Abstract:
The present invention provides a content reproduction system that can continue reproduction of a plurality of content even if a part of content is unreproducible. The content reproduction system includes a content storage apparatus including a content storage section that stores a plurality of content whose reproduction order has previously been specified based on reproduction order information, and a content reproduction apparatus including a communication section that communicates with the content storage apparatus, a request section that requests the content storage apparatus to transmit content stored in the content storage section in the order according to the reproduction order information, and a reproduction section that reproduces the content, wherein when content that the request section has requested from the content storage apparatus is unreproducible, the request section requests the content storage apparatus to transmit content which is listed as content to be reproduced subsequent to the unreproducible content in the reproduction order information.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of prior application Ser. No. 11/351,027, filed Feb. 9, 2006, which claims the priority benefit of Japanese patent application number 2005-033406, filed in the Japanese Patent Office on Feb. 9, 2005, each of which is hereby incorporated by reference to the maximum extent allowable by law. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a content reproduction system, a content reproduction apparatus, and a content reproduction method that sequentially reproduce a plurality of content. 
         [0004]    2. Description of the Related Art 
         [0005]    In the past, an optical recording medium such as CD (Compact Disc) or MD (Mini Disc™) has been available. Not only music content, but also management information of the music content is recorded on such an optical recording medium. The management information includes items of start/end address of content, title of a recording medium, title of music, artist name, and the like. Information related to reproduction order is not recorded in TOC (Table Of Contents) which is management information of a CD. In the CD, content is reproduced in the order that it has been recorded on the CD. On the other hand, a management table that manages the reproduction order of the content is recorded in UTOC (User Table Of Contents) which is management information of an MD. The management table describes a recording position of the content and a music number of the content corresponding to the recording position. The management table can be rewritten by a user side. The MD can sequentially reproduce content in a user-specified order (refer to, for example, Jpn. Pat. Appln. Laid-Open Publication No. 2003-36654). 
         [0006]    In recent years, a content reproduction system that connects a server and a client by a network and allows the client to reproduce content stored in the server has existed. In such a content reproduction system, reproduction order information is stored in the server. The reproduction order information includes items of album list, playlist, reproduction order list classified by artist&#39;s name, and the like. When reproducing content in the content reproduction system in a sequential manner, a user selects desired reproduction order information such as album list or playlist. The client outputs a content transmission request to the server according to received reproduction order information. The server transmits content in response to the transmission request issued by the client. 
       SUMMARY OF THE INVENTION 
       [0007]    In recent years, a content format has been diversified. In order to reproduce content of various formats, a decoder that converts content into a desired reproduction signal is necessary. For example, an MP3 (MPEG Audio layer 3) decoder is necessary in order to reproduce MP3 music content. When a client in a conventional system receives content of a format that the client cannot reproduce, the client determines that the content is unreproducible and stops reproduction operation after reproducing reproducible portion. 
         [0008]    The user instructs the client to sequentially reproduce a plurality of music pieces in units of album or playlist. Although the user has designated a given album or playlist, sequential reproduction of all music pieces is forced to stop due to existence of only one unreproducible music piece in the album. Accordingly, the user needs to perform additional operation for the client for the reproduction of remaining music pieces. 
         [0009]    The present invention has been made in view of the above problem, and it is desirable to provide a content reproduction system and a content reproduction apparatus capable of continuing reproduction operation even if there is any unreproducible content in a plurality of content to be reproduced in a sequential manner. 
         [0010]    According to the present invention, there is provided a content reproduction system including: a content storage apparatus including a content storage means for storing a plurality of content whose reproduction order has previously been specified based on reproduction order information; and a content reproduction apparatus including: a communication means for communicating with the content storage apparatus; a request means for requesting the content storage apparatus to transmit content stored in the content storage means in the order according to the reproduction order information; and a reproduction means for reproducing the content, wherein when content that the request means has requested from the content storage apparatus is unreproducible, the request means requests the content storage apparatus to transmit content which is listed as content to be reproduced subsequent to the unreproducible content in the reproduction order information. 
         [0011]    According to the present invention, there is provided a content reproduction apparatus including: a reproduction order information acquisition means for acquiring the reproduction order information related to content; a content acquisition means for acquiring content in the order according to the reproduction order information; a reproduction means for reproducing the content, wherein when the content acquired by the content acquisition means is unreproducible, content which is listed as content to be reproduced subsequent to the unreproducible content in the reproduction order information is acquired and reproduced. 
         [0012]    According to the present invention, there is provided a content reproduction method including: a reproduction order information acquisition step of acquiring the reproduction order information describing the reproduction order of content; a readout step of reading out content stored in content storage means in the order according to the reproduction order information; a subsequent content readout step of, when content listed in the reproduction order information is unreproducible, reading out content which is listed in the reproduction order information as content subsequent to unreproducible content; and reproduction step of reproducing the readout content. 
         [0013]    In the case where content to be reproduced is unreproducible, the content reproduction system according to the present invention requests the content storage apparatus to transmit content which is listed in the reproduction order information as content to be reproduced subsequent to the unreproducible content. Then, when the requested content is reproducible, the system uses the reproduction means to reproduce the content. Thus, even if unreproducible content exists in the reproduction order information, it is possible to continue sequential reproduction using only reproducible content. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a block diagram showing a configuration of a content reproduction system; 
           [0015]      FIG. 2  is a view showing an example of a reproduction list; 
           [0016]      FIG. 3  is a view schematically showing processing performed by a music content delivery section; 
           [0017]      FIGS. 4A and 4B  views showing operations of a reception ring buffer; 
           [0018]      FIG. 5  is a view showing a display example for notifying a user that content cannot be reproduced; 
           [0019]      FIG. 6  is a flowchart showing operation of a client; and 
           [0020]      FIG. 7  is a block diagram showing a configuration of a CD player according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0021]    A content reproduction system  1  according to the present invention will be described below with reference to the accompanying drawings.  FIG. 1  shows a configuration of the content reproduction system  1 . The content reproduction system  1  includes a server  2  that stores content, a client  3  that reproduces the content, and a switching hub  4  that relays communication between the server  2  and the client  3 . The above components in the content reproduction system  1  are connected to each other by LAN (Local Area Network) and perform communication according to TCP/IP (Transport Protocol/Internet Protocol). The content reproduction system  1  may adopt another configuration or communication method. 
         [0022]    The server  2  includes a content storage section  21  that stores music content, a reproduction list storage section  22  that stores reproduction lists of the music content, a communication section  23  that performs communication with the client  3 , a music content delivery section  24  that performs a music content delivery service, and a system controller  25  that controls the entire server  2 . 
         [0023]    The content storage section  21  stores music content. The reproduction list storage section  22  stores a reproduction list that indicates the reproduction order of the music content. As shown in  FIG. 2 , the reproduction list describes items of music content name, content type (content format), sampling frequency, channel number, bit number, reproduction time length of music content, URL of music content, reproduction order of content, and the like. The reproduction list can be classified into album list, playlist, artist list, and the like. The album list is a reproduction list of music content included in a given album. The playlist is a user-created reproduction list of music content. The artist list is a reproduction list of music content of a single artist. 
         [0024]    The music content delivery section  24  delivers music content stored in the content storage section  21  to the client  3 .  FIG. 3  schematically shows processing performed by the music content delivery section  24 . The music content delivery section  24  firstly reads out a reproduction list from the reproduction list storage section  22 . The read out reproduction list is transmitted to the client  3  through the communication section  23  (I). The reproduction list describes the URLs of the music content to be reproduced. The client  3  selects music content to be reproduced from the reproduction list and transmits the URL of the selected music content to the server  2  (II). The music content delivery section  24  reads out music content corresponding to the URL received from the client  3  and transmits the readout music content to the client  3  (III). 
         [0025]    The client  3  includes a communication section  31  that performs communication with the server  2 , a content request section  32  that requests the server  2  to transmit required data thereto, a reception ring buffer  33  that temporarily stores the music content input from the server  2 , a converter  34  that converts the music content transmitted from the server  2  from a digital signal into an analog signal, an amplifier  35  that outputs the analog music signal to a speaker  36 , an input section  37  that receives user&#39;s operation, such as a key or remote controller, and a display section  38 . 
         [0026]    The client  3  receives music content from the server  2 , converts the received music content from a digital signal to an analog signal, and reproduces the analog music signal through the speaker  36 . Music content of a PCM format transmitted from the server  2  is stored in the reception ring buffer  33 . At the time point when a given amount of music content is stored in the reception ring buffer  33 , the music content is output to the converter  34 . As a result, the music content of a given album list is sequentially reproduced without interruption between music pieces, being suitable for reproduction of a live album. The converter  34  converts a digital music signal into an analog music signal and outputs the analog music signal to the amplifier  35 . The analog music signal is amplified by the amplifier  35  and thereby the music is output through the speaker  36 . 
         [0027]      FIGS. 4A and 4B  show operations of the reception ring buffer  33 . A write pointer and a read pointer are set in the reception ring buffer  33 .  FIG. 4A  shows reading operation. The data reading operation is performed at regular intervals and music content is output to the converter  34  at a regular speed. The area from which the music content has been read out according to the read pointer becomes a data writable area.  FIG. 4B  shows writing operation. In the writing operation, the write pointer moves in the data writable area and, when the data writable area becomes small, the reception ring buffer stops reception operation and waits until the reading operation has advanced. 
         [0028]    The content request section  32  requests the server  2  to transmit music content thereto. The reproduction order of the content is described in the reproduction list. Upon receiving a first track, the content request section  32  requests the server  2  to transmit a second track in the list thereto. The reception ring buffer  33  writes the received second track on the area following the end of the first track. After completion of the reception of the second track, the content request section  32  requests the server  2  to transmit a third track in the list thereto. If there is no track to be reproduced next, the content request section  32  does not issue additional transmission request. 
         [0029]    When the music content described in a reproduction list is unreproducible, the content request section  32  stops reproduction of the unreproducible music content and requests the server  2  to transmit the next music content. 
         [0030]    When target music content is not stored in the URL listed in the reproduction list, the content request section  32  determines that this music content is unreproducible. The absence of the music content occurs due to, for example, disconnect between the URL listed in the reproduction list and actual storage area of the music content. There is a time lag between reception of a reproduction list and reception of music content. If given music content included in a reproduction list is deleted or moved after transmission of the reproduction list to the client, the target content has disappeared from the corresponding URL in the reproduction list at the reception time of the music content. 
         [0031]    If there is no reproducible music content, the content request section  32  notifies the user that the music content to be reproduced next is unreproducible after completing reproduction of the current music content. A message saying, “Can&#39;t play” is displayed in the display section  38  of  FIG. 5  for notifying the user that the music content to be reproduced next is unreproducible. At this time, the massage may be blinked, or the title of the unreproducible music may be displayed together with the message. The content request section  32  determines the end of the music content based on the reproduction time length of the music content. The content request section  32  compares the storage amount of the music content in the reception ring buffer  33  and residual reproduction time of the currently reproduced track. The reception ring buffer  33  outputs the entire currently reproduced music content to the converter  34  based on a result of the comparison. 
         [0032]    Then, the content request section  32  mutes audio output, reads out the URL of a track following the reproduced music content, and transmits the URL to the server  2 . At the time point when a given amount of music content is stored in the reception ring buffer  33 , the content request section  32  releases the mute. The reception ring buffer  33  outputs the stored music content to the converter  34 . 
         [0033]    The content request section  32  determines that music content of a format that the client  3  cannot reproduce is unreproducible content. The client  3 , which is not provided with a decoder for expanding a compressed data, can only reproduce music content of a PCM format. The content request section  32  therefore determines that music content of a format other than a PCM is unreproducible content. 
         [0034]    The format of the music content can be determined from the reproduction list. The format of the content is listed in the content type of the reproduction list of  FIG. 2 . The content request section  32  refers to the reproduction list and, if the content type is not a PCM format, displays in the display section  38  that it is impossible to reproduce music content, followed by request of the next music content. 
         [0035]    Further, the format of the music content can be determined from a file header or the like of received music content. The format of the music content is included in the file header. When determining that the type of received music content is not a PCM format, the content request section  32  displays in the display section  38  that it is impossible to reproduce music content, followed by request of the next music content. 
         [0036]    As described above, the format of the music content is determined not only from the content type of the reproduction list, but also from received music content itself. Thus, if the description of the content type in the reproduction list is wrong, it is possible to stop reproduction of unreproducible music content and issue a transmission request of the next music content. 
         [0037]    In the case where there exist a reproducible part and unreproducible part in single music content, the content request section  32  firstly reproduces the reproducible part and, then, displays in the display section  38  that reproduction of the music content that is being reproduced has become impossible. After that, the content request section  32  reads out the URL of the music content following the one whose reproduction has been stopped and transmits the read out URL to the server  2 . 
         [0038]    The content request section  32  waits for network recovery if it cannot receive content due to a communication error. When the communication error continues for a predetermine time, the content request section  32  allows the display section  38  to display that content cannot be acquired due to a communication error. 
         [0039]    Operation of the client  3  will next be described with reference to a flowchart of  FIG. 6 . When the music content to be reproduced next is the one of an unreproducible format, the content request section  32  compares the residual reproduction time of the currently reproduced track and storage amount of the music content in the reception ring buffer  33 . When determining, based on the comparison, that the reception ring buffer  33  stores the entire currently reproduced music content (step S 1 ; YES), the content request section  32  allows the reception ring buffer  33  to output the entire currently reproduced music content to the converter  34  (step S 2 ). On the other hand, when determining that all the currently reproduced music content is not stored in the reception ring buffer  33  (step S 1 ; NO), the content request section  32  allows the reception ring buffer  33  to output a reproducible portion of the currently reproduced music content to the converter  34  (step S 3 ). 
         [0040]    The content request section  32  allows the display section  38  to display a message for notifying a user that music content is unreproducible (step S 4 ). At the same time, the content request section  32  reads out, from the reproduction list, the URL of the music content following the unreproducible music content and outputs the read out URL to the server  2 . Upon receiving the music content following the unreproducible music content from the server  2  (step S 5 ), the content request section  32  waits until a certain amount of the music content is stored in the reception ring buffer  33  (step S 6 ; NO). When a certain amount of the music content is stored (step S 6 ; YES), the content request section  32  allows the reception ring buffer  33  to output the stored music content to the converter  34  (step S 7 ). The music content output from the converter  34  is amplified by the amplifier  35  and reproduced through the speaker  36  as music. 
         [0041]    As described above, when the reproduction list describing the reproduction order of music content includes music content of an unreproducible format, the content reproduction system  1  according to the present invention skips the unreproducible music content and reproduces the next track. Further, in the case where music content being reproduced becomes unreproducible in the middle of the reproduction, the content reproduction system  1  skips the unreproducible part after reproducing up to the reproducible position and reproduces the next track. While the reproduction operation is interrupted due to existence of the unreproducible music content in a conventional system, the content reproduction system  1  is capable of continuing reproduction operation even if there is any unreproducible content in the reproduction list. 
         [0042]    A CD (Compact Disc) player  5  according to the present invention will next be described.  FIG. 7  is a block diagram showing a configuration of the CD player  5 . The CD player  5  includes a driver  51  that drives/rotates a CD, a pickup section  52  that reads out optical information from the CD, a signal processing section  53  that converts an electrical signal read out from the CD into a reproduction signal, a TOC memory  54  that stores TOC (Table Of Contents) information, an amplifier  55  that amplifies the reproduction signal, a speaker  56  through which the reproduction signal is reproduced as music, a display section  57 , and a sequential reproduction processing section  58  that sequentially reproduces music content recorded in the CD. 
         [0043]    Control information called TOC is recorded in the lead-in area of a CD. The TOC includes start/end address of music content, title of music content, artist name, and the like. The information recorded in the TOC is loaded into the TOC memory  54 . 
         [0044]    When there is something wrong with currently reproduced music content and the subsequent music content, the sequential reproduction processing section  58  reads out from a memory the start address of the music content following the defective music content and starts reproduction of the readout music content. Thus, even if there is something wrong with the reproduction of music content, it is possible to continue reproduction of music. 
         [0045]    The function corresponding to the sequential reproduction processing section  58  is applicable not only to the CD player, but also to an HDD player or MD (Mini Disc™) player. 
         [0046]    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.