in  FIG. 1  can be applied to for example a disc player, a game device, a car navigation system, and so forth. 
   In the disc device shown in  FIG. 1 , a disc  101  is an optical disc such as a DVD, a magneto-optical disc, a magnetic disc, or the like. Content data such as video data, audio data, and subtitle data and additional data necessary to reproduce those data are recorded on the disc  101 . 
   When necessary, data recorded on the disc  101  (referred to as record data) include a program that can be executed by a computer. According to the embodiment of the present invention, as a recording medium, the disc  101  that is a disc-shaped recording medium is used. Alternatively, the recording medium may be for example a semiconductor memory or a tape-shaped recording medium. Data that are read from a disc at a remote location may be transmitted and input to the disc device shown in  FIG. 1 . In other words, data can be read from the disc  101  by another device connected to the disc device. The data that are read by the other device can be received and processed by the disc device. In addition, the disc device can receive data from a server or the like that stores data similar to those recorded on the disc  101  through a network such as the Internet and process the received data. In addition, the disc device can also receive data from another device such as a server or the like, record the received data to the disc  101 , and then process the data recorded to the disc  101 . 
   The disc  101  can be loaded and unloaded to and from a disc drive  102 . The disc drive  102  has a build-in interface (not shown). The disc drive  102  is connected to a drive interface  114  through the built-in interface. The disc drive  102  drives the disc  101 , reads data from the disc  101  corresponding to for example a read command, and supplies the data to the drive interface  114 . 
   Connected to a bus  111  are a central processing unit (CPU)  112 , a memory  113 , a drive interface  114 , an input interface  115 , a video decoder  116 , an audio decoder  117 , a video output interface  118 , and an audio output interface  119 . 
   The CPU  112  and the memory  113  compose a computer system. In other words, the CPU  112  executes a software module group that is a program stored in the memory  113  to control the entire disc device and perform various processes that will be described later. The memory  113  also stores the software module group that the CPU  112  executes. In addition, the memory  113  temporarily stores data necessary to operate the CPU  112 . The memory  113  can be composed of only a non-volatile memory or a combination of a volatile memory and a non-volatile memory. When the disc device shown in  FIG. 1  has a hard disk to which the software module group is recorded (installed) that the CPU  112  executes, the memory  113  can be composed of only a non-volatile memory. 
   The program (software module group) that the CPU  112  executes can be pre-recorded (stored) in the memory  113  as a recording medium that is built in the disc device. 
   Alternatively, the program can be temporarily or permanently stored (recorded) to the disc  101  or a removable recording medium such as a flexible disc, a compact disc read-only memory (CD-ROM), a magneto-optical (MO) disc, a magnetic disc, or a memory card. The removable recording medium may be provided as so-called package software. 
   The program can be pre-stored in the memory  113  or installed from an above-described removable recording medium to the disc device. Alternatively, the program may be wirelessly transferred from a download site to the disc device through a satellite for a digital satellite broadcast or non-wirelessly transferred to the disc device through a local area network (LAN) or a network such as the Internet. The disc device receives the program through the input interface  115  and installs the program to the built-in memory  113 . 
   The program may be executed by one CPU or distributively executed by a plurality of CPUs. 
   The drive interface  114  controls the disc drive  102  under the control of the CPU  112 . The disc drive  102  supplies data that are read from the disc  101  to the CPU  112 , the memory  113 , the video decoder  116 , and the audio decoder  117  through the bus  111 . 
   The input interface  115  receives signals corresponding to user&#39;s operations of keys (buttons) and a remote controller (not shown) and supplies the signals to the CPU  112  through the bus  111 . The input interface  115  also functions as a communication interface for a modem (including an asymmetric digital subscriber line (ADSL) modem), a network interface card (NIC), or the like. 
   The video decoder  116  decodes encoded video data that have been read from the disc  101  by the disc drive  102  and supplied to the video decoder  116  through the drive interface  114  and the bus  111  and supplies the decoded video data to the CPU  112  and the video output interface  118  through the bus  111 . 
   The audio decoder  117  decodes encoded audio data that have been read from the disc  101  by the disc drive  102  and supplied to the audio decoder  117  through the drive interface  114  and the bus  111 and supplies the encoded audio data to the CPU  112  and the audio output interface  119  through the bus  111 . 
   The video output interface  118  performs a predetermined process for the video data supplied through the bus  111  and outputs the processed video data from a video output terminal  120 . The audio output interface  119  performs a predetermined process for the audio data supplied through the bus  111  and outputs the processed audio data from an audio output terminal  121 . 
   The video output terminal  120  is connected to a video output device such as a cathode ray tube (CRT) or a liquid crystal panel (not shown). Thus, the video data that are output from the video output terminal  120  are supplied to the video output device and displayed thereby. The audio output terminal  121  is connected to audio output devices such as a speaker and an amplifier (not shown). Thus, the audio data that are output from the audio output terminal  121  are supplied to the audio output devices and output thereby. 
   Video data and audio data can be wirelessly or non-wirelessly supplied from the disc device to the video output device and the audio output devices. 
   [Structure of Software Module Group] 
     FIG. 2A  and  FIG. 2B  show an example of the structure of the software module group that the CPU  112  shown in  FIG. 1  executes. 
   The software module group that the CPU  112  executes is mainly categorized as an operating system (OS)  201  and a video content reproduction program  210  as an application program. 
   [Operating System  201 ] 
   When the disc device is turned on, the operating system  201  gets started (the CPU  112  executes the operating system  201 ), performs predetermined processes such as initial settings, and calls the video content reproduction program  210 , which is an application program. 
   The operating system  201  provides infrastructural services such as a file read service to the video content reproduction program  210 . In other words, the operating system  201  provides a service that operates the disc drive  102  through the drive interface  114  against a file read request received from the video content reproduction program  210 , reads data from the disc  101 , and supplies the data to the video content reproduction program  210 . In addition, the operating system  201  also interprets the file system. 
   The operating system  201  has a function of a multitask process. In other words, the operating system  201  can simultaneously (apparently) operate a plurality of software modules on time sharing basis. In other words, although the video content reproduction program  210  is composed of several software modules, they can be operated in parallel. 
   [Video Content Reproduction Program  210 ] 
   The video content reproduction program  210  is composed of a script control module  211 , a player control module  212 , a content data supply module  213 , a decode control module  214 , a buffer control module  215 , a video decoder control module  216 , an audio decoder control module  217 , a subtitle decoder control module  218 , a graphics process module  219 , a video output module  220 , and an audio output module  221 . 
   The video content reproduction program  210  is software that performs a key role of the reproduction of data from the disc  101 . When the disc  101  is loaded (inserted) into the disc drive  102 , the video content reproduction program  210  checks whether the disc  101  is a disc on which a content has been recorded in a predetermined format (that will be described later). The video content reproduction program  210  reads a script file (that will be described later) from the disc  101 , executes the script, reads a meta data (database information) file necessary to reproduce a content from the disc  101 , and controls the reproduction of the content corresponding to the meta data. 
   Next, the software module that composes the video content reproduction program  210  shown in  FIG. 2A  and  FIG. 2B  will be described. In  FIG. 2A  and  FIG. 2B , in general, solid line arrow marks represent content data, whereas dotted line arrow marks represent control data. 
   [Script Control Module  211 ] 
   The script control-module  211  interprets and executes a script program (script) recorded on the disc  101 . A script program can describe operations such as “operate the graphics process module  219  to create an image such as a menu and display it,” “change a menu display corresponding to a signal supplied from a user interface (UI) such as a remote controller (for example, to move a cursor on a menu),” and “to control the player control module  212 .” 
   [Player Control Module  212 ] 
   The player control-module  212  references meta data (database information) and so forth recorded on the disc  101  to control the reproduction of a content recorded on the disc  101 . In other words, the player control module  212  analyzes PlayList( ) and Clip( ) recorded on the disc  101  and controls the content data supply module  213 , the decode control module  214 , and the buffer control module  215  corresponding to the analyzed results. In addition, the player control module  212  performs a stream change control that changes a stream to be reproduced corresponding to commands received from the script control module  211  and the input interface  115  as will be described later. In addition, the decode control module  214  obtains a time from the decode control module  214 , displays the time, and performs a process for a mark (Mark( )) (that will be described later). 
   [Content Data Supply Module  213 ] 
   The content data supply module  213  requests the operating system  201  to read content data, meta data, and so forth from the disc  101  under the control of the player control module  212  or corresponding to the amount of data stored in the buffer control module  215 . 
   The meta data and so forth that the operating system  201  has read from the disc  101  corresponding to the request received from the content data supply module  213  are supplied to predetermined modules. On the other hand, the content data that the operating system  201  has read from the disc  101  corresponding to the request received from the content data supply module  213  are supplied to the buffer control module  215 . 
   [Decode Control Module  214 ] 
   The decode control module  214  controls the operations of the video decoder control module  216 , the audio decoder control module  217 , and the subtitle decoder control module  218  under the control of the play control module  212 . The decode control module  214  has a time count portion  214 A that counts a time. The decode control module  214  manages the synchronization of an output of video data that are output under the control the video decoder control module  216  and an output of data that are synchronized with the video data. In this case, an output of data to be synchronized with an output of video data is audio data that are output under the control of the audio decoder control module  217 . 
   [Buffer Control Module  215 ] 
   The buffer control module  215  has a buffer  215 A as a part of a storage area of the memory  113  shown in  FIG. 1 . The content data supply module  213  temporarily stores content data read from the disc  101  to the buffer  215 A corresponding to a request received from the operating system  201 . 
   In addition, the buffer control module  215  supplies data stored in the buffer  215 A to the video decoder control module  216 , the audio decoder control module  217 , or the subtitle decoder control module  218  corresponding to a request received from the video decoder control module  216 , the audio decoder control module  217 , or the subtitle decoder control module  218 , respectively. 
   In other words, the buffer control module  215  has a video read function portion  233 , an audio read function portion  234 , and a subtitle read function portion  235  that will be described later in  FIG. 3 . The video read function portion  233  of the buffer control module  215  processes a data request received from the video decoder control module  216  to supply data stored in the buffer  215 A to the video decoder control module  216 . Likewise, the audio read function portion  234  in the buffer control module  215  processes a request received from the audio decoder control module  217  to supply data stored in the buffer  215 A to the audio decoder control module  217 . The video read function portion  233  in the buffer control module  215  processes a request received from the subtitle decoder control module  218  to supply data stored in the buffer  215 A to the subtitle decoder control module  218 . 
   [Video Decoder Control Module  216 ] 
   The video decoder control module  216  operates the video read function portion  233  ( FIG. 3 ) of the buffer control module  215  to read encoded video data one video access unit at a time from the buffer  215 A of the buffer control module  215  and supply the video data to the video decoder  116  shown in  FIG. 1 . In addition, the video decoder control module  216  controls the video decoder  116  to decode data one video access unit at a time. In addition, the video decoder control module  216  supplies video data decoded by the video decoder  116  to the graphics process module  219 . 
   One video access unit is for example one picture (one frame or one field) of video data. 
   [Audio Decoder Control Module  217 ] 
   The audio decoder control module  217  operates an audio read function portion  234  ( FIG. 3 ) of the buffer control module  215  to read encoded audio data one audio access unit at a time from the buffer  215 A of the buffer control module  215  and supplies the encoded audio data to the audio decoder  117  shown in  FIG. 1 . The audio decoder control module  217  controls the audio decoder  117  to decode the encoded audio data one audio access unit at a time. In addition, the audio decoder control module  217  supplies audio data decoded by the audio decoder  117  to the audio output module  221 . 
   One audio access unit is a predetermined amount of audio data (for example, an amount of data that are output in synchronization with one picture). According to this embodiment, it is assumed that one audio access unit is a predetermined fixed length. 
   [Subtitle Decoder Control Module  218 ] 
   The subtitle decoder control module  218  operates the subtitle read function portion  235  ( FIG. 3 ) of the buffer control module  215  to read encoded subtitle data one subtitle access unit at a time from the buffer  215 A of the buffer control module  215 . In addition, the subtitle decoder control module  218  has subtitle decode software (not shown). The subtitle decode software decodes data read from the buffer  215 A. The subtitle decoder control module  218  supplies the decoded subtitle data (image data of a subtitle) to the graphics process module  219 . 
   One subtitle access unit is a predetermined amount of subtitle data (for example, an amount of data that are output in synchronization with one picture). According to this embodiment, it is assumed that the size of one subtitle access unit is described at the beginning thereof. 
   [Graphics Process Module  219 ] 
   The graphics process module  219  enlarges or reduces subtitle data received from the subtitle decoder control module  218  under the control (corresponding to a command) of the player control module  212  and adds (overlays) the enlarged or reduced subtitle data to video data received from the video decoder control module  216 . The graphics process module  219  enlarges or reduces the size (image frame) of the video data that have been added to the subtitle data so that the frame size of the added (overlaid) video data matches the screen of the video output device connected to the video output terminal  120  shown in  FIG. 1 . The added (overlaid) video data are output to the video output module  220 . 
   In addition, the graphics process module  219  generates a menu, a message, and so forth corresponding to commands (under the control) of the script control module  211  and the player control module  212  and overlays the menu, message, and so forth with the output video data. 
   In addition, the graphics process module  219  converts the aspect ratio of video data that are output to the video output module  220  corresponding to the aspect ratio of the video output device connected to the video output terminal  120  shown in  FIG. 1  and information that represents the aspect ratio of the video data recorded on the disc  101 . 
   In other words, when the aspect ratio of the video output device is 16:9, if information that represents the aspect ratio of video data is 4:3, the graphics process module  219  performs a squeeze (reduction) process for video data that are output to the video output module  220  in the lateral (horizontal) direction, causes the left and right ends of the video data to be black, and outputs the resultant video data. When the aspect ratio of the video output device is 4:3, if information that represents the aspect ratio of video data is 16:9, the graphics process module  219  performs a squeeze (reduction) process for video data that are output to the video output module  220  in the longitudinal (vertical) direction, causes the upper and lower ends of the video data to be black, and outputs the resultant video data. 
   When the aspect ratio of the video output device and the aspect ratio that the information represents for the video data are the same, for example 4:3 or 16:9, the graphics process module  219  outputs non-squeezed video data to the video output module  220 . 
   In addition, the graphics process module  219  captures video data that are being processed corresponding to a request received from for example the player control module  212 . Moreover, the graphics process module  219  stores the captured video data or supplies the video data to the player control module  212 . 
   [Video Output Module  220 ] 
   The video output module  220  exclusively occupies a part of the memory  113  shown in  FIG. 1  as a first-in first-out (FIFO)  220 A (buffer) and temporarily stores video data received from the graphics process module  219 . In addition, the video output module  220  frequently reads video data from the FIFO  220 A and outputs the video data to the video output terminal  120  ( FIG. 1 ). 
   [Audio Output Module  221 ] 
   The audio output module  221  exclusively occupies a part of the memory  113  shown in  FIG. 1  as a FIFO  221 A (buffer) and temporarily stores audio data received from the audio decoder control module  217  (audio decoder  117 ). In addition, the audio output module  221  frequently reads audio data from the FIFO  221 A and outputs the audio data to the audio output terminal  121  ( FIG. 1 ). 
   In addition, when audio data received from the audio decoder control module  217  are dual (bilingual) mode audio data that have left and right channels of “main audio” data and “sub audio” data, the audio output module  221  outputs the audio data received from the audio decoder control module  217  to the audio output terminal  121  corresponding to a pre-designated audio output mode. 
   In other words, if the “main sound” has been designated as an audio output mode, the audio output module  221  copies the left channel of audio data received from the audio decoder control module  217  as the right channel of audio data and outputs the left and right channel of audio data (“main audio” data) to the audio output terminal  121 . If “sub audio” has been designated as an audio output mode, the audio output module  221  copies the right channel of audio data received from the audio decoder control module  217  as the left channel and outputs the left and right channel (“sub audio” data) to the audio output terminal  121 . If both “main and sub audios” have been designated as an audio output mode, the audio output module  221  directly outputs audio data received from the audio decoder control module  217  to the audio output terminal  121 . 
   If audio data received from the audio decoder control module  217  are stereo mode audio data, the audio output module  221  directly outputs the audio data received from the audio decoder control module  217  to the audio output terminal  121  regardless of what audio output mode has been designated. 
   The user can interactively designate an audio output mode on a screen for a menu generated by the video content reproduction program  210  with the remote controller. 
   [Structure of Buffer Control Module  215 ] 
     FIG. 3  shows an example of the structure of the buffer control module  215  shown in  FIG. 2A  and  FIG. 2B . 
   The buffer control module  215  exclusively uses a part of the memory  113  shown in  FIG. 1  as the buffer  215 A and temporarily stores data that are read from the disc  101  to the buffer  215 A. In addition, the buffer control module  215  reads data from the buffer  215 A and supplies the data to the video decoder control module  216 , the audio decoder control module  217 , and the subtitle decoder control module  218  shown in  FIG. 2A  and  FIG. 2B . 
   Besides the buffer  215 A, the buffer control module  215  has a data start pointer storage portion  231  and a data write pointer storage portion  232  that are part of the memory  113 . In addition, the buffer control module  215  has a video read function portion  233 , an audio read function portion  234 , and a subtitle read function portion  235  as internal modules. 
   The buffer  215 A is for example a ring buffer that successively stores data that are read from the disc  101 . After the buffer  215 A reads data for the storage amount thereof, the buffer  215 A stores data in so-called endless loop so that the buffer  215 A overwrites the newest data on the oldest data. 
   The data start pointer storage portion  231  stores a data start pointer that represents the position (address) of the oldest data that are not read from the buffer  215 A in the data stored in the buffer  215 A. 
   The data write pointer storage portion  232  stores a pointer that represents the position of the newest data that are read from the disc  101  in the buffer  215 A. 
   Whenever data that are read from the disc  101  are stored to the buffer  215 A, the position that the data write pointer represents is updated in the clockwise direction shown in  FIG. 3 . Whenever data are read from the buffer  215 A, the position that the data start pointer represents is updated in the clockwise direction shown in  FIG. 3 . Thus, valid data stored in the buffer  215 A are from the position that the data start pointer represents to the position that the data write pointer represents in the clockwise direction shown in  FIG. 3. 36 . 
   The video read function portion  233  reads a video stream (an elementary stream of video data) from the buffer  215 A corresponding to a request received from the video decoder control module  216  shown in  FIG. 2A  and  FIG. 2B  and supplies the video stream to the video decoder control module  216 . The audio read function portion  234  reads an audio stream (an elementary stream of audio data) from the buffer  215 A corresponding to a request received from the audio decoder control module  217  and supplies the audio stream to the audio decoder control module  217 . Likewise, the subtitle read function portion  235  reads a subtitle stream (an elementary stream of subtitle data) from the buffer  215 A corresponding to a request received from the subtitle decoder control module  218  and supplies the subtitle stream to the subtitle decoder control module  218 . 
   In other words, a program stream corresponding to for example the Moving Picture Experts Group (MPEG) 2 standard has been recorded on the disc  101 , the program stream being referred to as MPEG2-system program stream. In the program stream, at least one elementary stream of a video stream, an audio stream, and a subtitle stream has been multiplexed on time division basis. The video read function portion  233  has a demultiplexing function for the program stream. The video read function portion  233  demultiplexes a video stream from a program stream stored in the buffer  215 A and reads the video stream. 
   Likewise, the audio read function portion  234  has a demultiplexing function for a program stream. The audio read function portion  234  demultiplexes an audio stream from a program stream stored in the buffer  215 A and reads the audio stream. Likewise, the subtitle read function portion  235  has a demultiplexing function for a program stream. The subtitle read function portion  235  demultiplexes a subtitle stream from a program stream stored in the buffer  215 A and reads the subtitle stream. 
   The video read function portion  233  has a video read pointer storage portion  241 , a stream_id register  242 , and an au_information( ) register  243  that are part of the memory  113  shown in  FIG. 1 . 
   The video read pointer storage portion  241  stores a video read pointer that represents the position (address) of a video stream in the buffer  215 A. The video read function portion  233  reads data as a video stream from the position of the video read pointer in the buffer  215 A. The stream_id register  242  stores stream_id that is used to analyze a program stream stored in the buffer  215 A and to identify a video stream that is read from the program stream. The au_information( ) register  243  stores au_information( ) that is data necessary to read (that is used to read) a video stream from the buffer  215 A. 
   The audio read function portion  234  has an audio read pointer storage portion- 251 , a stream_id register  252 , and a private_stream_id register  253  that are part of the memory  113  shown in  FIG. 1 . 
   The audio read pointer storage portion  251  stores an audio read pointer that represents the position (address) of an audio stream stored in the buffer  215 A. The audio read function portion. 234  reads data as an audio stream from the position of the audio read pointer in the buffer  215 A. The stream_id register  252  and the private_stream_id register  253  store stream_id and private_stream_id (that will be described later), respectively, used to analyze a program stream stored in the buffer  215 A and identify an audio stream that is read from the program stream. 
   The subtitle read function portion  235  has a subtitle read function flag storage portion  261 , a subtitle read pointer storage portion  262 , a stream_id register  263 , and a private_stream_id register  264  that are part of the memory  113  shown in  FIG. 1 . 
   The subtitle read function flag storage portion  261  stores a subtitle read function flag. When the subtitle read function flag stored in the subtitle read function flag storage portion  261  is for example “0,” the subtitle read function portion  235  does not operate. When the subtitle read function flag stored in the subtitle read function flag storage portion  261  is for example “1,” the subtitle read function portion  235  operates. 
   The subtitle read pointer storage portion  262  stores a subtitle read pointer that represents the position (address) of a subtitle stream stored in the buffer  215 A. The subtitle read function portion  235  reads data as a subtitle stream from the position of the subtitle read pointer in the buffer  215 A. The stream_id register  263  and the private_stream_id register  264  stores stream_id and private_stream_id (that will be described later), respectively, used to analyze a program stream stored in the buffer  215 A and identify a subtitle stream that is read from the program stream. 
   [Description of Data Format of Data Recorded on Disc  101 ] 
   Next, the data format of data recorded on the disc  101  will be described. 
     FIG. 4  schematically shows the structure of directories of the disc  101 . 
   A file system used for the disc  101  is for example one of those defined in the International Organization for Standardization (ISO) -9660 and the Universal Disk Format. Files of data recorded on the disc  101  are hierarchically managed in a directory structure. A file system that can be used for the disc  101  is not limited to these file systems. 
   In  FIG. 4 , there is a “VIDEO” directory under a root directory that represents the base of the file system. There are two directories that are a “CLIP” directory and a “STREAM” directory under the “VIDEO” directory. 
   Besides the two directories, which are the “CLIP” directory and the “STREAM” directory, there are two data files that are a “SCRIPT.DAT” file and a “PLAYLIST.DAT” file under the “VIDEO” directory. 
   The “SCRIPT.DAT” file is a script file that describes a script program. In other words, the “SCRIPT.DAT” file describes a script program that allows data on the disc  101  to be interactively reproduced. The script program stored in the “SCRIPT.DAT” file is interpreted and executed by the script control module  211  shown in  FIG. 2A  and  FIG. 2B . 
   The “PLAYLIST.DAT” file stores at least one play list (PlayList( ) that will be described later with reference to  FIG. 5 ). A play list describes the reproduction procedure of a content such as video data recorded on the disc  101 . 
   There is at least one clip information file under the “CLIP” directory. There is at least one clip stream file under the “STREAM” directory. In other words, there are three clip information files “00001.CLP,” “00002.CLP,” and “00003.CLP” under the “CLIP” directory. There are three clip stream files “00001.PS,” “00002.PS,” and “00003.PS” under the “STREAM” directory. 
   A clip stream file stores a program stream of which at least one stream of video data, audio data, and subtitle data have been compressed and encoded is multiplexed on time division basis. 
   A clip information file stores a (file) meta data about a clip stream for example characteristics thereof. 
   In other words, a clip stream file and a clip information file are correlated in the relationship of 1 to 1. In  FIG. 4 , a clip stream file is named corresponding to a naming rule of five-digit number+period+“PS,” whereas a clip information file is named corresponding to a naming rule of the same five-digit number as the corresponding clip stream+period+“CLP.” 
   Thus, a clip stream file and a clip information file can be identified by the extension of the file name (the right side of period). In addition, it can be determined whether a clip stream file and a clip information file are correlated with their file names other than their extensions (the left side portion of period). 
   Next, files recorded on the disc  101  will be described in detail. 
   [PLAYLIST.DAT] 
     FIG. 5  shows the internal structure of the “PLAYLIST.DAT” file under the “VIDEO” directory. 
   In  FIG. 5 , the “PLAYLIST.DAT” file has a “Syntax” field that describes the data structure of the “PLAYLIST.DAT” file; a “No. of bits” field that describes the bit length of each data entry in the “Syntax” field; and a “Mnemonic” field in which “bslbf” (bit string left bit first) and “uimsbf” (unsigned integer most significant bit first)” represent that a data entry in the “Syntax” field is shifted from the left bit and that a data entry in the “Syntax” field is an unsigned integer and shifted from the most significant bit. These conditions apply to other lists similar to  FIG. 5 . 
   The “PLAYLIST.DAT” file starts with name_length (8 bits) and name_string (255 bytes) that describe information such as the name (file name). 
   In other words, name_length represents the size of name_string immediately preceded thereby in bytes. name_string represents the name (file name) of the “PLAYLIST.DAT” file. 
   Bytes for name_length from the beginning of name_string are used as a valid name. When the value of name_length is 10, 10 bytes from the beginning of name_string are interpreted as a valid name. 
   name_string is followed by number_of_PlayLists (16 bits) number_of_PlayLists represents the number of PlayList( )&#39;s preceded by name_string. number_of_PlayLists is followed by PlayList( )&#39;s represented by number_of_PlayLists. 
   PlayList( ) is a play list that describes the reproduction procedure of a clip stream file recorded on the disc  101 . PlayList( ) has the following internal structure. 
   PlayList( ) starts with PlayList_data_length (32 bits). PlayList_data_length represents the size of PlayList( ). 
   PlayList_data_length is followed by reserved_for_word_alignment (15 bits) and capture_enable_flag_PlayList (1 bit) in succession. reserved_for_word_alignment of 15 bits is followed by capture_enable_flag_PlayList of 1 bit for a word alignment at the position of capture_enable_flag_PlayList to place it at the position of 16 bits capture_enable_flag_PlayList is a 1-bit flag that represents whether video data (video data that belong to PlayList( )) of a video stream reproduced corresponding to PlayList( ) is permitted to be secondarily used in the disc device that reproduces data from the disc  101 . When the value of capture_enable_flag_PlayList is for example 1 (0 or 1), it represents that video data that belong to PlayList( ) are permitted to be secondarily used. When the value of capture_enable_flag_PlayList is for example 0 (0 or 1), it represents that video data that belong to PlayList( ) are not permitted to be secondarily used (namely, prohibited from being secondarily used). 
   In  FIG. 5 , capture_enable_flag_PlayList is composed of one bit. Alternatively, capture_enable_flag_PlayList may be composed of a plurality of bits. In this case, video data that belong to PlayList( ) may be gradually permitted to be secondarily used. In other words, capture_enable_flag_PlayList may be composed of two bits. When the value of capture_enable_flag_PlayList is 00B (where B represents that the preceding number is a binary number), video data are prohibited from being secondarily used. When the value of capture_enable_flag_PlayList is 01B, video data that are reduced to a size of 64×64 pixels or smaller are permitted to be secondarily used. When the value of capture_enable_flag_PlayList is 10B, video data are permitted to be secondarily used without any size reduction. 
   A secondary use of video data may be restricted with respect to applications rather than sizes. In other words, when the value of capture_enable_flag_PlayList is 01B, only the video content reproduction program  210  ( FIG. 2A  and  FIG. 2B ) may be permitted to secondarily use the video data. When the value of capture_enable_flag_PlayList is 10B, any application including the video content reproduction program  210  in the disc device shown in  FIG. 1  may be permitted to secondarily use the video data. In this example, an application other than the video content reproduction program  210  in the disc device shown in  FIG. 1  that displays a wall paper (background) or a screen saver. 
   When capture_enable_flag_PlayList is composed of 2 bits, reserved_for_word_alignment followed thereby is composed of 14 bits for a word alignment. 
   Alternatively, with capture_enable_flag_PlayList, video data may be permitted to be secondarily used outside the disc device. In the case that with capture_enable_flag_PlayList, video data are permitted to be secondarily used outside the disc device, the video data are recorded to for example a recording medium that can be loaded into the disc device or that can be connected to the disc device, or transmitted (distributed) to another device through a network such as the Internet. In this case, information that represents the number of times video data can be recorded to the recording medium or the number of times video data can be transmitted (distributed) can be added to the video data. 
   capture_enable_flag_PlayList is followed by PlayList_name_length (8 bits) and PlayList_name_string (255 bytes) in succession. PlayList_name_length represents the size of PlayList_name_string in bytes. PlayList_name_string represents the name of PlayList( ). 
   PlayList_name_string is followed by namber_of_PlayItems (16 bits). number_of_PlayItems represents that number of PlayItem( )&#39;s. 
   number_of_PlayItems is followed by PlayItem( )&#39;s represented by number_of_PlayItems. 
   One PlayList( ) can describe the reproduction procedure of a content in the unit of PlayItem( ). 
   Identification (ID) codes that are unique in PlayList( ) are added to PlayItem( )&#39;s represented by number_of_PlayItems. In other words, the first PlayItem( ) of PlayList( ) is identified by number 0. The other PlayItem( )&#39;s are successively identified by numbers 1, 2, . . . , and so forth. 
   PlayItem( )&#39;s represented by number_of_PlayItems are followed by one PlayListMark( ). PlayListMark( ) is a set of Mark( )&#39;s as marks on the time axis of the reproduction corresponding to PlayList( ). PlayListMark( ) will be described later in detail with reference to  FIG. 7 . 
   [Description of PlayItem( )] 
     FIG. 6  shows the internal structure of PlayItem( ) contained in PlayList( ) shown in  FIG. 5 . 
   PlayItem( ) starts with length (16 bits). length represents the size of PlayItem( ), including the size of length. 
   length is followed by Clip_Information_file_name length (16 bits) and Clip_Information_file name (variable length) in succession. Clip_Information file_name_length represents the size of Clip_Information_file_name in bytes. Clip_Information_file_name represents the file name of a clip information file (a file having an extension CLP shown in  FIG. 4 ) corresponding to a clip stream file (a file having an extension PS shown in  FIG. 4 ) reproduced by PlayItem( ). Corresponding to the foregoing naming rules for clip stream files and clip information files, the file name of a clip information file reproduced by PlayItem( ) is recognized with Clip_Information_file_name and the clip stream file can be identified. 
   Clip_Information_file_name is followed by IN_time (32 bits) and OUT_time (32 bits) in succession. 
   IN_time and OUT_time are time information that represent the reproduction start position and the reproduction end position of a clip stream file identified by Clip_Information_file_name. 
   IN_time can designate a middle position (including the beginning) of a clip stream file as a reproduction start position. OUT_time can designate a middle position (including the end) of a clip stream file as a reproduction end position. 
   PlayItem( ) reproduces a content from IN_time to OUT_time of a clip stream file identified by Clip_Information_file_name. A content reproduced by PlayItem( ) is sometimes referred to as a clip. 
   [Description of PlayListMark( )] 
     FIG. 7  shows the internal structure of PlayListMark( ) contained in PlayList( ) shown in  FIG. 5 . 
   As described above, PlayListMark( ) is a set of Mark( )&#39;s that are marks on the time axis of the reproduction corresponding to PlayList( ) shown in  FIG. 5 . The number of Mark( )&#39;s is 0 or larger. One Mark( ) has at least time information that represents one time (position) on the time axis of the reproduction performed corresponding to PlayList( ), type information that represents the type of Mark( ), and argument information of an argument of an event when type information represents the type of an event that takes place. 
   In other words, PlayListMark( ) starts with length (32 bits). length represents the size of PlayListMark( ), including the size of length. 
   length is followed by number_of_PlayList marks (16 bits). number_of_PlayList marks represents the number of Mark( )&#39;s that are preceded by number_of_PlayList_marks. number_of_PlayList marks is followed by Mark( )&#39;s represented by number_of_PlayList_marks. 
   Mark( ) starts with mark type (8 bits). mark_type is the foregoing type information and represents the type of Mark( ) to which mark type belongs. 
   According to this embodiment, Mark( ) has three types of for example chapter, index, and event. 
   When the type of Mark( ) is chapter (sometimes referred to as a chapter mark), it is a mark of the start position of a chapter that is a searching unit as a division of PlayList( ). When the type of Mark( ) is index (sometimes referred to as an index mark), it is a mark of the start position of an index that is a subdivide unit of a chapter. When the type of Mark( ) is event (sometimes referred to as an event mark), Mark( ) is a mark of a position at which an event takes place while a content is being reproduced corresponding to PlayList( ). The script control module  211  is informed that an event corresponding to an event mark has taken place. 
     FIG. 8  shows the relationship between the value of mark_type and the type of Mark( ). In  FIG. 8 , mark_type of a chapter mark is 1: mark_type of an index mark is 2; and mark type of an event mark is 3. In  FIG. 8 , other values represented by 8 bits of mark_type, namely 0 and 4 to 255, are reserved for future extension. 
   In  FIG. 7 , mark_type is followed by mark_name_length (8 bits). Mark( ) ends with mark_name_string. mark_name_length and mark_name_string are used to describe the name of Mark( ). mark_name_length represents the valid size of mark_name_string. mark_name_string represents the name of Mark( ). Thus, bytes for mark_name_length from the beginning of mark_name_string represent a valid name of Mark( ). 
   mark_name_length is followed by four elements ref_to_PlayItem_id (16 bits), mark_time_stamp (32 bits), entry_ES_stream_id (8 bits), and entry_ES_private_stream_id (8 bits) that correlate Mark( ) defined in PlayList( ) with a clip stream file. 
   ref_to_PlayItem_id describes an ID as a sequential number assigned to PlayItem( ) to which Mark( ) belongs. ref_to_PlayItem_id identifies PlayItem( ) ( FIG. 6 ) to which Mark( ) belongs. Thus, as was described in  FIG. 6 , a clip information file and a clip stream file are identified. 
   mark_time_stamp represents the position (time) that Mark( ) represents in a clip stream file identified by ref_to_PlayItem_id. 
     FIG. 9  shows the relationship of PlayList( ), PlayItem( ), clips, and program streams stored in a clip stream file. 
   In  FIG. 9 , PlayList( ) is composed of three PlayItem( )&#39;s that are sequentially numbered as ID# 0 , ID# 1 , and ID# 2 . In the following description, PlayItem( ) numbered as ID#i is denoted by PlayItem#i. 
   In  FIG. 9 , clips as contents reproduced by PlayItem# 0 , PlayItem# 1 , and PlayItem# 2  are denoted by clip A, clip B, and clip C, respectively. 
   An entity of a clip is from IN_time to OUT_time of a program stream stored in a clip stream file identified by Clip_Information_file_name of PlayItem( ) shown in  FIG. 6  (also identified by a clip information file). In  FIG. 9 , program streams as entities of clip A, clip B and clip C are represented as program stream A, program stream B, and program stream C, respectively. 
   In  FIG. 9 , in Mark( ) as a mark of position (time) t 0  on the time axis of the reproduction corresponding to PlayList( ), ref_to_PlayItem_id and mark_time_stamp are described as follows. 
   In  FIG. 9 , since time t 0  is a time at which PlayItem# 1  is reproduced, ref_to_PlayItem_id describes 1 as the ID of PlayItem# 1 . Since at time t 0  program stream B as the entity of clip B is reproduced, mark_time_stamp describes a time of a clip stream file that stores program stream B corresponding to time t 0 . 
   In  FIG. 7 , when Mark( ) is correlated with a particular elementary stream, entry_ES_stream_id and entry_ES_private_stream_id are used to identify the elementary stream. In other words, entry_ES_stream_id describes stream_id of the elementary stream that is correlated with Mark( ) (PES_packet( ) that contains the elementary stream, PES_packet( ) will be described later with referenced to  FIG. 16A  and  FIG. 16B  to  FIG. 18A  and  FIG. 18B ). On the other hand, entry_ES_private_stream_id describes private_stream_id of the elementary stream correlated with Mark( ) (private_header( ) of private_stream 1 _PES_payload( ) that contains the elementary stream, private_header( ) will be described later with reference to  FIG. 21 ). 
   When video stream# 1  of a clip of which video stream# 1  and video stream# 2  have been multiplexed is reproduced and when a chapter time needs to be changed while video stream# 2  is being reproduced, stream_id and private_stream_id of video stream# 1  are described in entry_ES_stream_id and entry_ES_private_stream_id of Mark( ) at a chapter mark time while video stream# 2  is being reproduced.: 
   entry_ES_stream_id and entry_ES_private_stream_id of Mark( ) that is not correlated with a particular elementary stream are for example 0. 
   entry_ES_private_stream_id is followed by mark_data (32 bits). When Mark( ) is an event mark, mark_data is argument information as an argument of an event that takes place with the event mark. When Mark( ) is a chapter mark or an index mark, mark_data can be used as a chapter number or an index number that the chapter mark or the index mark represents. 
   [Description of Clip( )] 
   Next, the internal structure of a clip information file having-an extension of CLP and that is stored in the “CLIP” directory shown in  FIG. 4  will be described. 
   In  FIG. 4 , there are three clip information files “00001.CLP,” “00002.CLP,” and “00003.CLP” under the “CLIP” directory. These clip information files contain meta data that represent characteristics of clip stream files. “00001.PS,” “00002.PS,” and “00003.PS” stored in the “STREAM” directory. 
     FIG. 10  shows the internal structure of the clip information file Clip( ). 
   The clip information file Clip( ) starts with presentation_start_time and presentation_end_time (32 bits each) presentation_start_time and presentation_end_time represent the start time and end time of (a program stream stored in) a clip stream file corresponding to the clip information file Clip( ). The time of the clip stream file is described as a multiple of 90 kHz used as the time of the MPEG2-System. 
   presentation_end_time is followed by reserved_for_word_alignment (7 bits) and capture_enable_flag_Clip (1 bit). reserved_for_word_alignment of 7 bits is used for a word alignment. capture_enable_flag_Clip is a flag that represents whether video data are permitted to be secondarily used like capture_enable_flag_PlayList shown in  FIG. 5 . 
   However, capture_enable_flag_PlayList shown in  FIG. 5  represents whether video data (that belong to PlayList( )) corresponding to a video stream reproduced corresponding to PlayList( ) is permitted to be secondarily used. In contrast, capture_enable_flag_Clip shown in  FIG. 10  represents whether video data corresponding to a video stream (an elementary stream of video data) stored in a clip stream file corresponding to the clip information file Clip( ) is permitted to be secondarily used. Thus, capture_enable_flag_PlayList shown in  FIG. 5  is different from capture_enable_flag_Clip shown in  FIG. 10  in the unit (range) of video data that are permitted to be secondarily used. 
   Like capture_enable_flag_PlayList described in  FIG. 5 , capture_enable_flag_Clip described in  FIG. 10  can be composed of a plurality of bits, not one bit. 
   capture_enable_flag_Clip is followed by number_of_streams (8 bits) number_of_streams describes the number of StreamInfo( )&#39;s. Thus, number_of_streams is followed by StreamInfo( )&#39;s represented by number_of_streams. 
   StreamInfo( ) starts with length (16 bits). length represents the size of StreamInfo( ), including the size of length. length is followed by stream_id (8 bits) and private_stream_id (8 bits) stream_id and private_stream_id identify an elementary stream that is correlated with StreamInfo( ). 
     FIG. 11  shows the relationship of stream_id, private_stream_id, and elementary streams identified thereby. 
   stream_id is the same as that defined in the MPEG2-System standard. The MPEG2-System standard defines the value of stream_id for each attribute (type) of an elementary stream (data). Thus, an attribute of an elementary stream defined in the MPEG2-System standard can be identified by only stream id. 
   This embodiment can deal with attributes of elementary streams that are not defined in the MPEG2-System standard private_stream_id is information that identifies an attribute of an elementary stream that is not defined in the MPEG2-System standard. 
     FIG. 11  shows the relationship of stream_id&#39;s and private_stream_id&#39;s of elementary streams having four attributes that are a video elementary stream encoded corresponding to the encoding (decoding) system defined in the MPEG, an audio elementary stream encoded corresponding to the adaptive transform acoustic coding (ATARC) system (hereinafter sometimes referred to as an ATRAC audio stream), an audio elementary stream encoded corresponding to the linear pulse code modulation (LPCM) system (hereinafter sometimes referred to as an LPCM audio stream), and a subtitle elementary stream (hereinafter sometimes referred to as a subtitle stream). 
   The MPEG2-System standard defines that a video elementary stream encoded corresponding to the encoding system defined in the MPEG is multiplexed with a value in the range from 0xE0 to 0xEF (where 0x represents that the character string preceded thereby is represented in hexadecimal notation). Thus, 16 video elementary streams encoded corresponding to the encoding system defined in the MPEG and identified by stream_id in the range from 0xE0 to 0xEF can be multiplexed with a program stream. 
   Since video elementary streams encoded corresponding to the encoding system defined in the MPEG can be identified by stream_id in the range from 0xE0 to 0xEF, private_stream_id is not required (can be ignored). 
   On the other hand, in the MPEG2-System, stream_id is not defined for an ATRAC audio stream, an LPCM audio stream, and a subtitle stream. 
   Thus, according to this embodiment, for elementary streams whose stream_id is not defined in the MPEG2-System, 0xBD that is a value representing an attribute private_stream_ 1  in the MPEG2-System is used. In addition, as shown in  FIG. 11 , these elementary streams are identified by private_stream_id. 
   In other words, an ATRAC audio stream is identified by private_stream_id in the range from 0x00 to 0x0F. Thus, 16 ATRAC audio streams can be multiplexed with a program stream. An LPCM audio stream is identified by private_stream_id in the range from 0x10 to 0x1F. Thus, 16 LPCM audio streams can be multiplexed with a program stream. A subtitle stream is identified by private_stream_id in the range from 0x80 to 0x9F. Thus, 32 subtitle streams can be multiplexed with a program stream. 
   stream_id and private_stream_id will be described later in detail. 
   In  FIG. 10 , private_stream_id is followed by StaticInfo( ) and reserved_for_word_alignment (8 bits) in succession. StaticInfo( ) describes information that does vary while an elementary stream identified by stream_id and private_stream_id (described in StreamInfo( ) including StaticInfo( )) is being reproduced. StaticInfo( ) will be described later with reference to  FIG. 12 . 
   reserved_for_word_alignment is used for a word alignment. 
   reserved_for_word_alignment is followed by number_of_DynamicInfo (8 bits) number of DynamicInfo represents the number of sets of pts_change_point&#39;s (32 bits each) and DynamicInfo( )&#39;s, which are preceded by number_of_DynamicInfo. 
   Thus, number_of_DynamicInfo is followed by sets of pts_change_point&#39;s and DynamicInfo( )&#39;s represented by number_of_DynamicInfo. 
   pts_change_point represents a time at which information of DynamicInfo( ) paired with pts_change_point becomes valid. pts_change_point that represents the start time of an elementary stream is equal to presentation_start_time described at the beginning of the clip information file Clip( ) corresponding to a clip stream file that stores the elementary stream. 
   DynamicInfo( ) describes so-called dynamic information that changes while an elementary stream identified by stream_id and private_stream_id is being reproduced. Information described in DynamicInfo( ) becomes valid at a reproduction time represented by pts_change_point paired with DynamicInfo( ). DynamicInfo( ) will be described later with reference to  FIG. 13 . 
   Sets of pts_change_point&#39;s and DynamicInfo( )&#39;s represented by number_of_DynamicInfo are followed by EP_map( ). EP_map( ) will be described later with reference to  FIG. 14 . 
   [Description of StaticInfo( )] 
   Next, with reference to  FIG. 12 , StaticInfo( ) shown in  FIG. 10  will be described in detail. 
     FIG. 12  shows the syntax of StaticInfo( ). 
   The content of StaticInfo( ) varies depending on the attribute (type) of the corresponding elementary stream. The attribute of an elementary stream corresponding to StaticInfo( ) is determined by stream_id and private_stream_id contained in StreamInfo( ), shown in  FIG. 10 , including StaticInfo( ). 
   When an elementary stream corresponding to StaticInfo( )is a video stream (stream==VIDEO), StaticInfo( ) is composed of picture size (4 bits), frame_rate (4 bits), cc_flag (1 bit), and reserved_for_word_alignment for a word alignment. 
   picture_size represents the size of (an image displayed with) video data corresponding to a video stream. frame_rate represents the frame frequency of video data corresponding to a video stream. cc_flag represents whether a video stream contains closed caption data. When a video stream contains closed caption data, cc_flag is 1. When a video stream does not contain closed caption data, cc_flag is 0. 
   When an elementary stream corresponding to StaticInfo( ) is an audio stream (stream==AUDIO), StaticInfo( ) is composed of audio_language_code (16 bits), channel_configuration (8 bits), lfe_existence (1 bit), sampling_frequency (4 bits), and reserved_for_word_alignment for a word alignment. 
   audio_language_code describes a code that represents the language of audio data contained in an audio stream. channel_configuration represents an attribute such as monaural (mono), stereo, multi-channels, and so forth of audio data contained in an audio stream. lfe_existence represents whether an audio stream contains a low frequency effect channel. When an audio stream contains a low frequency effect channel, lfe_existence is 1. When an audio stream does not contain a low frequency effect channel, lfe_existence is 0. sampling_frequency is information that represents a sampling frequency of audio data contained in an audio stream. 
   When an elementary stream corresponding to StaticInfo( ) is a subtitle stream (stream==SUBTITLE), StaticInfo( ) is composed of subtitle_language code (16 bits), configurable_flag (1 bit), and reserved_for_word_alignment for a word alignment. 
   subtitle_language_code describes a code that represents the language of subtitle data contained in a subtitle stream. configurable_flag is information that represents whether a subtitle data display mode is permitted to be changed from a default display mode. When a display mode is permitted to be changed, configurable_flag is 1. When a display mode is not permitted to be changed, configurable_flag is 0. The display mode of subtitle data includes display size of subtitle data, display position, display color, display pattern (for example, blinking), display direction (vertical or horizontal), and so forth. 
   [Description of DynamicInfo( )] 
   Next, with reference to  FIG. 13 , DynamicInfo( ) will be described in detail. 
     FIG. 13  shows the syntax of DynamicInfo( ). 
   DynamicInfo( ) starts with reserved_for_word_alignment (8 bits) for a word alignment. Elements preceded by reserved_for_word_alignment depend on an attribute of an elementary stream corresponding to DynamicInfo( ). An attribute of an elementary stream corresponding to DynamicInfo( ) is determined by stream_ID and private_stream_id contained in StreamInfo( ), shown in  FIG. 12 , that includes DynamicInfo( ). 
   As described in  FIG. 10 , DynamicInfo( ) describes dynamic information that varies while an elementary stream is being reproduced. The dynamic information is not specific. However, in the embodiment shown in  FIG. 13 , data of an elementary stream corresponding to DynamicInfo( ), namely an output attribute of data that is an output of a process for an elementary stream (an output attribute of data obtained from an elementary stream) is described in DynamicInfo( ). 
   Specifically, when an elementary stream corresponding to DynamicInfo( ) is a video stream (stream==VIDEO), DynamicInfo( ) is composed of display_aspect_ratio (4 bits) and reserved_for_word_alignment for a word alignment. display_aspect_ratio describes an output attribute (display mode) of video data of a video stream, for example an aspect ratio of video data. In other words, display_aspect_ratio describes information that represents either 16:9 or 4:3 as an aspect ratio. DynamicInfo( ) of a video stream can describe such as the size of an image of video data (X pixels×Y pixels) as well as an aspect ratio. 
   When an elementary stream corresponding to DynamicInfo( ) is an audio stream (stream==AUDIO), DynamicInfo( ) is composed of channel_assignment (4 bits) and reserved_for_word_alignment for a word alignment. When an audio stream contains two channels of audio data, channel_assignment describes output attributes of two channels (output mode). In other words, channel_assignment describes information that represents a channel assignment of stereo or dual (bilingual). 
   When an elementary stream corresponding to DynamicInfo( ) is a subtitle stream (stream==SUBTITLE), DynamicInfo( ) is composed of reserved_for_word_alignment for a word alignment. In other words, according to the embodiment shown in  FIG. 13 , an output attribute as dynamic information is not defined for a subtitle stream. 
   [Description of EP_map( )] 
   Next, with reference to  FIG. 14 , EP_map( ) shown in  FIG. 10  will be described in detail. 
     FIG. 14  shows the syntax of EP_map( ). 
   EP_map( ) describes information of a decodable start point (entry point) from which each of elementary streams multiplexed with a program stream stored in a clip stream file corresponding to the clip information file Clip( ) that includes EP_map( ) can be decoded. 
   A decodable start point of a stream having a fixed rate can be obtained by a calculation. However, for a stream whose size varies in each video access unit such as a video stream encoded corresponding to the MPEG standard, the decodable start point cannot be obtained by a calculation. The decodable start point cannot be obtained unless the stream is analyzed. To randomly access data, it is necessary to quickly recognize the decodable start point. With EP_map( ), a decodable start point can be quickly recognized. 
   In the MPEG2-Video, the beginning of an intra picture including Sequence_header( ) and so forth is a decodable start point. 
   EP_map( ) starts with reserved_for_word_alignment (8 bits) for a word alignment. reserved_for_word_alignment is followed by number_of_stream_id_entries (8 bits). number_of_stream_id entries represents the number of elementary streams that describe information of decodable start points in EP_map( ). 
   number_of_stream_id entries is followed by sets of information that identifies an elementary stream and information of a decodable start point of the elementary stream represented by number_of_stream_id_entries. 
   In other words, number_of_stream_id_entries is followed by stream_id (8 bits) and private_stream_id (8 bits) as information that identifies an elementary stream. private_stream_id is followed by number_of_EP_entries (32 bits). number_of_EP_entries represents the number of decodable start points identified by stream_id and private_stream_id followed by number_of_EP_entries. 
   number_of_EP_entries is followed by sets of PTS_EP_start&#39;s (32 bits each) and RPN_EP_start&#39;s (32 bits each) represented by number_of_EP_entries as information of decodable start points of an elementary stream identified by stream_id and private_stream_id. 
   PTS_EP start as one element of information of decodable start points represents a time (reproduction time) of a decodable start point in a clip stream file that stores a program stream multiplexed with an elementary stream identified by stream_id and private_stream_id. 
   RPN_EP_start that is another element of information of decodable start points describes the position of a decodable start point in a clip stream file that stores a program stream multiplexed with an elementary stream identified by stream_id and private_stream_id as a value as the number of pack( )&#39;s of a program stream. According to this embodiment, the size of pack( ) is 2048 bytes, fixed. In addition, according to this embodiment, one sector of the disc  101  ( FIG. 1 ) is 2048 bytes. 
   A decodable start point (entry point) of a video stream is immediately preceded by a private_stream_ 2  packet (PES_packet( ) as an attribute of private_stream_ 2 ). A private_stream_ 2  packet stores information used to decode video stream stored between two adjacent private_stream_ 2  packets. Thus, for a video stream, RPN_EP_start as information of a decodable start point describes the start position of a private_stream_ 2  packet immediately followed by a real decodable start point. 
   Sets of PTS_EP_start&#39;s and RPN_EP_start&#39;s as information of decodable start points are pre-sorted in the ascending order for each elementary stream identified by stream_id and private_stream_id in EP_map( ). Thus, sets of PTS_EP_start&#39;s and RPN_EP_start&#39;s as information of decodable start points can be binary-searched. 
   A random access method for variable rate streams and streams whose sizes differ in video access units is described in for example Japanese Patent Laid-Open Publication No. 2000-341640 (Japanese Patent Application No. HEI 11-317738). 
   [Description of Clip Stream File] 
   Next, the internal structure of clip stream files having an extension of PS and stored in the “STREAM” directory shown in  FIG. 4  (“00001.CLP,” “00002.PS,” and “00003.PS” in  FIG. 4 ) will be described. 
   A clip stream file is composed on the basis of MPEG2_Program_Stream( ) defined in the MPEG-2 System (ISO/IEC 13818-1). 
     FIG. 15A  and  FIG. 15B  show Table 2-31, Table 2-32, and Table 2-33 described in the MPEG-2 System (ISO/IEC 13818-1: 20000) standard. 
   A program stream stored in a clip stream file is MPEG2_Program_Stream( ) defined in Table 2-31 of the MPEG2-System standard. The program stream is composed of at least one pack( ) and one MPEG_program_end_code. MPEG2_Program_Stream( ) is described in Japanese Patent No. 2785220. 
   One pack( ) is composed of one Pack_header( ) and any number of PES_packet( )&#39;s as defined in Table 2-32 of the MPEG-2 System standard. Pack_header( ) is described in Table 2-33 of the MPEG2-System standard in detail. 
   In the MPEG2-System standard, pack( ) has a size of variable length. However, as described in  FIG. 14 , it is assumed that the size of pack( ) is 2048 bytes, fixed. In this example, the number of PES_packet( )&#39;s of one pack( ) is 1, 2, or 3. When Pack( ) starts with a private_stream_ 2  packet, it is always followed by PES_packet( ) of the corresponding video stream (in the same Pack( )). In addition, as the third PES_packet( ), there may be padding_packet. A private_stream_ 2  packet is always present at the beginning of Pack( ). 
   When Packet( ) does not start with a private_stream_ 2  packet, Pack( ) starts with PES_packet( ) that contains content data of video data, audio data, subtitle data, or the like. The second PES_packet( ) may be padding_packet. 
     FIG. 16A  and  FIG. 16B  to  FIG. 18A  and  FIG. 18B  show PES_packet( ) defined in Table 2-17 of the MPEG2-System standard. 
   PES_packet( ) is mainly composed of packet_start_code_prefix, stream_id, PES_packet_length (they are shown in  FIG. 16A  and  FIG. 16B ), header portions (including stuffing_byte) that vary corresponding to stream_id or the like (these portions are shown in  FIG. 16A  and  FIG. 16B  to  FIG. 18A  and  FIG. 18B ), and PES_packet_data byte (shown in  FIG. 18A  and  FIG. 18B ). When PES_packet( ) is padding_packet (stream_id==padding_stream), a required number of padding_byte&#39;s (0xFF) ( FIG. 18A  and  FIG. 18B ) are repeated instead of PES_packet_data_byte. 
   As shown in  FIG. 16A ,  FIG. 16B ,  FIG. 17A ,  FIG. 17B  and  FIG. 17C , the header portions of PES_packet( ) can describe information that represents a display timing called a presentation time stamp (PTS) and information that represents a decode timing called a decoding time stamp. According to this embodiment, a PTS is added to each of all access units (decode units that compose an elementary stream defined in the MPEG2-System). When specified in the MPEG2-System, a DTS is added. 
   An elementary stream multiplexed with a programs stream is stored in PES_packet_data_byte ( FIG. 18A  and  FIG. 18B ) of PES_packet( ). stream_id of PES_packet( ) describes a value corresponding to an attribute of an elementary stream to identify the elementary stream stored in PES_packet_data_byte. 
   The relationship of values described in stream_id of PES_packet( ) and attributes (types) of elementary streams is defined in Table 2-18 of the MPEG2-System standard.  FIG. 19A  and  FIG. 19B  show Table 2-18 of the MPEG-2 System standard. 
   According to the embodiment of the present invention, values shown in  FIG. 20  are used as stream_id defined in the MPEG2-System standard. 
   In other words, according to this embodiment, five patterns 10111101B, 10111110B, 10111111B, 110xxxxxB, and 1110xxxxB are used as values of stream_id where “x” represents any one of 0 and 1. 
   Corresponding to the table shown in  FIG. 20 , stream_id of PES_packet( ) of an elementary stream having an attribute of private_stream_ 1  is 10111101B. Corresponding to the table shown in  FIG. 20 , stream_id of PES_packet( ) of padding_packet is 10111110B. According to the table shown in  FIG. 20 , stream_id of PES_packet( ) of an elementary stream having an attribute of private_stream_ 2  is 10111111B. 
   stream_id of PES_packet( ) of an audio stream (audio elementary stream) defined in the MPEG is 110xxxxxB. The low order five bits xxxxx of 110xxxxxB is an audio stream byte that identifies an audio stream. 32 (=2 5 ) audio streams (audio streams defined in the MPEG) that can be identified by the audio stream number can be multiplexed with a program stream. 
   stream_id of PES_packet( ) of a video stream (video elementary stream) defined in the MPEG is 1110xxxxB. The low order four bits xxxx of 110xxxxB is a video stream number that identifies a video stream. 16 (=2 4 ) video streams (video streams defined in the MPEG) can be multiplexed with a program stream. 
   PES_packet( ) whose stream id is 110xxxxB is used to store a video stream defined in the MPEG. PES_packet( ) whose stream_id is 110xxxxxB is used to store an audio stream defined in the MPEG. On the other hand, stream_id of PES_packet( ) for an elementary stream corresponding to an encoding system (for example, the ATRAC system) is not defined in the MPEG. Thus, like a video stream and an audio stream defined in the MPEG, an elementary stream corresponding to an encoding system that is not defined in the MPEG cannot be stored in PES_packet( ) with stream_id. 
   Thus, according to this embodiment, PES_packet_data_byte of PES_packet( ) of private_stream_ 1  is extended to store an elementary stream corresponding to an encoding system that is not defined in the MPEG. 
   Extended PES_packet_data_byte of PES_packet( ) of private_stream_ 1  is described as private_stream 1 _PES payload( ). 
   [Description of Private_Stream 1 _PES_Payload( )] 
     FIG. 21  shows the syntax of private_stream 1 _PES_payload( ). 
   private_stream 1 _PES_payload( ) is composed of private_header( ) and private_payload( ). private_payload( ) stores an elementary stream such as an ATRAC audio stream, an LPCM audio stream, a subtitle stream, or the like encoded corresponding to an encoding system not defined in the MPEG system. 
   private_header( ) starts with private_stream_id (8 bits) private_stream_id is identification information that identifies an elementary stream stored in private_payload( ). private_stream_id has the following value corresponding to the attribute (type) of an elementary stream. 
     FIG. 22  shows the relationship of the value of private_stream_id and the attribute of an elementary stream stored in private_payload( ). 
     FIG. 22  shows three patterns 0000xxxxB, 0001xxxxB, and 100xxxxxB as the value of private_stream_id where “x” is any value of 0 and 1 like the case shown in  FIG. 20 . 
   According to the table shown in  FIG. 22 , private_stream_id of private_stream 1 _PES_payload( ) of private_payload( ) of an ATRAC stream is 0000xxxxB. The low order four bits xxxx of 0000xxxxB is an audio stream number that identifies an ATRAC audio stream. 16 (=2 4 ) ATRAC audio streams that can be identified by the audio stream number can be multiplexed with a program stream (MPEG2_Program_Stream( )). 
   According to the table shown in  FIG. 22 , private_stream_id of private stream 1 _PES_payload( ) of private_payload( ) of an LPCM audio stream is 0001xxxxB. The low order four bits xxxx of 0001xxxxB is an audio stream number that identifies an LPCM audio stream. 16 (=2 4 ) that can be identified by the audio stream number can be multiplexed with a program stream. 
   According to the table shown in  FIG. 22 , private_stream_id of private_stream 1 _PES_payload( ) of private_payload( ) of a subtitle stream is 100xxxxB. The low order five bits xxxxx of 1000xxxxxB is a subtitle stream number that identifies a subtitle stream. 32 (=2 5 ) subtitle streams can be multiplexed with a program stream. 
     FIG. 11  shows the relationship of  FIG. 20  and  FIG. 22 . 
   In  FIG. 21 , elements preceded by private_stream_id of private_stream 1 _PES_payload( ) vary depending on the attribute of an elementary stream stored in private_payload( ). The attribute of an elementary stream stored in private_payload( ) is determined by private_stream_id at the beginning of private_header( ). 
   When an elementary stream stored in private_payload( ) is an ATRAC audio stream (private_stream_id==ATRAC), reserved_for_future_use (8 bits) is described for a future extension. reserved_for_future_use is followed by AU_locator (16 bits). AU_locator represents the start position of an audio access unit (ATRAC audio access unit) (audio frame) of an ATRAC audio stream stored in private_payload( ) on the basis of the position immediately preceded by AU_locator. When private_payload( ) does not store an audio access unit, for example 0xFFFF is described in AU_locator. 
   When an elementary stream stored in private_payload( ) is an LPCM audio stream (private_stream_id==LPCM), fs_flag (1 bit), reserved_for_future_use (3 bits), ch_flag (4 bits), and AU_locator (16 bits) are described in succession. 
   fs_flag represents a sampling frequency of an LPCM audio stream stored in private_payload( ). When the sampling frequency of an LPCM audio stream is 48 kHz, fs_flag is 0. When the sampling frequency of an LPCM audio stream is 44.1 kHz, fs_flag is 1. 
   ch_flag represents the number of channels of an LPCM audio stream stored in private_payload( ). When an LPCM audio stream is monaural, ch_flag is 1. When an LPCM audio stream is stereo, ch_flag is 2. 
   AU_locator represents the start position of an audio access unit (LPCM audio access unit) (audio frame) of an LPCM audio stream stored in private_payload( ) on the basis of the position immediately preceded by AU_locator. When private_payload( ) does not store an audio access unit, for example 0xFFFF is described in AU_locator. 
   When an elementary stream stored in private_payload( ) is a subtitle stream (private_stream_id==SUBTITLE), reserved_for_future_use (8 bits) is described for a future extension. reserved_for_future_use is immediately followed by AU_locator (16 bits). AU_locator represents the start position of a subtitle access unit of a subtitle stream stored in private_payload( ) on the basis of the position immediately after AU_locator. When private_payload( ) does not store a subtitle access unit, for example 0xFFFF is-described in AU_locator. 
   [Description of Private_stream 2 _PES_Payload( )] 
     FIG. 23  shows the syntax of private_stream 2 _PES_payload( ). 
   private_stream 2 _PES_payload( ) is an extension of PES_packet_data_byte ( FIG. 18A  and  FIG. 18B ) of private_payload( ) of private_stream_ 2 , namely an extension of PES_packet_data_byte of PES_packet( ) of private_stream_ 2 . private_stream 2 _PES_payload( ) describes information used to decode a video stream. 
   According to this embodiment, PES_packet( ) of private_stream_ 2  is immediately preceded by a decodable start point of a video stream. Thus, according to this embodiment, when PES_packet( ) of private_stream_ 2  is detected from a program stream, video streams immediately preceded by PES_packet( ) can be decoded. 
   RPN_EP_start of EP_map( ) shown in  FIG. 14  represents the start position of PES_packet( ) of private_stream_ 2  for a video stream. 
   private_stream 2 _PES_payload( ) starts with reserved_for_future_use (8 bits) for a future extension. reserved_for_future_use is followed by video_stream_id (8 bits), 1stRef_picture (16 bits), 2ndRef_picture (16 bits), 3rdRef_picture (16 bits), 4thRef_picture (16 bits), au_information( ), and VBI( ) in succession. 
   video_stream_id describes stream_id (the same value as stream-id) of PES_packet( ) of a video stream immediately preceded by PES_packet( ) of private_stream_ 2 . video_stream_id identifies a video stream (PES_packet( ) that stores a video stream) that is decoded with information stored in PES_packet( ) (private_stream 2 _PES_payload( ) of PES_packet( )) of private_stream_ 2 . 
   1stRef_picture, 2ndRef_picture, 3rdRef_picture, and 4thRef_picture represent relative values of positions of the last pack( )&#39;s including first, second, third, and fourth reference images from PES_packet( ) of private_stream_ 2  to PES_packet( ) of the next private_stream_ 2  of a video stream identified by video_stream_id, respectively. The details of 1stRef_picture, 2ndRef_picture, 3rdRef_picture, and 4thRef_picture are disclosed as bytes_to _first_P_pic and bytes_to_second_P_pic in Japanese Patent Laid-Open Publication No. HEI 09-46712 (Japanese Patent Application No. HEI 07-211420). 
   au_information( ) describes information about a video access unit of a video stream from PES_packet( ) of private_stream_ 2  to PES_packet( ) of the private_stream_ 2 . au_information( ) will be described in detail with reference to  FIG. 24 . 
   VBI( ) is used to describe information about a closed caption. 
   PES_packet( ) of private_stream_ 2  that has private_stream 2 _PES_payload( ) is described for the decodable start point of each video stream. 
     FIG. 24  shows the syntax of au_information( ) shown in  FIG. 23 . 
   au_information( ) starts with length (16 bits). length represents the size of au_information( ) including the size of length. length is followed by reserved_for_word_alignment (8 bits) and number_of_access_unit (8 bits) in succession. reserved_for_word_alignment is used for a word alignment. 
   number_of_access_unit represents the number of access units (pictures) stored from PES_packet( ) of private_stream 2  to PES_packet( ) of the next private_stream 2 . 
   In other words, number_of_access_unit represents the number of access units (pictures) contained in a video stream represented by video_stream_id from au_information( ) to the next au_information (or the end of the clip stream file when au_information( ) is the last au_information( ) thereof) in PES_packet( )&#39;s of private_stream_ 2 &#39;s whose video_stream_id in private_stream 2 _PES_payload( ) is the same. 
   number_of_access_unit is followed by the contents of a for loop corresponding to number_of _access_unit. In other words, information about at least one video access unit from PES_packet( ) of private_stream_ 2  including number_of _access_unit to PES_packet( ) of the next private_stream_ 2  is described. 
   Information described in the for loop (information about video access units) is as follows. 
   The for loop contains pic_struct_copy (4 bits), au_ref_flag (1 bit), AU_length (21 bits), and reserved. 
   pic_struct_copy describes a copy of pic_struct( ) defined in ISO/IEC 14496-10, D.2.2 for a video access unit corresponding to the MPEG4-AVC (ISO/IEC 14496-10) pic_struct( ) is information that represents that for example a picture frame is displayed or after a top field of a picture is displayed, a bottom field is displayed. 
   au_ref_flag represents whether a corresponding access unit is a reference picture that is referenced when (a picture of) another access unit is decoded. When the corresponding access unit is a reference picture, au_ref_flag is 1. When the corresponding access unit is not a reference picture, au_ref_flag is 0. 
   AU_length represents the size of a corresponding access unit in bytes. 
   [Specific Example of Data Recorded on Disc  101 ] 
     FIG. 25  to  FIG. 28  show specific examples of data that have the foregoing format and that have been recorded on the disc  101  shown in  FIG. 1 . 
   In  FIG. 25  to  FIG. 28 , a video stream corresponding to the MPEG2-Video and an audio stream corresponding to the ATRAC are used. However, a video stream and an audio stream used in the present invention are not limited to these streams. In other words, a video stream corresponding to the MPEG4-Visual, a video stream corresponding to the MPEG4-AVC, or the like may be used. On the other hand, an audio stream corresponding to the MPEG1/2/4 audio, an audio stream corresponding to the LPCM audio, or the like may be used. 
   Unlike a video stream and an audio stream, a subtitle stream may not be successively decoded and displayed (output) at the same intervals. In other words, a subtitle stream is sometimes supplied from the buffer control module  215  shown in  FIG. 2A  and  FIG. 2B  to the subtitle decoder control module  218 . The subtitle decoder control module  218  decodes the subtitle stream. 
     FIG. 25  to  FIG. 28  show specific examples of “PLAYLIST.DAT” file, three clip information files “00001.CLP,” “00002.CLP,” and “00003.CLP,” and so forth in the case that the three clip information files “00001.CLP,” “00002.CLP,” and “00003.CLP” are stored in the “CLIP” directory and three clip stream files “00001.” PS, “00002.PS,” and “00003.PS” corresponding to the three clip information files “00001.CLP,” “00002.CLP,” and “00003.CLP” are stored in the “STREAM” directory. However, in  FIG. 25  to  FIG. 28 , a part of data such as the “PLAYLIST.DAT” file and so forth are omitted. 
     FIG. 25  shows a specific example of the “PLAYLIST.DAT” file shown in  FIG. 5 . 
   In  FIG. 25 , number_of_PlayLists is 2. Thus, the number of PlayList( )&#39;s stored in the “PLAYLIST.DAT” file is 2. In  FIG. 25 , the two PlayList( )&#39;s are PlayList# 0  and PlayList# 1 . 
   capture_enable_flag_PlayList of the first PlayList( ), namely PlayList# 0 , is 1. Thus, video data reproduced corresponding to PlayList# 0  are permitted to be secondarily used. On the other hand, number_of_PlayItems of PlayList# 0  is 2. Thus, the number of PlayItem( )&#39;s contained in PlayList# 0  is 2. Specific examples of PlayItem# 0  and PlayItem# 1  as two PlayItem( )&#39;s are described below a “PlayList# 0 ” field shown in  FIG. 2A  and  FIG. 2B . 
   In PlayItem# 0  as the first PlayItem( ) contained in PlayList# 0 , Clip_Information_file_name described in  FIG. 6  is “00001.CLP”, IN_time being 180,090., OUT_time being 27,180,090. Thus, a clip reproduced by PlayItem# 0  of PlayList# 0  is from time 180,090 to time 27,180,090 of the clip stream file “00001.CLP” corresponding to the clip information file “00001.CLP.”. 
   In PlayItem# 1  as the second PlayItem( ) contained in PlayList# 0 , Clip_Information_file_name described in  FIG. 6  is “00002.CLP,” In-time being 90,000, OUT_time being 27,090,000. Thus, a clip reproduced by PlayItem# 1  of PlayList# 0  is from time 90,000 to time 27,090,000 of the clip stream file “00002.PS” corresponding to the clip information file “00002.CLP.” 
   In  FIG. 25 , in PlayList# 1  as the second PlayList( ), capture_enable_flag_PlayList is 0. Thus, video data reproduced corresponding to PlayList# 1  are not permitted to be secondarily used (prohibited from being secondarily used). In PlayList# 1 , number_of_PlayItems is 1. Thus, the number of PlayItem( )&#39;s contained in PlayList# 1  is 1. In  FIG. 25 , a specific example of PlayItem# 0  as one PlayItem( ) is described below a. “PlayList# 1 ” field. 
   In PlayItem# 0  as one PlayItem( ) contained in PlayList# 1 , Clip_Information_file_name described in  FIG. 6  is “00003.CLP,” IN_time being 90,000, OUT_time being 81,090,000. Thus, a clip reproduced by PlayItem# 0  of PlayList# 1  is from time 90,000 to time 81,090,000 of the clip stream file “00003.PS” corresponding to the clip information file “00003.CLP.” 
     FIG. 26A  and  FIG. 26B  show a specific example of the clip information file Clip( ) described in  FIG. 10 . Thus,  FIG. 26A  and  FIG. 26B  show specific examples of the clip information files “00001.CLP,” “00002.CLP,” and “00003.CLP.” 
   In the clip information file “00001.CLP,” presentation_start_time is 90,000 and presentation_end_time is 27,990,000. Thus, a program stream stored in the clip stream file “00001.CLP” corresponding to the clip information file “00001.CLP” can use a content for 310 seconds (27,990,000−90,000/90 kHz). 
   In the clip information file “00001.CLP,” capture_enable_flag_Clip is 1. Thus, a video stream (video data corresponding thereto) multiplexed with a program stream stored in the clip stream file “00001.CLP” corresponding to the clip information file “00001.CLP” is permitted to be secondarily used. 
   In  FIG. 26A  and  FIG. 26B , in the clip information file “00001.CLP,” number_of_streams is 4. Thus, four elementary streams are multiplexed with a program stream stored in the clip stream file “00001.CLP.” 
   Assuming that the four elementary streams are denoted by stream# 0 , stream# 1 , stream# 2 , and stream# 3 , specific examples of StreamInfo( )&#39;s ( FIG. 10 ) of the four elementary streams, which are stream# 0 , stream# 1 , stream# 2 , and stream# 3  are described below a “00001.CLP” field shown in  FIG. 26A  and  FIG. 26B . 
   In the first elementary stream stream# 0  of the clip stream file “00001.CLP,” stream_id is 0xE0. Thus, as described in  FIG. 20  and  FIG. 22  (or  FIG. 11 ), the elementary stream stream# 0  is a video stream. According to this embodiment, private_stream_id is not correlated with a video stream. In  FIG. 26A  and  FIG. 26B , private_stream_id is 0x00. 
   In the video stream stream# 0  as the first elementary stream of the clip stream file “00001.CLP,” picture_size of StaticInfo( ) ( FIG. 12 ) contained in StreamInfo( ) is “720×480”, frame rate being “29.97 Hz,” cc_flag being “Yes.” Thus, the video stream stream# 0  is video data having 720×480 pixels and a frame period of 29.97 Hz. In addition, the video stream stream# 0  contains closed caption data. 
   In the video stream stream# 0  as the first elementary stream of the clip stream file “00001.CLP,” number_of_DynamicInfo of StreamInfo( ) ( FIG. 10 ) is 0. There is no pair of pts change-point and DynamicInfo( ). 
   In the second elementary stream stream# 1  of the clip stream file “00001.CLP,” stream id is 0xBD, private_stream_id being 0x00. Thus, as described in  FIG. 20  and  FIG. 22 , the elementary stream stream# 1  is an ATRAC audio stream. 
   In the ATRAC audio stream stream# 1  as the second elementary stream of the clip stream file “00001.CLP,” audio_language_code of StaticInfo( ) ( FIG. 12 ) contained in StreamInfo( ) is “Japanese,” channel_configuration being “STEREO,” lfe_existence, being “NO,” sampling_frequency being “48 kHz.” Thus, the ATRAC audio stream stream# 1  is Japanese and stereo audio data. In addition, the ATRAC audio stream stream# 1  does not contain a low frequency effect channel and the sampling frequency is 48 kHz. 
   In addition, in the ATRAC audio stream stream# 1  as the second elementary stream of the clip stream file “00001.CLP,” number_of_DynamicInfo of StreamInfo( ) ( FIG. 10 ) is 0. There is no pair of pts_change_point and Dynamicinfo( ). 
   In the third elementary stream stream# 2  of the clip stream file “00001.CLP,” stream_id is 0xBD, private_stream_id being 0x80. Thus, as described in  FIG. 20  and  FIG. 22 , the elementary stream stream# 2  is a subtitle stream. 
   In the subtitle stream stream# 2  as the third elementary stream of the clip stream file “00001.PS,” subtitle_language_code of StaticInfo( ) contained in StreamInfo( ) is “Japanese,” configurable_flag being 0. Thus, the subtitle stream stream# 2  is Japanese subtitle data. In addition, this display mode is not permitted to be changed (prohibited from being changed). 
   In the subtitle stream stream# 2  as the third elementary stream of the clip stream file “00001.CLP,” number_of_DynamicInfo of StreamInfo( ) ( FIG. 10 ) is 0. There is no pair of pts_change_point and DynamicInfo( ). 
   In the fourth elementary stream stream# 3  of the clip stream file “00001.CLP,” stream_id is 0xBD, private_stream_id being 0x81. Thus, as described in  FIG. 20 and 22 , the elementary stream stream# 3  is a subtitle stream. 
   To distinguish the subtitle stream stream# 2  as the third elementary stream of the clip stream file “00001.CLP” from the subtitle stream stream# 3  as the fourth elementary stream, their private_stream_id&#39;s are 0x80 and 0x81, respectively. 
   In the subtitle stream stream# 2  as the fourth elementary stream of the clip stream file “00001.CLP,” subtitle_language_code of StaticInfo( ) ( FIG. 12 ) contained in StreamInfo( ) is “Japanese,” configurable_flag being 1. Thus, the subtitle stream stream# 3  is Japanese subtitle data. The display mode of the subtitle stream stream# 3  is permitted to be changed. 
   In the subtitle stream stream# 3  as the fourth elementary stream of the clip stream file “00001.PS,” number_of_DynamicInfo of StreamInfo( )( FIG. 10 ) is 0. There is no pair of pts_change_point and DynamicInfo( ). 
   In  FIG. 26A  and  FIG. 26B , in the clip information file “00002.CLP,” presentation_start_time is 90,000, presentation_end_time being 27,090,000. Thus, a program stream stored in the clip stream file “00002.PS” corresponding to the clip information file “00002.CLP” can use a content for 300 seconds ((27,090,000−90,000/90 kHz). 
   In the clip information file “00002.CLP,” capture_enable_flag_Clip is 0. Thus, a video stream (video data corresponding thereto) multiplexed with a program stream stored in the clip stream file “00002.PS” corresponding to the clip information file “00002.CLP” is not permitted to be secondarily used (prohibited from being secondarily used). 
   In  FIG. 26A  and  FIG. 26B , in the clip information file “00002.CLP,” number_of_streams is 4. Thus, like the foregoing clip stream file “00001.CLP,” four elementary streams are multiplexed with a program stream stored in the corresponding clip stream file “00002.PS.” 
   Assuming that the four elementary streams are denoted by stream# 0 , stream# 1 , stream# 2 , and stream# 3 , specific examples of StreamInfo( )&#39;s ( FIG. 10 ) of the four elementary streams, which are stream# 0 , stream# 1 , stream# 2 , and stream# 3 , are described below a “00002.CLP” field shown in  FIG. 26A  and  FIG. 26B . 
   In  FIG. 26A  and  FIG. 26B , the contents of StreamInfo.( )&#39;s of the first to fourth elementary streams of the clip stream file “00002.PS” are the same as those of the first to fourth elementary streams of the clip stream file “00001.PS.” Thus, their description will be omitted. 
   As described above, the contents of StreamInfo( )&#39;s of the first to fourth elementary streams, stream# 0  to stream# 3 , of the clip stream file. “00002.PS” are the same as those of the first to fourth elementary streams, stream# 0  to stream# 3 , of the clip stream file “00001.CLP.” Thus, the first elementary stream stream# 0  of the clip stream file “00002.PS” is a video stream. The second elementary stream stream# 1  is an ATRAC audio stream. The third and fourth elementary streams, stream# 2  and stream# 3 , are subtitle streams. 
   In  FIG. 26A  and  FIG. 26B , in the clip information file “000.03.CLP,” presentation_start_time is 90,000, presentation_end_time being 81,090,000. Thus, a program stream stored in the clip stream file “00003.PS” corresponding to the clip information file “00003.CLP” can use a content for 900 seconds ((81,090,000−90,000)/90 kHz). 
   In the clip information file “00003.CLP,” capture_enable_flag_Clip is 1. Thus, a video stream multiplexed with a program stream stored in the clip stream file “00003.PS” corresponding to the clip information file “00003.CLP” is permitted to be secondarily used. 
   In  FIG. 26A  and  FIG. 26B , in the clip information file “00003.CLP,” number_of_streams is 3. Thus, three elementary streams are multiplexed with a program stream stored in the clip stream file “00003.PS.” 
   Assuming that the three elementary streams are denoted by stream# 0 , stream# 1 , and stream# 2 , specific examples of StreamInfo( )&#39;s ( FIG. 10 ) of the three streams, which are stream# 0 , stream# 1 , and stream# 2 , are described below a “00003.CLP” field shown in  FIG. 26A  and  FIG. 26B . 
   In the first elementary stream stream# 0  of the clip stream file “00003.PS,” stream_id is 0xE0. Thus, as described in  FIG. 20  and  FIG. 22  (or  FIG. 11 ), the elementary stream stream# 0  is a video stream. Like the first elementary stream stream# 0  of the clip stream file “00001.CLP,” private_stream_id is 0x00. 
   In the video stream stream# 0  as the first elementary stream of the clip stream file “00003.PS,” picture_size of StaticInfo( ) ( FIG. 12 ) contained in StreamInfo( ) is “720×480”, frame_rate being “29.97 Hz,” cc_flag being “No.” Thus, the video stream stream# 0  is video data having 720×480 pixels and a frame period of 29.97 Hz. The video stream stream# 0  does not contain closed caption data. 
   In the video stream stream# 0  as the first elementary stream of the clip stream file “00003.PS,” number_of_DynamicInfo of StreamInfo( ) ( FIG. 10 ) is 2. Thus, two sets of pts_change_point&#39;s and DynamicInfo( )&#39;s are described in StreamInfo( ). 
   In the second elementary stream stream# 1  of the clip stream file “00003.PS,” stream_id is 0xE1. Thus, as described in  FIG. 20  and  FIG. 21  (or  FIG. 11 ), the elementary stream stream# 1  is a video stream. To distinguish the video stream stream# 0  as the first elementary stream of the clip stream file “00003.PS” from the video stream stream# 1  as the second elementary stream, their stream id&#39;s are 0xE0 and 0xE1, respectively. Like the first elementary stream stream# 0  of the clip stream file “0001.CLP,” private_stream_id is 0x00. 
   In the video stream stream# 1  as the second elementary stream of the clip stream file “00003.PS,” picture_size, frame_rate, and cc_flag of StaticInfo( ) ( FIG. 12 ) contained in StreamInfo( ) are the same as those of the video stream stream# 0  as the first elementary stream. Thus, the video stream stream# 1  as the second elementary stream of the clip stream file “00003.PS” is video data having 720×480 pixels and a frame period of 29.97 Hz. The video stream stream# 1  does not contain closed caption data. 
   In the video stream stream# 1  as the second elementary stream of the clip stream file “00003.PS,” number_of_DynamicInfo of StreamInfo( ) ( FIG. 10 ) is 0. Thus, there is no pair of pts_change_point and DynamicInfo( ). 
   In the third elementary stream stream# 2  of the clip stream file “00003.PS,” stream_id is 0xBD, private_stream_id being 0x00. Thus, as described in  FIG. 20  and  FIG. 22 , the elementary stream stream# 2  is an ATRAC audio stream. 
   In the ATRAC audio stream stream# 2  as the third elementary stream of the clip stream file “00003.PS,” audio_language_code, channel_configuration, lfe_existence, and sampling_frequency of StaticInfo( ) ( FIG. 12 ) contained in StreamInfo( ) are the same as those of the ATRAC audio stream stream# 1  as the second elementary stream of the clip stream file “00001.CLP.” Thus, the ATRAC audio stream stream# 2  as the third elementary stream of the clip stream file “00003.PS” is Japanese and stereo audio data. In addition, the ATRAC audio stream stream# 2  does not contain a low frequency effect channel. The ATRAC audio stream stream# 2  has a sampling frequency of 48 kHz. 
   In the ATRAC audio stream stream# 2  as the third elementary stream of the clip stream file “00003.PS,” number_of_DynamicInfo of StreamInfo( ) ( FIG. 10 ) is 3. Thus, StreamInfo( ) describes three sets of pts_change_point&#39;s and DynamicInfo.( )&#39;s. 
     FIG. 27  shows a specific example of EP_map( ) of the clip information file Clip( ) described in  FIG. 10 .  FIG. 27  shows a specific example of EP_map( ), shown in  FIG. 14 , of the clip information file “00001.CLP” shown in  FIG. 4 . 
   In  FIG. 27 , in EP_map( ), number_of_stream_id entries is 1. Thus, EP_map( ) describes information of a decodable start point of one elementary stream. 
   In EP_map( ) shown in  FIG. 27 , stream_id is 0xE0. Thus, as described in  FIG. 20  and  FIG. 22 , EP_map( ) describes information (PTS_EP_start and RPN_EP_start ( FIG. 14 )) of a decodable start point of a video stream identified by stream_id that is 0xE0. In  FIG. 270  EP_map( ) is the clip information file “00001.CLP.” As described in  FIG. 26A  and  FIG. 26B , in the clip stream file “00001.PS” corresponding to the clip information file “00001.CLP,” an elementary stream whose stream_id is 0xE0 is the first video stream of the clip stream file “00001.PS.” Thus, information described in EP_map( ) shown in  FIG. 27  is PTS_EP_start and RPN_EP_start of a decodable start point of the video stream stream# 0 . 
   In  FIG. 27 , the first five PTS_EP_start&#39;s and RPN_EP_start&#39;s of decodable start points of the first video stream stream# 0  of the clip stream file “00001.PS” are described, but sixth and later PTS_EP_start&#39;s and RPN_EP_start&#39;s are omitted. 
   In EP_map( ) shown in  FIG. 27 , private_stream_id is 0x00. When stream_id represents a video stream, private_stream_id is ignored. 
     FIG. 28  shows specific examples of PlayListMark( )&#39;s of PlayList# 0  and PlayList# 1  described in  FIG. 25  (PlayList( ) shown in  FIG. 5 ). 
   An upper table shown in  FIG. 28  represents PlayListMark( ) ( FIG. 7 ) of PlayList# 0 . 
   In the upper table shown in  FIG. 28 , number_of_PlayList marks of PlayListMark( ) of PlayList# 0  is 7. Thus, the number of Mark( )&#39;s contained in PlayList# 0  (PlayListMark( ) thereof) is 7. 
   In the upper table shown in  FIG. 28 , mark_type ( FIG. 7 ) of Mark# 0  as the first Mark( ) of seven Mark( )&#39;s contained in PlayList# 0  is “Chapter.” Thus, Mark# 0  is a chapter mark. In addition, since ref_to_PlayItem_id ( FIG. 7 ) is 0, Mark# 0  belongs to PlayItem# 0  of two PlayItem# 0  and # 1  shown in  FIG. 25 . In addition, mark_time_stamp of Mark# 0  is 180,090. Thus, Mark# 0  is a mark of time (reproduction time) 180,090 of a clip stream file reproduced by PlayItem# 0  contained in PlayList# 0 . Both entry_ES_stream_id and entry_ES_private_stream_id of Mark# 0  are 0. Thus, Mark# 0  is not correlated with any elementary stream. In addition, mark_data of Mark# 0  is 1. Thus, Mark# 0  represents a chapter whose number is 1. 
   A clip stream file reproduced by PlayItem# 0  contained in PlayList# 0  is the clip stream file “00001.PS” identified by “00001.CLP” described in Clip_Information_file_name of PlayItem# 0  ( FIG. 25 ). Thus, time 180,090 represented by mark_time_stamp of Mark# 0  is the time of the clip stream file “00001.PS.” 
   In the upper table shown in  FIG. 28 , Mark# 4  as the fifth Mark( ) of seven Mark( )&#39;s contained in PlayList# 0  is a chapter mark that is the same as the first Mark# 0 . 
   In other words, mark_type ( FIG. 7 ) of Mark# 4  as the fifth Mark( ) is “Chapter.”. Thus, Mark# 4  is a chapter mark. In addition, ref_to_PlayItem_id ( FIG. 7 ) of Mark# 4  is 1. Thus, Mark# 4  belongs to PlayItem# 1  of two PlayItem# 0  and # 1 , shown in  FIG. 25 , contained in PlayList# 0  mark_time_stamp of Mark# 4  is 90,000. Thus, Mark# 4  is a mark of time 90,000 of a clip stream file reproduced by PlayItem# 1  contained in PlayList# 0 . In addition, both entry_ES_stream_id and entry_ES_private_stream_id of Mark# 4  are 0. Thus, Mark# 4  is not correlated with any elementary stream. In addition, mark_data of Mark# 4  is 2. Thus, Mark# 4  represents a chapter whose number is 2. 
   In this example, a clip stream file reproduced by PlayItem# 1  contained in PlayList# 0  is the clip stream file “00002.PS” identified by “00002.CLP” described in Clip_Information_file_name of PlayItem# 1  ( FIG. 25 ). Thus, time 90,000 represented by mark_time_stamp of Mark# 4  is time of the clip stream file “00002.PS.” 
   In the upper table shown in  FIG. 28 , mark_type ( FIG. 7 ) of Mark# 1  as the second Mark( ) of seven Mark( )&#39;s contained in PlayList# 0  is “Index.” Thus, Mark# 1  is an index mark. In addition, ref_to_PlayItem_id ( FIG. 7 ) of Mark# 1  is 0. Thus, Mark# 1  belongs to PlayItem# 0  of two PlayItem# 0  and # 1 , shown in  FIG. 25 , contained in PlayList# 0 . In addition, mark_time stamp of Mark# 1  is 5,580,090. Thus, Mark# 1  is a mark of time 5,580,090 of a clip stream file reproduced by PlayItem# 0  contained in PlayList# 0 . In addition, both entry_ES_stream_id and entry_ES_private_stream_id of Mark# 1  are 0. Thus, Mark# 1  is not correlated with any elementary stream. In addition, mark_data of Mark# 1  is 1. Thus, Mark# 1  represents an index whose number is 1. 
   In this example, a script stream file reproduced by PlayItem# 0  contained in PlayList# 0  is the clip stream file “00001.PS” as described above. Thus, time 5,580,090 represented by mark_time_stamp of Mark# 1  is the time of the clip stream file “00001.PS.” 
   In the upper table shown in  FIG. 28 , Mark# 2 , Mark# 5 , and Mark# 6  as the third, sixth, and seventh Mark( )&#39;s of the seven Mark( )&#39;s contained in PlayList# 0  are index marks like the second Mark# 1 . 
   In the upper table shown in  FIG. 28 , mark_type ( FIG. 7 ) of Mark# 3  as the fourth Mark( ) of the seven Mark( )&#39;s contained in PlayList# 0  is “Event.” Thus, Mark# 3  is an event mark. In addition, ref_to_PlayItem_id ( FIG. 7 ) of Mark# 3  is 0. Thus, Mark# 3  belongs to PlayItem# 0  of two PlayItem# 0  and # 1 , shown in  FIG. 25 , contained in PlayList# 0 . In addition, mark_time_stamp of Mark# 3  is 16,380,090. Thus, Mark# 3  is a mark of time 16,380,090 of a clip stream file reproduced by PlayItem# 0  contained in PlayList# 0  entry ES_stream_id and entry_ES_private_stream_id of Mark# 3  are 0. Thus, Mark# 3  is not correlated with any elementary stream. In addition, mark_data of Mark# 3  is 0. Thus, Mark# 3  causes an event with an argument of 0 to take place. 
   As described above, a clip stream file reproduced by PlayItem# 0  contained in PlayList# 0  is the clip stream file “00001.PS.” Time 16,380,090 represented by mark_time_stamp of Mark# 3  is the time of the clip stream file “00001.PS.” 
   In the upper table shown in  FIG. 28 , cumulative times of PlayItem( )′ to which Mark( )&#39;s belong are described in a left field on the right side of the table of PlayListMark( ) of PlayList# 0 . Cumulative times of PlayList# 0  are described in a right field on the right side of the table. 
   A lower table shown in  FIG. 28  represents PlayListMark( ) of PlayList# 1  ( FIG. 7 ). 
   In the lower table shown in  FIG. 28 , number_of_Playlist_marks of PlayListMark( ) of PlayList# 1  is 3. Thus, the number of Mark( )&#39;s contained in PlayList# 1  (PlayListMark( ) thereof) is 3. 
   In the lower table shown in  FIG. 28 , mark_type ( FIG. 7 ) of Mark# 0  as the first Mark( ) of three Mark( )&#39;s contained in PlayList# 1  is “Chapter.” Thus, Mark# 0  is a chapter mark. In addition, ref_to_PlayItem_id ( FIG. 7 ) of Mark# 0  is 0. Thus, Mark# 0  belongs to one PlayItem# 0 , shown in  FIG. 25 , contained in PlayList# 1  mark_time_stamp of Mark# 0  is 90,000. Thus, Mark# 0  is a mark of time 90,000 of a clip stream file reproduced by PlayItem# 0  contained in PlayList# 1 . Both entry_ES_stream_id and entry_ES_private_stream_id of Mark# 0  are 0. Thus, Mark# 0  is not correlated with any elementary stream. In addition, mark_data of Mark# 0  is 0. Thus, Mark# 0  represents a chapter whose number is 0. 
   A clip stream file reproduced by PlayItem# 0  contained in PlayList# 1  is the clip stream file “00003.PS” identified by “00003.CLP” described in Clip_Information_file_name of PlayItem# 0  ( FIG. 25 ). Thus, time 90,000 represented by mark_time_stamp of Mark# 0  is the time of the clip stream file “00003.PS.” 
   In the lower table shown in  FIG. 28 , mark_type ( FIG. 7 ) of Mark# 1  as the second Mark( ) of three Mark( )&#39;s contained in PlayList# 1  is “Event.” Thus, Mark# 1  is an event mark. In addition, ref_to_PlayItem_id ( FIG. 7 ) of Mark# 1  is 0. Thus, Mark# 1  belongs to PlayItem# 0 , shown in  FIG. 25 , which contained in PlayList# 1 . In addition, mark_time_stamp of Mark# 1  is 27,090,000. Thus, Mark# 1  is a mark of time 27,090,000 of a clip stream file reproduced by PlayItem# 0  contained in PlayList# 1 . In addition, in Mark# 1 , entry_ES_stream_id is 0xE0 and entry_ES_private_stream_id is 0. Thus, Mark# 1  is correlated with an elementary stream whose stream_id is 0xE0, namely Mark# 1  is correlated with a video stream as described in  FIG. 20  and  FIG. 22 . In addition, mark_data of Mark# 1  is 1. Mark# 1  causes an event with an attribute of 1 to take place. 
   As described above, a clip stream file reproduced by PlayItem# 0  contained in PlayList# 1  is “00003.PS.” Thus, time 27,090,000 represented by mark_time_stamp of Mark# 1  is the time of the clip stream file “00003.PS.” 
   A video stream, whose stream_id is 0xE0, correlated with Mark# 1  is the first elementary stream (video stream) stream# 0  of three elementary streams stream# 0  to # 2  multiplexed with the clip stream file “00003.PS” identified by the clip information file “00003.CLP” shown in  FIG. 26A  and  FIG. 26B . 
   In the lower table shown in  FIG. 28 , mark_type of Mark# 2  as the third Mark( ) of three Mark( )&#39;s contained in PlayList# 1  is “Event.” Thus, Mark# 2  is an event mark. In addition, ref_to_PlayItem_id ( FIG. 7 ) of Mark# 2  is 0. Thus, Mark# 2  belongs to PlayItem# 0 , which is one of PlayItem&#39;s, shown in  FIG. 25 , contained in PlayList# 1 . In addition, mark_time_stamp of Mark# 2  is 27,540,000. Thus, Mark# 1  is a mark of time 27,540,000 of a clip stream file reproduced by PlayItem# 0  contained in PlayList# 1 . In addition, in Mark# 2 , entry_ES_stream_id is 0xE1 and entry_ES_private_stream_id is 0. Thus, Mark# 2  is an element stream whose stream id is 0xE1, namely correlated with a video stream as described in  FIG. 20  and  FIG. 22 . In addition, mark_data of Mark# 2  is 2. Thus, Mark# 2  causes an event with an argument of 2 to take place. 
   In this example, as described above, a clip stream file reproduced by PlayItem# 0  contained in PlayList# 1  is the clip stream file “00003.PS.” Thus, time 27,540.000 represented by Mark# 2  is a time of the clip stream file “00003.PS.” 
   A video stream, whose stream_id is 0xE1, correlated with Mark# 2 , is a video stream described in “00003.CLP” described in Clip_Information_file_name of PlayItem# 0  contained in PlayList# 1  shown in  FIG. 25 , namely the second elementary stream (video stream) stream# 1  of three elementary streams stream# 0  to # 2  multiplexed with the clip stream file “00003.PS” recognized from the clip information file “00003.CLP” shown in  FIG. 26A  and  FIG. 26B . 
   In the lower table shown in  FIG. 28 , cumulative times of PlayItem( )&#39;s to which Mark( )&#39;s belong are described on the right side of the table of PlayListMark( ) of PlayList# 1 . 
   In  FIG. 28 , although mark_data describes chapter and index numbers that chapter and index marks represent, they may not been described in mark_data. Instead, by counting chapter and index marks of PlayListMark( ), chapter and index numbers can be recognized. 
   [Description of Operation of Disc Device] 
   Next, the operation of the disc device shown in  FIG. 1  will be described assuming that data (files) described in  FIG. 25  to  FIG. 28  have been recorded on the disc  101  shown in  FIG. 1 . 
   When the disc  101  is loaded into the disc drive  102 , a corresponding message is sent through the drive interface  114  and the operating system  201  shown in  FIG. 2A  and  FIG. 2B  to the video content reproduction program  210 . When the video content reproduction program  210  has received from the operating system  201  the message that represents that the disc  101  had been loaded into the disc drive  102 , the video content reproduction program  210  starts a pre-reproduction process shown in  FIG. 29 . 
   [Pre-Reproduction Process] 
     FIG. 29  is a flow chart describing the pre-reproduction process that the video content reproduction program  210  executes. 
   It should be noted that the disc device does not need to perform operations or processes in the time sequence of the flow chart. Alternatively, the disc device may perform the operations or processes in parallel or discretely. However, in the specification, for convenience, the operations or processes of the disc device will be described corresponding to the flow chart. 
   In the pre-reproduction process, at step S 101 , the video content reproduction program  210  checks the disc  101  with a file system function of the operating system  201  and determines whether the disc  101  is a normal disc for the video content reproduction program  210 . 
   As described above, although the disc  101  is accessed (files are read therefrom) with the file system function of the operating system  201 , the description thereof will be omitted. 
   When the determined result at step S 101  represents that the disc  101  is not a normal disc, namely the file system used in the disc  101  does not comply with the operating system  201  or the root directory of the disc  101  does not contain the “VIDEO” directory, the video content reproduction program  210  determines that the video content reproduction program  210  do not comply with the disc  101 , the flow advances to step S 102 . At step S 102 , the graphics process module  219  performs an error process and completes the pre-reproduction process. 
   In other words, the graphics process module  219  generates an error message (video data thereof) that represents that the disc  101  is not normal as an error process and causes the video output module  220  to output the error message so that the error message is displayed. The error process may be performed for example by outputting an alarm sound from the audio output module  221  or unloading the disc  101  from the disc drive  102 . 
   When the determined result at step S 101  represents that the disc  101  is a normal disc, the flow advances to step S 103 . At step S 103 , the video content reproduction program  210  causes the content data supply Module  213  to request the operating system  201  to read the two data files, “SCRIPT.DAT” and “PLAYLIST.DAT,” stored in the “VIDEO” directory of the disc  101  ( FIG. 4 ). Thereafter, the flow advances to step S 104 . At step S 104 , the “SCRIPT.DAT” file is supplied to the script control module  211 . In addition, the “PLAYLIST.DAT” file is supplied to the player control module  212 . 
   Thereafter, the flow advances from step S 104  to steps S 105  through S 107 . At steps S 105  through S 107 , the player control module  212  performs an initialization process. The script control module  211  waits until the player control module  212  has completed the initialization process. 
   [Initialization Process of Player Control Module  212 ] 
   In the initialization process, at step S 105 , the player control module  212  analyzes the “PLAYLIST.DAT” file and checks the number of clip information files described in the “PLAYLIST.DAT” file and their file names. 
   In other words, since the “PLAYLIST.DAT” file is as shown in  FIG. 25  and number_of_PlayLists of the “PLAYLIST.DAT” file shown in  FIG. 25  is 2, the player control module  212  recognizes that there are two PlayList( )&#39;s that are PlayList# 0  and PlayList# 1 . In addition, since number_of_PlayItems of the first PlayList# 0  of the “PLAYLIST.DAT” file shown in  FIG. 25  is 2, the player control module  212  recognizes that PlayList# 0  contains two PlayItem( )&#39;s that are PlayItem# 0  and PlayItem# 1 . Thereafter, the player control module  212  references Clip_Information_file_name&#39;s of the first PlayItem# 0  and the second PlayItem# 1  contained in PlayList# 0  of the “PLAYLIST.DAT” file shown in  FIG. 25  and recognizes that the clip information file (the file name thereof) of the first PlayItem# 0  contained in PlayList# 0  is “00001.CLP” and the clip information file of the second PlayItem# 1  is “00002.CLP.” 
   Likewise, the player control module  212  recognizes that the second PlayList# 1  contains one PlayItem( ) (PlayItem# 0 ) because number_of_PlayItems is 1 and that the clip information file of PlayItem# 0  is “00003.CLP” because of Clip_Information_file_name of PlayItem# 0 . 
   Thereafter, the flow advances from step S 105  to step S 106 . At step S 106 , the player control module  212  reads clip information files recognized at step S 105 , namely three clip information files “00001.CLP,” “00002.CLP,” and “00003.CLP” from the “CLIP” directory under the “VIDEO” directory of the disc  101 . 
   A clip information file of PlayItem of PlayList( ) that is needed to be read at step S 106  is only a clip information of PlayItem of PlayList( ) that is first reproduced. According to this embodiment, however, as described above, all clip information files of PlayItem( ) of PlayList( ) are pre-read. 
   After step S 106 , the flow advances to step S 107 . At step S 107 , the player control module  212  determines whether clip information files recognized at step S 105  have been successfully read. In addition, the player control module  212  determines (checks) whether clip stream files corresponding to the clip information files are present on the disc  101 . In other words, at step S 107 , the player control module  212  determines whether the clip information files “00001.CLP,” “00002.CLP,” and “00003.CLP” have been successfully read and the clip stream files “00001.PS,” “00002.PS” and “00003.PS” corresponding to the clip information files “00001.CLP,” “00002.CLP,” and “00003.CLP” are present in the “STREAM” directory under the “VIDEO” directory of the disc  101 . 
   When the determined result at step S 107  represents that the clip information files recognized at step S 105  have not been successfully read or that the clip stream files corresponding to the clip information files are not present on the disc  101 , namely clip information files and clip stream files, corresponding to the “PLAYLIST.DAT” file have not been recorded on the disc  101 , the video content reproduction program  210  determines that the disc  101  is not correct. Thereafter, the flow returns to step S 102 . At step S 102 , the video content reproduction program  210  performs the foregoing error process and completes the pre-reproduction process. 
   On the other hand, when the determined result at step S 107  represents that clip information files recognized at step S 105  have been successfully read and that the clip stream files corresponding to the clip information files are present on the disc  101 , the player control module  212  completes the initialization process. Thereafter, the flow advances to step S 108 . 
   At step S 108 , the script control module  211  interprets and execute the “SCRIPT.DAT” file. 
   When the script control module  211  executes the “SCRIPT.DAT” file, assuming that the player control module  212  has caused the first PlayList( ) (PlayList# 0 ) to be reproduced, a reproduction process shown in  FIG. 30  is performed. 
   [Reproduction Process] 
     FIG. 30  is a flow chart of the reproduction process that the video content reproduction program  210  performs. 
   [Reproduction Preparation Process] 
   At steps S 121  and S 122 , the player control module  212  performs a reproduction preparation process for PlayList( ) that the script control module  211  has caused to be reproduced, namely the first PlayList( ) (PlayList# 0 ). 
   In other words, at step S 121 , the player control module  212  checks IN_time ( FIG. 6 ) of the first PlayItem# 0  contained in the first PlayList# 0 . Thereafter, the flow advances to step S 122 . At step S 122 , the player control module  212  checks the reproduction start position corresponding to IN_time of PlayItem# 0  of the clip stream file “00001.CLP” reproduced by the first PlayItem# 0  contained in the first PlayList# 0 . 
   When IN_time ( FIG. 6 ) of PlayItem( ) represents the beginning of a clip stream file, a program stream is read from the beginning of the clip stream file. However, when IN_time represents other than the beginning of a clip stream file, the player control module  211  needs to search (check) for the position corresponding to IN_time and read the clip stream file from the position. 
   Specifically, in  FIG. 25 , IN_time of the first PlayItem# 0  contained in the first PlayList# 0  is 180,090. The player control module  212  searches EP_map( ), shown in  FIG. 27 , of the clip stream file “00001.CLP” reproduced by the first PlayItem# 0  contained in the first PlayList# 0 , for the reproduction start position where IN_time of PlayItem# 0  is 180,090. 
   In other words, the player control module  212  searches for the maximum PTS_EP_start that satisfies PTS_EP_start IN_time where PTS_EP_start represents a decodable start point described in EP_map( ) by the binary search method or the like. This is because the position represented by IN_time is not always a decodable start point. 
   In this case, as described above, IN_time is 180,090. In addition, in EP_map( ) shown in  FIG. 27  of the clip stream file “00001.CLP” reproduced by the first PlayItem# 0  contained in the first PlayList# 0 , the maximum value of PTS_EP_start that satisfies PTS_EP_start IN_time is 180,090. Thus, the player control module  212  searches EP_map( ) shown in  FIG. 27  for PTS_EP_start that is 180,090. 
   In addition, the player control module  212  reads  305  (sectors) searched for RPN_EP_start and decides a position represented by RPN_EP_start in the clip stream file “00001.CLP” as the reproducing start position. 
   After the player control module  212  has decided the reproduction start position, the flow advances from S 122  to step S 123 . At step S 123 , the player control module  212  controls the graphics process module  219  to display a time code. The graphics process module  219  generates a time code (video data thereof) under the control of the player control module  212  and outputs the time code to the video output module  220 . Thus, the time code is displayed. 
   The time code displayed at step S 123  is for example a value of which the beginning of PlayList( ) is converted into 00:00:00 (hour:minute:second). In addition to or instead of the time code, a chapter number and an index number may be displayed. 
   [Analysis Process of PlayListMark( )] 
   After the time code has been displayed at step S 123 , the flow advances to step S 124 . At step S 124 , the player control module  212  performs an analysis process that analyzes PlayList( ) that the script control module  211  has caused to be reproduced, namely PlayListMark( ) ( FIG. 7 ) described in the first PlayList( ) (PlayList# 0 ). 
   Specifically, in the upper table shown in  FIG. 28 , number_of_PlayList_marks of PlayListMark( ) of the first PlayList# 0  of the “PLAYLIST.DAT” file that has been pre-read is 7. Thus, the player control module  212  recognizes that the number of Mark( )&#39;s contained in PlayList# 0  is 7. 
   In addition, the player control module  212  analyzes seven Mark( )&#39;s of the upper table shown in  FIG. 28  and recognizes that four Mark( )&#39;s of the first to fourth Mark( )&#39;s of seven Mark( )&#39;s belong to the first PlayItem( ) (PlayItem# 0 ) of PlayList# 0 . 
   Thereafter, the player control module  212  obtains mark_time_stamp&#39;s in four Mark( )&#39;s that belong to the first PlayItem# 0  of PlayList# 0  and supplies them as a four-element matrix to the decode control module  214 . Thus, four times {180,090}, {5,580,090}, {10,980,090}, and {16,380,090} as mark_time_stamp&#39;s of four Mark( )&#39;s of the first to fourth Mark( )&#39;s of the seven Mark( )&#39;s in the upper table shown in  FIG. 28  are sent from the player control module  212  to the decode control module  214 . At this point, an attribute of “mark process” of these times is sent from the player control module  212  to the decode control module  214 . When the time counted by the time count portion  214 A matches a time having an attribute of “mark process,” the decode control module  214  sends a corresponding message, the time matched with the time having an attribute of “mark process,” and an attribute of “mark process” to the player control module  212 . 
   [Decision Process of Elementary Stream to be Reproduced] 
   Thereafter, the flow advances from step S 124  to step S 125 . At step S 125 , the player control module  212  decides an elementary stream to be reproduced. 
   In other words, in the clip information file “00001.CLP,” shown in  FIG. 26A  and  FIG. 26B , described in Clip_Information_file name of the first PlayItem# 0  ( FIG. 25 ) of the first PlayList# 0  as PlayList( ) that the script control module  211  has caused to be reproduced, number_of_streams is 4. Thus, the player control module  212  recognizes that four elementary streams have been multiplexed with the corresponding clip stream file “00001.PS.” In addition, the player control module  212  checks stream_id and private_stream_id of StaticInfo( ) of the clip information file “00001.CLP”, shown in  FIG. 26A  and  FIG. 26B , of the four elementary streams and recognizes that the four elementary streams are one video stream, one ATRAC audio stream, and two subtitle streams. In other words, the player control module  212  recognizes the number of elementary streams having individual attributes multiplexed with the clip stream file “00001.PS.” 
   Information about the number of elementary streams having individual attributes multiplexed with a clip stream file is used to change one elementary stream to another elementary stream to be reproduced (from one audio mode to another audio mode or from one subtitle mode to another subtitle mode). When a clip stream file does not contain a subtitle stream file, namely, a content does not include subtitle data, it is determined whether there is a subtitle stream with the information about the number of elementary streams having an attribute of “subtitle stream.” 
   The player control module  212  selects and decides an elementary stream to be reproduced corresponding to the check result of StaticInfo( ). In this case, four elementary streams multiplexed with the clip stream file “00001.PS” contain one elementary stream having an attribute of “video stream” and one elementary stream having an attribute of “audio stream.” Thus, the elementary stream having an attribute of “video stream” and the elementary stream having an attribute of “audio stream” (ATRAC audio stream) are individually decided as elementary streams to be reproduced. 
   On the other hand, four elementary streams multiplexed with the clip stream file “00001.PS” contain two elementary streams having an attribute of “subtitle stream.” Thus, one of these two subtitle streams is selected and decided. In this example, a subtitle stream that first appears in the two subtitle streams in the clip information file “00001.CLP” is selected. 
   When the attributes and the number of elementary streams multiplexed with the clip stream file “00001.PS” are recognized, four elementary streams need to be identified. The player control module  212  identifies the four elementary streams multiplexed with the clip stream file “00001.PS” with stream_id and private_stream_id. 
   In other words, the player control module  212  identifies an elementary stream having an attribute of “video stream” from the four elementary streams multiplexed with the clip stream file “00001.PS” with stream_id that is 0xE0 as described in the clip information file “00001.CLP” shown in  FIG. 26A  and  FIG. 26B . 
   In addition, the player control module  212  identifies an ATRAC audio stream, which is an elementary stream having an attribute of “audio stream”, from the four elementary streams multiplexed with the clip stream file “00001.PS” with stream_id that is 0xBD and private_stream_id that is 0x00 as described in the clip information file “00001.CLP” shown in  FIG. 26A  and  FIG. 26B . 
   In addition, the player control module  212  identifies two subtitle streams, which are elementary streams having an attribute of “subtitle stream,” from the four elementary streams multiplexed with the clip stream file “00001.PS” with stream_id that is 0xBD and private_stream_id that is 0x80 and with stream_id that is 0xBD and private_stream_id that is 0x81. 
   As described above, an elementary stream multiplexed with a clip stream file can be identified by stream_id and private_stream_id described as meta data of a clip information file corresponding to the clip stream file. 
   A combination of stream_id and private_stream_id is a mechanism provided to extend the multiplexing of the MPEG2-System. When a combination of stream_id and private_stream_id is used as meta data that are a database, an elementary stream can be securely identified. In addition, when private_stream_id is extended for increases of the number and types of corresponding elementary streams, the current mechanism can be used without any change. Thus, a combination of stream_id and private_stream_id has high extensibility. 
   In other words, for example the blu-ray disc (BD) standard uses a packet ID (PID) of a transport stream of the MPEG2 standard to identify data. Thus, the BD standard is restricted by the MPEG2 standard. On the other hand, the DVD-Video standard defines sub_stream_id that is similar to private_stream_id. However, sub_stream_id cannot be described in a database to identify a stream sub_stream_id is described in a fixed region for information of only eight to 32 streams (see VI4-49, Table 4.2.1-2 (VTS_AST_ATRT) and VI4-52, Table 4.2.1-3 (VTS_SPST_ATRT)). Thus, sub_stream_id does not have high extensibility. 
   On the other hand, a combination of stream_id and private_stream_id can be described with meta data. For example, clip-information files Clip( ) shown in  FIG. 10  can describe a combination of stream_id and private_stream_id corresponding to a value represented by number_of_streams. Thus, elementary streams multiplexed with a clip stream file can be identified by a combination of stream_id and private_stream_id as meta data described in the clip information file Clip( ) regardless of the number of elementary streams (in the range represented by number_of_streams). 
   According to this embodiment, a combination of stream_id and private_stream_id is used to identify an elementary stream multiplexed with a clip stream file corresponding to a clip information file shown in  FIG. 10 . In addition, this combination can be used to identify an elementary stream that correlates Mark( ) as a combination of entry_ES_stream_id and entry_ES_private_stream_id of PlayListMark( ) shown in  FIG. 7 . In addition, a combination of stream_id and private_stream_id is used to identify an elementary stream that describes information of a decodable start point in EP_map( ) shown in  FIG. 14 . 
   [Output Attribute Control Process] 
   Thereafter, the flow advances from step S 125  to step S 126 . At step S 126 , the player control module  212  performs an output attribute control process for an elementary stream decided at step S 125  as that to be reproduced at step S 125 . 
   Specifically, the player control module  212  checks number_of_DynamicInfo ( FIG. 10 ), which represents the number of DynamicInfo( )&#39;s ( FIG. 13 ), which describe output attributes of a video stream, an ATRAC audio stream, and an subtitle stream decided at step S 125  as those to be reproduced. 
   In this case, a video stream, an ATRAC audio stream, and a subtitle stream to be reproduced are elementary streams multiplexed with the clip stream file “00001.PS”. In the clip information file “00001.CLP” shown in  FIG. 26A  and  FIG. 26B , number_of_DynamicInfo&#39;s are all 0. When number_of_DynamicInfo&#39;s are all 0, the player control module  212  does not perform the output attribute control process for output attributes of elementary streams to be reproduced. 
   When number_of_DynamicInfo of elementary streams to be reproduced is not 0, the output attribute control process for the elementary streams is performed. The output attribute control process will be described later. 
   [Reproduction Start Preparation Process] 
   After step S 126 , the flow advances to step S 127 . At step S 127 , the player control module  212  performs the reproduction start preparation process for elementary streams to be reproduced. 
   In other words, the player control module  212  supplies the file name of the clip stream file “00001.PS” with which an elementary stream to be reproduced has been multiplexed and RPN_EP_start (= 305 ) described in EP_map( ) as the reproduction start position decided at step S 122  to the content data supply module  213 . 
   In addition, the player control module  212  initializes the buffer control module  215  before the program stream stored in the clip stream file “00001.PS” with which the elementary stream to be reproduced has been multiplexed is supplied to the buffer control module  215 . 
   Specifically, the buffer control module  215  ( FIG. 3 ) sets the same value to the data start pointer stored in the data start pointer storage portion  231 , the data write pointer stored in the data write pointer storage portion  232 , the video read pointer stored in the video read pointer storage portion  241 , the audio read pointer stored in the audio read pointer storage portion  251 , and the subtitle read pointer stored in the subtitle read pointer storage portion  262 . 
   Thus, the data start pointer stored in the data start pointer storage portion  231  and the data write pointer stored in the data write pointer storage portion  232  hold the same position of the buffer  215 A of the buffer control module  215 . This represents that no valid data have been stored in the buffer  215 A. 
   In addition, the player control module  212  supplies stream_id and if necessary private_stream_id as identification information for an elementary stream to be reproduced to the buffer control module  215 . 
   In other words, as described above, a video stream having an attribute of “video stream” in elementary streams to be reproduced is identified by stream_id that is 0xE0. An ATRAC audio stream having an attribute of “audio stream” is identified by stream_id that is 0xBD and private_stream_id that is 0x00. A subtitle stream having an attribute of “subtitle stream” is identified by stream_id that is 0xBD and private_stream_id that is 0x80. The player control module  212  supplies these stream_id&#39;s and private_stream_id&#39;s to the buffer control module  215 . 
   In the buffer control module  215  ( FIG. 3 ), the video read function portion  233  stores stream_id that is 0xE0 for a video stream, received from the player control module  212 , to the stream_id register  242 . In addition, the audio read function portion  234  stores stream_id that is 0xBD and private_stream_id that is 0x00, received from the player control module  212 , to the stream_id register  252  and the private_stream_id register  253 , respectively. In addition, the subtitle read function portion  235  stores stream_id that is 0xBD and private_stream_id that is 0x80, received from the player control module  212 , to the stream_id register  263  and the private_stream_id register  264 , respectively. 
   The player control module  212  stores stream_id and private_stream_id for an elementary stream to be reproduced, supplied to the buffer control module  215 , for a later process. The player control module  212  uses stream_id and private_stream_id when a stream change request message takes place or a stream that is being reproduced in a mark process, that will be described later, is identified. 
   To initialize the buffer control module  215  ( FIG. 3 ), the player control module  212  sets the subtitle read function flag having a value corresponding to the clip stream file multiplexed with an elementary stream to be reproduced to the subtitle read function flag storage portion  261 . 
   In other words, in this case, since the clip stream file “00001.PS” with which elementary streams to be reproduced have been multiplexed contains a subtitle stream, the subtitle read function flag whose value is 1 is set to the subtitle read function flag storage portion  261  to activate the subtitle read function portion  235 . When a clip stream file with which an elementary stream to be reproduced has not been multiplexed does not contain a subtitle stream, the subtitle read function flag whose value is 0 is set to the subtitle read function flag storage portion  261 . In this case, the subtitle read function portion  235  is not activated (the subtitle read function portion  235  does not perform any process). 
   In addition, the player control module  212  supplies IN_time that is 180,090 and OUT_time that is 27,180,090, of the first PlayItem# 0  ( FIG. 25 ) contained in the first PlayList# 0  that the script control module  211  has caused the player control module  212  to reproduce to the decode control module  214 . The decode control module  214  uses IN_time to start decoding a clip reproduced by PlayItem( ) and OUT_time to stop decoding the clip and to control a PlayItem change process, that will be described later. 
   The player control module  212  initializes a subtitle stream display mode in which the graphics process module  219  displays a subtitle stream. In other words, the player control module  212  controls the graphics process module  219  to display a subtitle stream in a default display mode. 
   [Start Reading Data] 
   Thereafter, the flow advances from step S 127  to step S 128 . The player control module  212  controls the content data supply module  213  to read a clip stream file that contains a program stream with which an elementary stream to be reproduced has been multiplexed using the function of the operating system  201 . In other words, the content data supply module  213  designates the clip stream file “00001.PS” of the “STREAM” directory under the “VIDEO” directory of the disc  101  ( FIG. 4 ), designates sector  305 , which is the reproduction start position, which has been decided at step S 122 , and causes the operating system  201  to read the file. The content data supply module  213  causes the operating system  201  to supply data that have been read from the disc  101  to the buffer control module  215 . 
   Thus, the program stream of the clip stream file “00001.PS” is read from the disc  101 . The program stream is supplied to the buffer control module  215 . 
   The buffer control module  215  ( FIG. 3 ) writes the program stream that has been read from the disc  101  to the position represented by the data write pointer of the data write pointer storage portion  232  of the buffer  215 A and increments the data write pointer by the size of the write data. 
   Unless otherwise specified, when the buffer  215 A of the buffer control module  215  has a free space, the content data supply module  213  reads data from the disc  101 , supplies and stores the data to the buffer  215 A of the buffer control module  215 . Thus, the buffer  215 A always stores sufficient amount of data. 
   [Start of Controlling Decoder] 
   When data are read from the disc  101  and the data are stored to the buffer  215 A of the buffer control module  215 , the flow advances from step S 128  to step S 129 . At step S 129 , the decode control module  214  controls the video decoder control module  216 , the audio decoder control module  217 , and the subtitle decoder control module  218  to start reading data from the buffer  215 A as a pre-decode operation. 
   Thus, the video decoder control module  216  requests the video read function portion  233  of the buffer control module  215  ( FIG. 3 ) to send data. The video decoder control module  216  obtains one video access unit stored in the buffer  215 A, the PTS and DTS (sometimes referred to as time stamps) added to the video access unit, pic_struct_copy, au_ref_flag, and AU_length that are information (sometimes referred to as additional information) described in PES_packet( ) of private_stream_ 2  immediately preceded by a decodable start point, and so forth from the buffer control module  215  corresponding to the request. The time stamps are supplied from the video decoder control module  216  to the decode control module  214  whenever the video decoder control module  216  obtains a video access unit. 
   On the other hand, the audio decoder control module  217  requests the audio read function portion  234  of the buffer control module  215  ( FIG. 3 ) to send data. The audio decoder control module  217  obtains one (ATRAC) audio access unit stored in the buffer  215 A and the time stamps (PTS and DTS) added to the audio access unit from the buffer control module  215  corresponding to the request. The time stamps are supplied from the audio decoder control module  217  to the decode control module  214  whenever the audio decoder control module  217  obtains an audio access unit. 
   In addition, the subtitle decoder control module  218  requests the subtitle read function portion  235  of the buffer control module  215  ( FIG. 3 ) to send data. The subtitle decoder control module  218  obtains one subtitle access unit stored in the buffer  215 A and the time stamps added to the subtitle access unit from the buffer control module  215  corresponding to the request. The time stamps are supplied from the subtitle decoder control module  218  to the decode control module  214  whenever the subtitle decoder control module  218  obtains a subtitle access unit. When an elementary stream to be reproduced does not contain a subtitle stream or the buffer  215 A does not store a subtitle access unit, data are not supplied from the buffer control module  215  to the subtitle decoder control module  218 . 
   Whenever the video decoder control module  216 , the audio decoder control module  217 , and the subtitle decoder control module  218  request the buffer control module  215  to send data, they send the results to the decode control module  214 . 
   Details of data that are read from the buffer  215 A when the buffer control module  215  sends the data to the video decoder control module  216 , the audio decoder control module  217 , and the subtitle decoder control module  218  will be described later. 
   [Start of Decoding Data] 
   When the video decoder control module  216 , the audio decoder control module  217 , and the subtitle decoder control module  218  start reading data from the buffer  215 A of the buffer control module  215 , the flow advances from step S 129  to step S 130 . At step S 130 , these modules start decoding the data that have been read. 
   In other words, the decode control module  214  causes the video decoder control module  216 , the audio decoder control module  217 , and the subtitle decoder control module  218  to start decoding corresponding to IN_time, which is 180,090, of the first PlayItem# 0  contained in PlayList# 0 , supplied from the player control module  212  at step S 127  and corresponding to the time stamps supplied from the video decoder control module  216 , the audio decoder control module  217 , and the subtitle decoder control module  218  at step S 129  or if necessary at changed timing so that data that are decoded are securely synchronized. 
   A method for starting decoding data at changed timing so that the data are securely synchronized is described in for example Japanese Patent No. 3496725. In short, the minimum value of time stamps supplied from the video decoder control module  216 , the audio decoder control module  217 , and the subtitle decoder control module  218  is set as an initial value of the time count portion  214 A. The time count portion  214 A starts counting a time from this set time. When the time counted by the time count portion  214 A matches a time stamp, the decode control module  214  causes these modules to start decoding data. 
   The video decoder control module  216  receives a decode start command from the decode control module  214 , supplies one video access unit obtained from the video read function portion  233  of the buffer control module  215  ( FIG. 3 ) to the video decoder  116  ( FIG. 1 ), and causes the video decoder  116  to decode the video access unit. In addition, the video decoder control module  216  supplies video data decoded by the video decoder  116  to the graphics process module  219 . 
   Thereafter, the video decoder control module  216  causes the video decoder  116  to successively decode video access units obtained from the video read function portion  233  of the buffer control module  215  one at a time and supplies the decoded video access unit as video data to the graphics process module  219 . 
   The audio decoder control module  217  receives a decode start command from the decode control module  214 , supplies one audio access unit obtained from the audio read function portion  234  of the buffer control module  215  ( FIG. 3 ) to the audio decoder  117  ( FIG. 1 ), and causes the audio decoder  117  to decode the audio access unit. The audio decoder control module  217  supplies audio data decoded by the audio decoder  117  to the audio output module  221 . 
   Thereafter, the audio decoder control module  217  causes the audio decoder  117  to successively decode audio access units obtained from the audio read function portion  234  of the buffer control module  215  one at a time and supplies the decoded audio access unit as audio data to the audio output module  221 . 
   In addition, the subtitle decoder control module  218  receives a decode start command from the decode control module  214 , causes the internal subtitle decode software to decode one subtitle access unit obtained from the subtitle read function portion  235  corresponding to the command, and supplies the decoded subtitle access unit as subtitle data (image data of a subtitle) to the graphics process module  219 . 
   Thereafter, the subtitle decoder control module  218  causes the internal decode software to successively decode subtitle access units obtained from the subtitle read function portion  235  of the buffer control module  215  one at a time and supplies the decoded subtitle access unit as subtitle data to the graphics process module  219 . 
   [Graphics Process] 
   Thereafter, the flow advances from step S 130  to step S 131 . At step S 131 , the graphics process module  219  performs a graphics process for video data supplied from the video decoder control module  216  and if necessary for subtitle data supplied from the subtitle decoder control module  218 . 
   In other words, the graphics process module  219  performs a subtitle process that for example enlarges or reduces subtitle data supplied from the subtitle decoder control module  218  corresponding to a display mode command received from the player control module  212 . When the graphics process module  219  has not received a display mode command from the player control module  212  or there is a default display mode, the graphics process module  219  stores subtitle data received from the subtitle decoder control module  218 . 
   In addition, the graphics process module  219  adds video data received from the video decoder control module  216  and subtitle data received from the subtitle decoder control module  218  or subtitle data that have been processed, obtains output video data with which subtitle data have been overlaid, and supplies the overlaid video data to the video output module  220 . 
   When the graphics process module  219  receives an information display command for a menu, a message, a time code, a chapter number, or an index number from the script control module  211  or the player control module  212 , the graphics process module  219  generates the information, overlays it with output video data, and supplies the overlaid data to the video output module  220 . 
   [Output Process] 
   After step S 131 , the flow advances to step S 132 . At step S 132 , the video output module  220  successively stores output video data supplied from the graphics process module  219  to the FIFO  220 A and outputs video data stored in the FIFO  220 A at a predetermined output rate. 
   As long as the FIFO  220 A has a sufficient storage capacity (free space), the video output module  220  receives output video data from the graphics process module  219 . When the FIFO  220 A does not have a sufficient storage capacity, the video output module  220  causes the graphics process module  219  to stop receiving the output video data. Thus, the graphics process module stops receiving the output data. In addition, the video output module  220  causes the video decoder control module  216  and the subtitle decoder control module  218  to stop their processes. Thus, the video decoder control module  216  and the subtitle decoder control module  218  stop their processes. 
   After the video output module  220  has caused the graphics process module  219  to stop receiving output video data and the FIFO  220 A has output video data, when the FIFO  220 A has a sufficient storage capacity, the video output module  220  causes the graphics process module  219  to receive output video data. Like output video data, the graphics process module  219  causes the video decoder control module  216  and the graphics process module  219  to stop receiving data. Thus, the graphics process module  219 , the video decoder control module  216 , and the subtitle decoder control module  218  resume the stopped processes. 
   On the other hand, the audio output module  221  also causes the FIFO  221 A to successively store audio data supplied from the audio decoder control module  217  at step S 130  and to output audio data at a predetermined output rate (sampling frequency). 
   As long as the FIFO  221 A has a sufficient storage capacity (blank space), the audio output module  221  receives audio data from the audio decoder control module  217 . However, when the FIFO  221 A does not have a sufficient storage capacity, the audio output module  221  causes the audio decoder control module  217  to stop receiving audio data. Thus, the audio decoder control module  217  stops its process. 
   After the audio output module  221  has caused the audio decoder control module  217  to stop receiving audio data and the FIFO  221 A has output audio data, when the FIFO  221 A has a sufficient storage capacity, the audio output module  221  causes the audio decoder control module  217  to receive audio data. Thus, the audio decoder control module  217  resumes the stopped process. 
   In the foregoing manner, as the video output module  220  and the audio output module  221  output data, elementary streams are decoded. 
   The disc device shown in  FIG. 1  reproduces data from the disc  101  corresponding to the flow charts shown in  FIG. 29  and  FIG. 30 . Next, other processes or operations of the disc device that performs while it is reproducing data from the disc  101  will be described. 
   [Changing PlayItem&#39;s] 
   As described in  FIG. 29  and  FIG. 30 , the first PlayItem# 0  of the first PlayList# 0  shown in  FIG. 25  is reproduced. Corresponding to PlayList# 0 , after the first PlayItem# 0  is reproduced, the second PlayItem# 1  is reproduced. In other words, a PlayItem change process that changes PlayItem&#39;s from PlayItem# 0  to PlayItem# 1  is performed. 
   Next, with reference to a flow chart shown in  FIG. 31 , the PlayItem change process will be described. 
   As described in  FIG. 29  and  FIG. 30 , after the first-PlayItem# 0  (a clip-thereof) of PlayList# 0  shown in  FIG. 25  is reproduced, while the first PlayItem# 0  is being reproduced, the decode control module  214  ( FIG. 2A  and  FIG. 2B ) checks time that a time count portion  214 A is counting. 
   [End of Reproduction of PlayItem# 0 ] 
   When the time that time count portion  214 A has counted became 27,180,090 ( FIG. 25 ) that is the same as OUT_time of the first PlayItem# 0  supplied from the player control module  212  at step S 127  shown in  FIG. 30 , the decode control module  214  performs a decode stop control to stop reproducing PlayItem# 0  at step S 151 . 
   In other words, the decode control module  214  operates the video decoder control module  216 , the audio decoder control module  217 , and the subtitle decoder control module  218  to stop their decode operations. The decode control module  214  controls the video output module  220  to successively output video data. 
   In addition, the decode control module  214  sends a message that represents that the first PlayItem# 0  has been reproduced to the player control module  212 . 
   [Start of Reproduction of PlayItem# 1 ] 
   As described above, the player control module  212  has recognized that the first PlayList# 0  contains the first PlayItem# 0  and the second PlayItem# 1  at step S 105  shown in  FIG. 29 . When the decode control module  214  has informed the player control module  212  that the first PlayItem# 0  had been reproduced, the flow advances from step S 151  to step S 152 . At step S 152 , in the same manner as the first PlayItem# 0 , the player control module  212  starts reproducing the second PlayItem# 1 . 
   Like step S 122  shown in  FIG. 30 , the player control module  212  decides one of RPN_EP_start&#39;s described in EP_map( ) as the reproduction start position of the second PlayItem# 1 . 
   In addition, the player control module  212  recognizes Mark( )&#39;s that belong to the second PlayItem# 1  described at step S 124  shown in  FIG. 30  and the number of elementary streams having attributes multiplexed with the clip stream file “00002.PS” reproduced by PlayItem# 1  described at step S 125   FIG. 30  and decides an elementary stream to be reproduced. 
   The player control module  212  performs the same process as that at step S 127  shown in  FIG. 30 . 
   In other words, the player control module  212  supplies RPN_EP_start of EP_map( ) decided as the reproduction start position and the file name of a clip stream file multiplexed with an elementary stream to be reproduced, namely the file name of the clip stream file “00002.PS” corresponding to “00002.CLP” described in Clip_Information_file_name of the second PlayItem# 1  ( FIG. 25 ) to the content data supply module  213 . 
   In addition, before a program stream stored in the clip stream file “00002.PS” multiplexed with an elementary stream to be reproduced is supplied to the buffer control module  215 , the player control module  212  initializes the buffer control module  215 . 
   In other words, the buffer control module  215  ( FIG. 3 ) sets the same value to the data start pointer stored-in the data start pointer storage portion  231 , the data write pointer stored in the data write pointer storage portion  232 , the video read pointer stored in the video read pointer storage portion  241 , the audio read pointer stored in the audio read pointer storage portion  251 , and the subtitle read pointer stored in the subtitle read pointer storage portion  262 . 
   In addition, the player control module  212  supplies stream_id and if necessary private_stream_id as identification information that identifies an elementary stream to be reproduced to the buffer control module  215 . 
   The video read function portion  233  of the buffer control module  215  ( FIG. 3 ) receives stream_id of a video stream of elementary streams to be reproduced from the player control module  212  and stores it to the stream_id register  242 . In addition, the audio read function portion  234  receives stream_id and private_stream_id of an audio stream of elementary streams to be reproduced from the player control module  212  and stores them to the stream_id register  252  and the private_stream_id register  253 . 
   Since the clip stream file “00002.PS” multiplexed with an elementary stream to be reproduced contains a subtitle stream, stream_id and private_stream_id of the subtitle stream of elementary streams to be reproduced are supplied from the player control module  212  to the subtitle read function portion  235 . The subtitle read function portion  235  stores stream_id and private_stream_id to the stream_id register  263  and the private_stream_id register  264 , respectively. 
   The player control module  212  sets a subtitle read function flag that has a value corresponding to a clip stream file multiplexed with an elementary stream to be reproduced to the subtitle read function flag storage portion  261  to initialize the buffer control module  215  ( FIG. 3 ). 
   In this case, since the clip stream file “00002.PS” multiplexed with elementary streams to be reproduced contains a subtitle stream, the subtitle read function flag having a value of 1 is set to the subtitle read function flag storage portion  261  to activate the subtitle read function portion  235 . 
   The player control module  212  supplies 90,000 as IN_time and 27,090,000 as OUT_time of the second PlayItem# 1  to be reproduced ( FIG. 25 ) to the decode control module  214 . 
   In addition, the player control module  212  initializes a subtitle stream display mode command for the graphics process module  219 . In other words, the player control module  212  controls the graphics process module  219  to display subtitle data in the default display mode. 
   When configurable_flag ( FIG. 12 ) of a subtitle stream to be reproduced is 1, which represents that the display mode is permitted to be changed, the subtitle stream display mode command that the player control module  212  sends to the graphics process module  219  may be the current display mode command. 
   In the same manner as the first PlayItem# 0 , the second PlayItem# 1  is reproduced. While the second PlayItem# 1  is being reproduced, the decode control module  214  monitors the time that the time count portion  214 A is counting. When the time that the time count portion  214 A has counted became 27,090,000 ( FIG. 25 ) that is the same as OUT_time of the second PlayItem# 1  supplied from the player control module  212  at step S 152  ( FIG. 31 ), the decode control module  214  performs the same decode stop control as that at step S 151  to stop reproducing PlayItem# 1 . 
   [Display of Time Code] 
   Next, as described above, at step S 123  shown in  FIG. 30 , a time code is displayed. The time code is successively updated. 
   Next, with reference to a flow chart shown in  FIG. 32 , a time code display process will be described. 
   When the time count portion  214 A of the decode control module  214  ( FIG. 2A  and  FIG. 2B ) has counted one second, the flow advances to step S 171 . At step S 171 , the decode control module  214  supplies a message that represents that one second has elapsed and the current time that the time count portion  214 A has counted to the player control module  212 . Thereafter, the flow advances to step S 172 . At step S 172 , the player control module  212  receives the message and the current time from the decode control module  214  and converts the current time into a time code. Thereafter, the flow advances to step S 173 . 
   At step S 173 , the player control module  212  controls the graphics process module  219  to display the time code obtained at step S 172 . Thereafter, the flow returns to step S 171 . 
   Thus, the time code is updated at intervals of one second. The update intervals of the time code are not limited to one second. 
   [Changing Streams] 
   The clip stream file “00001.PS” reproduced by the first PlayItem# 0 , which composes the first PlayList# 0  described in  FIG. 25 , and the clip stream file “00002.PS” reproduced by the second PlayItem# 1  are multiplexed with two subtitle streams as described in  FIG. 26A  and  FIG. 26B . 
   When a plurality of elementary streams having the same attribute are multiplexed with a clip stream file, elementary streams to be reproduced can be changed from one elementary stream to another elementary stream. 
   Next, with reference to a flow chart shown in  FIG. 33 , a stream change process will be described. 
   When a stream change command is described as a script program in for example the “SCRIPT.DAT” file ( FIG. 4 ) and the script control module  211  executes the script program or the user operates the remote controller to change streams, a stream change command is supplied to the player control module  212 . 
   When the script control module  211  executes a script program that describes the stream change request, the script control module  211  supplies a stream change request message to the player control module  212 . When the user inputs a stream change command with the remote controller, the input interface  115  receives the stream change command signal from the remote controller and supplies the stream change request message to the player control module  212 . 
   When the subtitle stream change request message, which causes the player control module  212  to change subtitle streams, is supplied to the player control module  212 , it checks the number of subtitle streams of elementary streams to be reproduced, which has been recognized at step S 125  shown in  FIG. 30 . 
   When the number of subtitle streams that the player control module  212  has checked is 1 or less, the player control module. 212  ignores the subtitle stream change request message. Thus, the player control module  212  does not perform the process from step S 192  to step S 194 . 
   In contrast, when the number of subtitle streams is two or more, the flow advances to step S 192  to S 194 . At these steps, the player control module  212  changes a subtitle stream that is being reproduced to another subtitle stream. 
   In other words, at step S 192 , the player control module  212  identifies a subtitle stream, which is being reproduced, on a clip information file. Specifically, assuming that a subtitle stream whose stream_id is 0xBD and private_stream_id is 0x80 and that is multiplexed with the clip stream file “00002.PS” is being reproduced corresponding to the second PlayItem# 1 , which composes the first PlayList# 0  described in  FIG. 25 , the player control module  212  identifies a subtitle stream that is being reproduced as stream# 2 , which is the third subtitle stream of the clip information file “00002.CLP”, of two subtitle streams multiplexed with the clip stream file “00002.PS” at step S 192 . 
   Thereafter, the flow advances to step S 193 . At step S 193 , the player control module  212  recognizes (identifies) the next subtitle stream of the clip information file identified at step S 192  as a subtitle stream to be reproduced next. In  FIG. 26A  and  FIG. 26B , the next subtitle stream of the third subtitle stream stream# 2  is the fourth subtitle stream stream# 3 . Thus, at step S 193 , the player control module  212  recognizes the fourth subtitle stream stream# 3  as a subtitle stream to be reproduced next. 
   When a subtitle stream that is being reproduced is identified as stream# 3 , which is the fourth subtitle stream in the clip information file “00002.CLP” shown in  FIG. 26A  and  FIG. 26B , of two subtitle streams multiplexed with the clip stream file “00002.PS,” the player control module  212  recognizes for example the third subtitle stream stream# 2  as a subtitle stream to be reproduced next. 
   Thereafter, the flow advances to step S 194 . At step S 194 , the player control module  212  supplies stream_id and private_stream_id of the subtitle recognized at step S 193  as a subtitle stream to be reproduced next to the subtitle read function portion  235  of the buffer control module  215  ( FIG. 3 ) so that the subtitle read function portion  235  reads the next subtitle access unit identified by stream_id and private_stream id from the buffer  215 A. 
   The subtitle read function portion  235  of the buffer control module  215  ( FIG. 3 ) newly sets stream_id and private_stream_id supplied from the player control module  212  at step S 194  to the stream_id register  263  and the private_stream_id register  264 , respectively. The subtitle read function portion  235  reads the next subtitle access unit identified by stream_id and private_stream_id newly set to the stream_id register  263  and the private_stream_id register  264 , respectively. 
   In the foregoing manner, a subtitle stream that is being reproduced is changed to another subtitle stream that is reproduced next. 
   [Processes of Buffer Control Module  215 ] 
   Next, with reference to  FIG. 34  to  FIG. 38 , processes of the buffer control module  215  ( FIG. 3 ), data write process and data read process to and from the buffer  215 A, will be described. 
   As described in  FIG. 3 , the buffer control module  215  has five pointers that are used to read and write data from and to the buffer  215 A. 
   In other words, as shown in  FIG. 34  and  FIG. 35 , the buffer control module  215  has the data start pointer stored in the data start pointer storage portion  231 , the data write pointer stored in the data write pointer storage portion  232 , the video read pointer stored in the video read pointer storage portion  241 , the audio read pointer stored in the audio read pointer storage portion  251 , and the subtitle read pointer stored in the subtitle read pointer storage portion  262 . 
   In  FIG. 34  and  FIG. 35 , the stream_id register  242 ,and the au_information( ) register  243  of the video read function portion  233  shown in  FIG. 3 , the stream_id register  252  and the private_stream_id register  253  of the audio read function portion  234 , and the subtitle read function flag storage portion  261 , the stream_id register  263 , and the private_stream_id register  264  of the subtitle read function portion  235  are omitted. 
   The data start pointer stored in the data start pointer storage portion  231  represents the position of the oldest data (that need to be read and have not been read) stored in the buffer  215 A. The data write pointer stored in the data write pointer storage portion  232  represents the write position of data in the buffer  215 A. This position is the position to which the newest data are written. 
   The video read pointer stored in the video read pointer storage portion  241  represents the position of a video stream that is read from the buffer  215 A. The audio read pointer stored in the audio read pointer storage portion  251  represents the position of an audio stream read from the buffer  215 A. The subtitle read pointer stored in the subtitle read pointer storage portion  262  represents the position of a subtitle stream read from the buffer  215 A. 
   As described in  FIG. 3 , the data start pointer, the data write pointer, the video read pointer, the audio read pointer, and the subtitle read pointer are moved in the clockwise direction in the buffer  215 A. 
   As shown in  FIG. 35 , according to this embodiment, the data start pointer is always updated so that it represents the same position as the oldest data position of the video read pointer, the audio read pointer, and the subtitle read pointer. In  FIG. 35 , the audio read pointer represents the position of the oldest data in the video read pointer, the audio read pointer, or the subtitle read pointer. The data start pointer matches the audio read pointer. 
   In the buffer control module  215 , which has the data start pointer, the data write pointer, the video read pointer, the audio read pointer, and the subtitle read pointer, when new data are read from the disc  101  and written to the buffer  215 A, the data write pointer is updated in the clockwise direction so that the data write pointer represents the position immediately after the newly written data. 
   When a video stream, an audio stream, or a subtitle stream is read from the buffer  215 A, the video read pointer, the audio read pointer, or the subtitle read pointer is updated in the clockwise direction for the amount of data that are read. The amount of data that are read is the sum of video data, audio data, or subtitle data that are actually read and a data portion of another stream intervened in the data that are read and that are omitted when they are read. 
   When the video read pointer, the audio read pointer, or the subtitle read pointer is updated, the data start pointer is updated so that it represents the position of the oldest data represented by the video read pointer, the audio read pointer, or the subtitle read pointer. 
   The buffer control module  215  controls the data write operation of the buffer  215 A so that the data write pointer does not get ahead of the data start pointer. 
   Unless the data write pointer gets ahead of the data start pointer, the buffer control module  215  writes data read from the disc  101  to the position of the buffer  215 A represented by the data write pointer and updates the data write pointer. On the other hand, if the data write pointer is going to get ahead of the data start pointer, the buffer control module  215  causes the content data supply module  213  to stop reading data from the disc  101  and stops writing data to the buffer  215 A. Thus, the buffer  215 A can be prevented from overflowing. 
   As described above, data that are read from the disc  101  are written to the buffer  215 A corresponding to the relationship of the positions of the two pointers, the data start pointer and the data write pointer. 
   On the other hand, the buffer control module  215  controls the data read operation of the buffer  215 A so that the video read pointer, the audio read pointer, and the subtitle read pointer, and the data start pointer do not get ahead of the data write pointer. 
   In other words, unless the video read pointer, the audio read pointer, or the subtitle read pointer gets ahead of the data write pointer, the buffer control module  215  reads data from the position of the buffer  215 A represented by the video read pointer, the audio read pointer, or the subtitle read pointer corresponding to a request received from the video decoder control module  216 , the audio decoder control module  217 , or the subtitle decoder control module  218  and updates the video read pointer, the audio read pointer, or the subtitle read pointer and if necessary the data start pointer. On the other hand, if the video read pointer, the audio read pointer, or the subtitle read pointer is going to get ahead of the data write pointer, the buffer control module  215  causes the video decoder control module  216 , the audio decoder control module  217 , or the subtitle decoder control module  218  to stop sending the request or wait until the buffer  215 A stores enough data. As a result, the buffer  215 A can be prevented from under-flowing. 
   Thus, the buffer  215 A stores data to be supplied to the video decoder control module  216 , the audio decoder control module  217 , and the subtitle decoder control module  218  in a region (shaded in  FIG. 34  and  FIG. 35 ) in the clockwise direction from the position represented by the data start pointer to the position represented by the data write pointer. In addition, the video read pointer, the audio read pointer, and the subtitle read pointer are present in the region. 
   In the foregoing case, the data start pointer is updated so that it represents the position of the oldest data represented by the video read pointer, the audio read pointer, and the subtitle read pointer represent. Alternatively, the data start pointer may be updated so that it represents the position of data that are earlier by a predetermined time (for example, one second) than the position of the oldest data. 
   It can be assumed that the video read pointer and the audio read pointer in the video read pointer, the audio read pointer, and the subtitle read pointer represent the position of the oldest data. 
   Thus, when the data start pointer is updated so that it represents the position of data that are earlier by for example one second than the position of the oldest data that the video read pointer or the audio read pointer represents, as shown in  FIG. 34 , earlier data by one second than the oldest data that the video read pointer or the audio read pointer represents can be stored in the buffer  215 A. In  FIG. 34 , the audio read pointer represents the position of the oldest data, whereas the data start pointer represents the position of data that are earlier by one second than the oldest data. 
   When the data start pointer is updated so that it represents the position of data that are earlier by one second than the position of the oldest data, the response of the disc device can be improved. 
   In other words, as shown in  FIG. 35 , when the data start pointer is updated so that it represents the position of the oldest data that the audio read pointer represents, if a special reproduction command for example a reverse reproduction command is issued, data that have been read from the buffer  215 A need to be re-read from the disc  101 . Thus, after the special reproduction command is issued until the special reproduction operation is performed, it takes a time to some extent. 
   In contrast, when the data start pointer is updated so that it represents the position of data that are earlier by one second than the position of the oldest data that the audio read pointer represents, if a special reproduction command for example a reverse reproduction command is issued and data necessary for starting the special reproduction operation are data earlier by one second than the oldest data and stored in the buffer  215 A, the special reproduction operation can be quickly started without need to re-read the data from the disc  101 . 
   When the data start pointer is updated so that it represents the position of data that are earlier by one second than the position of the oldest data that the audio read pointer represents, data necessary for starting the special reproduction operation may not be stored in the buffer  215 A. In this case, the data necessary for starting the special reproduction operation are re-read from the disc  101 . 
   Next, the read operations for a video stream, an audio stream, and a subtitle stream from the buffer  215 A will be described in detail. 
   As described at step S 127  shown in  FIG. 30 , when the reproduction operation of a clip stream file is started, the buffer control module  215  initializes the data start pointer, the data write pointer, the video read pointer, the audio read pointer, and the subtitle read pointer so that they represent the same position in the buffer  215 A. 
   When a program stream (MPEG2-system program stream) stored in a clip stream file is read from the disc  101  and supplied to the buffer control module  215 , it stores the program stream at the position that the data write pointer of the buffer  215 A represents. In addition, the data write pointer is updated in the clockwise direction. 
   In addition, the video read function portion  233  of the buffer control module  215  ( FIG. 3 ) parses the program stream stored in the buffer  215 A, extracts (separates) a video stream (a video access unit) from the program stream stored in the buffer  215 A corresponding to a request received from the video decoder control module  216 , and supplies the extracted video stream to the video decoder control module  216 . 
   Likewise, the audio read function portion  234  parses a program stream stored in the buffer  215 A, extracts an audio stream (an audio access unit) from the program stream stored in the buffer  215 A corresponding to a request received from the audio decoder control module  217 , and supplies the audio stream to the audio decoder control module  217 . The subtitle read function portion  235  parses a program stream stored in the buffer  215 A, extracts a subtitle stream (a subtitle access unit) from the program stream stored in the buffer  215 A corresponding to a request received from the subtitle decoder control module  218 , and supplies the subtitle stream to the subtitle decoder control module  218 . 
   [Reading Video Stream] 
   Next, with reference to a flow chart shown in  FIG. 36 , a video stream read process for the buffer  215  of the video read function portion  233  ( FIG. 3 ) will be described in detail. 
   At step S 211 , the video read function portion  233  searches a program stream stored in the buffer  215 A for PES_packet( ) of private_stream_ 2 . As described in  FIG. 20 , in PES_packet( ) of private_stream_ 2 , stream_id is 10111111B (=0xBF). The video read function portion  233  searches for PES_packet( ) whose stream_id is 10111111B. 
   Assuming that an elementary stream multiplexed with a program stream stored in the clip stream file “00001.PS” is an elementary stream to be reproduced, when the program stream is read from the disc  101  and stored in the buffer  215 A, sector  305  is decided as the reproduction start position with information about a decodable start point described in EP_map( ) ( FIG. 27 ) of the clip stream file “00001.PS.” At step S 128  shown in  FIG. 30 , sector  305 , which is the reproduction start point, is designated. The video read function portion  233  causes the operating system  201  to read the program stream from the clip stream file “00001.PS.” 
   Information about the decodable start point described in EP_map( ) of the video stream represents the position of PES_packet( ) of private_stream_ 2  immediately preceded by the real decodable start point. 
   Thus, immediately after the program stream stored in the clip stream file “000001.PS” is read from the disc  101  and stored in the buffer  215 A, PES_packet( ) of private_stream_ 2  is stored at a position represented by the data start pointer and the video read pointer in the buffer  215 A. 
   When the video read function portion  233  has found PES_packet( ) of private_stream_ 2  at step S 211 , the flow advances to step S 212 . At step S 212 , the video read function portion  233  extracts video_stream_id from private_stream 2 _PES_payload( ) ( FIG. 23 ), which is PES_packet_data_byte of PES_packet( ) of private_b. At step S 127  shown in  FIG. 30 , the video read function portion  233  determines whether video_stream_id matches stream_id of the video stream to be reproduced, which is stored in the stream_id register  242  ( FIG. 3 ). 
   When the determined result at step S 212  represents that video_stream_id described in private_stream 2 _PES_payload( ) does not match stream_id stored in the stream_id register  242 , namely PES_packet( ) of private_stream_ 2 , found at step S 211 , is not at the decodable start point of the video stream to be reproduced, the flow returns to step S 211 . At step S 211 , the video read function portion  233  searches the program stream stored in the buffer  215 A for PES_packet( ) of private_stream_ 2  and repeats the same process. 
   In contrast, when the determined result at step S 212  represents that video_stream_id described in private_stream 2 _PES_payload( ) matches stream_id stored in the stream_id register  242 , namely PES_packet( ) of private_stream_ 2  found at step S 211  is at the decodable start point of the video stream to be reproduced, the flow advances to step S 213 . At step S 213 , the video read function portion  233  reads au_information( ) described in private_stream 2 _PES payload( ) of PES_packet( ) of private_stream_ 2  from the buffer  215 A and stores au_information( ) to the au_information( ) register  243  ( FIG. 3 ). Thereafter, the flow advances to step S 214 . 
   At step S 214 , the video read function portion  233  updates the video read pointer stored in the data start pointer storage portion  231  for the size of PES_packet( ) of private_stream_ 2 , which matches stream_id stored in the stream_id register  242  ( FIG. 3 ). 
   In other words, in a clip stream file, PES_packet( ) of private_stream_ 2  is immediately followed by a video stream (PES_packet( )) whose stream_id matches video_stream_id. Thus, at step S 214 , the video read function portion  233  updates the video read pointer so that it represents the position of the decodable start point of the video stream. 
   Thereafter, the flow advances from S 214  to step S 215 . The video read function portion  233  determines whether the video decoder control module  216  has issued a data request. When the determined result at step S 215  represents that the video read function portion  233  has not issued a data request, the flow returns to step S 215 . At step S 215 , the video decoder control module  216  repeats the same process. 
   In contrast, when the determined result at step S 215  represents that the video decoder control module  216  has issued a data request, the flow advances to step S 216 . At step S 216 , the video read function portion  233  parses the program stream from the position represented by the video read pointer in the buffer  215 A, reads data of bytes described in AU_length of au_information( ) stored in the au_information( ) register  243 , namely one video access unit, from the buffer  215 A, supplies the data to the video decoder control module  216 , and updates the video read pointer for the size of one video access unit that has been read from the buffer  215 A. 
   In other words, as described in  FIG. 24 , au_information( ) describes number_of_access_unit that represents the number of video access units (pictures) contained from PES_packet( ) of private_stream_ 2 , containing au_information( ), to PES_packet( ) of the next private_stream_ 2 . 
   In addition, as shown in  FIG. 24 , au_information( ) describes pic_struct_copy, au_ref_flag, and AU_length as information about each of video access units represented by number_of_access_unit. 
   As described in  FIG. 24 , since each of AU_length&#39;s described in au_information( ) corresponding to number_of_access_unit represents the size of each of video access units represented by number_of_access_unit from PES_packet( ) of private_stream_ 2  to PES_packet( ) of the next private_stream_ 2 , the video read function portion  233  can extract access units with AU_length&#39;s without need to parse the video stream. 
   In other words, when MPEG2-Video or MPEG4-AVC access units are extracted, it is necessary to know the structure of the video stream and then parse it. However, a program stream stored in a clip stream file recorded on the disc  101  contains PES_packet( ) of private_stream_ 2 , which describes AU_length that represents the size of a video access unit, and which is immediately followed by at least one decodable start point of the video stream. Thus, the video read function portion  233  can read video access units (a video stream as video access units) from the buffer  215 A and supply the video access units to the video decoder control module  216  corresponding to AU_length described in PES_packet( ) of private_stream_ 2  without need to parse the video stream. 
   At step S 216 , when the video read function portion  233  supplies video access units to the video decoder control module  216 , the video read function portion  233  also supplies pic_struct_copy, au_ref_flag, and AU_length described in au_information( ) and time stamps (PTS and DTS) added for each of the video access units as information about the video access units to the video decoder control module  216 . 
   After the video read function portion  233  has read one video access unit from the buffer  215 A and supplied it to the video decoder control module  216 , the flow advances to step S 217 . At step S 217 , the video read function portion  233  determines whether it has processed access units represented by number_of_access_unit of au_information( ) ( FIG. 24 ) stored in the au_information( ) register  243 . 
   When the determined result at step S 217  represents that the video read function portion  233  has not yet processed access units represented by number_of_access_unit, namely the video read function portion  233  has not yet read access units represented by number_of_access_unit from the buffer  215 A and supplied them to the video decoder control module  216 , the flow returns to step S 215 . At step S 215 , the video read function portion  233  repeats the same process. 
   In contrast, when the determined result at step S 217  represents that the video read function portion  233  has already processed access units represented by number_of_access_unit, namely the video read function portion  233  has already read access units represented by number_of_access_unit from the buffer  215 A and supplied them to the video decoder control .module  216 , the flow returns to step S 211 . A step S 211 , the video read function portion  233  searches for PES_packet( ) of private_stream_ 2  and repeats the same process. 
   [Reading Audio Stream] 
   Next, with reference to a flow chart shown in  FIG. 37 , an audio stream read process for the buffer  215 A of the audio read function portion  234  ( FIG. 3 ) will be described. 
   At step S 230 , the audio read function portion  234  determines whether stream_id of an audio stream to be reproduced, which has been stored in the stream_id register  252  ( FIG. 3 ) at step S 127  shown in  FIG. 30 , represents PES_packet( ) of private_stream_ 1 . 
   When the determined result at step S 230  represents that stream_id stored in the stream_id register  252  does not represent PES_packet( ) of private_stream_ 1 , namely as described in  FIG. 20 , stream_id stored in the stream_id register  252  is 110xxxxxB assigned to an audio stream that has been encoded corresponding to the MPEG standard, the flow advances to step S 231 . At step S 231 , the audio read function portion  234  searches a program stream stored in the buffer  215 A for a synchronous code that represents the beginning of an audio frame defined in the MPEG Audio. Since the position of the synchronous code is at the beginning of an audio frame, the audio read function portion  234  updates the audio read pointer so that it represents the position of the beginning of an audio frame. Thereafter, the flow advances from step S 231  to step S 232 . At step S 232 , the audio read function portion  234  searches the program stream stored in the buffer  215 A for PES_packet( ) that matches stream_id stored in the stream_id register  252  corresponding to the position represented by the audio read pointer and obtains PES_packet( ). Thereafter, the flow advances to step S 233 . 
   At step S 233 , the audio read function portion  234  updates the audio read pointer stored in the audio read pointer storage portion  251  so that the audio read pointer represents the beginning of PES_packet_data_byte of PES_packet( ) ( FIG. 16A  and  FIG. 16B  to  FIG. 18A  and  FIG. 18B ), which has been found at step S 232 . Thereafter, the flow advances to step S 237 . 
   At step S 237 , the audio read function portion  234  determines whether the audio decoder control module  217  has issued a data request. When the determined result at step S 237  represents that audio decoder control module  217  has not issued a data request, the flow returns to step S 237 . At step S 237 , the audio read function portion  234  repeats the same process. 
   In contrast, when the determined result at step S 237  represents that the audio decoder control module  217  has issued a data request, the flow advances to step S 238 . At step S 238 , the audio read function portion  234  parses the program stream from the position represented by the audio read pointer in the buffer  215 A, reads one audio access unit having a predetermined fixed length from the buffer  215 A, and supplies the audio access unit together with time stamps (PTS and DTS) added to the audio access unit to the audio decoder control module  217 . 
   The audio read function portion  234  updates the audio read pointer for the size of one audio access unit read from the buffer  215 A. Thereafter, the flow returns to step S 237 . At step S 237 , the audio read function portion  234  repeats the same process. 
   In contrast, when the determined result at step S 230  represents that stream_id stored in the stream_id register  252  represents PES_packet( ) of private_stream_ 1 , namely stream_id stored in the stream_id register  252  is 10111101B (=0xBD) and represents PES_packet( ) of private_stream_ 1  as described in  FIG. 20 , the flow advances to step S 234 . At step S 234 , the audio read function portion  234  searches the program stream stored in the buffer  215 A for PES_packet( ) of private_stream_ 1  and obtains PES_packet( ). In other words, the audio read function portion  234  searches for PES_packet( ) whose stream_id is 101111101B and obtains PES_packet( ). 
   When the audio read function portion  234  has found PES_packet( ) of private_stream_ 1  at step S 234 , the flow advances to step S 235 . At step S 235 , the audio read function portion  234  extracts private_stream_id from private_stream 1 _PES_payload( ) ( FIG. 21 ), which is PES_packet_data_byte of PES_packet( ) of private_stream_ 1  and determines whether private_stream_id matches private_stream_id of an audio stream to be reproduced, which has been stored in the private_stream_id register  253  ( FIG. 3 ) at step S 127  shown in  FIG. 30 . 
   When the determined result at step S 235  represents that private_stream_id described in private_stream 1 _PES_payload( ) does not match private_stream_id stored in the private_stream_id register  253 , namely PES_packet( ) of private_stream_ 1  found at step S 234  is not an audio stream to be reproduced, the flow returns to step S 234 . At step S 234 , the audio read function portion  234  searches the program stream stored in the buffer  215 A for PES_packet( ) of private_stream_ 1 . Thereafter, the audio read function portion  234  repeats the same process. 
   On the other hand, when the determined result at step S 235  represents that private_stream_id described in program_stream_PES_payload( ) matches private_stream_id stored in the private_stream_id register  253 , namely PES_packet( ) of private_stream_ 1  found at step S 234  is an audio stream to be reproduced, the flow advances to step S 236 . At step S 236 , the audio read function portion  234  reads AU_locator described in private_stream 1 _PES_payload( ) ( FIG. 21 ) of PES_packet( ) of private_stream_ 1  from the buffer  215 A, adds the position immediately after AU_locator and the value that AU_locator represents, and obtains the start position of the audio access unit. 
   In other words, as described in  FIG. 21 , AU_locator represents the start position of an audio access unit (or a subtitle access unit) stored in private_payload( ) of private_stream 1 _PES_payload( ) based on the position immediately after AU_locator. Thus, by adding the value of AU_locator and the position immediately after AU_locator, the (absolute) start position of the audio access unit can be obtained. 
   At step S 236 , the audio read function portion  234  updates the audio read pointer stored in the audio read pointer storage portion  251  so that the audio read pointer represents the start position of the audio access unit that has been obtained. Thereafter, the flow advances to step S 237 . 
   At step S 237 , the audio read function portion  234  determines whether the audio decoder control module  217  has issued a data request. When the determined result at step S 237  represents that the audio decoder control module  217  has not issued a data request, the flow returns to step S 237 . At step S 237 , the audio read function portion  234  repeats the same process. 
   In contrast, when the determined result at step S 237  represents that the audio decoder control module  217  has issued a data request, the flow advances to step S 238 . At step S 238 , the audio read function portion  234  parses the program stream from the position represented by the audio read pointer in the buffer  215 A, reads one audio access unit having a predetermined length from the buffer  215 A, and supplies the audio access unit together with time stamps added to the audio access unit to the audio decoder control module  217 . 
   The audio read function portion  234  updates the audio read pointer for the size of one audio access unit read from the buffer  215 A. Thereafter, the flow returns to step S 237 . At step S 237 , the audio read function portion  234  repeats the same process. 
   [Reading Subtitle Stream] 
   Next, with reference to a flow chart shown in  FIG. 38 , a subtitle stream read process for the buffer  215 A of the subtitle read function portion  235  ( FIG. 3 ) will be described. 
   At step S 251 , the subtitle read function portion  235  determines the subtitle read function flag, which has been stored in the video decoder control module  216  at step S 127  shown in  FIG. 30 . When the determined result at step S 251  represents that the subtitle read function flag is 0, namely a clip stream file multiplexed with an elementary stream to be reproduced does not contain a subtitle stream and  0  has been set to the subtitle read function flag storage portion  261  at step S 127  shown in  FIG. 30 , the subtitle read function portion  235  does not perform any process. 
   In contrast, when the determined result at step S 251  represents that the subtitle read function flag is 1, namely a clip stream file multiplexed with an elementary stream to be reproduced contains a subtitle stream and 1 has been set to the subtitle read function flag storage portion  261  at step S 127  shown in  FIG. 30 , the flow advances to step S 252 . At step S 252 , the subtitle read function portion  235  searches the program stream stored in the buffer  215 A for PES_packet( ) that matches stream_id of the subtitle stream to be reproduced, which has been stored in the stream_id register  263  ( FIG. 3 ). 
   As described at step S 127  shown in  FIG. 30 , stream_id of the subtitle stream to be reproduced is stored in the stream_id register  263  ( FIG. 3 ). On the other hand, as described in  FIG. 20 , stream_id of the subtitle stream is 10111101B (=0xBD), which represents PES_packet( ) of private_stream_ 1 . 
   Thus, at step S 252 , the subtitle read function portion  235  searches the program stream stored in the buffer  215 A for PES_packet( ) of private_stream_ 1 . 
   When the subtitle read function portion  235  has searched for PES_packet( ) of private_stream_ 1  and obtained it, the flow advances to step S 253 . The subtitle read function portion  235  extracts private_stream_id from private_stream_PES_payload( ) ( FIG. 21 ), which is PES_packet_data byte of PES_packet( ) of private_stream_ 1  and determines whether private_stream_id matches private_stream_id of the subtitle stream to be reproduced, which has been stored in the private_stream_id register  264  ( FIG. 3 ) at step S 127  shown in  FIG. 30 . 
   When the determined result at step S 253  represents that private_stream_id described in private_stream_PES_payload( ) does not match private_stream_id stored in the private_stream_id register  264 , namely PES_packet( ) of private_stream_ 1 , which has been obtained at step S 252 , is not the subtitle stream to be reproduced, the flow returns to step S 252 . At step S 252 , the subtitle read function portion  235  searches the program stream stored in the buffer  215 A for PES_packet( ) of another private_stream_ 1 . Thereafter, the subtitle read function portion  235  repeats the same process. 
   In contrast, when the determined result at step S 253  represents that private_stream_id described in private_stream 1 _PES_payload( ) matches private_stream_id stored in the private_stream_id register  264 , namely PES_packet( ) of private_stream_ 1 , which has been obtained at step S 252 , is the subtitle stream to be reproduced, the flow advances to step S 254 . At step S 254 , the subtitle read function portion  235  reads AU_locator described in private_stream 1 _PES_payload( ) ( FIG. 21 ) of PES_packet( ) of private_stream_ 1  from the buffer  215 A, adds the position immediately after AU_locator and the value that AU_locator represents, and obtains the start position of the subtitle access unit. 
   As described in  FIG. 21 , AU_locator represents the start position of a subtitle access unit (or an audio access unit) stored in private_payload( ) of private_stream 1 _PES_payload( ) based on the position immediately after AU_locator. Thus, by adding the value that AU_locator represents and the position immediately after AU_locator, the (absolute) start position of the subtitle access unit can be obtained. 
   In addition, at step S 254 , the subtitle read function portion  235  updates the subtitle read pointer stored in the subtitle read pointer storage portion  262  so that the subtitle read pointer represents the start position of the obtained subtitle access unit. Thereafter, the flow advances to step S 255 . 
   At step S 255 , the subtitle read function portion  235  determines whether the subtitle decoder control module  218  has issued a data request. When the determined result at step S 255  represents that the subtitle read function portion  235  has not issued a data request, the flow returns to step S 255 . At step S 255 , the subtitle read function portion  235  repeats the same process. 
   In contrast, when the determined result at step S 255  represents that the subtitle decoder control module  218  has issued a data request, the flow advances to step S 256 . At step S 256 , the subtitle read function portion  235  parses the program stream from the position represented by the subtitle read pointer in the buffer  215 A, reads one subtitle access unit for the size described at the beginning of the subtitle access unit from the buffer  215 A, and supplies the subtitle access unit together with time stamps added to the subtitle access unit to the subtitle decoder control module  218 . As described in  FIG. 2A  and  FIG. 2B , the size of a subtitle access unit is described at the beginning thereof. The subtitle read function portion  235  reads data for the size from the position represented by the subtitle read pointer in the buffer  215 A and supplies the subtitle access unit together with time stamps added to the subtitle access unit to the subtitle decoder control module  218 . 
   The subtitle read function portion  235  updates the subtitle read pointer for the size of one subtitle access unit read from the buffer  215 A. Thereafter, the flow returns to step S 255 . At step S 255 , the subtitle read function portion  235  repeats the same process. 
   [Re-Synchronization Process] 
   Next, a synchronization control for video data and audio data of the decode control module  214  shown in  FIG. 2A  and  FIG. 2B  will be described. 
   As described at step S 130  shown in  FIG. 30 , the decode control module  214  causes the video decoder control module  216 , the audio decoder control module  217 , and the subtitle decoder control module  218  to start decoding their data. If necessary, the decode control module  214  causes these modules to start decoding their data at different timings to synchronize them. For example, when the video decoder  116  and the audio decoder  117  perform their decode processes, depending on their progress degrees, they may output video data and audio data at different timings. 
   Thus, the decode control module  214  performs a re-synchronization process that compensates the difference of the output timings for video data and audio data and causes the video decoder  116  and the audio decoder  117  to synchronously output video data and audio data. 
   Next, with reference to a flow chart shown in  FIG. 39 , the re-synchronization process will be described. 
   In the re-synchronization process, at step S 271 , the decode control module  214  determines the difference between the time stamp of a video access unit that is output from the video decoder control module  216  and the time stamp of an audio access unit that is output from the audio decoder control module  217  is large. 
   As described at step S 129  shown in  FIG. 30 , whenever the video decoder control module  216  receives a video access unit from the buffer control module  215 , the video decoder control module  216  supplies the time stamp of the video access unit to the decode control module  214 . Likewise, whenever the audio decoder control module  217  receives an audio access unit from the buffer control module  215 , the audio decoder control module  217  supplies the time stamp of the audio access unit to the decode control module  214 . 
   At step S 271 , the decode control module  214  compares the time stamps received from the video decoder control module  216  and the audio decoder control module  217  at the same timing (in a predetermined time period considered to be the same timing) and determines whether the difference of the time stamps is large. 
   When the determined result at step S 271  represents that the difference between the time stamp of the video access unit received from the video decoder control module  216  and the time stamp of the audio access unit received from the audio decoder control module  217  is not large, namely the difference between the time stamp of the video access-unit and the time stamp of the audio access unit is in a predetermined range of which the access units can be considered to be synchronized, for example two video frames (around 66 milliseconds), the flow returns to step S 271 . At step S 271 , the decode control module  214  determines (monitors) the difference of the time stamps. 
   In contrast, when the determined result at step S 271  represents that the difference between the time stamp of the video access unit received from the video decoder control module  216  and the time stamp of the audio access unit received from the audio decoder control module  217  is large, namely the difference is not in a predetermined range of which the access units cannot be considered to be synchronized, the flow advances to step S 272 . At step S 272 , the decode control module  214  compares the time stamp of the video access unit received from the video decoder control module  216  and the time stamp of the audio access unit received from the audio decoder control module  217  so as to determine which of the output of the video data and the output of the audio data is later than the other. 
   When the determined result at step S 272  represents that the output of the video data is later than the output of the audio data, the flow advances to step S 273 . At step S 273 , the decode control module  214  causes the video decoder control module  216  to stop decoding and outputting (displaying) a video access unit, namely skip the process for a video access unit, to advance the process for one video access unit. Thereafter, the flow advances to step S 274 . 
   At step S 274 , the video decoder control module  216  receives a skip request from the decode control module  214  and checks au_ref_flag ( FIG. 24 ) supplied together with the video access unit from the buffer control module  215 . 
   In other words, au_information( ) ( FIG. 24 ) stored in private_stream 2 _PES_payload( ) ( FIG. 23 ) of PES_packet( ) of private_stream_ 2  contains au_ref_flag as information about an access unit. As described at step S 129  shown in  FIG. 30  and step S 216  shown in  FIG. 36 , together with the video access unit, the buffer control module  215  supplies au_ref_flag thereof to the video decoder control module  216 . 
   At step S 274 , the video decoder control module  216  checks au_ref_flag of the access unit supplied together with the access unit. 
   Thereafter, the flow advances from step S 274  to step S 275 . At the step S 275 , the video decoder control module  216  determines whether the video access unit is a non-reference image that is not referenced when another picture is decoded corresponding to the check result of au_ref_flag of the video access unit, which has been supplied from the buffer control module  215 . 
   As described in  FIG. 24 , au_ref_flag of a video access unit represents whether the access unit is a reference image. When the access unit is a reference image, au_ref_flag is 1. In contrast, when the access unit is not a reference image, au_ref_flag is 0. 
   When the determined result at step S 275  represents that the video access unit supplied from the buffer control module  215  is not a non-reference image (a video access unit thereof), namely the video access unit supplied from the buffer control module  215  is a reference image, the flow advances to step S 276 . At step S 276 , the video decoder control module  216  causes the video decoder  116  to normally process the video access unit. After the video decoder control module  216  has received the next video access unit from the buffer control module  215 , the flow returns to step S 274 . 
   In contrast, when the determined result at step S 275  represents that the video access unit supplied from the buffer control module  215  is a non-reference image, the flow advances to step S 277 . At step S 277 , the video decoder control module  216  causes the video decoder  116  to skip the process for the video access unit. After the buffer control module  215  has supplied the next video access unit, the flow returns to step S 271 . 
   Since the process for a video access unit is skipped, the process is advanced for almost one video access unit (the process time is decreased). As a result, the output of video data that is later than the output of audio data is advanced. 
   In contrast, when the determined result at step S 272  represents that the output of video data is not later than the output of audio data, namely the output of audio data is later than the output of video data, the flow advances to step S 278 . At step S 278 , the decode control module  214  outputs a continuous output command to the video decoder control module  216  to continuously output video data corresponding to the video access unit that is being decoded to keep the video decoder control module  216  waiting for the process for the next video access unit. Thereafter, the flow advances to step S 279 . 
   At step S 279 , the video decoder control module  216  receives the continuous output request from the decode control module  214  and continuously outputs video data of the video access unit that is being decoded to the graphics process module  219  corresponding to the continuous output request. After the buffer control module  215  has supplied the next video access unit, the flow advances to step S 271 . 
   As described above, the decode control module  214  determines whether the output of video data is later than the output of audio data. When the output of video data is later than the output of audio data, the decode control module  214  causes the video decoder control module  216  to skip the process for one access unit. The video decoder control module  216  determines whether the access unit to be skipped is a reference image or a non-reference image corresponding to au_ref_flag of the access unit. When the access unit is a non-reference image, the decode control module  214  causes the video decoder  116  to skip the process for the access unit. Thus, the output of video data and the output of audio data can be easily synchronized. 
   In other words, when an access unit to be skipped is a reference image, video data of the access unit need to be decoded so that the video data are referenced when another access unit is decoded. Thus, when the output of video data and the output of audio data are synchronized, if the process for an access unit of a reference image is skipped, another access unit that references the reference image cannot be decoded. As a result, when video data synchronized with audio data are displayed, noise appears. 
   Thus, it is preferred that an access unit that is not a non-reference image be skipped. 
   On the other hand, to search a conventional elementary stream for an access unit that is a non-reference image, the elementary stream needs to be parsed. An elementary stream encoded corresponding to for example the MPEG4-AVC system is very complicated. Thus, when the elementary stream is parsed, very high cost is required. 
   In contrast, a program stream stored in a clip stream file recorded on the disc  101  is multiplexed with PES_packet( ) of private_stream_ 2  that contains private_stream 2 _PES_payload( ) ( FIG. 23 ), which is an extension of PES_packet_data_byte, besides PES_packet( ) ( FIG. 16A  and  FIG. 16B  to  FIG. 18A  and  FIG. 18B ) having PES_packet_data_byte, which contains a video access unit. au_information( ) ( FIG. 24 ) of private_stream 2 _PES_payload( ) describes au_ref_flag, which represents whether the video access unit is a reference image or a non-reference image. au_ref_flag and the corresponding video access unit are supplied from the buffer control module  215  to the video decoder control module  216 . Thus, the video decoder control module  216  can determine whether a video access unit is a reference image or a non-reference image by checking au_ref_flag of the video access unit almost without extra cost. 
   [Mark Process] 
   Next, with reference to a flow chart shown in  FIG. 40 , a mark process based on Mark( ) described in PlayListMark( ) ( FIG. 7 ) will be described. 
   The decode control module  214  always checks the current time counted by the built-in time count portion  214 A. At step S 301 , the decode control module  214  determines whether the current time matches mark_time_stamp of any Mark( ) described in PlayListMark( ) ( FIG. 7 ). 
   As described at step S 124  shown in  FIG. 30 , when the player control module  212  reproduces the first PlayItem# 0  of the first PlayList# 0  shown in  FIG. 25 , the player control module  212  recognizes that four Mark( )&#39;s, which are the first to fourth Mark( )&#39;s, of seven Mark( )&#39;s contained in PlayListMark( ) in the upper table shown in  FIG. 28  belong to the first PlayItem# 0  of PlayList# 0  and supplies {180,090}, {5,580,090}, {10,980,090}, and {16,380,090}, which are mark_time_stamp&#39;s of the four Mark( )&#39;s together with information that represents that an attribute of times that mark_time_stamp&#39;s represent is “mark process” to the decode control module  214 . 
   At step S 301 , the decode control module  214  determines which of the four times (mark_time_stamp&#39;s) having an attribute of “mark process,” which have been supplied from the player control module  212 , matches the current time. 
   When the determined result at step S 301  represents that the current time does not match any of the times having an attribute of “mark process,” the flow returns to step S 301 . At step S 301 , the decode control module  214  repeats the same process. 
   In contrast, when the determined result at step S 301  represents that the current time matches one of the four times having an attribute of “mark process,” the decode control module  214  supplies a message that represents that the current time became a time having an attribute of “mark process” together with the matched time having an attribute of “mark process” to the player control module  212 . Thereafter, the flow advances to step S 302 . 
   At step S 302 , the player control module  212  receives the message, which represents that the current time became a time having an attribute of “mark process,” together with the matched time, which has an attribute of “mark process,” from the decode control module  214  and recognizes Mark( ) whose mark_time_stamp matches the current time as Mark( ) to be processed for the mark process (hereinafter, this Mark( ) is sometimes referred to as a target mark). 
   In other words, the player control module  212  has recognized PlayItem( ) of PlayList( ) that is being reproduced. By referencing PlayListMark( ) ( FIG. 7 ) of the “PLAYLIST.DAT” file ( FIG. 5 ) with PlayList( ), PlayItem( ), and the matched time (mark_time_stamp), which an attribute of “mark process” (hereinafter this time is sometimes referred to as a mark time), the player control module  212  recognizes a target mark. 
   Specifically, assuming that the first PlayItem# 0  of the first PlayList# 0  shown in  FIG. 25  is being reproduced, the player control module  212  recognizes a mark time is mark_time_stamp of any one of the four Mark( )&#39;s, which are the first to fourth Mark( )&#39;s of seven Mark( )&#39;s contained in PlayListMark( ) in the upper table shown in  FIG. 28 . 
   When the mark time supplied from the decode control module  214  to the player control module  212  is for example 16,380,090, the player control module  212  recognizes the fourth Mark( ) whose mark_time_stamp matches 16,380,090, which is the mark time, of four Mark( )&#39;s, which are the first to fourth Mark( )&#39;s, contained in PlayListMark( ) in the upper table shown in  FIG. 28  as the target mark. 
   When the player control module  212  has recognized the target mark, the flow advances from step S 302  to step S 303 . At step S 303 , the player control module  212  determines whether the target mark describes entry_ES_stream_id and entry ES_private_stream_id ( FIG. 7 ), which identify an elementary stream. 
   When the determined result at step S 303  represents that the target mark does not describe entry_ES_stream_id and entry_ES_private_stream_id ( FIG. 7 ), which identify an elementary stream, namely both entry_ES_stream_id and entry_ES_private_stream_id are 0x00, the flow advances to step S 305 , skipping step S 304 . At step S 305 , the decode control module  214  performs the process for the target mark. 
   In contrast, when the determined result at step S 303  represents that the target mark describes entry_ES_stream_id and entry_ES_private_stream_id ( FIG. 7 ), which identify an elementary stream, the flow advances to step S 304 . At step S 304 , the player control module  212  determines whether the elementary stream that is being reproduced contains an elementary stream identified by entry_ES_stream_id and if necessary entry_ES_private_stream_id. 
   When the determined result at step S 304  represents that the elementary stream that is being reproduced does not contain an elementary stream identified by entry_ES_stream_id and entry_ES_private_stream_id of the target mark, the flow returns to step S 301 . In other words, when the elementary stream identified by entry_ES_stream_id and entry_ES_private_stream_id of the target mark is not being reproduced, the target mark is ignored. 
   In contrast, when the determined result at step S 304  represents that the elementary stream that is being reproduced contains an elementary stream identified by entry_ES_stream_id and entry_ES_private_stream_id of the target mark, namely an elementary stream identified by entry_ES_stream_id and entry_ES_private_stream_id of the target mark is being reproduced, it is determined that the target mark be valid. Thereafter, the flow advances to step S 305 . At step S 305 , the player control module  212  performs the process for the target mark. 
   In other words, at step S 305 , by referencing mark_type of a target mark ( FIG. 7 ), the player control module  212  determines the-target mark. 
   When the determined result at step S 305  represents that the target mark is a chapter mark or an index mark, namely mark_type of the target mark is “Chapter” or “Index,” the flow advances to step S 306 . At step S 306 , the player control module  212  causes the graphics process module  219  to update the chapter number or index number with that of the target mark. Thereafter, the flow returns to step S 301 . 
   When the determined result at step S 305  represents that the target mark is an event mark, namely mark_type of the target mark is “Event,” the flow advances to step S 307 . At step S 307 , the player control module  212  informs the script control module  211  of both an event message that represents that an event has taken place and mark_data of the target mark. Thereafter, the flow advances to step S 308 . 
   At step S 308 , the script control module  211  receives an event message and mark_data from the player control module  212  and performs a sequence of processes described in the “SCRIPT.DAT” file with an argument of mark_data corresponding to an interrupt request of the event message. Thereafter, the flow returns to step S 301 . 
   In other words, the script control module  211  performs a process corresponding to mark_data. 
   Specifically, in PlayListMark( ) of PlayList# 1  in the lower table shown in  FIG. 28 , mark_type of each of the second Mark( ) (Mark# 1 ) and the third Mark( ) (Mark# 2 ) is “Event” and mark_data of Mark# 1  is different from mark_data of Mark# 2 . 
   When the script control module  211  receives an event message corresponding to the second Mark( ) and an event message corresponding to the third Mark( ), the script control module  211  performs a process corresponding to the received event message with the same event handler (interrupt process routine). The script control module  211  checks mark_data supplied together with the event message and performs a process corresponding to mark_data. 
   Specifically, when mark_data is for example 1, the script control module  211  controls the graphics process module  219  to display a first type icon. When mark_data is for example 2, the script control module  211  controls the graphics process module  219  to display a second type icon. 
   mark_data is not limited to 1 and 2. In addition, the process corresponding to mark_data is not limited to the display of simple icons. 
   In other words, when mark_data is in the range from 3 to 18, the script control module  211  controls the graphics process module  219  to display the first type icon with intensity corresponding to a value of which 2 is subtracted from mark_data (a value in the range from 1 to 16). On the other hand, when mark_data is in the range from 19 to 34, the script control module  211  controls the graphics process module  219  to display the second type icon with intensity corresponding to a value of which 18 is subtracted from mark_data (a value in the range from 1 to 16). 
   When a controller that the user operates is connected to the input interface  115  ( FIG. 1 ) and the controller has a vibration motor that is a direct current (DC) motor with an eccentric weight mounted on the motor shaft and that vibrates when the motor is driven, if the value of mark_data is in the range from 35 to 42, the vibration motor can be driven for an operation time period corresponding to a value of which 34 is subtracted from mark_data (a value in the range from 1 to 8). 
   mark_data is a numeric value. The use and algorithm of mark_data can be described with a script program that the script control module  211  executes. Thus, mark_data can be used corresponding to a predetermined rule or an original rule designated by the manufacturer of the disc  101  or a content provider that provides data recorded on the disc  101 . 
   When the current time matches a time having an attribute of “mark process,” a target mark is recognized from the mark time, which is the time having an attribute of “mark process.” When a target mark does not describe entry ES_stream_id and entry_ES_private_stream_id that identify an elementary stream, a process corresponding to mark_type of the target mark is preformed. Even if a target mark describes entry_ES_stream_id and entry_ES_private_stream_id that identify an elementary stream, while the elementary stream identified by entry_ES_stream_id and entry_ES_private_stream_id is being reproduced, a process corresponding to mark_type of the target mark is performed. 
   While the second PlayList# 1  shown in  FIG. 25  is being reproduced, the following mark process is performed. 
   In other words, as shown in the lower table shown in  FIG. 28 , PlayListMark( ) of the second PlayList# 1  describes first Mark( ) (Mark# 0 ), second Mark( ) (Mark# 1 ), and third Mark( ) (Mark# 2 ), whose mark_time_stamp&#39;s are 90,000, 27,090,000, and 27,540,000, respectively. 
   In addition, since entry_ES_stream_id&#39;s of the second Mark( ) and the third Mark( ) of PlayListMark( ) in the lower table shown in  FIG. 28  describe 0xE0 and 0xE1, the second Mark( ) and the third Mark( ) are correlated with elementary streams identified by stream_id&#39;s that are 0xE0 and 0xE1, respectively. 
   As described in  FIG. 25 , the second PlayList# 1  describes only one PlayItem( ) (PlayItem# 0 ). With PlayItem# 0 , the clip stream file “00003.PS” is reproduced. As described in the clip information file “00003.CLP” shown in  FIG. 26A  and  FIG. 26B , which corresponds to the clip stream file “00003.PS,” the clip stream file “00003.PS” is multiplexed with three elementary streams, which are the video stream stream# 0  identified by stream_id that is 0xE0, the video stream stream# 1  identified by stream_id that is 0xE1, and the audio stream# 2  identified by private_stream_id that is 0x00. 
   Thus, the second Mark( ) of PlayListMark( ) in the lower table shown in  FIG. 28  is correlated with the video stream file stream# 0  whose stream_id is 0xE0, which is multiplexed with the clip stream file “00003.PS.” The third Mark( ) is correlated with the video stream stream# 1  whose stream_id is 0xE1, which is multiplexed with the clip stream file “00003.PS.” 
   When PlayItem# 0  of the second PlayItem# 1  shown in  FIG. 25  is reproduced, as described at step S 124  shown in  FIG. 30 , the player control module  212  recognizes that three Mark( )&#39;s contained in PlayListMark( ) in the lower table shown in  FIG. 28  belong to PlayItem# 0  of PlayList# 1  and supplies {90,000}, {27,090,000}, and {27,540,000}, which are mark_time_stamp&#39;s of three Mark( )&#39;s, together with information that represents that the times have an attribute of “mark process” to the decode control module  214 . 
   In the mark process, while PlayItem# 0  of PlayList# 1  is being reproduced, the decode control module  214  always determines which of times, {90,000}, {27,090,000}, and {27,540,000} matches the current time counted by the time count portion  214 A (at step S 301 ). When the current time matches a time having an attribute of “mark process,” the decode control module  214  supplies a mark time that is a time having an attribute of “mark process,” matches the current time, together with a message that represents that the current time became a time having an attribute of “mark process” to the player control module  212 . 
   When the current time matches 27,090,000 of times {90,000}, {27,090,000}, and {27,540,000} having an attribute of “mark process,” the decode control module  214  supplies a mark time having an attribute of “mark process,” 27,090,000, together with the message that represents that the current time became a time having an attribute of “mark process” to the player control module  212 . 
   The player control module  212  has recognized that PlayItem# 0  of PlayList# 1  is being reproduced. The player control module  212  compares 90,000, 27,090,000, and 27,540,000, which are mark_time_stamp&#39;s of three Mark( )&#39;s that belong to PlayItem# 0  of Mark( )&#39;s described in PlayListMark( ) in the lower table shown in  FIG. 28  with 27,090,000, which is the mark time supplied from the decode control module  214  and recognizes that Mark( ) whose mark_time_stamp matches 27,090,000, which is a mark time, namely the second Mark( ) (Mark# 1 ) described in PlayListMark( ) in the lower table shown in  FIG. 28  is a target mark (at step S 302 ). 
   In the second Mark( ), which is a target mark, described in PlayListMark( ) in the lower table shown in  FIG. 28 , entry_ES_stream_id is 0xE0. As described above, entry_ES_stream_id, which is 0xE0, represents the video stream stream# 0  ( FIG. 26A  and  FIG. 26B ) whose stream_id is 0xE0, multiplexed with the clip stream file “00003.PS.” The player control module  212  determines whether an elementary stream that is being reproduced contains the video stream stream# 0  (at steps S 303  and S 304 ). 
   When an elementary stream that is being reproduced does not contain the video stream stream# 0 , the player control module  212  ignores the target mark (at step S 304 ). 
   In contrast, when an elementary stream that is being reproduced contains the video stream stream# 0 , the player control module  212  treats the target mark to be valid and performs a process corresponding to the target mark (at steps S 305  to S 308 ). 
   In this case, in the second Mark( ), which is a target mark, described in PlayListMark( ) in the lower table shown in  FIG. 28 , mark_type is “Event.” Thus, the second Mark( ) is an event mark. The player control module  212  supplies an event message that represents that an event has taken place and mark_data of the target mark to the script control module  211  (at steps S 305  and S 307 ). The script control module  211  performs a sequence of processes described in the “SCRIPT.DAT” with an argument of mark_data corresponding to an interrupt request of the event message received from the player control module  212  (at step S 308 ). 
   As described above, in the mark process, the player control modules determines whether the current time that is a reproduction time of a clip stream file reproduced corresponding to mark_time_stamp that represents one reproduction time on the time axis of PlayList( ), mark_type that represents the type of Mark( ), and PlayList( ) that contains PlayListMark( ) ( FIG. 7 ) that has no Mark( ) or more than one Mark( ) that contains mark_data as an argument of an event mark matches mark_time_stamp. When the current time matches mark_time_stamp, the player control module  212  recognizes Mark( ) that has mark_time_stamp equal to a mark time, which is the current time, as a target mark. When mark_type that has a target mark represents a type of which an event takes place, namely the target mark is an event mark, mark_type that the target mark has and the event message are supplied. The player control module  212  executes a process corresponding to mark_data. Thus, the player control module  212  can execute a process corresponding to mark_data for the reproduction time of the clip stream file. 
   [Output Attribute Control Process] 
   Next, with reference to a flow chart shown in  FIG. 41 , an output attribute control process performed at step S 126  shown in  FIG. 30  will be described in detail. 
   As described at step S 126  shown in  FIG. 30 , the player control module  212  checks number_of_DynamicInfo ( FIG. 10 ), which represents the number of DynamicInfo( )&#39;s ( FIG. 13 ), which describe an output attribute for at least one elementary stream to be reproduced, namely at least one elementary stream to be reproduced, which has been decided at step S 125 . 
   When number_of_DynamicInfo of each of at least one elementary stream to be reproduced is 0, the player control module  212  does not perform any process. 
   In contrast, when number_of_DynamicInfo of an elementary stream to be reproduced is not 0, the player control module  212  performs an output attribute control process corresponding to a flow chart shown in  FIG. 41 . 
   Thus, when three clip information files “00001.CLP,” “00002.CLP,” and “00003.CLP” recorded on the disc  101  are as shown in  FIG. 26A  and  FIG. 26B  and the clip stream file “00001.PS” (the first PlayItem# 0  of the first PlayList# 0  that reproduces the clip stream file “00001.PS”) corresponding to the clip information file “00001.CLP” is reproduced, since number_of_DynamicInfo&#39;s of all the four elementary streams, which are stream# 0  to stream# 3 , are 0, the player control module  212  does not perform the output attribute control process. 
   Likewise, when the clip stream file “00002.PS” (the second PlayItem# 1  of the first PlayList# 0  that reproduces the clip stream file “00002.PS) corresponding to the clip information file “00002.CLP” is reproduced, since all number_of_DynamicInfo&#39;s of four elementary streams, which are stream# 0  to stream# 3 , multiplexed with the clip stream file “00002.PS” are 0, the player control module  212  does not perform the output attribute control process. 
   In contrast, when the clip stream file “00003.PS” (PlayItem# 0  of the second PlayList# 1  that reproduces the clip stream file “00003.PS”) corresponding to the clip information file “00003.CLP” is reproduced, since number_of_DynamicInfo&#39;s of the video stream stream# 0 , which is the first elementary stream, and the audio stream stream# 2 , which is the third elementary stream, are 2 and 3, respectively, the player control module  212  performs the output attribute control process. 
   In other words, in the output attribute control process, at step S 320 , the player control module  212  supplies pts_change_point described in the clip information file Clip( ) ( FIG. 10 ) corresponding to the clip stream file to be reproduced together with information that represents a time having an attribute of “DynamicInfo( ) process” to the decode control module  214 . The decode control module  214  receives pts_change_point, which is a time having an attribute of “DynamicInfo( ) process” from the player control module  212 . Thereafter, the flow advances to step S 321 . 
   At step S 321 , the decode control module  214  determines whether the current time counted by the time count portion  214 A matches one of pts_change_point&#39;s, which are times having an attribute of “DynamicInfo( ) process.” When the determined result at step S 321  represents that the current time does not match any one of pts_change_point&#39;s, the flow returns to step S 321 . 
   In contrast, when the determined result at step S 321  represents that the current time matches any one of times having an attribute of “DynamicInfo( ) process,” the decode control module  214  supplies a message that represents that the current time became a time having an attribute of “DynamicInfo( ) process” and the matched time, which has an attribute of “DynamicInfo( ) process” (hereinafter sometimes referred to as DynamicInfo time), to the player control module  212 . Thereafter, the flow advances to step S 322 . 
   At step S 332 , the player control module  212  receives the message, which represents that the current time became a time having an attribute of “Dynamicinfo( ) process,” and a DynamicInfo time from the decode control module  214  and recognizes DynamicInfo( ) paired with pts_change_point ( FIG. 10 ) that matches the DynamicInfo time as a target DynamicInfo( ). Thereafter, the flow advances to step S 323 . 
   At step S 323 , the player control module  212  supplies an output attribute described in DynamicInfo( ) ( FIG. 13 ) that is the target DynamicInfo( ) to the graphics process module  219  or the audio output module  221 . Thereafter, the flow advances to step S 324 . 
   At step S 324 , the graphics process module  219  or the audio output module  221  starts controlling an output of video data or audio data corresponding to the output attribute, which has been supplied from the player control module  212  at step S 323 . Thereafter, the flow returns to step S 321 . 
   Thus, video data are output corresponding to for example an aspect ratio described as the output attribute (display mode). Alternatively, audio data are output corresponding to for example stereo mode or dual (bilingual) mode described as the output attribute. 
   Next, with reference to  FIG. 42 , the output attribute control process will be described in detail. 
     FIG. 42  shows a pair of pts_change_point and DynamicInfo( ) ( FIG. 10 ) described in the clip information file “00003.CLP” shown in  FIG. 26A  and  FIG. 26B . 
   As described above, number_of_DynamicInfo&#39;s of the video stream stream# 0  and the audio stream stream# 2 , which are the first elementary stream and the third elementary stream of the three elementary streams, stream# 0  to stream# 2  multiplexed with the clip stream file “00003.PS,” are 2 and 3, respectively, in the clip information file “00003.CLP” shown in  FIG. 26A  and  FIG. 26B . 
   Thus, the clip information file “00003.CLP” describes two sets of pts_change_point&#39;s and DynamicInfo( )&#39;s for the first video stream stream# 0  of the clip stream file “00003.PS” and three sets of pts_change_point&#39;s and DynamicInfo( )&#39;s for the third audio stream stream# 2  of the clip stream file “00003.PS.” 
   An upper table shown in  FIG. 42  shows two sets of pts_change_point&#39;s and DynamicInfo( )&#39;s of the first video stream stream# 0  of the clip stream file “00003.PS.” A lower table shown in  FIG. 42  shows three sets of pts_change_point&#39;s and DynamicInfo( )&#39;s of the third audio stream stream# 2  of the clip stream file “00003.PS.” 
   In addition to the two sets of pts_change_point&#39;s and DynamicInfo( )&#39;s of the first video stream stream# 0 , the upper table shown in  FIG. 42  also represents stream_id (=0xE0), private_stream_id (=0x00), and number of DynamicInfo (=2) of the clip information file “00003.CLP,” shown in  FIG. 26A  and  FIG. 26B , of the first video stream# 0 . Likewise, in addition to the three sets of pts_change_point&#39;s and DynamicInfo( )&#39;s of the third audio stream stream# 2 , the lower table shown in  FIG. 42  also represents stream_id (=0xBD), private_stream_id (=0x00), and number_of_DynamicInfo (=3) of the clip information file “00003.CLP,” shown in  FIG. 26A  and  FIG. 26B , of the audio stream stream# 2 . 
   In the upper table shown in  FIG. 42 , pts_change_point of the first set of two sets of pts_change_point&#39;s and Dynamicinfo( )&#39;s of the video stream stream# 0  is 90,000 and display_aspect_ratio ( FIG. 13 ) of DynamicInfo( ) thereof is “4:3.” pts_change_point of the second set is 54,090,000 and display_aspect_ratio of DynamicInfo( ) thereof is “16:9.” 
   In the lower table shown in  FIG. 42 , pts_change_point of the first set of the three sets of pts_change_point&#39;s and DynamicInfo( )&#39;s of the audio stream stream# 2  is 90,000 and channel_assignment ( FIG. 13 ) of DynamicInfo( ) thereof is “Dual.” pts_change_point of the second set is 27,090,000 and channel_assignment of DynamicInfo( ) thereof is “Stereo.” pts_change_point of the third set is 32,490,000 and channel_assignment of DynamicInfo( ) thereof is “Dual.” 
   Now, it is assumed that at step S 125  shown in  FIG. 30 , the first video stream stream# 0 , identified by stream_id that is 0xE0, and the third audio stream stream# 2 , identified by stream_id that is 0xBD and private_stream_id that is 0x00, have been decided as streams to be reproduced from the clip stream file “00003.PS.” 
   In this case, the player control module  212  checks the two sets of pts_change_point&#39;s and Dynamicinfo( )&#39;s in the upper table shown in  FIG. 42  for the video stream stream# 0 , identified by stream_id that is 0xE0, and three sets of pts_change_point&#39;s and DynamicInfo( )&#39;s in the lower table shown in  FIG. 42  for the audio stream stream# 2 , identified by stream_id that is 0xBD and private_stream_id that is 0x00, and recognizes an initial value. 
   In other words, pts_change_point of the first set of the two sets of pts_change_point&#39;s and DynamicInfo( )&#39;s in the upper table shown in  FIG. 42  for the video stream stream# 0 , identified by stream_id that is 0xE0, is 90,000. 90,000 matches 90,000 described in presentation_start_time, which represents the start time of the clip stream file “00003.PS” in the clip information file “00003.CLP” shown in  FIG. 26A  and  FIG. 26B  corresponding to the clip stream file “00003.PS” with which the video stream stream# 0  has been multiplexed. 
   Likewise, pts_change_point of the first set of the three sets of pts_change_point&#39;s and DynamicInfo( )′ in the lower table shown in  FIG. 42  for the audio stream stream# 2 , identified by stream_id that is 0xBD and private_stream_id that is 0x00, is 90,000. 90,000 matches 90,000 described in presentation_start_time, which represents the start time of the clip stream file “00003.PS” in the clip information file “00003.CLP” shown in  FIG. 26A  and  FIG. 26B  corresponding to the clip stream file “00003.PS” with which the audio stream stream# 2  has been multiplexed. 
   The player control module  212  recognizes pts_change_point that matches 90,000 described in presentation_start_time, which represents the start time of the clip stream file “00003.PS” as an initial value. Thus, the player control module  212  recognizes pts_change_point of the first set of the two sets of pts_change_point&#39;s and DynamicInfo( )&#39;s in the upper table shown in  FIG. 42  and pts_change_point of the first set of the three sets of pts_change_point&#39;s and DynamicInfo( )&#39;s in the lower table shown in  FIG. 42  as initial values. 
   The player control module  212  designates an output attribute of an elementary stream corresponding to DynamicInfo( ) paired with pts_change_point recognized as an initial value before the clip stream file “00003.PS” is reproduced (at step S 126  shown in  FIG. 30 ). 
   For the video stream stream# 0 , identified by stream_id that is 0xE0, in the upper table shown in  FIG. 42 , display_aspect_ratio of DynamicInfo( ) paired with pts_change_point, which is 90,000 as an initial value, is “4:3.” In this case, the player control module  212  controls the graphics process module  219  with information that represents that display_aspect_ratio is “4:3,” namely information about an output attribute that represents that the video stream stream# 0  is video data whose aspect ratio is 4:3. 
   For the audio stream stream# 2 , identified by stream_id that is 0xBD and private_stream_id that is 0x00, in the lower table shown in  FIG. 42 , channel_assignment of DynamicInfo( ) paired with pts_change_point, which is 90,000 as an initial value, is “Dual.” In this case, the player control module  212  supplies information that represents that channel_assignment is “Dual,” namely information about an output attribute that represents that the audio stream stream# 2  is dual audio data to the audio output module  221 . 
   At step S 126  shown in  FIG. 30 , the player control module  212  performs the output attribute control process for pts_change_point&#39;s as initial values. 
   Thereafter, the player control module  212  supplies 90,000 and 54,090,000, which are two pts_change_point&#39;s, for the video stream stream# 0  in the upper table shown in  FIG. 42  and {27,090,000}, and {32,490,000} of 90,000, 27,090,000, and 32,490,000, which are times of three pts_change_point&#39;s except for 90,000, which is an initial value, for the audio stream stream# 2  in the lower table shown in  FIG. 42  together with information that represents that these times have an attribute of “DynamicInfo( ) process” to the decode control module  214  (at step S 320 ). 
   The decode control module  214  receives times {27,090,000}, {32,490,000}, and {54,090,000} having an attribute of “DynamicInfo( ) process” from the player control module  212 . After starting reproducing the video stream stream# 0  and the audio stream stream# 2  (PlayItem# 0  of the second PlayList# 1  that reproduces the clip stream file “00003.PS”), the decode control module starts monitoring the current time counted by the time count portion  214 A. 
   When the current time matches one of times {27,090,000}, {32,490,000}, and {54,090,000}, which have an attribute of “DynamicInfo( ) process,” the decode control module  214  supplies a DynamicInfo time, which is a time that has an attribute of “DynamicInfo( ) process” and that matches the current time, to the player control module  212  (at step S 321 ). 
   When the current time became for example 27,090,000, the decode control module  214  supplies 27,090,000, which matches the current time and is one of times having an attribute of “DynamicInfo( ) process” as a DynamicInfo time, to the player control module  212 . 
   The player control module  212  receives 27,090,000, which is a DynamicInfo time, from the decode control module  214 , checks pts_change_point that matches 27,090,000 as a DynamicInfo time from two pts_change_point&#39;s for the video stream# 0  in the upper table shown in  FIG. 42  and three pts_change_point&#39;s for the audio stream# 2  in the lower table shown in  FIG. 42 , and recognizes DynamicInfo( ) paired with pts_change_point that matches 27,090,000, namely the second DynamicInfo( ) for the audio stream stream# 2  in the lower table shown in  FIG. 42  as a target DynamicInfo( ) (at step S 322 ). 
   When the target DynamicInfo( ) is DynamicInfo( ) of a video stream, the player control module  212  supplies an output attribute described in the target DynamicInfo( ) to the graphics process module  219  (at step S 323 ). When the target DynamicInfo( ) is DynamicInfo( ) of an audio stream, the player control module  212  supplies an output attribute described in the target DynamicInfo( ) to the audio output module  221  (at step S 323 ). 
   When the graphics process module  219  has received an output attribute from the player control module  212 , the graphics process module  219  starts controlling an output of video data corresponding to the output attribute (at step S 324 ). 
   In other words, the graphics process module  219  converts an aspect ratio of video data that are output to the video output module  220  corresponding to an aspect ratio of video data (display_aspect_ratio ( FIG. 13 )) represented by an output attribute received from for example the player control module  212  and an aspect ratio of a video output device connected to the video output terminal  120  shown in  FIG. 1 . 
   Specifically, when the aspect ratio of the video output device is for example 16:9 and the aspect ratio of video data represented by the output attribute is 4:3, the graphics process module  219  performs a squeeze process for video data that are output to the video output module  220  in the horizontal direction and causes the left and right ends of the video data to be black. When the aspect ratio of video data of the video output device is for example 4:3 and the aspect ratio of video data represented by the output attribute is 16:9, the graphics process module  219  performs a squeeze process for the video data that are output to the video output module  220  in the vertical direction and causes the upper and lower ends of the video data to be black. When the aspect ratio of the video output device and the aspect ratio of video data as an output attribute are the same, for example 4:3 or 16:9, the graphics process module  219  outputs the video data to the video output module  220  without performing a squeeze process for the video data. 
   With two sets of pts_change_point&#39;s and DynamicInfo( )&#39;s for the video stream stream# 0 , identified by stream_id that is 0xE0, in the upper table shown in  FIG. 42 , video data having an aspect ratio of 4:3 are obtained after time 90,000, which is a reproduction start time of the video stream stream# 0 , before time 54,090,000. After time 54,090,000, video data having an aspect ratio of 16:9 are obtained. 
   Thus, assuming that the aspect ratio of the video output device connected to the video output terminal  120  shown in  FIG. 1  is 4:3, the graphics process module  219  supplies video data having an aspect ratio of 4:3 obtained from the video stream stream# 0  to the video output device whose aspect ratio is 4:3 after time 90,000 before time 54,090,000. The video output device displays the received video data. 
   After time 54,090,000, the graphics process module  219  performs a squeeze process for video data having an aspect ratio of 16:9 in the vertical direction and causes upper and lower ends of the video data to be black to convert the video data having an aspect ratio of 16:9 into a video signal having an aspect ratio of 4:3. The converted video signal is supplied to the video output device. The video output device displays the converted video data. 
   When the audio output module  221  receives an output attribute from the player control module  212 , the audio output module  221  starts controlling an output of audio data corresponding to the output attribute (at step S 324 ). 
   In other words, the audio output module  221  processes audio data received from the audio decoder control module  217  corresponding to a channel assignment for audio data (channel_assignment ( FIG. 13 )) represented by an output attribute received from the player control module  212  and corresponding to an audio output mode supplied from the player control module  212  through the input interface  115  ( FIG. 1 ) that the user operates with the remote controller and outputs the processed audio data to the audio output terminal  121  ( FIG. 1 ). 
   Specifically, when the channel assignment for audio data represented by the output attribute is a dual (bilingual) mode of which the left channel is “main audio” data and the right channel is “sub audio” data, the audio output module  221  processes the audio data supplied from the audio decoder control module  217  corresponding to the audio output mode supplied from the player control module  212  and outputs the processed audio data to the audio output terminal  121 . 
   In other words, if the “main sound” has been designated as an audio output mode, the audio output module  221  copies the left channel of audio data received from the audio decoder control module  217  as the right channel of audio data and outputs the left and right channel of audio data (“main audio” data) to the audio output terminal  121 . If “sub audio” has been designated as an audio output mode, the audio output module  221  copies the right channel of audio data received from the audio decoder control module  217  as the left channel and outputs the left and right channel (“sub audio” data) to the audio output terminal  121 . If both “main and sub audios” have been designated as an audio output mode, the audio output module  221  directly outputs audio data received from the audio decoder control module  217  to the audio output terminal  121 . 
   If the channel assignment of audio data represented by the output attribute is for example stereo mode, the audio output module  221  directly outputs the audio data received from the audio decoder control module  217  to the audio output terminal  121  regardless of what audio output mode has been designated. 
   With the three sets of pts_change_point&#39;s and DynamicInfo( )&#39;s for the audio stream stream# 2 , identified by stream_id that is 0xBD and private_stream_id that is 0x00, in the lower table shown in  FIG. 42 , dual audio data are obtained from the audio stream stream# 2  after time 90,000 as the reproduction start time before time 27,090,000. In addition, stereo audio data are obtained from the audio stream stream# 2  after time 27,090,000 before time 32,490,000. In addition, dual audio data are obtained from the audio stream stream# 2  after time 32,490,000. 
   Thus, when “main audio” has been designated as an audio output mode, the audio output module  221  copies audio data of the left channel of the dual audio data that are obtained from the audio stream stream# 2  after time 90,000 before time 27,090,000 as the right channel of audio data. The left channel and right channel of audio data are output to the audio output terminal  121 . 
   Stereo audio data obtained from the audio stream stream# 2  after time 27,090,000 before time 32,490,000 are output to the audio output terminal  121 . 
   The left channel of the dual audio data obtained from the audio stream stream# 2  after time 32,490,000 are copied as the right channel of audio data. The left channel and right channel of audio data are output to the audio output terminal  121 . 
   As described above, in the output attribute control process, it is determined whether a reproduction time of an elementary stream that is being reproduced matches pts_change_point corresponding to the clip information file Clip( ) ( FIG. 10 ) that contains n sets of pts_change_point&#39;s that represent a reproduction time of each elementary stream multiplexed with a clip stream file and DynamicInfo( )&#39;s that represents an output attribute of the elementary stream (where n is 0 or larger any integer). When the reproduction time of an elementary stream that is being reproduced matches pts_change_point, DynamicInfo( ) paired with pts_change_point is recognized. The output of the elementary stream that is being reproduced is controlled corresponding to the output attribute described in DynamicInfo( ). Thus, the output of the elementary stream can be controlled corresponding to the reproduction time of the elementary stream and the output attribute. 
   [Subtitle Display Control Process] 
   Next, with reference to a flow chart shown in  FIG. 43 , a subtitle display control process that controls the display of subtitle data corresponding to a subtitle stream will be described. 
   When the reproduction of PlayList( ) ( FIG. 5 ) (PlayList( ) thereof) is started, the player control module  212  initializes a subtitle data display mode for the graphics process module  219  at step S 341 . In other words, the player control module  212  controls the graphics process module  219  to change the subtitle data display mode to the default display mode. The initialization of the display mode performed at step S 341  corresponds to the initialization of the display mode performed at step S 127  shown in  FIG. 30 . 
   After step S 341 , the flow advances to step S 342 . At step S 342 , the player control module  212  determines whether the user has input a new subtitle data display mode command to the input interface  115  through the remote controller. 
   When the determined result at step S 342  represents that a new display mode command has been input, the flow advances to step S 343 . At step S 343 , the player control module  212  determines whether a subtitle stream (subtitle data corresponding thereto) is being reproduced. 
   When the determined result at step S 343  represents that a subtitle stream is not being reproduced, the flow returns to step S 342 . 
   In contrast, when the determined result at step S 343  represents that a subtitle stream is being reproduced, the flow advances to step S 345 . At step S 345 , the player control module  212  determines whether the new display mode command is the default display mode command. When the determined result at step S 343  represents that the new display mode command is the default display mode command, the flow returns to step S 341 . At step S 341 , as described above, the player control module  212  controls the graphics process module  219  to change the subtitle data display mode to the default display mode. 
   In contrast, when the determined result at step S 345  represents that the new display mode command is not the default display mode command, namely the new display mode command is a non-default display mode command for example a subtitle data enlargement command, a subtitle data reduction command, or a brightness increase command, the flow advances to step S 346 . At step S 346 , the player control module  212  obtains StaticInfo( ) of the subtitle stream, which is being reproduced, of StaticInfo( )&#39;s ( FIG. 12 ) of the clip information file Clip( ) ( FIG. 10 ) corresponding to the clip stream file with which the subtitle stream that is being reproduced is multiplexed. Thereafter, the flow advances to step S 347 . 
   At step S 347 , the player control module  212  determines configurable flag of StaticInfo( ) obtained at step S 346 . 
   When the determined result at step S 347  represents that configurable_flag is 0, which represents that the subtitle data display mode is not permitted to be changed, the flow advances to step S 348 . At step S 348 , the player control module  212  controls the graphics process module  219  to overlay output video data with a message that represents that the subtitle data display mode cannot be changed. Thereafter, the flow returns to step S 342 . At step S 342 , the error message is displayed. 
   In contrast, when the determined result at step S 347  represents that configurable_flag is 1, which represents that the subtitle data display mode is permitted to be changed, the flow advances to step S 349 . At step S 349 , the player control module  212  supplies the new display mode command, which has been input from the remote controller by the user through the input interface  115 , to the graphics process module  219 . Thereafter, the flow advance to step S 350 . 
   At step S 350 , the graphics process module  219  starts performing an enlargement process, a reduction process, or a brightness change process for the subtitle data supplied from the subtitle decoder control module  218  corresponding to the display mode command, which has been supplied from the player control module  212  at step S 349 . Thereafter, the flow returns to step S 342 . Thus, the subtitle data are displayed in the display size, at the display position, or in the display colors corresponding to the display mode command that has been input by the user through the remote controller. 
   In contrast, when the determined result at step S 342  represents that the new display mode command has not been input, the flow advances to step S 351 . At step S 351 , the player control module  212  determines whether PlayItem( )&#39;s have been changed as described in  FIG. 31 . When the determined result at step S 342  represents that PlayItem( )&#39;s have not been changed, the flow returns to step S 342 . 
   In contrast, when the determined result at step S 351  represents that PlayItem( )&#39;s have been changed, the flow returns to step S 341 . At step S 341 , as was described above, the player control module  212  controls the graphics process module  219  to change the subtitle data display mode to the default display mode. In other words, when PlayItem( )&#39;s have been changed, the subtitle data display mode is restored to the default display mode. 
   As was described above, only when configurable_flag of the subtitle stream is 1, which represents that the display mode is permitted to be changed, the subtitle data display mode for the subtitle stream can be changed corresponding to a display mode command that is input by the user through the remote controller. 
   Thus, for example in the clip information file “00001.CLP” shown in  FIG. 26A  and  FIG. 26B , since configurable_flag of the subtitle stream stream# 2 , which is the third elementary stream of four elementary streams multiplexed with the clip stream file “00001.PS,” is 0, which represents that the display mode is not permitted to be changed, while the subtitle stream stream# 2  is being displayed, even if the user operates the remote controller to change the subtitle display mode, the display mode is not changed. 
   In contrast, since configurable_flag of the subtitle stream stream# 3 , which is the fourth elementary stream of four elementary streams multiplexed with the clip stream file “00001.PS,” is 1, which represents that the display mode is permitted to be changed, while the subtitle stream stream# 3  is being displayed, when the user operates the remote controller to change the subtitle display mode, the display size of the subtitle is changed. 
   Now, it is assumed that the clip stream file “00001.PS” is being reproduced corresponding to the first PlayItem# 1  of the first PlayList# 1  shown in  FIG. 25 . In addition, in the clip information file “00001.CLP” described in  FIG. 26A  and  FIG. 26B , it is assumed that the third and fourth elementary streams of four elementary streams multiplexed with the clip stream file “00001.PS” are subtitle streams and that the third subtitle stream stream# 2  of the third and fourth subtitle streams stream# 2  and stream# 3  is being reproduced. 
   When the user operates the remote controller to input a subtitle display mode command (at step S 342 ), the display mode command is supplied from the input interface  115  ( FIG. 1 ) to the player control module  212 . When the player control module  212  receives the display mode command, the player control module  212  searches the clip information file for StaticInfo( ) ( FIG. 10 ) corresponding to the subtitle stream that is being reproduced (at step S 346 ). 
   In other words, the subtitle stream that is being reproduced is the third subtitle stream stream# 2  multiplexed with the clip stream file “00001.PS.” The player control module  212  searches the corresponding clip information file “00001.CLP” for StaticInfo( ) of the third subtitle stream stream# 2 . 
   In addition, the player control module  212  determines configurable_flag, which is 0, described in StaticInfo( ) of the third subtitle stream stream# 2  shown in  FIG. 26A  and  FIG. 26B  (at step S 347 ). Thus, the player control module  212  recognizes that the display mode of the third subtitle stream stream# 2  is not permitted to be changed. 
   In this case, the player control module  212  determines that the subtitle stream (subtitle data corresponding thereto) that is being reproduced does not correspond to enlargement and reduction modes and controls the graphics process module  219  to generate a corresponding error message (at step S 348 ), overlays the error message with video data, and outputs the overlaid video data. 
   While the fourth subtitle stream stream# 3  of the third and fourth subtitle streams stream# 2  and stream# 3  of the four elementary streams multiplexed with the clip stream file “00001.PS” is being reproduced, when the player control module  212  receives a display mode command that has been input by the user through the remote controller, the player control module  212  searches the corresponding clip information file “00001.CLP” for StaticInfo( ) of the fourth subtitle stream stream# 3 . 
   The player control module  212  determines configurable_flag, which is 1, described in StaticInfo( ) of the fourth subtitle stream stream# 3  shown in  FIG. 26A  and  FIG. 26B  (at step S 347 ). Thus, the player control module  212  recognizes that the display mode of the fourth subtitle stream stream# 3  has been permitted to be changed. 
   In this case, the player control module  212  determines that subtitle stream (subtitle data corresponding thereto) that is being reproduced corresponds to an enlargement mode or a reduction mode and supplies the display mode command that has been input by the user through the remote controller to the graphics process module  219  (at step S 349 ). 
   Thus, the graphics process module  219  for example enlarges or reduces subtitle data received from the subtitle decoder control module  218  corresponding to the display mode command received from the player control module  212 , overlays the resultant subtitle data with video data supplied from the video decoder control module  212 , and outputs the overlaid data. 
   When the player control module  212  starts reproducing the first PlayItem( ) of PlayList( ), the player control module  212  initializes the subtitle data display mode for the graphics process module  219  (at step S 341 ). In other words, the player control module  212  controls the graphics process module  219  to change the subtitle data display mode to the default display mode. 
   When PlayItem( )&#39;s are changed, the player control module  212  initializes the subtitle data display mode for the graphics process module  219  (at steps-S 341  and S 351 ). 
   When PlayItem( )&#39;s are changed, the player control module  212  checks configurable_flag for a new subtitle stream to be reproduced corresponding to PlayItem( ) that is newly reproduced. When configurable_flag is 0, the player control module  212  initializes the subtitle data display mode for the graphics process module  219 . When configurable_flag is 1, the player control module  212  causes the graphics process module  219  to keep the display mode for PlayItem( ). 
   In the subtitle display control process shown in  FIG. 43 , when a new display mode command is input by the user through the remote controller, the new display mode command is supplied to the graphics process module  219  (at step S 349 ). The display mode command may be stored in for example a non-volatile memory that composes the memory  113  ( FIG. 1 ). The display mode command stored in the non-volatile memory may be supplied to the graphics process module  219 . 
   Assuming that a display mode command that the user has set is stored in the non-volatile memory as an initial setting of the disc device shown in  FIG. 1 , when the user inputs a new display mode command with the remote controller, the display mode command stored in the non-volatile memory is replaced with the new display mode command and the new display mode command stored in the non-volatile memory is supplied to the graphics process module  219 . In this case, since the non-volatile memory stores the display mode command that has been set upon completion of the last reproduction, when the next PlayList( ) is reproduced, the subtitle data are displayed with the display mode command without need to input the display command through the remote controller. 
   In this case, it is assumed that the display mode command stored in the non-volatile memory includes for example an enlargement rate or a reduction rate at which a subtitle stream is enlarged or reduced. 
   As was described above, in the subtitle display control process, it is determined whether the subtitle data display mode is permitted to be changed from the default display mode corresponding to configurable_flag contained in StaticInfo( ) for subtitle data that are not changed while elementary streams contained in the clip information file Clip( ) ( FIG. 10 ) are being reproduced. When the default display mode of the subtitle data that are being reproduced is permitted to be changed, a display process for example an enlargement process, a reduction process, or a color change process for subtitle data is performed. Thus, the subtitle data display mode can be controlled. 
   [Capture Control Process] 
   Next, with reference to a flow chart shown in  FIG. 44 , a capture control process that controls capturing of video data corresponding to a video stream will be described.  FIG. 44  also shows a flow chart that describes a background/screen saver process that secondarily uses video data that have been captured in the capture control process. 
   When a video data capture command is input by the user from the remote controller through the input interface  115  ( FIG. 1 ) to the player control module  212 , the capture control process is started. 
   In other words, in the capture control process, at step S 371 , the player control module  212  determines whether a video stream is being reproduced. When the determined result at step S 371  represents that a video stream is not being reproduced, the player control module  212  completes the capture control process. 
   In contrast, when the determined result at step S 371  represents that a video stream is being reproduced, the flow advances to step S 372 . The player control module  212  obtains capture_enable_flag_PlayList from PlayList( ) ( FIG. 5 ) corresponding to the video stream that is being reproduced and capture_enable_flag_Clip from the clip information file Clip( ) ( FIG. 10 ) corresponding to the video stream that is being reproduced. 
   As was described in  FIG. 5 , capture_enable_flag_PlayList of PlayList( ) represents whether video data (video data contained in PlayList( )) corresponding to a video stream reproduced corresponding to PlayList( ) is permitted to be secondarily used. On the other hand, as was described in  FIG. 10 , capture_enable_flag_Clip of the clip information file Clip( ) represents whether video data corresponding to the video stream stored in a clip stream file corresponding to the clip information file Clip( ) is permitted to be secondarily used. 
   After step S 372 , the flow advances to step S 373 . The player control module  212  determines whether a picture of video data that are being reproduced when the capture command is input from the input interface  115  ( FIG. 1 ) is permitted to be captured corresponding to capture_enable_flag_PlayList and capture_enable_flag_Clip, which have been obtained at step S 373 . 
   When the determined result at step S 373  represents that a picture of video data that is being reproduced when the capture command is input from the input interface  115  is not permitted to be captured, namely at least one of capture_enable_flag_PlayList and capture_enable_flag_Clip obtained at step S 373  is 0, which represents that video data are not permitted to be secondarily used, the flow advances to step S 374 . At step S 374 , the player control module  212  controls the graphics process module  219  to overlay an error message that represents that video data are not permitted to be captured with video data and completes the capture control process. As a result, the error message is displayed. 
   In contrast, when the determined result at step S 373  represents that a picture of video data that is being reproduced when the capture command is input from the input interface  115  is permitted to be captured, namely both capture_enable_flag_PlayList and capture_enable_flag_Clip that have been obtained at step S 373  are 1, which represents that video data are permitted to be secondarily used, the flow advances to step S 375 . At step S 375 , the player control module  212  supplies the capture command for the video data that are being reproduced when the capture command is input from the input interface  115  to the graphics process module  219 . Thereafter, the flow advances to step S 376 . 
   At step S 376 , the graphics process module  219  captures a picture of video data from the video decoder control module  216  corresponding to the capture command received from the player control module  212 , stores the picture in the memory  113  ( FIG. 1 ), and completes the capture control process. When capture_enable_flag is composed of a plurality of bits and their use conditions are designated, at this point, a corresponding operation is performed. In other words, when the size of a capture picture is restricted, a picture whose size is reduced is captured. When an application that is used is restricted, a flag that represents the restriction is also recorded. 
   As described above, in the capture control process, capture_enable_flag_PlayList&#39;s and capture_enable_flag_Clip&#39;s of PlayList( ) ( FIG. 5 ) and the clip information file Clip( ) ( FIG. 10 ) corresponding to a video stream that is being reproduced when the user inputs the capture command and are ANDed. When the ANDed result is 1, namely both capture_enable_flag_PlayList&#39;s and capture_enable flag Clip&#39;s are 1, which represents that video data are permitted to be secondarily used, it is determined that video data can be secondarily used. As a result, the video data are captured. 
   When a video stream is reproduced corresponding to the first PlayItem# 0  of the first PlayList# 0  shown in  FIG. 25 , namely a video stream multiplexed with the clip stream file “00001.PS” is being reproduced, if the user inputs the capture command, since capture_enable_flag_PlayList of the first PlayList# 0  is 1 and capture_enable_flag_Clip of the clip information file “00001.CLP,” shown in  FIG. 26A  and  FIG. 26B , corresponding to the clip stream file “00001.PS” reproduced by the first PlayItem# 0  is 1, it is determined that video data that are being reproduced (video data corresponding to a video stream multiplexed with the clip stream file “00001.PS”) can be secondarily used and the video data are captured. 
   While a video stream is being reproduced corresponding to the second PlayItem# 1  of the first PlayList# 0  shown in  FIG. 25 , namely a video stream multiplexed with the clip stream file “00002.PS” is being reproduced, when the user inputs the capture command, since capture_enable_flag_PlayList of the first PlayList# 0  is 1 and capture_enable_flag_Clip of the clip information file “00002.CLP,” shown in  FIG. 26A  and  FIG. 26B , corresponding to the clip stream file “00002.PS” represented corresponding to the second PlayItem# 1  is 0, it is determined that video data that are being reproduced (video data corresponding to a video stream multiplexed with the clip stream file “00002.PS”) cannot be secondarily used and the video data are not captured. 
   While a video stream is being reproduced corresponding to PlayItem# 0  of the second PlayList# 1  shown in  FIG. 25 , namely a video stream multiplexed with the clip stream file “00003.PS” is being reproduced, when the user inputs the capture command, since capture_enable_flag_PlayList of the second PlayList# 1  is 0 and capture_enable_flag_Clip of the clip information file “00003.CLP” shown in  FIG. 26A  and  FIG. 26B  corresponding to the clip stream file “00003.PS” reproduced corresponding to PlayItem# 0  of the second PlayList# 1  is 1, it is determined that video data that are being reproduced (video data corresponding to a video stream multiplexed with the clip stream file “00003.PS”) is not permitted to be secondarily used. Thus, the video data are not captured. 
   In this case, when it has been checked that capture_enable_flag_PlayList of the second PlayList# 1  is 0, it can be determined that the video data are not permitted to be secondarily used. Thus, checking of capture_enable_flag_Clip of the clip information file “00003.CLP,” shown in  FIG. 26A  and  FIG. 26B , corresponding to the clip stream file “00003.PS” reproduced corresponding to PlayItem# 0  of the second PlayList# 1  can be omitted. 
   A picture captured in the capture control process and stored in the memory  113  can be secondarily used in the background/screen saver process. 
   The background/screen saver process is performed for example while the player control module  212  is operating, but an elementary stream is not being reproduced, namely the disc  101  has not been inserted into the disc drive  102  ( FIG. 1 ) or an elementary stream has been already reproduced. 
   In the background/screen saver process, at step S 381 , the player control module  212  controls the graphics process module  219  to display a picture that has been stored in the memory  113  in the capture control process. The graphics process module  219  displays a picture that has been stored in the memory  113  in the capture control process under the control of the player control module  212 . 
   When the graphics process module  219  displays a picture stored in the memory  113  as a still picture, so-called wall paper (background) is accomplished. When a picture is displayed while it is being enlarged, reduced, and moved, a screen saver is accomplished. The background/screen saver process that displays a picture stored in the memory  113  in the capture control process can be performed by another independent application rather than the player control module  212 . 
   When a flag that represents a restriction is added to a picture stored in the memory  133 , the picture that is displayed is restricted corresponding to the flag. 
   As described above, capture_enable_flag_PlayList and capture_enable_flag_Clip, which represent whether video data being reproduced are permitted to be secondarily used, are obtained corresponding to for example PlayList( ) or PlayItem( ), which is larger than a video access unit. Corresponding to capture_enable_flag_PlayList and capture_enable_flag_Clip, it is determined whether video data that are being reproduced are permitted to be secondarily used. When the determined result represents that video data that are being reproduced are permitted to be secondarily used, the video data that are being reproduced are captured and the background/screen saver process using the captured video data is executed. Thus, the secondary use of the video data can be controlled. 
   In the capture control process shown in  FIG. 44 , PlayList( ) ( FIG. 5 ) contains capture_enable_flag_PlayList and clip information file ( FIG. 10 ) corresponding to a clip stream file reproduced by PlayItem( ) contains capture_enable_flag_Clip. With both capture_enable_flag_PlayList and capture_enable_flag_Clip, it is determined whether video data are permitted to be secondarily used. Alternatively, when PlayList( ) ( FIG. 5 ) that contains capture_enable_flag_PlayList and the clip information file Clip( ) ( FIG. 10 ) corresponding to a clip stream file reproduced by PlayItem( ) that contains capture_enable_flag_Clip, with either capture_enable_flag_PlayList or capture_enable_flag_Clip, it can be determined whether video data are permitted to be secondarily used. 
   In the capture control process shown in  FIG. 44 , at step S 376 , the graphics process module  219  captures only one picture of video data from the video decoder control module  216  corresponding to a capture command received from the player control module  212 . Alternatively, the graphics process module  219  may capture a plurality of pictures from the video decoder control module  216 . In other words, a plurality of pictures (a series of a plurality of pictures as a moving picture) that the video decoder control module  216  outputs can be captured. In this case, the number of pictures captured at a time can be pre-designated. Alternatively, bits of capture_enable_flag_PlayList and capture_enable_flag_Clip can be extended for information that represents the number of pictures that can be captured at a time. 
   In the foregoing case, use permission information that represents whether video data are permitted to be secondarily used, which are capture_enable_flag_PlayList and capture_enable_flag_Clip, is described in PlayList( ) and clip information file Clip( ). With the use permission information, it is determined whether entire video data reproduced corresponding to PlayList( ) and entire video data corresponding to a video stream multiplexed with a clip stream file corresponding to the clip information file Clip( ) are permitted to be secondarily used. The use permission information can describe video data of any unit. With the use permission information, it can be determined whether video data in any unit are permitted to be secondarily used. 
     FIG. 45  shows the syntax of private_stream 2 _PES_payload( ) that contains use permission information.  FIG. 46  shows the syntax of au_information( ) that contains use permission information. 
   private_stream 2 _PES_payload( ) shown in  FIG. 45  is the same as that shown in  FIG. 23  except that the video_stream_id is immediately preceded by capture_enable_flag_ps2 as use permission information. Likewise, au_information( ) shown in  FIG. 46  is the same as that shown in  FIG. 24  except that pic_struct_copy is immediately preceded by capture_enable_flag_AU as use permission information. 
   capture_enable_flag_ps2 contained in private_stream 2 _PES_payload( ) shown in  FIG. 45  represents whether video data of a video stream after PES_packet( ) of private_stream_ 2  that contains private_stream 2 _PES_payload( ) before PES_packet( ) of the next private_stream_ 2  are permitted to be secondarily used. Thus, with capture_enable_flag_ps2 contained in private_stream 2 _PES_payload( ) shown in  FIG. 45 , it can be determined whether video data after a particular decodable start point before the next decodable start point are permitted to be secondarily used. 
   In addition, capture_enable_flag_AU contained in au_information( ) shown in  FIG. 46  represents whether video data in each video access unit corresponding to capture_enable_flag_AU are permitted to be secondarily used. Thus, with capture_enable_flag_AU contained in au_information( ) shown in  FIG. 46 , it can be determined whether video data in each video access unit, namely in each picture, are permitted to be secondarily used. 
   At least two of capture_enable_flag_PlayList as use permission information of PlayList( ) ( FIG. 5 ), capture_enable_flag_Clip as use permission information of the clip information file Clip( ) ( FIG. 10 ), capture_enable_flag_ps2 as use permission information of private_stream 2 _PES_payload( ) ( FIG. 45 ), and capture_enable_flag_AU as use permission information of au_information( ) ( FIG. 46 ) can be simultaneously used. In this case, with the result of which at least two of them as use permission information are ANDed, it can be determined whether a picture of video data is permitted to be secondarily used. 
   As described at step S 211  shown in  FIG. 36 , the video read function portion  233  searches a program stream stored in the buffer  215 A for PES_packet( ) of private_stream_ 2  that contains private_stream 2 _PES_payload( ), shown in  FIG. 23  or  FIG. 34 , which contains au_information( ) shown in  FIG. 46 . Thus, when private_stream 2 _PES_payload( ), shown in  FIG. 45 , which contains capture_enable_flag_ps2 , and au_information( ), shown in  FIG. 45 , which contains capture_enable_flag_AU, are used, the player control module  212  needs to ask the video read function portion  233  for capture_enable_flag_ps2 and capture_enable_flag_AU to determine whether video data are permitted to be secondarily used. 
   According to the foregoing embodiment, the sequence of processes are performed by software. Alternatively, these processes may be performed by dedicated hardware. 
   In addition, according to the embodiment, the video decoder  116  ( FIG. 1 ) is a hardware decoder. Alternatively, the video decoder  116  may be a software decoder. This relation applies to the audio decoder  117  ( FIG. 1 ). 
   In addition, according to the embodiment, the subtitle decoder is a software decoder. Alternatively, the subtitle decoder may be a hardware decoder. 
   It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alternations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.