Method, apparatus and recording medium for recording digital data stream

A recording medium, apparatus and method for recording a digital data stream on the recording medium are discussed. The method according to an embodiment includes recording the digital data stream by dividing the digital data stream into stream objects; recording common information for the stream objects; and recording stream time map information in a stream information file of the recording medium, the stream time map information including a time mapping list having time search information for searching the stream objects.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method, apparatus and recording medium for recording a digital data medium.

2. Description of the Related Art

In a conventional analog television broadcast, video signals are transmitted over the air or through cables after being AM or FM modulated. With the recent advance of digital technologies such as digital image compression or digital modulation/demodulation, standardization for digital television broadcast is in rapid progress. Based upon the Moving Picture Experts Group (MPEG) format, the satellite and cable broadcast industries are also moving towards digital broadcasts.

The digital broadcast offers several advantages that its analog counterpart cannot provide. For example, the digital broadcast is capable of providing services with far more improved video/audio quality, transmitting several different programs within a fixed bandwidth, and offering enhanced compatibility with digital communication media or digital storage media.

In the digital broadcast, a plurality of programs encoded based upon the MPEG format are multiplexed into a single transport stream before they are transmitted. The transmitted transport stream is received by a set top box at the receiver and demultiplexed into the original programs. If a program is chosen from among the demultiplexed programs, the chosen program is decoded by a decoder in the set top box and original audio and video signals are retrieved. The retrieved audio and video signals can be presented by an A/V output apparatus such as a TV.

It is also possible to record the received digital broadcast signals on a storage medium instead of directly outputting the received broadcast signals to A/V output devices. The stored digital broadcast signals can be edited and retrieved afterwards. For example, a digital data stream received by the set top box can be transmitted to a streamer such as a digital video disk (DVD) recording apparatus through communication interfaces such as an IEEE-1394 serial bus and stored in the streamer. The stored digital data stream can be edited and transmitted back to the set top box so that the digital audio and video data can be presented.

For recording a received digital broadcast stream on a recording medium, it is necessary to develop schemes to organize the digital data stream on the recording medium and to create management information for rapid access to the recorded data stream.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a method, apparatus and recording medium for recording a digital data medium.

To achieve the object and other advantages and in accordance with the purpose of the invention, a method for recording a digital data stream on a recording medium, as embodied, comprises: recording the digital data stream by dividing the digital data stream into stream objects; recording common information for the stream objects; and recording stream time map information in a stream information file of the recording medium, the stream time map information including a time mapping list having time search information for searching the stream objects.

In another aspect of the present invention, an apparatus for recording a digital data stream on a recording medium, as embodied, comprises a recording unit to record the digital data stream by dividing the digital data stream into stream objects, to record common information for the stream objects, and to record stream time map information in a stream information file of the recording medium, the stream time map information including a time mapping list having time search information for searching the stream objects.

In another aspect of the present invention, a recording medium for recording digital data using a digital data recorder, as embodied, comprises: a digital data stream divided into stream objects and recorded on the recording medium; common information recorded on the recording medium for the stream objects; and stream time map information recorded in a stream information file of the recording medium, the stream time map information including a time mapping list having time search information for searching the stream objects.

In another aspect of the present invention, a method for recording a digital data stream on a recording medium, as embodied, comprises: recording the digital data stream by dividing the digital data stream into stream objects; recording a playlist for the stream objects, the playlist being recorded in a common information file of the recording medium; and recording stream time map information in a stream information file of the recording medium, the stream time map information including a mapping list having time search information for searching each of the stream objects.

In another aspect of the present invention, an apparatus for recording a digital data stream on a recording medium, as embodied, comprises a recording unit to record the digital data stream by dividing the digital data stream into stream objects, to record a playlist for the stream objects, the playlist being recorded in a common information file of the recording medium, and to record stream time map information in a stream information file of the recording medium, the stream time map information including a mapping list having time search information for searching the stream objects.

In another aspect of the present invention, a recording medium for recording digital data using a digital data recorder, as embodied, comprises: a digital data stream divided into stream objects and recorded on the recording medium; a playlist for the stream objects, the playlist being recorded in a common information file of the recording medium; and stream time map information recorded in a stream information file of the recording medium, the stream time map information including a mapping list having time search information for searching the stream objects.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In order that the invention may be fully understood, preferred embodiments thereof will now be described with reference to the accompanying drawings.

FIG. 1depicts a block diagram of an apparatus in which the present invention may be advantageously employed. The apparatus comprises a set top box100, a communication interface (IEEE-1394), and a streamer200.

The set top box100receives transport streams encoded by system encoders and broadcast by a plurality of broadcasting stations and demultiplexes the received transport streams. After a system decoder120decodes the transport stream of a program tuned by a tuning unit110, a control unit140outputs the decoded transport stream to an A/V output device such as a TV set for presentation.

The set top box100may transmit a program chosen by a user to the streamer200through the IEEE-1394 interface so that the transmitted program is recorded on a recording medium230such as a digital video disk by the streamer200.

Upon a request by a user, the set top box100may receive a program retrieved from the recording medium230by the streamer200through the IEEE-1394 communication interface so that the received program can be presented on a TV set after being decoded by the decoder120.

For carrying out these tasks, the set top box100and the streamer200should be able to access the management information regarding the programs recorded on the recording medium230. To this end, information files are used to deal with the recorded data. An application information file is utilized by the set top box100and a streamer information file is utilized by the streamer200. A common information file is utilized by both the set top box100and the streamer200. These information files are recorded on the recording medium230.

The application information file is retrieved by a stream reproducing unit240of the streamer200when the set top box100is initialized or requests the file. The retrieved application information is transmitted to the set top box100through the IEEE-1394 communication interface and loaded into the management information area M2of a memory150by a control unit140of the set top box100. When a new program is recorded or recorded data is edited, the application information loaded in the memory150is updated by the control unit140to include management information on the newly recorded or edited program. If a user requests retrieval of a specific program, the control unit140requests the streamer200to retrieve the program, with reference to the application information. When the set top box100terminates a recording mode or is shut down, the application information in the memory150is transmitted through the IEEE-1394 communication interface to the streamer200and recorded on the recording medium230by a stream recording unit220controlled by a control unit250of the streamer200.

The streamer information file and common information file are retrieved by the stream reproducing unit240of the streamer200when the streamer200is initialized and loaded into a memory260by the control unit250of the streamer200. When a new program is recorded or recorded data is edited, the streamer and common information is updated to include management information on the newly recorded or edited program by the control unit250. If a user requests retrieval of a specific program, the control unit250, responsive to a request signal from the set top box100retrieves the associated program recorded on the recording medium230with reference to the streamer and common information loaded in the memory260. When the set top box100terminates a recording mode or is shut down, the streamer and common information in the memory260are recorded on the recording medium230by the stream recording unit220controlled by the control unit250.

The syntax of the information files and the structure of recorded data will be explained with reference toFIG. 2.

As shown inFIG. 2, the application information file (application.IFO) comprises a table of content (TOC) and a service information (SI) table. The table of content (TOC) contains random-access entry points that allow random access to the recorded data stream and the service information (SI) table contains the information on the recorded digital stream. The common information file (common.IFO) contains an original playlist automatically created when a digital data stream is recorded, presentation sequence information (Cell) of the recorded data stream, and a user-defined playlist created when a user edits the presentation sequence of the recorded data stream. The table of content and the playlist are common information for the stream objects (SOBs).

The streamer information file (streamer.IFO) is intended to deal with stream time map general information (STMAP_GI) and a mapping list (MAPL). The stream time map general information (STMAP_GI) is management information regarding stream object units (SOBUs) organized on the recording medium and stream objects (SOBs) each, of which comprises a plurality of stream object units (SOBUs) and the mapping list (MAPL) is time search information regarding the stream object units (SOBUs) and stream objects (SOBs). Each stream object (SOB) has a one-to-one correspondence with each Cell contained in the original playlist and each Cell is contained in the user-defined playlist and has a one-to-one correspondence with each stream object (SOB).

The stream time map general information (STMAP_GI), as shown inFIG. 3, comprises several fields representing the stream object unit size (MAPU_SZ), the weight of the LSB of the mapping list entries (MTU_SHFT), index number (INDEX_NO) indicating an arbitrary entry of the mapping list (MAPL), the number of mapping list entries (MAPL_ENT_Ns), start packet arrival time (S_SAPAT), and last packet arrival time (S_E_APAT). The mapping list (MAPL) comprises mapping entries (MAPU_ENT), each mapping entry containing the incremental application packet time (IAPAT).

The method for creating and recording search information for recorded digital data streams in accordance with an embodiment of the present invention will be explained with reference toFIGS. 1,2, and3. If a user requests recording of a received digital data stream on the recording medium230, the control unit140of the set top box100notifies the control unit250of the streamer200that a recording mode has been set and begins to transmit the received digital data stream to the streamer200through the IEEE-1394 interface. Concurrently, the control unit140of the set top box100records the entry point information that allows random access to the transport stream packets of the digital data stream in the application information (application.IFO) loaded in the management information area (M2) of the memory150or records the entry point information in the common information (common.IFO) as a part of the playlist. Also, the control unit140detects the information on the data stream currently being recorded from the program service information (SI) loaded in the program information area (M1) of the memory150and records the service information in the service information (SI) table of the application information (application.IFO).

The control unit250of the streamer200controls the stream recording unit220so that the data stream received through the IEEE-1394 communication interface is recorded on the recording medium230. The data stream is organized in sectors on the recording medium230and a predetermined number of sectors constitute a stream object unit (SOBU). The process is repeated until the recording mode terminates, thereby creating a stream object (SOB) which is a group of data streams recorded by a single recording operation.

The control unit250of the streamer200creates presentation sequence information (Cell) regarding the created stream object (SOB) and records the Cell in the Cell layer of the common information (common.IFO) as presentation sequence information corresponding to the record (RCD) of the original playlist. For searching for stream object units (SOBUs) constituting the stream object (SOB), the time length of every stream object unit (SOBU) is sequentially recorded in the mapping list (MAPL). To be more specific, a count value counted at a constant time interval while a stream object unit (SOBU) is created, namely, the incremental application packet time (IAPAT) is recorded in the mapping entry field (MAPU_ENT) corresponding to the associated stream object unit (SOBU), as shown inFIGS. 4 and 5. In addition, the sum of a predetermined number of incremental application packet times IAPATs (the numbers parenthesized inFIG. 5) is calculated and the sum is recorded as a coarse mapping entry (C_MAP_ENT) which is coarse search time information.

The index number (INDEX_NO) of the first mapping entry (MAPU_ENT) of the mapping list (MAPL) or the first coarse mapping entry (C_MAP_ENT) associated with the stream object (SOB) is recorded in the stream time map general information (STMAP_GI). InFIG. 5, the index number K of the first mapping entry related to the stream object SOB #n is recorded as identification information for indexing the location of the stream object SOB #n.

If a user requests retrieval of a certain interval of a data stream recorded on the recording medium, for example recorded data corresponding to the time interval from 10 minutes to 20 minutes, the control unit150of the streamer200first searches Cells for a Cell (Cell2inFIG. 2) having a recording time corresponding to the start time 10 minutes. Then, the control unit150detects the index number pointing to the start position of the stream object SOB2corresponding to the chosen Cell2from the stream time map general information (STMAP_GI). Subsequently, the control unit150begins to detect the incremental application packet times (IAPATs), starting from the mapping entry pointed to by the index number. By summing the detected incremental application packet times (IAPATs) and multiplying the sum value by the unit time of each count, the start position of the stream object unit (SOBU) corresponding to the requested search time 10 minutes can be found. Finally, data retrieval begins from the transport stream packet whose packet arrival time coincides with the requested time.

If a user requests retrieval of the recorded data corresponding to the time interval from 40 minutes to 60 minutes and the Cell having a recording time corresponding to the requested time 40 minutes is Cell3, the control unit150detects the index number pointing to the start position of the stream object SOB3corresponding to the chosen Cell3from the stream time map general information (STMAP_GI). Subsequently, the control unit150begins to detect the incremental application packet times (IAPATs) listed in the mapping list MAPL3. By summing the detected incremental application packet times (IAPATs) and multiplying the sum value by the unit time of each count, the start position of the stream object unit (SOBU) corresponding to the requested time 40 minutes can be found. Finally, data retrieval begins from the transport stream packet whose packet arrival time coincides with the requested time.

The method for creating and recording search information for recorded digital data streams of the present invention enables rapid and precise search of a specific interval of the recorded digital data, provided that the digital data streams are recorded on a recording medium as groups of stream objects.