Information recording medium, apparatus and method for recording or reproducing data thereof

0001[0001] This application is based on application No. 10-289089 filed in Japan, the contents of which is herein incorporated by reference.

BACKGROUND OF THE INVENTION

0002[0002] 1. Field of the Invention

0003[0003] The present invention relates to readable/writable information recording medium. More specifically, the present invention relates to an information recording medium for recording multimedia data in different kinds of formats such as movie image data, still picture data and audio data; and a data recording apparatus and replaying apparatus for the medium.

0004[0004] 2. Related Art

0005[0005] Development of phase change type disc DVD-RAM has increased recording capacity of a rewritable optical disc from about 650 MB to a few GB. The DVD-RAM is now expected to become a medium not only for computers but also a recording/playing medium for audio/video (hereinafter abbreviated as AV) technologies in combination with standardization of a digital AV data coding technique called MPEG (MPEG2). Specifically, the DVD-RAM is expected to replace magnetic tape which has been a major AV recording medium.

0006[0006] (DVD-RAM)

0007[0007] Advancement in high-density recording technology for rewritable optical discs in recent years has made it possible to store not only computer data and audio data but also image data as well.

0008[0008] Conventionally, land and groove are formed on a signal recording surface of the optical disc.

0009[0009] Signals used to be recorded only on the land portion or in the groove portion. Later, land-group recording method was developed for recording signals both in the land portion and in the groove portion, practically doubling the recording density. For example, a technique disclosed in Japanese Patent Laid-Open Publication No. 8-7282 is well known.

0010[0010] Another of such techniques is CLV (Constant Linear Velocity recording) method for improving recording density. From this technique, zone CLV method was developed and is now commercially practiced for simplified control in application. Japanese Patent Laid-Open Publication No. 7-93873 is a known example of this technique.

0011[0011] With such development in the optical disc for greater recording capacity, a technological challenge is how to record AV data including image data, thereby achieving new performances and functions that have never been realized by prior art AV apparatuses.

0012[0012] The development of the large-capacity rewritable optical disc is expected to replace the conventional tape medium for recording/playing AV data. The change from tape to disc will bring substantial changes in the function and performance of the AV equipment.

0013[0013] The biggest change to be brought by the disc is tremendous improvement in random access capability. If tape is to be accessed randomly, rewinding time of the tape, which is usually a few minutes per reel, must be taken into account. Such an access time is extremely slower than a seek time (which is shorter than a few tens of millisecond.) for the optical disc. Thus, in a practical sense, the tape cannot be a random access medium.

0014[0014] Such a superb random access capability of the optical disc can realize distributed recording of AV data in the optical disc, which was not possible with the conventional tape medium.

0015[0015] Referring now to the attached drawings, FIG. 1 is a block diagram of a DVD recorder drive unit. The drive unit comprises an optical pickup <b>11</b> for reading data stored in a DVD-RAM disc <b>100</b>, an ECC (Error Correcting Code) processor <b>12</b>, a one-track buffer <b>13</b>, a switch <b>14</b> for selecting between input and output to and from the track buffer <b>13</b>, an encoder <b>15</b>, and a decoder <b>16</b>.

0016[0016] As shown in the figure, the DVD-RAM disc <b>100</b> uses one sector (1 sector=2 KB) as a smallest unit of data recording, and one ECC block (1 ECC block=16 sectors) is used as a unit for error correcting operation performed by the ECC processor <b>12</b>.

0017[0017] The track buffer <b>13</b> is a buffer for storing AV data at a variable bit rate to record AV data effectively in the DVD-RAM disc <b>100</b>. Specifically, reading/writing for the DVD-RAM <b>100</b> is performed at a fixed rate (Va), whereas the bit rate (Vb) of AV data is varied according to complexity of contents (e.g. an image for video data). The buffer <b>13</b> absorbs difference between these two bit rates. When the AV data have a fixed bit rate such as in a video CD, then the track buffer <b>13</b> is not required.

0018[0018] If this track buffer <b>13</b> is used more effectively, distributed recording of AV data on the disc <b>100</b> becomes possible. This will be described more specifically here below, referring to FIGS. 2A and 2B.

0019[0019]FIG. 2A is a diagram showing address space on the disc. According to FIG. 2A, AV data is stored in a distributed manner, i.e. in a continuous area [a1, a2] and in another continuous area [a3, a4]. In such a case, the AV data can be replayed continuously supplying data stored in the buffer <b>13</b> to the decoder portion <b>16</b> while seek is being made from point a2 to point a3. This situation is shown in FIG. 2B.

0020[0020] The AV data starting from the location a1 are read, and then entered to the track buffer <b>13</b> from time t1, upon which time the track buffer <b>13</b> begins to output the data. Thus, the buffer <b>13</b> accumulates data at a rate equal to the difference (Va−Vb) between the input rate (Va) to the buffer <b>13</b> and the output rate (Vb) from the buffer <b>13</b>. This situation continues until the retrieval reaches a2 represented by a time point t2, by which time the amount of data in the buffer <b>13</b> has accumulated to amount B(t2). From time t2 to time t3, until the data pickup operation is resumed from the area starting at a3, the amount of data B(t2) stored in the track buffer <b>13</b> is being consumed in order to keep the decoder <b>16</b> supplied with data.

0021[0021] In other words, when the amount of data ([a1, a2]) read before the seeking is greater than a certain volume, then the AV data can be continuously supplied without being interrupted by the seek.

0022[0022] The above description is for reading of data from the DVD-RAM, i.e. for a play back operation. The same goes with writing data to the DVD-RAM, i.e. for a recording operation.

0023[0023] As described above, with the DVD-RAM, continuous replaying/recording is possible even if AV data is stored in the distributed manner, as long as the amount of data on each continuous record is greater than a certain volume.

0024[0024] In order to enhance advantages of the large-capacity recording medium, i.e. DVD-RAM, a UDF (Universal Disc Format) file system is used in the DVD-RAM as shown in FIG. 3 to allow access to the disc by using a PC. UDF information is recorded in “Volume” area of the diagram. Details of the UDF file system is disclosed in the “Universal Disc Format Standard.”

0025[0025] (Prior-Art AV Equipment)

0026[0026] Next, description will be made for prior art AV equipment commonly used by many users.

0027[0027]FIG. 4 is a diagram showing relationships among conventional AV equipment, media and formats. For example, if a user wants to watch a video program, a videocassette must be loaded into a VTR, and the program must be viewed using a TV set. If the user wants to listen to music, then a CD must be loaded into a CD player or CD radio-cassette player, and the program must be listened through a speaker system or through headphones. Specifically, according to the conventional AV system, each format (video or audio) is paired with a corresponding medium, respectively.

0028[0028] For this reason, each time when listening or watching a program, the user must select an appropriate medium and change one to another AV equipment appropriate to the medium. This is inconvenient from the user's viewpoint.

0029[0029] (Digitization)

0030[0030] Meanwhile, along with recent popularization of digital technology, a DVD videodisc was introduced as package software, whereas satellite digital broadcast was introduced in the broadcasting industry. These developments are backed by digital technology innovation, especially by MPEG as an internationally accepted standard.

0031[0031]FIG. 5 is a diagram showing MPEG streams used in the DVD videodisc and the satellite digital broadcast mentioned above. The MPEG standard has a hierarchy structure as shown in FIG. 5. An important point to note here is that the MPEG stream eventually used by an application in the package medium such as the DVD videodisc is different from the MPEG stream in the communication medium such as the satellite digital broadcasting. The former is called “MPEG program stream”, in which data transfer is made by the unit of pack, reflecting the size of a sector (2048 bytes in DVD video disc) as the unit of recording in the package software. On the other hand, the latter is called “MPEG transport stream”, in which the unit of data transfer is a TS packet having a size of 188 bytes, reflecting the application to ATM (Asynchronous Transfer Mode) systems.

0032[0032] The MPEG is expected to eliminate borders between different AV media, as a universal coding technology of image signals and digital data. However, because of such small differences as described above, there is not yet any AV equipment or media capable of handling both the package media and communication media.

0033[0033] (Changes Brought by DVD-RAM)

0034[0034] Introduction of the large capacity DVD-RAM is a step forward to elimination of the inconvenience that users feel in conventional AV equipment. As described earlier, the DVD-RAM incorporated with the UFD file system is accessible from the PC. By using different pieces of application software on the PC, it is now possible to play varieties of contents such as video, still picture and audio programs on a single piece of equipment, i.e. the PC.

0035[0035] As shown in FIG. 6, the user can move a cursor with a mouse onto a file displayed on a screen, and then double-click (or single-click) to replay contents of the file such as a movie displayed in left-top area of the screen.

0036[0036] Such a convenience becomes possible by combination of flexibility offered by the PC and large storage capacity offered by the DVD-RAM.

0037[0037] Backed by increasing popularity of the PC in recent years a number of different AV data can now be handled fairly simply on the PC as shown in FIG. 6. However, even though number of PC users is expected to increase, the popularity and easiness of operation of the PC are not so high and simple as those of the home TV or home video systems.

0038[0038] It is therefore an object of the present invention to solve the following problems identified as hurdles to optimum performance of the optical discs such as the DVD-RAM, as an AV recording medium of the next generation.

0039[0039] A world to be realized by the DVD recorder would be a world in which the user can freely handle different formats and contents without caring about the differences, by using a single medium on a single piece of AV equipment as shown in FIG. 7.

0040[0040]FIG. 8 shows an example of a menu used in the DVD recorder. According to this menu, the user can select from 1) “The Foreign Movie Theater” recorded from satellite digital broadcasting, 2) “The Morning Drama Series”, 3) “The World Cup Finals” each recorded from conventional terrestrial broadcasting, and 4) a Beethoven dubbed from a CD, on a TV screen without caring about the original medium or the recording format.

0041[0041] The biggest problem in developing such a DVD recorder as above is how to manage uniformly the AV data and streams of many different formats.

0042[0042] No special managing method will be necessary if only a limited number of existing formats are to be handled. However, a managing method capable of handling not only a number of existing formats but also new formats to be introduced in the future has to be developed in order to realize the above-mentioned world of DVD recorder.

0043[0043] Even so, certain difference between a future user interface and those incorporated in the capability of uniformly handling the different AV streams may create a certain level of inconvenience similar to the inconvenience described for the prior-art. Specifically, the user may have to perform different operation depending upon the contents or format.

SAMMARY OF THE INVENTION

0044[0044] The present invention is made to solve the above problem, and it is therefore an object of the present invention to provide an information recording medium capable of uniformly handling different kinds of AV streams, and to provide a recording apparatus and a playing apparatus for said information recording medium.

0045[0045] In a first aspect of the invention, an information recording medium is provided for recording objects which include at least one of image data and audio data. The recording medium stores object information and playback control information.

0046[0046] The object information includes identification information and map information for each object. The identification information identifies the object. The map information associates a playback time of the object with a logical address (or address on a disc) of a component of the object on the medium. The component is played back at the playback time.

0047[0047] The playback control information includes at least one of cell information in a predetermined order. The cell information contains type information, identification information and playback section information. The type information indicates a kind of the object. The identification information identifies the object. The playback section information specifies a section in which the object is being played.

0048[0048] The order of cell information in the playback control information indicates the order in which the objects specified by respective cell information are played.

0049[0049] In a second aspect of the invention, an apparatus for recording data to the information recording medium comprises a unit for receiving an MPEG transport stream from external equipment, a unit for reading the “random_access_indicator” from the received MPEG transport stream and a unit for generating an access point information based on the read “random_access_indicator”.

0050[0050] In a third aspect of the invention, an apparatus for recording data to the information recording medium comprises a unit for recording type information and the type information indicating a kind of object to the playback section information.

0051[0051] In a forth aspect of the invention, an apparatus for reading data from the information recording medium comprises a pickup unit for reading data of the object recorded in the recording medium, a plurality of decoding units for decoding the data of the object according to the kind of the object, a selecting unit for selecting one of the decoding units for playback operation and a controlling unit for reading the type information of the object specified in the object information, and controlling the selecting units to select one of the decoding units according to the read type information.

0052[0052] In a fifth aspect of the invention, a method for recording data to the information recording medium comprises the steps of receiving an MPEG transport stream from external equipment, reading the “random_access_indicator” from the received MPEG transport stream and generating an access point information based on the read “random_access_indicator”.

0053[0053] In a sixth aspect of the invention, a method for reproducing data from the information recording medium, comprises the steps of reading out object data from the recording medium, reading out the type information of the playback control information in the recording medium, and decoding the read object data according to the read type information.

0054[0054] The recording medium according to the present invention makes possible not only to record but also to integrally manage different AV formats on the same disc, thereby making possible to manage a variety of objects each recorded in a different format on one recording medium.

0055[0055] The apparatus and method for recording according to the present invention makes possible to create and record the type information for indicating the kind of objects to be recorded, thereby making possible to embody the above optical disc compatible to the variety of AV formats.

0056[0056] The apparatus and method for reproducing according to the present invention makes possible to decode data of read object in the external equipment even if the playing apparatus does not have the capability to decode the data of the read object.

BRIEF DESCRIPTION OF THE DRAWINGS

0057[0057]FIG. 1 is a block diagram of a drive unit of a DVD recorder.

0058[0058]FIG. 2A is a diagram showing address space on a disc.

0059[0059]FIG. 2B is a diagram showing data accumulation in a track buffer.

0060[0060]FIG. 3 is a diagram showing a file structure through a file system.

0061[0061]FIG. 4 is a diagram showing relationships among different kinds of prior art AV equipment and corresponding media.

0062[0062]FIG. 5 is a diagram showing an MPEG program stream and an MPEG transport stream.

0063[0063]FIG. 6 is an illustration of a PC screen when an AV data file is being accessed on the PC.

0064[0064]FIG. 7 is a diagram showing relationships to be created by a DVD recorder among different kinds of AV equipment.

0065[0065]FIG. 8 is an example of a selection menu given by the DVD recorder.

0066[0066]FIG. 9A is a diagram showing relationships between an AV file and a directory on the computer readable DVD-RAM disc.

0067[0067]FIG. 9B is a diagram showing address space on the disc.

0068[0068]FIG. 10 is a diagram showing relationships among an object, object information and PGC information.

0069[0069]FIG. 11 is a diagram showing management information derived from the object information for each stream.

0070[0070]FIG. 12 is a diagram showing relationships among a movie object (M_VOB), movie object information (M_VOBI), and PGC information (PGCI).

0071[0071]FIGS. 13A, 13B, <b>13</b>C, <b>13</b>D, <b>13</b>E and <b>13</b>F are diagrams describing a time map according to the present invention.

0072[0072]FIGS. 14A, 14B, <b>14</b>C and <b>14</b>D are diagrams each of which shows each stage of the MPEG transport stream.

0073[0073]FIG. 15 is a diagram showing relationships between an audio object (AOB), audio object information (AOBI) and PGC information (PGCI).

0074[0074]FIG. 16 is a diagram showing relationships among a still picture object (S_VOBS), still picture object information (S_VOBS), and PGC information (PGCI).

0075[0075]FIG. 17 is a diagram describing management information in a DVD-RAM.

0076[0076]FIG. 18 is a block diagram of a player model according to the present invention.

0077[0077]FIG. 19 is a block diagram of the DVD recorder according to the present invention.

0078[0078]FIG. 20 is a Block diagram of a DVD player or a data reproducing apparatus according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

0079[0079] With reference to the accompanying drawings, detailed description will be made for a DVD-RAM, a DVD recorder, and a DVD player as preferred embodiments of the present invention.

0080[0080] (Logic Structure of Data on DVD-RAM)

0081[0081] The DVD-RAM according to the present invention makes possible to record and manage integrally AV data and AV streams of many different kinds of formats on a single disc. This allows it to record on a single disc AV streams of different formats including a terrestrial broadcasting TV program, a digital broadcasting TV program transmitted in the MPEG transport stream format, a video stream taken by a digital video camera, a still picture taken by a digital still camera, and video data coded in the MPEG program stream, and so on. Further, the data recorded in the DVD-RAM can be played in a given sequence. For this purpose, the DVD-RAM according to the present invention is provided with management information for managing the AV streams without depending on the types of format of the AV data or AV streams.

0082[0082] First, structure of the data recorded in the DVD-RAM according to the present invention is described with reference to FIGS. 9A and 9B. A diagram in FIG. 9A is a data structure of a DVD-RAM disc <b>100</b>, which can be seen by a file system. FIG. 9B shows a structure of a physical sector in the disc <b>100</b>.

0083[0083] As shown in the figure, a first portion of the physical sector is a lead-in area <b>31</b> which stores therein standard signals necessary for stabilizing servo mechanism, identification signals for differentiating from other media, and so on. The lead-in area <b>31</b> is followed by a data area <b>33</b> which stores logically available data. A last portion is a lead-out area <b>35</b> storing signals similar to those in the lead-in area <b>31</b>.

0084[0084] A front portion of the data area <b>33</b> stores with volume information which is management information for the file system. Since the file system is a known technique, no details will be described herein.

0085[0085] The file system allows the data in the disc <b>100</b> to be handled as directories and files as shown in FIG. 9A. As understood from FIG. 9A, all the data handled by the DVD recorder is managed under VIDEO_RT directory immediately below the ROOT directory.

0086[0086] The DVD recorder according to the present embodiment handles two kinds of files, i.e. AV files containing audio-video data (AV data), and management information files containing information for managing the AV files. According to the example shown in FIG. 9A, the management information file is identified as “VIDEO_RT. IFO”, whereas the AV files include a file “M_VOB.VOB” which contains movie data, “D_VOB.VOB” which contains image data from digital broadcasting, “AOB. AOB” which contains audio data, and so on. Each of these files will be detailed here below.

0087[0087] It should be noted here that according to the present embodiment, each AV stream is defined as an object (“Object”). Specifically, the objects may include a variety of AV streams such as MPEG program stream, MPEG transport stream, audio stream, still picture data, and so on. Each of these AV streams is abstracted as the object so that the management information of these AV streams can be defined as object information (Object I) of a universal format.

0088[0088] (Management Information)

0089[0089] First, the management information will be described referring to FIG. 10. The management information has object information <b>80</b> for management of recording locations of the object and attribute thereof, and program chain information (PGC information) <b>50</b> and <b>70</b> which define playback sequence, playback time and so on for data to be played back from the DVD-RAM.

0090[0090] The above-described abstraction is possible for the AV streams because the AV streams have time attribute and other elements in common, although each of the different formats has certain differences from the others. AV streams having a common format are stored in a same AV file in the order of recording.

0091[0091] The object information (Object I) <b>80</b> includes general information about the object (Object GI) <b>80</b><i>a</i>, attribute information of the object (Attribute I) <b>80</b><i>b</i>, and an access map <b>80</b><i>c </i>for converting the object playback time into addresses on the disc.

0092[0092] The access map <b>80</b><i>c </i>is necessary because the AV stream generally has two standards, i.e. a time domain and a data (binary digit string) domain, which do not have perfect correlation with each other. For example, in a video stream coded by MPEG-2 video which is now an international standard of the video stream, use of variable bit rate (a method in which the bit rate is changed depending on the level of complexity of an image) is becoming a mainstream. According to this method, there is no proportional relationship between the amount of data from the beginning and the accumulated length of playback time, and therefore random accessing cannot be performed based on the time axis. In order to solve this problem, the object information <b>80</b> has the access map <b>80</b><i>c </i>for conversion between the time axis and the data (binary digit string) axis. As will be described later, one object comprises a plurality of object units (VOBU), and therefore the access map <b>80</b><i>c </i>has data that correlates or associates the time region with the address region for each of the object units.

0093[0093] The PGC information <b>50</b>, <b>70</b> are the information for controlling the playback of the object, i.e. image data and audio data. The PGC information <b>50</b>, <b>70</b> represent a unit of data to be played back when the DVD player plays continuously data back. Specifically, each of the PGC information <b>50</b>, <b>70</b> indicates an object to be replayed, and a playback sequence of cells <b>60</b>, <b>61</b>, <b>62</b> and <b>63</b>. Each of cells <b>60</b>, <b>61</b>, <b>62</b> and <b>63</b> indicates any playback section of this particular object. The cells <b>60</b>, <b>61</b> . . . will be described later in more detail. Thee PGC information comprises two kinds of information comprising an original PGC information <b>50</b> and a user defined PGC information <b>70</b>. The original PGC information <b>50</b> is automatically generated by the DVD recorder upon recording the object so that all of the recorded objects are included. On the other hand, with the user-defined PGC information <b>70</b>, the user can freely define the playback sequence. The PGC information <b>50</b> and <b>70</b> have the same structure and function differing only in that the user-defined PGC information <b>70</b> is defined by the user. Thus, description in further detail will be made only for the original PGC information <b>50</b>.

0094[0094] As shown in FIG. 10, the original PGC information <b>50</b> includes at lease one of the cell information. The cell information <b>60</b> . . . specifies an object to be replayed, and a replay section of the object. Generally, the PGC information <b>50</b> records a plurality of cells in a certain sequence. This recording sequence of the cell information in the PGC information <b>50</b> indicates the sequence in which the objects specified in respective cells are replayed.

0095[0095] Each cell, the cell <b>60</b> for example, includes type information (“Type”) <b>60</b><i>a </i>which indicates the kind of object specified, an object identification (Object ID) <b>60</b><i>b </i>which identifies the object, starting position information (“Start”) <b>60</b><i>c </i>on the time axis of the object, and ending position information (“End”) <b>60</b><i>e </i>oh the time axis in the object.

0096[0096] When the data is replayed, the cell information <b>60</b> in the PGC information <b>50</b> is read out successively, so that the object specified by the cell is replayed by successively playing portions of the object represented by the playback sections specified by respective cells.

0097[0097] (Subclasses of the Object Information)

0098[0098] In order for the abstracted object information to be applied to an actual AV stream, a concretization must be provided. This principle may be understood easily as the class concept employed in an object-oriented model. More specifically, understanding will become easier if the object information is considered as a super-class, and more concrete structures created for each of the AV streams are considered as subclasses. FIG. 11 shows these concretized subclasses.

0099[0099] According to the present embodiment, as shown in FIG. 11, the object information has subclasses defined as a movie subclass, a still picture subclass, an audio subclass, and a digital broadcast subclass. Specifically, following subclasses are defined as concrete information: Movie object information (M_VOBI) is defined as the object information for video data (in MPEG program stream). Digital video object information (D_VOBI) is defined as the object information for digital broadcasting (in MPEG transport stream). Audio object information (AOBI) is defined as the object information for audio, and still picture video object information (S_VOBI) is defined as the object information for still pictures. Each of the above will be described here below.

0100[0100] The movie object information <b>82</b> includes MPEG program stream general information (M_VOB_GI) <b>82</b><i>a</i>, movie object stream information (M_VOB_STI) <b>82</b><i>b</i>, and a T map <b>82</b><i>c. </i>

0101[0101] The general information (M_VOB_GI) <b>82</b><i>a </i>includes movie object Identification information (M_VOB_ID), movie object recording time (M_VOB_REC_TM), movie object starting time information (M VOB_V_S_PTM), and movie object ending time information (M_VOB_V_E PTM).

0102[0102] The movie object stream information (M_VOB_STI) <b>82</b><i>b </i>includes video stream information (V_ATR) having coding attributes of the video stream, the number of audio streams (AST_Ns), and audio stream information (A_ATR) having coding attributes of the audio stream.

0103[0103] The T map <b>82</b><i>c </i>includes a leading address of the movie object in the AV file, playback time (VOBU_PB_TM) and data size (VOBU_SZ) of each of the movie object units (VOBU). The movie object unit (VOBU) is the smallest unit to be accessed in the movie object (M_VOB), and will be detailed later.

0104[0104] The digital broadcast object information (D_VOBI) <b>86</b> includes MPEG transport stream general information (D_VOB_GI) <b>86</b><i>a</i>, stream information (D_VOB_STI) <b>86</b><i>b</i>, and a T map <b>86</b><i>c. </i>

0105[0105] The general information of the digital broadcasting object (D_VOB_GI) <b>86</b><i>a </i>includes digital broadcasting object identification information (D_VOB_ID), digital broadcasting object recording time (D_VOB_REC_TM), digital broadcasting object starting time information (D_VOB_V_S_PTM), and digital broadcasting object ending time information (D_VOB_V_E PTM).

0106[0106] The digital video object stream information (D_VOB_STI) includes information (PROVIDER_INF) which contains additional information provided in the digital broadcasting. The T map <b>86</b><i>c </i>includes a leading address of the digital broadcasting object (D_VOB) in the AV file, playback time (VOBU_PB_TM) and data size (VOBU_SZ) for each object unit (VOBU).

0107[0107] The audio object information (AOBI) <b>88</b> includes audio stream general information (AOB_GI) <b>88</b><i>a</i>, stream information (AOB_STI) <b>88</b><i>b</i>, and a T map <b>88</b><i>c</i>. The audio stream general information (AOB_GI) <b>88</b><i>a </i>includes audio object identification information (AOB_ID), audio object recording time (AOB_REC_TM), audio object starting time information (AOB_S_TM), and audio object ending time information (AOB_E_TM). The AOB stream information (AOB_STI) <b>88</b><i>b </i>includes audio stream information (A_ATR) having coding attributes of the audio stream. The T map <b>88</b><i>c </i>includes a leading address of the audio object in the AV file, playback time (AOBU_PB_TM) and data size (AOBU_SZ) for each audio object unit (AOBU). The audio object unit (AOBU) is the smallest access unit in the audio object (AOB), and will be detailed later.

0108[0108] Still picture object information (S_VOBSI) <b>84</b> includes still picture general information (S_VOBS_GI) <b>84</b><i>a</i>, still picture stream information (S_VOBS_STI) <b>84</b><i>b</i>, and an S map <b>84</b><i>c</i>. The still picture general information (S_VOBS_GI) <b>84</b><i>a </i>includes still picture object identification information (S_VOBS_ID), still picture object recording time (S_VOBS_REC_TM), still picture object starting picture number (SVOBS_S_NO), and still picture object ending picture number (SVOBS_E_NO). The still picture stream information (S_VOBS_STI) <b>84</b><i>b </i>includes still picture attribute information (V_ATR) having information about a compression format of the still picture object. The S map <b>84</b><i>c </i>includes a leading address of still picture object (S_VOBS) in the AV file, and data size (S_VOB_SZ) for each still picture.

0109[0109] As described above, a stream information table corresponding to each type of AV stream can be defined as shown in FIG. 11 by putting the abstracted object information into a more concrete data.

0110[0110] (Correspondence Between Object Information and Cell Information)

0111[0111] Referring next to FIG. 12, the movie object information (M_MOBI), which is one of the concrete forms of the object information (Object I), is taken as an example to see correspondence with the cell information.

0112[0112] When the type information (Type) specified in the cell information has the value “M_VOB”, this cell corresponds to a movie object. Likewise, when the type information has the value “D_VOB”, then the cell corresponds to a digital broadcasting object, and when the type information has the value “AOB”, then the cell corresponds to an audio object.

0113[0113] Based on the object ID (Object ID), the object information (VOBI) corresponding to the ID can be found. The object ID has a one-to-one correspondence to the movie object ID (M_VOB_ID) contained in the general information (M_VOB_GI) of the movie object information (M_VOB_I).

0114[0114] As described above, the object information corresponding to the cell information can be retrieved by using the type information (Type) and the object ID (Object ID).

0115[0115] The starting position information (Start) in the cell information corresponds to the start time information (M_VOB_V_S_PTM) of the movie object information. When the two values indicate a same time, it indicates that the cell is the first portion to be played of the movie object. On the other hand, when the starting position information (Start) has a value greater than that of the start time information (M_VOB_V_S_PTM), it indicates that the cell is to be played as a middle portion of the movie object. In such a case, the playback of the cell is delayed from the top of the object by the difference (time difference) between the start time information (M_VOB_V_S_PTM) and the starting position information (Start). The same relationship exists between the cell ending position information (End) and the end time information (M_VOB_V_E_PTM) of the movie object.

0116[0116] As described above, playback starting and the ending of a given cell can be obtained as relative points of time within the object by using the starting information (Start) and the ending information respectively in the cell information, and the start time information (M_VOB_V_S_PTM) and end time information (M_VOB_V_E_PTM) respectively in the general information (M_VOB_GI) of the movie object information (M_VOBI).

0117[0117] The T map of the movie object is a table comprising a playback time and data size for each movie object unit (VOBU). By using the T map, the relative playback start time and the relative playback end time of a given cell within the movie object described above can be converted to address data.

0118[0118] Now, the address conversion using the T map mentioned above will be specifically described with reference to FIGS. 13A, 13B, <b>13</b>C, <b>13</b>D, <b>13</b>E and <b>13</b>F.

0119[0119]FIG. 13A shows movie objects (M VOB) representing video display on the time axis. FIG. 13B shows the time map comprising the length of playback time and the data size for each movie object unit (VOBU). FIG. 13C shows the movie object expressed on the data (sector series) axis. FIG. 13D shows pack series as an enlarged portion of the movie object. FIG. 13E shows a video stream. FIG. 13F shows an audio stream.

0120[0120] The movie object (M_VOB) is an MPEG program stream. In MPEG program stream, a video stream and an audio stream are assembled into a packet (PES packet), and a plurality of the packets (PES packets) are packed into a sequence. In the example, one pack contains one packet (PES packet), and a pack is allocated with one sector (=2048B) for easier access. Further, packed video packs (V_PCK) and audio packs (A_PCK) are multiplexed into a single stream. All of these are illustrated in FIGS. 13C, 13D, <b>13</b>E and <b>13</b>F.

0121[0121] Further, an MPEG system stream (a general term for the program stream and transport stream) contains time stamps for synchronized playback of the multiplexed video and audio streams. The time stamp for the program stream is PTS (Presentation Time Stamp) which indicates the time when the frame is to be played. The movie object start time information (M_VOB_V_S_PTM) and the movie object end time information (M_VOB_V_E_PTM) mentioned earlier are time information obtained from the PTS. On the other hand, the time stamp for the transport stream is PCR (Program Clock Reference) which indicates the time of input of data to the buffer.

0122[0122] The movie object unit (VOBU) is described below. The movie object unit (VOBU) is the smallest access unit within the movie object (M_VOB). In order to accomplish highly efficient image compression, the MPEG video stream uses not only image compression using spatial frequency characteristics within a video frame but also image compression using motion characteristics between the frames, i.e. motion characteristics on the time axis. This means that expansion of a video frame requires information on the time axis, i.e. information about a future video frame or a past vide frame is required, or that the video frame may not be expanded by itself. In order to solve this problem, in MPEG video stream, a video frame (called I-picture) having no motion characteristics on the time axis is inserted every about 0.5 second, achieving higher random accessibility.

0123[0123] The movie object unit (VOBU) includes some packs from a pack containing the leading data of an I-picture to a pack immediately before a pack containing the leading data of the next I-picture. Thus, the T map comprises the data size (the number of packs) of each object unit (VOBU) and the playback time (the number of fields) of the video frames within the object unit (VOBU).

0124[0124] For example, an assumption is made that the value of Start in the cell differs from the value of start time information (M_VOB_V_S_PTM) of the movie object by one second (60 fields).

0125[0125] Now, the playback start time of each object unit in the movie object (M_VOB) can be obtained by accumulating the playback time (length) of each object unit (VOBU) in the T map from the first movie object. Likewise, the address of each object unit in the movie object (M_VOB) can be obtained by accumulating the data size (the number of packs) of each object unit from the first object unit.

0126[0126] According to the present embodiment, the first three object units (VOBU) of the movie object (M_VOB) have 24, 30 and 24 fields respectively. Thus, from the above calculation method, the video frame after one second (60 fields) from the top of the movie object (M_VOB) is found to be included in the third object unit (VOBU#3). Likewise, the start address of the third object unit (VOBU#3) is found to be the 223rd sector from the head of the object since these object units (VOBU) respectively have data sizes of 125, 98 and 115 sectors.

0127[0127] Adding the obtained address value to address value for 5010 sectors which is the M_VOB start address (ADD_OFF) within the AV file provides the start address of the data to be played.

0128[0128] In the above example, assumption is made that the video frame which is the 60th field from the top of the movie object (M_VOB) is to be played. As mentioned earlier however, the MPEG video does not allow decoding or playback from any one of all video frames. For this reason, the playback starts from the top of the object unit (VOBU) shifted by 6 fields away from the 60th field so that the playback starts from the I-picture. It should be noted that a playback can be started exactly from the video field specified by the cell by decoding the above 6 fields without displaying.

0129[0129] The method described above can also provide playback end time of the movie object corresponding to the end location in the cell information, and the address of the movie object in the AV file.

0130[0130] Next, the digital broadcasting object information (D_VOBI) will be described. The digital broadcasting object information is basically the same as the movie object information because the digital broadcasting object is a subclass derived from the object information. A big difference, however, is that the movie object (M_VOB) is created by recording a terrestrial broadcasting. Specifically, while the movie object is an AV stream encoded by the recorder itself, the digital broadcasting object (D_VOB) is not an AV stream encoded by the recorder itself since in the digital broadcasting object data transmitted from a digital broadcast satellite is recorded directly.

0131[0131] More specifically, when encoding is made by the recorder, internal structure of the stream is clearly known; however, when the data is a result of direct recording, internal structure is not known unless the stream is not analyzed, and therefore it is impossible to make the T map.

0132[0132] It is possible to analyze the MPEG transport stream supplied through the digital satellite broadcast. In the present embodiment, the T map is created by using information within the MPEG transport stream as to be described here below.

0133[0133]FIG. 14A shows an MPEG transport stream. FIG. 14B shows an enlarged view of transport packets. FIG. 14C shows PES packets. FIG. 14D shows a video stream.

0134[0134] As shown in FIG. 14A, the MPEG transport stream comprises a series of transport packets. The transport packet includes a header, an adaptation field, and a payload. The adaptation field includes a random access indicator (“random_access_indicator”). The random access indicator indicates that in this transport packet or the following transport packet (more precisely, the transport packet having the same program ID), a next PES packet (i.e. the PES packet in which the first byte of the PES packet appears first) contains an access point of the video stream or the audio-stream. Particularly, for the video stream, this indicates that the I-picture is included.

0135[0135] This random access indicator can be used for determining the video object unit, and creating the T map.

0136[0136] The transport packet has a fixed size of 188 bytes. Therefore, a plurality of transport packets (2048 bytes/188 bytes=10 TS packets) are recorded in one sector of the DVD-RAM comprising 2048 bytes. While it is possible to handle as 1 pack=1 sector in the movie object (M_VOB), it is impossible in the digital broadcasting object (D_VOB). Data reading/writing in the DVD-RAM can only be made by the sector. Therefore even in the digital broadcasting object, information in the T map is made up of the playback time length of the movie object unit (VOBU) expressed by the number of video fields, and the data size of the movie object unit expressed by the number of sectors.

0137[0137] For the above reason, accuracy of the address is not secured in the T map when the movie object unit is defined to be from a transport packet to the next transport packet. Therefore, the movie object unit (VOBU) is defined by using the sector containing the transport packet.

0138[0138] A PROVIDER_INF field of the digital broadcasting object stream information (D_VOB_STI) includes an ID for identifying a broadcasting company and particular information related to each broadcasting company.

0139[0139] Referring now to FIG. 15, description will be made for the audio object information (AOBI). Again, as a subclass derived from the object information, the audio object information is basically the same as in the case of the movie object information. A big difference, however, is that the audio object is an object for the audio system only and is not formatted into the MPEG system stream. More details will be described here below.

0140[0140] Since the audio object is not formatted into the MPEG system stream, no time stamps are included in the audio object. Therefore, there is no reference time for indicating the playback start time or the playback end time of the cell or the object. Thus, the audio object start time (AOB_A_S_TM) in the audio object general information (AOBI_GI) is entered with 0, whereas the audio object end time (AOB_A_E_TM) is entered with the playback time length. Further, each of the Start field and the End field in the cell information is entered with relative time within the audio object.

0141[0141] Another difference of the audio data from the MPEG video data is that playback of the audio data can be started at any audio frame unit. Therefore, the audio object unit (AOBU) can be defined as the audio frame multiplied by any integer. If the audio object unit is too small, however, a huge amount of data must be handled in the T map. So, the audio object unit is made to be almost same length of the object unit of the movie object, which is about 0.5 second. The T map manages the playback time length and the data size for each audio object unit.

0142[0142] Referring now to FIG. 16, description will be made for the still picture object information (S_VOBSI). Again, as a subclass derived from the object information, the still picture object information (S_VOBSI) is basically the same as in the case of the movie object information. A big difference, however, is that the still picture object is an object including data of a plurality of sill pictures, and that the still picture object is not formatted into the MPEG system stream. More details will be described for the audio object information here below.

0143[0143] The still picture, differing from the movie or the sound, does not have time information. Thus, fields of the starting information and the ending information in the still picture object general information (S_VOBS_GI) are entered with a number representing the starting still picture (Start_Video) and a number representing the last still picture (End_Video) respectively. Further, the Start field and the End field in the cell are entered with respective picture numbers within the still picture object instead of the time information.

0144[0144] The smallest access unit in still pictures is the frame of still picture. Thus, the S map is defined as the access map, which is a table containing the data size (S_VOB_SZ) of each still picture.

0145[0145] The overall data structure described so far above is shown in FIG. 17. FIG. 17 shows the entirety of the management information in the DVD-RAM. With reference to FIG. 17, all of the management information will be described here below. As shown in FIG. 17, the DVD-RAM according to the present embodiment is provided with video manager general information (VMGI) <b>90</b> and a variety of information tables <b>92</b>, <b>94</b>, <b>96</b> and <b>98</b> in addition to the PGC information <b>50</b> and <b>70</b>.

0146[0146] The VMGI <b>90</b> is management information for the whole disc, which contains pointer information, i.e. start addresses, of the original PGC information <b>50</b>, the user-defined PGC information <b>70</b>, and the variety of file management tables <b>92</b>, <b>94</b> . . . . Access to these tables <b>50</b>, <b>70</b>, <b>92</b>, <b>94</b> . . . becomes possible by referring to the pointer information.

0147[0147] Now, the file management tables <b>92</b>, <b>94</b>, <b>96</b> and <b>98</b> shown in FIG. 17 will be detailed here. Each of these tables <b>92</b>, <b>94</b>, <b>96</b>, <b>98</b> is a table for managing data files comprising the objects, and is prepared for each kind of objects. For example, the table <b>92</b> is for managing the movie files containing movie objects, whereas the table <b>94</b> is for managing the still picture files containing still picture objects.

0148[0148] As described above, the object information is identified based on the object ID stored in the cell information in the PGC information. During this operation address of the object information is identified via the file management table <b>92</b>, <b>94</b>, <b>96</b> or <b>98</b>. For this purpose, each of the file management tables <b>92</b>, <b>94</b>, <b>96</b>, <b>98</b> contains information about the number of objects under management, ID's of the objects, the size of each object information, and so on. For example, when the object ID shows a sequent order, based on this object ID specified by the cell information, it is possible to determine an order of the object specified by the cell information in the object information managed by the file management table. Then, from the order of this determined object information and the file size, an offset based on the start address of the file management table can be calculated to obtain logical address of this determined object information.

0149[0149] As shown in FIG. 17, the movie file management table <b>92</b> is a table for managing movie files containing movie objects. The movie file management table <b>92</b> includes the movie object information (M_VOBI) <b>92</b><i>a</i>, <b>92</b><i>b</i>, . . . , and the table managing information (M_AVFITI) <b>92</b><i>h </i>containing the number of movie object information and the size of the movie objects managed by the table <b>92</b>. The disc successively records same number of movie object information as the number of movie object information contained in the information <b>92</b><i>h</i>. As mentioned earlier, the movie object information <b>92</b><i>a </i>. . . each includes the general information (M_VOB_GI), stream information (M_VOB_STI), and the T map. Further, the T map includes the display time and size (VOBU_ENT) for each object unit (VOBU).

0150[0150] The same structure is used in a table (S_AVFIT) <b>94</b> for managing still picture files containing still picture objects, a table (D_AVFIT) <b>96</b> for managing digital broadcasting files containing digital broadcasting objects, and a table (A_AVFIT) <b>98</b> for managing audio files containing audio objects.

0151[0151] The original PGC information <b>50</b> contains the cell information <b>61</b>, <b>62</b>, <b>63</b> . . . in the order of playback. The cell information contains information corresponding to the object information (type and object ID) and the playback section information (Start and End) within the object. The playback section information shown in the cell can be converted to address information of the object substance through the access map in the object information.

0152[0152] As described earlier, the original PGC information <b>50</b> differs from the user-defined PGC information <b>70</b> only in that the original PGC information <b>50</b> is automatically generated by the recorder so that all of the objects recorded in the disc will be played whereas the user-defined PGC information <b>70</b> is information in which the user can freely define the playback sequence. Thus, the user-defined PGC information <b>70</b> has the same structure with the original PGC information <b>50</b>.

0153[0153] By abstracting in advance the information for managing the AV streams, it becomes possible to define the playback control information such as the PGC information and cell information without depending on the information peculiar to a given AV stream format, making possible to integrally manage AV streams. Thus, environment can be realized in which users can play AV data without paying attention to the AV format.

0154[0154] Further by using the above-described data structure, a new AV format can be easily incorporated into the data structure in DVD-RAM by simply defining the management information derived from the object information in the same manner as the other existing AV formats.

0155[0155] (Player Model)

0156[0156] Referring now to FIG. 18, a player model for playing the above optical disc is described. As shown in FIG. 18, the player comprises a pickup <b>1701</b>, an ECC processor <b>1702</b>, a track buffer <b>1703</b>, a PS decoder <b>1705</b>, a TS decoder <b>1706</b>, an audio decoder <b>1707</b>, a still picture decoder <b>1708</b>, a switch <b>1710</b> and a controller <b>1711</b>. The optical pickup <b>1701</b> reads out data from the optical disc <b>100</b>. The ECC processor <b>1702</b> performs error correction and other operations to the read data. The track buffer <b>1703</b> tentatively stores the data after the error correction. The PS decoder <b>1705</b> decodes to play program streams such as the movie object (M_VOB). The TS decoder <b>1706</b> decodes to play transport streams such as the digital broadcast object (D_VOB). The audio decoder <b>1707</b> decodes to play the audio object (AOB). The still picture decoder <b>1708</b> decodes to play the still picture object. The switch <b>1708</b> switches among the decoders <b>1705</b>, <b>1706</b> . . . for entry of data. The controller <b>1711</b> controls each component of the player.

0157[0157] The data recorded on the optical disc <b>100</b> is read by the pickup <b>1701</b>, goes through the ECC processor <b>1702</b>, and stored in the track buffer <b>1703</b>. The data stored in the track buffer <b>1703</b> is then entered into one of the decoders <b>1705</b>, <b>1706</b>, <b>1707</b> and <b>1708</b>, and then decoded to be outputted therefrom. In this switching operation, the controller <b>1711</b> checks the read data and sees the type information of the cell information in the PGC information providing the playback sequence according to the method described earlier. The switch <b>1710</b> is controlled to switch according to the type information so that the read information is sent to an appropriate decoder.

0158[0158] The player of the present embodiment further comprises a digital interface <b>1704</b> for supplying the AV stream to external equipment. Through this interface with an appropriate communication protocol such as IEEE1394 and IEC958, the AV stream can be fed to the external equipment. This is especially advantageous when a program of a new AV format is outputted through the digital interface <b>1704</b> to be played in the external AV equipment, without using the decoders in this player.

0159[0159] On the other hand, to support a new AV format in this player, a new decoder <b>1709</b> adapting to the new AV format may be coupled to the track buffer <b>1703</b> in the same way as the other existing decoders <b>1705</b>-<b>1708</b>.

0160[0160] (Recording Operation by DVD Recorder)

0161[0161] Next, reference is made to FIG. 19 to describe structure and operation of a DVD recorder according to the present invention for playing (reproducing)/recording the above optical disc.

0162[0162] As shown in the figure, the DVD recorder comprises a user interface <b>1901</b>, a system controller <b>1902</b>, an analog tuner <b>1903</b>, an encoder <b>1904</b>, a digital tuner <b>1905</b>, an analyzer <b>1906</b>, a display apparatus <b>1907</b>, and a decoder <b>1908</b>. The user interface <b>1901</b> provides a display for the user and receives requests from the user. The system controller <b>1902</b> manages and controls overall of the DVD recorder. The analog tuner <b>1903</b> receives VHF and UHF waves. The encoder <b>1904</b> converts analog signals into digital signals to encode the digital signal into an MPEG program stream. The digital tuner <b>1905</b> receives satellite digital broadcasting. The analyzer <b>1906</b> analyzes an MPEG transport stream sent from the digital broadcast satellite. The display apparatus <b>1907</b> includes a TV monitor and speaker system. The decoder <b>1908</b> decodes the AV streams. The decoder <b>1908</b> includes decoders shown in FIG. 18. The DVD recorder further comprises a digital interface <b>1909</b>, a track buffer <b>1910</b> for temporary storage of the data to be written, and a drive <b>1911</b> for writing data on the DVD-RAM <b>100</b>. The digital interface <b>1909</b> is an interface for outputting to external equipment through such a protocol as IEEE1394.

0163[0163] In the DVD recorder having the above configuration, the user interface portion <b>1901</b> first receives demand from the user. The user interface <b>1901</b> transmits a request from the user to the system controller <b>1902</b>. The system controller <b>1902</b> interprets the request into commands to send to appropriate modules. When the request from the user is to record an analog broadcasting program, the system controller <b>1902</b> requests the tuner <b>1903</b> to receive the program, and the encoder <b>1904</b> to encode.

0164[0164] The encoder <b>1904</b> performs video encoding, audio encoding and system encoding on the AV data received from the analog tuner <b>1903</b> to output the encoded data to the track buffer <b>1910</b>.

0165[0165] The encoder <b>1904</b>, upon commencing the encoding operation, sends the playback start time (M_VOB_V_S_PTM) of the MPEG program stream encoded to the system controller <b>1902</b>, and then in parallel with the encoding operation, sends the time length and size information of the movie object unit (VOBU) to the system controller <b>1902</b> as source information for creating the T map.

0166[0166] Next, the system controller <b>1902</b> issues a recording request to the drive <b>19111</b> so that the drive <b>1911</b> takes data stored in the track buffer <b>1910</b> and records this information on the DVD-RAM disc <b>100</b>. At that time, the system controller <b>1902</b> instructs the drive <b>1911</b> where to store the information on the disc <b>100</b> according to the allocation information of the file system.

0167[0167] Ending of the recording operation is demanded by the user through a stop request. The stop request from the user is transmitted through the user interface <b>1901</b> to the system controller <b>1902</b>. The system controller <b>1902</b> then issues the stop request to the analog tuner <b>1903</b> and the encoder <b>1904</b>.

0168[0168] Upon reception of the stop request from the system controller <b>1902</b>, the encoder stops the encoding operation, and sends the playback stop time (M_VOB_V_E_PTM) of the last encoded MPEG program stream to the system controller <b>1902</b>.

0169[0169] After the encoding operation is over, the system controller <b>1902</b> creates the movie object information (M_VOBI) based on the information received from the encoder <b>1904</b>. Next, the system controller <b>1902</b> creates the cell information corresponding to the movie objet information (M_VOBI). The important point here is that the type information in the cell information must be specified as “M_VOB”. As described earlier, the information in the cell information is configured without depending on the movie object (M_VOB), and all information which depends on the movie object (M_VOB) is concealed into the movie object information (M_VOBI). Therefore, an error in recognizing the type information in the cell information will lead to inability to perform normal playback, possibly resulting in system down.

0170[0170] Finally, the system controller <b>1902</b> requests the drive <b>1911</b> to finish recording the data stored in the track buffer <b>1910</b>, and to record the movie object information (M_VOBI) and cell information. The drive <b>1911</b> records the data remaining in the track buffer <b>1910</b>, the movie object information (M_VOBI) and the cell information on the DVD-RAM, subsequently completing the recording operation.

0171[0171] Next, description will be made in a case of the user's request for recording a digital broadcast program.

0172[0172] The user's request for recording the digital broadcasting program is transmitted through the user interface <b>1901</b> to the system controller <b>1902</b>. The system controller <b>1902</b> then requests the digital tuner <b>1905</b> to record, and the analyzer <b>1906</b> to analyze received data.

0173[0173] An MPEG transport stream sent from the digital tuner <b>1905</b> is sent through the analyzer <b>1906</b> to the track buffer <b>1910</b>. The analyzer <b>1906</b> first picks up from the MPEG transport stream the start time information (D_VOB_V_S_PTM) as information necessary for generating the digital broadcasting object information (D_VOBI), and sends this information to the system controller <b>1902</b>. Next, the analyzer <b>1906</b> determines the movie object unit (VOBU) in the MPEG transport stream, and sends the time length and size of the movie object unit as information necessary for creating the T map to the system controller <b>1902</b>. It should be noted that the movie object unit (VOBU) can be determined, as described earlier, based on the random access indicator (random_access_indicator) in the application field contained in the TS packet header.

0174[0174] Next, the system controller <b>1902</b> outputs a recording request to the drive <b>1911</b>. Then the drive <b>1911</b> picks up the data stored in the track buffer <b>1910</b> and records the data in the DVD-RAM disc <b>100</b>. At this time, the system controller <b>1902</b> also informs the drive <b>1911</b> where the drive <b>1911</b> should record the information on the disc <b>100</b>, based on allocation information of the file system.

0175[0175] Ending of the recording operation is instructed by the user through a stop request. The stop request from the user is transmitted through the user interface <b>1901</b> to the system controllers <b>1902</b>. The system controller <b>1902</b> then issues the stop request to the digital tuner <b>1905</b> and the analyzer <b>1906</b>.

0176[0176] The analyzer <b>1906</b>, upon reception of the stop request from the system controller <b>1902</b>, stops the analyzing operation, and sends the display end time (D_VOB_V_E_PTM) of the movie object unit (VOBU) of the last analyzed MPEG transport stream to the system controller <b>1902</b>.

0177[0177] After the completion of receiving the digital broadcasting, the system controller <b>1902</b> creates the digital broadcasting object information (D_VOBI) based on the information received from the analyzer <b>1906</b>, and next, creates the cell information corresponding to the digital broadcasting objet information (D_VOBI), at which time the type information in the cell information is specified as “D_VOB”.

0178[0178] Finally, the system controller <b>1902</b> requests the drive <b>1911</b> to finish recording the data stored in the track buffer <b>1910</b>, and to record the digital broadcasting object information and cell information. The drive <b>1911</b> records the data remaining in the track buffer <b>1910</b>, the digital broadcasting object information (D_VOBI) and the cell information on the DVD-RAM disc <b>100</b>, completing the recording operation.

0179[0179] The above description is made on the basis that the user makes request to start and stop recording. When a timer recording function commonly provided in a VTR system is used, the system controller automatically issues recording start and stop commands in stead of user's request, and thus the steps of operation performed by the DVD recorder are essentially the same.

0180[0180] (Playback Operation by DVD Recorder)

0181[0181] Next, playback operation in the DVD recorder will be described.

0182[0182] First, the user interface <b>1901</b> receives a request from the user. The user interface <b>1901</b> transmits the request to the system controller <b>1902</b>. The system controller <b>1902</b> interprets the user's request to commands to send them to appropriate modules. For example, when the use's request demands playback of a PGC information, the system controller <b>1902</b> analyzes the PGC information and cell information to see which object should be played. Description will be made below for a case in which an original PGC comprising one movie object (M_VOB) and one cell information is played.

0183[0183] The system controller <b>1902</b> first analyzes the type information stored in the cell information in the PGC information. When the type information is “M_VOB”, it means that the AV stream to be played is the stream recorded as the MPEG program stream. Next, the system controller <b>1902</b> refers to the ID of the cell information to find the corresponding movie object information (M_VOBI) from the table (M_AVFIT). The system controller <b>1902</b> then finds start address and end address of the AV data to be played according to the start time information (M_VOB_V_S_PTM) and end time information (M_VOB_V_E_PTM) contained in the movie object information, and T map.

0184[0184] Next, the system controller <b>1902</b> sends to the drive <b>1911</b> a request for reading from DVD-RAM <b>100</b>, together with the start address of the reading. The drive <b>1911</b> then reads out AV data from the address given by the system controller <b>1902</b>, and stores the read data to the track buffer <b>1910</b>.

0185[0185] Next, the system controller <b>1902</b> sends to the decoder <b>1908</b> a decoding request of the MPEG program stream. The decoder <b>1908</b> then read out the AV data stored in the track buffer <b>1910</b> to decode the read data. The decoded AV data is outputted through the display apparatus <b>1907</b>.

0186[0186] On the completion of reading all the data instructed by the system controller <b>1902</b>, the drive <b>1911</b> reports to the system controller <b>1902</b> that the reading operation is completed. The system controller <b>1902</b> then issues a command to the decoder <b>1908</b> to stop the playback operation. The decoder <b>1908</b> continues to decode data until the track buffer <b>1910</b> is emptied. After all the data is decoded and played, the decoder <b>1908</b> reports to the system controller <b>1902</b> that the replay operation is finished, then bringing the playback operation to a complete end.

0187[0187] The above description was made for the case in which one original PGC containing one movie object (M_VOB) and one cell information is to be played. However, the playback operation of the AV stream can be performed by the same steps of operation whether the original PGC contains only one digital broadcasting object (D_VOB), contains a plurality of movie objects, contains a plurality of digital broadcasting objects, or contains both movie objects and digital broadcasting object. Further, the same goes with a case in which the original PGC contains a plurality of cells, or in a case of the user-defined PGC.

0188[0188] Further, the audio object (AOB) and other AV stream, i.e. the still picture object (S_VOBS) are handled essentially in the same procedures by the same modules, differing only in the configuration within the decoder <b>1908</b>. In these cases, the decoder <b>1908</b> may be configured by the PS decoder <b>1705</b>, the TS decoder <b>1706</b>, the audio decoder <b>1707</b>, or the still picture decoder <b>1708</b> as shown in FIG. 18.

0189[0189] Next, an example is taken for a case in which the decoder <b>1908</b> does not have capabilities for playing all kinds of the AV streams.

0190[0190] If the decoder <b>1908</b> does not have playback capability for the MPEG transport stream, playback operation by the decoder <b>1908</b> is impossible as described above. In such a case the digital interface portion <b>1909</b> is used to supply external equipment with the data, so that the data can be played by the external equipment.

0191[0191] When the system controller <b>1902</b> finds from the cell information in the PGC information that the user requests playback of a digital broadcasting object (D_VOB) not supported by the system, the system controller <b>1902</b> requests the digital interface <b>1909</b> for external output instead of requesting the decoder <b>1908</b> for playback. The digital interface <b>1909</b> transmits AV data stored in the track buffer <b>1910</b> in accordance with the communication protocol of the connected digital interface. Other operations performed are the same as those performed when the movie object (M_VOB) is played.

0192[0192] A judgment must be made whether or not the decoder <b>1908</b> is compatible with the AV stream requested for replay. This judgment may be made by the system controller <b>1902</b> by itself, or the system controller <b>1902</b> may ask the decoder <b>1908</b>.

0193[0193] (DVD Player)

0194[0194] Next, with reference to FIG. 20, a DVD player according to the present invention is described. The DVD player is a realization of the player model described above to play the above optical disc.

0195[0195] As shown in the figure, the DVD player comprises a user interface <b>2001</b>, a system controller <b>2002</b>, a display apparatus <b>2003</b>, a decoder <b>2004</b>, a digital interface <b>2005</b>, a track buffer <b>2006</b> and a drive <b>2007</b>. The user interface <b>2001</b> receives requests from the user and displays some indications to the user. The system controller <b>2002</b> manages and controls overall of the DVD player. The display apparatus <b>2003</b> includes a TV monitor and speaker system. The decoder <b>2004</b> decodes the MPEG stream. The digital interface <b>2005</b> connects to IEEE1394 and so on. The track buffer <b>2006</b> temporally stores the data read from the DVD-RAM <b>100</b>. The drive <b>2007</b> reads data out from the DVD-RAM <b>100</b>. The DVD player configured as above performs the same playback operations as in the DVD recorder described earlier.

0196[0196] It should be noted that the DVD-RAM is taken as an example in the present embodiment. However, the same description so far has been made applies to other media. The present invention should not be limited to such media as the DVD-RAM and other optical discs.

0197[0197] Further, according to the present embodiment, the AV stream not supported by the decoder is played through the digital interface. However, those AV streams which are supported by the decoder may be outputted to external equipment through the digital interface depending on the request from the user.

0198[0198] Further, according to the present embodiment, the audio data and the still picture data were treated as unique data differing from the MPEG streams. However, these data may also be recorded in the format of MPEG system stream.

0199[0199] Although the present invention has been described in connection with specified embodiments thereof, many other modifications, corrections and applications are apparent to those skilled in the art. Therefore, the present invention is not limited by the disclosure provided herein but limited only to the scope of the appended claims.