JP4191207B2 - recoding media - Google Patents

Description

  The present invention relates to a recording medium suitable for use when a moving image and audio are compressed and time-division multiplex recorded on a disk and a predetermined image is searched at high speed.

  Examples of a conventional encoding device and decoding device are shown in FIGS. In FIG. 6, the video signal is compressed and encoded (encoded) by the video encoder 1, and is input to the code buffer 4 in the multiplexing device 3. The audio signal is compressed and encoded by the audio encoder 2 and input to the code buffer 5 of the multiplexing device 3.

  The output terminals of the code buffers 4 and 5 are connected to the input terminals E1 and E2 of the switching circuit 6, respectively. The output terminal F of the switching circuit 6 is connected to the input terminal of the header addition circuit 7. The output of the header addition circuit 7 is supplied to a recording medium drive device (DSM) 10 composed of, for example, a magneto-optical disk or a magnetic disk (hard disk). The control device 8 receives the system clock output from the multiplexed system clock generation circuit 9 and sequentially connects the input terminals E1 and E2 of the switching circuit 6 with the output terminal F at a predetermined cycle, so that the code buffer 4 Alternatively, the data from 5 are sequentially taken out and time-division multiplexed.

  The control device 8 controls the switching circuit 6 and the header addition circuit 7 so that a bit stream is generated according to the format shown in FIG.

  That is, as shown in FIG. 8, in the multiplexing scheme of ISO11172 (MPEG), one multiplexed bit stream is composed of one or more packs (PACK) and one ISO_11172_end_code. ISO_11172_end_code is a 32-bit code, which is 0x000001b9 in hexadecimal. Where x means indefinite.

  One pack is composed of a header composed of Pack_Start_Code, SCR (System Clock Reference), and MUX_Rate, and one or more packets. The Pack_Start_Code of the header is a 32-bit code and is 0x000001b4 in hexadecimal. The length of the pack is defined as a variable length, but the maximum length is 2048 bytes.

  One packet includes a header composed of Packet_Start_Code_Prefix, Stream_ID, Packet_length, PTS (Presentation Time Stamp), and DTS (Decoding Time Stamp), and packet data (Code Data). Packet_Start_Code_Prefix is a 24-bit code and is 0x000001. Stream_ID is an 8-bit code and represents the type of packet as shown in FIG. Packet_length (16 bits) indicates the length of the subsequent packet.

  In the Code Data of each packet, audio data (audio stream) or video data (video stream) is recorded. Since the audio stream has 32 types and the video stream has 16 different stream ids, a plurality of audio signals and video signals up to this number can be multiplexed.

  The reserved stream has data such as subtitles. Private_stream_1 and private_stream_2 are not specified for use. padding_stream is used to increase the amount of data.

  In accordance with the above format, the control device 8 performs header addition and code reading processing using, for example, an algorithm as shown in FIG. 10 so that the pack interval is 2048 bytes.

  First, the control device 8 instructs the header adding circuit 7 to add a pack header (step S1). Then, the process waits until the sum of M4 and M5 becomes equal to or larger than the code data amount D included in one pack (step S2). That is, it waits until data enough to be stored in one pack is accumulated in the code buffers 4 and 5.

  Here, M4 is the amount of data written to the code buffer 4, and M5 is the amount of data written to the code buffer 5. D indicates the total amount of data contained in one pack. Here, for simplification, it is assumed that D is a constant, that is, the size of the pack (2048) minus the size of the pack header, the size of the video packet header, and the size of the audio packet header.

  Next, the amount P1 of video data stored in the pack and the amount P2 of audio data stored in the pack are calculated according to the following equations (step 3). P1 = D.times.M4 / (M4 + M5) P2 = D-P1 Here, the total amount D of code data contained in the pack is simply distributed by the ratio of the data amounts of the code buffers 4 and 5.

  When the amount of data is determined, the control device 8 instructs the header addition circuit 7 to output a video packet header (step S4). Next, P1 byte video data is read from the code buffer 4 and output to the driving device 10 (step S5). Similarly, an audio packet header is added (step S6), and P2-byte audio data is read from the code buffer 5 and output to the driving device 10 (step S7). In the drive device 10, these input data are recorded on a built-in disk.

  The data recorded on the disk in this way is decrypted by the decryption apparatus shown in FIG. That is, the header separation circuit 22 of the separation device 21 separates the pack header and the packet header from the data read from the drive device 10 and supplies them to the control device 24, and the time division multiplexed data is switched to the switching circuit 23. To the input terminal G. Output terminals H1 and H2 of the switching circuit 23 are connected to input terminals of a video decoder 25 and an audio decoder 26, respectively. The control device 24 of the separation device 21 sequentially connects the input terminal G and the output terminals H1 and H2 of the switching circuit 23 in accordance with the stream id of the packet header supplied from the header separation circuit 22, and time-division multiplexed data. Are correctly separated and supplied to the corresponding decoder.

  As described above, when the multiplexed video data is compressed by the MPEG encoding method, the random access and the search operation are limited. In other words, MPEG has an intra-frame coded picture (I (intra) picture) and an inter-frame coded picture (P (forward prediction) picture, B (bidirectional prediction) picture). Since the I picture is encoded using only the data in the image (frame or field), the data compression efficiency is low. This I picture itself can be decoded. Since the P picture and the B picture are obtained by encoding the difference signal from the preceding and succeeding pictures, the data compression efficiency is increased. In order to decode this P picture or B picture, a predicted picture before or after that is required. For this reason, normally, about two I-pictures appear per second to balance random accessibility and compression efficiency.

  FIG. 11 shows a conceptual diagram of a bit stream including an I picture, a P picture, and a B picture recorded on the disc by the driving device 10. A series of video bitstreams is divided into one or more GOPs (Group of Pictures). A GOP has an I picture at the top. When video data is compressed at a fixed rate, an I picture periodically appears at a predetermined position, so that the position can be obtained by calculation and accessed. However, when variable-rate compression is performed, the position of the I picture becomes indefinite, making access difficult.

  That is, in the multiplexed data decoding device of FIG. 7, when receiving a search command, the main control device (not shown) commands the control device 24, the video decoder 25 and the audio decoder 26 to shift to the search mode. To do. In the search mode, the video decoder 25 decodes only I picture data from the input video data. Alternatively, only I picture data is selected by the separation device 21 and input to the video decoder 25. The video decoder 25 decodes the input data.

  In the search mode, the control device 24 commands the drive device 10 to move the data reading position on the disk forward (or backward). The amount of movement of the reading position at this time depends on the search speed, coding rate, and the like, but generally the amount of movement increases as the search speed increases and the coding rate increases. When the reading position moves to a predetermined position, the data output from the driving device 10 is input to the separation device 21. The header separation circuit 22 separates the video data and supplies it to the video decoder 25. The video decoder 25 decodes and outputs the first I picture that appears. In the search mode, the audio decoder 26 is in a muted state.

  In this way, the search operation (continuous reproduction of I pictures) is realized as repeated random access. That is, for example, when a high-speed forward search is instructed by the user, the video decoder 25 skips reading a predetermined number of frames of the input data, searches for an I picture, decodes it, and outputs it. Alternatively, an I picture search is performed by the driving device 10, and only I picture data is supplied to the video decoder 25 and decoded. By repeating such an operation, a search operation (continuous reproduction of I pictures) is realized.

  Thus, in the conventional apparatus, since the position (access point) of the I picture cannot be known, an operation of waiting for the access point after moving the reproduction position to some extent is required. For this reason, there has been a problem that the repetition cycle of the search operation becomes long and a quick search operation becomes difficult.

  The present invention has been made in view of such a situation, and can quickly find an access point of video data and enable a quick search.

A recording medium according to the present invention is a recording medium that is mounted on a playback apparatus and is read out by controlling a reading position based on recorded address information. A bit stream encoded in the inter-coded picture is recorded, and has an area for recording position information of a plurality of discretely selected intra-frame encoded pictures for access according to the search speed An entry packet is placed in front of the intra-frame coded picture in this bit stream, and the positions of a plurality of discretely selected intra-frame coded pictures for accessing this entry packet according to the search speed Information is recorded .

According to the recording medium of the present invention, in the recording medium that is mounted on the playback device and is read out by controlling the reading position based on the recorded address information, the moving image is an intra-frame coded picture, And an area for recording positional information of a plurality of discretely selected intra-frame encoded pictures for access according to a search speed, in which a bit stream encoded in an inter-frame encoded picture is recorded Is placed in front of an intra-frame coded picture in the bitstream, and the position information of a plurality of discretely selected intra-frame coded pictures for accessing the entry packet according to the search speed since There has been recorded, in correspondence with the entry packet, a plurality of intra-frame coded picture Position can sequentially to quickly search for. As a result, the access point of the video data can be quickly found, and a quick search becomes possible.

  FIG. 1 and FIG. 2 are block diagrams showing the configuration of an embodiment of the data encoding device and data decoding device of the present invention. The same reference numerals are used for the same components as in FIG. 6 and FIG. Is attached.

  In the encoding device of FIG. 1, the output terminal of the video encoder 1 is connected to the input terminal of the video entry point detection circuit 31, and the output terminal is connected to the input terminal of the code buffer 4. The entry packet generation circuit 32 receives the control input of the control device 8 and supplies the output to the input terminal E3 of the switching circuit 6. The control device 8 receives an input of the system clock output from the multiplexed system clock generation circuit 9 and sequentially connects the input terminals E1, E2, and E3 of the switching circuit 6 with the output terminal F at a predetermined cycle. Data is sequentially taken out from the buffers 4 and 5 or the entry packet generation circuit 32, time-division multiplexed, and output to the header addition circuit 7.

  The control device 8 controls the header adding circuit 7 to add a video packet header to the video data read from the code buffer 4. An audio packet header is added to the audio data read from the code buffer 5.

  Furthermore, the control device 8 receives an entry point generation signal generated at the I picture generation timing from the video encoder 1 or the video entry point detection circuit 31, and controls the entry packet generation circuit 32 to control the bit stream. An entry packet is inserted at a predetermined position. When the video encoder 1 is configured to output the entry point generation signal, the video encoder 1 outputs the entry point generation signal at the I picture generation timing.

  Further, when the video encoder 1 cannot output the entry point generation signal, or when the video bit stream that has already been encoded is multiplexed, the video entry point detection circuit 31 performs the I picture generation timing. An entry point generation signal is generated, or an entry point is detected from video data input from the video encoder 1 and an entry point generation signal is output. The entry point storage device 33 is a memory that can be read and written from the control device 8 and stores the position of the detected entry point. Other configurations are the same as those in FIG.

  Also in the embodiment shown in FIG. 1, the multiplexed bit stream is composed of at least one pack and ISO_11172_end_code. Each pack has a format as shown in FIG. 3, for example.

  That is, first, as in the case of FIG. 8, Pack_Header (header) composed of Pack_Start_Code, SCR, and MUX_Rate is arranged, then Video_Packet_Header is arranged, and video data not including I picture is next. Arranged in a packet structure. Next to the video data, Entry_Packet is arranged, followed by Video_Packet_Header, and then, video data including an I picture is arranged in a packet structure. That is, Entry_Packet is arranged immediately before video data including an I picture (entry point) (immediately before Video_Packet_Header). In this embodiment, Audio_Packet_Header is placed next to video data, and then audio data having a packet structure is placed next.

  The Entry_Packet (entry packet) has the format shown in FIG. This format corresponds to the private_stream_2 packet format among MPEG packets. Packet_Start_Code_Prefix is arranged at the top, and next, stream_id which is set to 0xbf in hexadecimal is arranged. Next, length indicating the length of the subsequent packet is arranged. The above arrangement is the same as in the packet header in FIG.

  In this embodiment, next, sony_id is arranged. This indicates that this private packet is the applicant's original format. Next, sony_packet_type is arranged, which indicates classification within the applicant's own private packet format, and is 0xff in the case of an entry packet. Furthermore, current _ # _ data_streams, current _ # _ video_streams, and current _ # _ audio_streams sequentially arranged after that are data packets multiplexed immediately after this entry packet until immediately before the next entry packet, The numbers of video packets and audio packets are shown respectively.

  Next, entry_packet_-3, entry_packet_-2, entry_packet_1, entry_packet_ + 1, entry_packet_ + 2, and entry_packet_ + 3 are arranged in sequence, and these are the two before the three. Recorded is the position of the entry packet of the front, the front, the first, the second, the third, and the relative distance between them and the number of sectors of the disk driven by the drive device 10 ing.

  Next, the operation of the embodiment of FIG. 1 will be described. The control device 8 receives the entry point generation signal from the video encoder 1 or the video entry point detection circuit 31, and inserts an entry packet immediately before the video entry point (FIG. 3). That is, when the entry point generation signal is received, the entry packet generation circuit 32 generates an entry packet, and the switching circuit 6 is switched to the input terminal E3 side to be supplied to the header addition circuit 7, and the code buffer 4 , 5 are multiplexed with video data and audio data.

  As shown in FIG. 4, each entry packet has the entry packet positions three, two, one, one, two, and three from the entry packet. _Packet_-3, entry_packet_2, entry_packet_1, entry_packet_ + 1, entry_packet_ + 2, and entry_packet_ + 3 are recorded respectively. The position of the previous (past) entry packet (the position before the third, the position before the second, and the position before the previous one) is stored in the entry point storage device 33, and this is known when the current entry packet is recorded. (Thus, at this timing, it can be supplied to the drive 10 and recorded on the disc if necessary).

  However, the position of the previous (future) entry packet cannot be known at this time. Therefore, the control device 8 stores all the entry point positions in the entry point storage device 33, and after all the multiplexing is completed (after the recording of the bit stream of the video data and the audio data to the disc is completed). ) Reads the position of the entry packet of the 3rd, 2nd, 1st, 1st, 2nd, and 3rd entry packets from the entry point storage device 33, and this is read as the drive device 10 To be recorded (added) to each entry packet on the disk.

  The video encoder 1 and the audio encoder 2 encode the video signal and the audio signal, respectively, at a variable rate. The control device 8 controls the header addition circuit 7 so that the pack interval is 2048 bytes. Add a pack header. For this reason, the control device 8 controls the processing of adding a header, reading a code, and inserting an entry packet, for example, using an algorithm as shown in FIG.

  Here, as in the case of the processing of FIG. 10, M4 is the amount of data stored in the code buffer 4, and M5 is the amount of data stored in the code buffer 5. D indicates the total amount of data contained in one pack. Here, for simplification, it is assumed that D is a constant, that is, the pack size (2048) minus the pack header size, the video packet header size, and the audio packet header size. D2 indicates the total amount of data in the pack including the entry packet. That is, the size of the entry packet and the size of the video packet header are subtracted from D.

  First, the control device 8 instructs the header adding circuit 7 to add a pack header (step S11). The process waits until the sum of M4 and M5 becomes equal to or larger than the amount D of code data contained in one pack (step S12). That is, it waits until data enough to be stored in one pack is accumulated in the code buffers 4 and 5.

Next, the amount P1 of video data stored in the pack and the amount P2 of audio data stored in the pack are calculated from the following equations (step S13). P1 and P2 are such that the total amount D of code data contained in the pack is distributed by the ratio of the data amounts M4 and M5 of the code buffers 4 and 5.
P1 = D × M4 / (M4 + M5)
P2 = D-P1

  Next, the control device 8 checks whether or not there is a video entry point in the data up to the first P1 byte in the data of M4 (step S14). If the video entry point is not included in the pack, the control device 8 instructs the header addition circuit 7 to output a video packet header (step S15). Next, P1 byte video data is read from the code buffer 4 and output to the driving device 10 (step S16). Similarly, an audio packet header is added (step S17), P2 bytes of audio data are read from the code buffer 5, and output to the driving device 10 (step S18).

  When the video entry point is not included in the pack, the above processing is repeated. This process is the same as the process in FIG.

On the other hand, when the video entry point is included in the pack, the control device 8 first stores the current pack position in the entry point storage device 33. Then, the amount P1 of video data and the amount P2 of audio data stored in the pack are calculated according to the following equations (step S19).
P1 = D2 * M4 / (M4 + M5)
P2 = D2-P1
The reason why the same calculation is further performed after the calculation in step S13 is that the capacity of data is reduced because the entry packet is included in the pack. Here, P1 and P2 are such that D2 is allocated by the ratio of the data amounts M4 and M5 of the respective code buffers 4 and 5.

  Next, the video packet header is output from the header addition circuit 7 to the driving device 10 (step S20), and the video data up to immediately before the video entry point is converted into the video encoder 1, the video entry point detection circuit 31, the code buffer 4, The signal is output to the driving device 10 through the path of the input terminal E1, the output terminal F, and the header addition circuit 7 of the switching circuit 6 and recorded on the disk (step S21). Next, the entry packet generation circuit 32 outputs the entry packet and records it on the disk (step S22). However, at this time, the relative position information of the entry packet is not yet written to the disk.

  Thereafter, the video packet header is output and recorded again (step S23), and the remaining video data is output and recorded (step S24). In steps S17 and S18, an audio packet header is added and P2 byte audio data is recorded.

  When the algorithm of FIG. 5 is repeated and there is no input to the video encoder 1 and the audio encoder 2, the position data is written in the entry packet already recorded on the disc. That is, the control device 8 reads the position of the pack including the entry packet from the entry point storage device 33 and writes the position of the pack including the three entry packets before and after the entry packet on the disk of the drive device 10.

  Next, an apparatus for decoding the data encoded in the embodiment of FIG. 1 will be described with reference to FIG. The header separation circuit 22 of the separation device 21 separates the pack header, the packet header, and the entry packet from the data read from the drive device 10 and supplies them to the control device 24. The header separation circuit 22 also supplies the time division multiplexed data to the switching circuit. 23 to the input terminal G. Output terminals H1 and H2 of the switching circuit 23 are connected to input terminals of a video decoder 25 and an audio decoder 26, respectively.

  Further, the control device 24 reads information on entry points (information on entry packets) from the data input from the header separation circuit 22, and supplies the information to the entry point storage device 41 for storage. Since the information on the current reading position is supplied from the driving device 10 to the control device 24, the control device 24 can store the position of the entry point and its content in association with each other.

  The control device 24 of the separation device 21 sequentially connects the input terminal G and the output terminals H1 and H2 of the switching circuit 23 in accordance with the stream id of the packet header supplied from the header separation circuit 22, and time-division multiplexed data. The video data is supplied to the video decoder 25 and the audio data is supplied to the audio decoder 26, respectively.

  Next, the operation when the search operation of the multiplexed data decoding apparatus in FIG. 2 is instructed will be described. When the search operation is instructed, the main control device (not shown) instructs the control device 24, the video decoder 25, and the audio decoder 26 to shift to the search mode. Further, the control device 24 reads the current read position from the output of the driving device 10 and extracts the entry point near the position from the entry point storage device 41. The entry point storage device 41 stores information on entry packets reproduced in the reproduction mode as needed. Alternatively, all or a predetermined range recorded on the disk mounted on the drive device 10 at a predetermined timing, such as when the power of the apparatus is turned on, when a disk is mounted, or when reproduction is instructed. The entry packet information can be read and stored in advance.

  When the control device 24 obtains the entry point, it sends a search command to the drive device 10 to move the reading position to the entry point at a high speed. When the movement is completed, the driving device 10 reproduces data from the entry point and supplies it to the separation device 21. As described with reference to FIG. 3, the entry packet is arranged immediately before the video data in which the I picture is recorded. Therefore, when the video data following the entry packet is separated by the header separation circuit 22 and supplied to the video decoder 25, the first picture of the video data is an I picture. The video decoder 25 immediately decodes and outputs the first I picture that appears. In the search mode, the audio decoder 26 is in a muted state.

  Since the position information of the three entry points before and after is recorded in the entry packet, the control device 24 searches the next entry packet from the position information and repeats the operation of reproducing. As a result, I pictures are successively and sequentially reproduced.

  When the search speed is high, the control device 24 allows access to a farther entry point, and when the search speed is low, the control apparatus 24 accesses a closer entry point. Since three entry points are recorded in each of the forward and reverse directions, three or more search speed variations can be provided depending on the combination of entry points to be selected.

  As described above, when the entry packet is first sent to the drive device 10 for the first time, since the position of the entry packet in the previous position (future) cannot be known, the controller 8 finishes all multiplexing. Later, using the information recorded in the entry point storage device 33, the position information of the entry packet, entry_packet_ + 1, entry_packet_ + 2, and entry_packet_ + 3 are entered in the multiplexed bit stream of the activation device 10. Append to packet.

  However, when there is not enough or no capacity of the entry point storage device 33, the position information of the entry packet at the previous position cannot be held sufficiently or not, so the entry packet in the multiplexed bit stream recorded in the driving device 10 Cannot add. If there is no capacity of the entry packet storage device 33, when the entry packet is first sent to the drive device 33, the position information of the entry packet at the previous position, entry_packet_-3, entry_packet_-2, entry_packet_- Cannot write 1 In such a case, the value contained in the position information of the entry packet in the completed multiplexed bitstream cannot be predicted, and therefore an unexpected operation may occur when a search is performed based on such a value. There is.

  Therefore, a flag indicating the validity of the position information of the entry packet is provided. Specifically, the format of the entry packet generated from the entry packet generating circuit 32 is set to the format shown in FIG. The format of FIG. 12 is a method of expressing the validity of the position information of all entry points included in the entry packet by one 1-bit flag. In the case of FIG. 13, a flag representing the validity for each entry point is set. It is a method of adding.

  When the entry packet of the format of FIG. 12 is used, since the position information of the entry packet cannot be completely written at the stage of multiplexing and sending the multiplexed bit stream to the driving device 10 first, The effective flag and Enable Flag are set to 0 meaning “invalid” and recorded in the drive device 10. After all the multiplexed data has been recorded, when adding to the entry packet using the position information of the entry packet recorded in the entry point recording device 33, for the entry packet in which all the position information has been written, The control device 8 updates the Enable Flag in the entry packet to 1 which means “valid”.

  In the case of using the entry packet in the format of FIG. 13, at the stage of multiplexing and first sending the multiplexed bit stream to the driving device 10, it was possible to write among the valid flags of Enable Flag -3 to EnableFlag +3. The valid flag corresponding to the position information is set to 1 indicating “valid”, and the valid flag corresponding to the position information that could not be written is set to 0 indicating “invalid” and recorded in the driving device 10. . After all the multiplexed data has been recorded, when the additional information is added to the entry packet using the position information of the entry packet recorded in the entry point recording device 33, the control device 8 relates to the position information that can be additionally recorded. Updates the corresponding valid flag to 1 meaning “valid”.

  In FIG. 13, if enable_flag_N and entry_packet_N (−3 ≦ N ≦ + 3) are considered to be continuous bit strings, and this bit string represents one number, instead of providing a position information valid flag for the entry packet, The packet position information itself is equivalent to expressing the validity of the value. That is, when valid position information cannot be written, a function equivalent to adding a position information valid flag can be realized by writing a value in a specific range or an invalid value as position information. When each entry point is invalid by writing a specific value in the position information of the entry packet, a plurality of specific values indicating invalidity can be provided. For example, when recording of entry point position information simply failed, the entry point information is invalid, and when intentionally prohibiting the reading point from being moved to the entry point are set to different values. By writing in the entry packet, the multiplexed data decoding apparatus can be notified.

  Next, a multiplexed data decoding apparatus that performs a search operation using the entry packet position information valid flag as shown in FIG. 12 or FIG. 13 will be described with reference to FIG. The control device 24 supplies the entry packet information read from the header separation circuit 22 to the entry point storage device 41 for storage. At this time, as shown in FIG. 12 or FIG. 13, when the entry packet position information valid flag is added to the entry packet, the control device 24 supplies the entry packet including the flag to the entry point storage device 41. The entry point storage device 41 stores it.

  When the search operation is commanded, the main control device (not shown) commands the control device 24, the video decoder 25, and the audio decoder 26 to shift to the search mode. The control device 24 reads out to instruct the drive device 10 to perform a search operation from the current read position information read from the output of the drive device 10 and the position information of the entry packet read from the entry point storage device 41. Get position. At this time, the control device 24 determines the validity of the position information of the entry packet from the entry point storage device 41, and does not instruct the driving device 10 to perform a search operation for an invalid entry point. Alternatively, when the position of the entry point can be calculated by interpolation, estimation or the like from the position information of other entry points, the drive device 10 may be searched for the position of the entry point thus obtained. it can.

  In the entry packet entry_packet_-3, entry_packet_-2, entry_packet_1, entry_packet_ + 1, entry_packet_ + 2, and entry_packet_ + 3 shown in FIG. The relative position of the entry point before, one before, one ahead, two ahead, and three ahead is recorded (by sector number), but the relative position of the entry point written here is not necessarily relative to the entry packet. It does not have to be the entry point position at -3, -2, -1, + 1, + 2, + 3, for example -25, -8, -1, + 1, + 5, + 20 It is also possible to record the relative position of any entry packet.

  As a result, the relative position of the entry point to be written is set for each recording device, each multiplexed data, each entry packet according to various characteristics such as the type of recording media, the signal format of the multiplexed bit stream, and the nature of the video or audio data to be multiplexed. The search speed can be adjusted by changing each time. For example, in a multiplexed bit stream specified by ISO11172 (MPEG), the number of pictures from an I picture to the next I picture is variable. In such a case, when the entry points at the positions of -3, -2, -1, + 1, +2, +3 are always written in the entry packet, Although the search playback speed for real-time playback changes, the search speed is adjusted by changing the relative position of the entry point and recording it in the entry packet in accordance with the number of pictures between I pictures. A constant search reproduction speed can be realized between bit streams having different numbers of I pictures.

  The relative position of the entry point written in the position information of the entry packet does not necessarily have to be the entry point position of -3, -2, -1, +1, +2, +3 with respect to the entry packet. For example, it is possible to record the relative position of any entry packet, for example, -25, -8, -1, + 1, + 5, + 20. When special playback such as motion is performed, the position of the entry point at the position of -1, +1 may be necessary.

  Therefore, for bitstreams that require special playback, there are restrictions on the positions of entry points recorded in entry_packet_1 and entry_packet_ + 1, and entry points at positions before and after -1, + 1 are always specified. It is also possible to write the position of. As described above, when recording the position information of an entry point ahead or an arbitrary number in the entry packet, for example, -25, -8, -1, + 1, + 5, + 20 ahead When the entry packet of the format shown in FIG. 4 is used in the case where the relative position of the entry packet is recorded, in the multiplexed data decoding as shown in FIG. It cannot be determined how many pieces of position information are related to the position information of the previous or previous entry point. Therefore, when such relative position information is used for the search operation, there is a problem that it is impossible to predict how much search speed can be realized.

  Therefore, the entry packet is formatted as shown in FIG. 19, and entry_packet_-3, entry_packet_-2, entry_packet_1, entry_packet_ + 1, entry_packet_ + 2, and entry_packet_ + 3, respectively, Entry Point Position -3, Entry Point Position -2, Entry Point Position -1, Entry Point Position +1, Entry Point Position +2, Entry Point Position +3 It can also be recorded in an entry packet.

  For example, entry_packet_-3, entry_packet_-2, entry_packet_1, entry_packet_ + 1, entry_packet_ + 2, entry_packet_ + 3 are respectively -25, -8, -1, + 1, + 5, + Entry Point Position-3, Entry Point Position-2, Entry Point Position-1, Entry Point Position + 1, Entry Point Position + 2, Entry Point Position + 3 Record -25, -8, -1, + 1, + 5, + 20 respectively. The operation of the multiplexed data decoding apparatus shown in FIG. 2 when a search is performed using information from Entry Point Position −3 to +3 will be described.

  The main control device (not shown) gives a search speed target value to the control device 24 and instructs a search operation. The header separation circuit 22 determines an entry packet from the multiplexed bit stream sent from the DSM 10 and sends the contents of the entry packet to the control device 24. The control device 24 selects an entry packet from among Entry Point Position-3, Entry Point Position-2, Entry Point Position-1, Entry Point Position + 1, Entry Point Position + 2, and Entry Point Position + 3 in the entry packet. The one that realizes the speed closest to the search speed instructed by the main controller (not shown) is selected, and the position information of the corresponding entry point is changed to entry_packet_-3, entry_packet_2, entry_packet_1, entry_packet_ + 1. Obtain from entry_packet_ + 2 and entry_packet_ + 3. The control device 24 instructs the DSM 10 to search for the next entry point using the position information of the entry point thus selected.

  In this way, using the information indicating how many positions ahead or the position of the previous entry point the position information of each entry point, the entry point position information that realizes the closest search speed to any desired search speed is obtained. You can choose. The format of the entry packet is as shown in FIG. 14, and the size I-picture length of the data of the I picture immediately following the entry point, or the pack position I- where the end of the data of the I picture is multiplexed. It is also possible to record picture END sector-No. or both in the entry packet.

  FIG. 15 shows the configuration of a multiplexing apparatus for recording I-picture length and I-picture END sector-No. In an entry packet. The I picture end point detection circuit 51 has a function of finding the end of I picture data from the bit stream sent from the video encoder 1 and notifying the controller 8 of the position. In addition to the position of the entry packet and the value of the entry point (entry_packet_-3, entry_packet_2, ..., entry_packet_ + 3) written in the entry packet, the entry point storage device 33 stores the entry packet. It has a function of holding the data length I-picture length of the immediately following I picture and the pack position information I-picture END sector-No. In which the end of the I picture data is multiplexed. Other block functions are the same as those in FIG.

  The control device 8 detects, from the video encoder 1, the video entry point detection circuit 31, and the I picture end point detection circuit 51, the position of the entry point and the end point of the data of the I picture immediately following the entry point. Since the position of the entry point is the position of the start point of the data of the I picture, the control device 8 takes the difference between the position of the end point of the data of the I picture and the position of the entry point to obtain the length of the data of the I picture. Calculate the I-picture length.

  Since the length of the I picture data may be larger than the storage capacity of the code buffer 4, when the entry packet is multiplexed and written to the drive circuit 10, the length of the I picture data to be written to the entry packet I-picture length may not be calculated yet. In such a case, 0 or a specific value indicating uncalculated is written in the I-picture length portion of the entry packet and recorded in the drive device 10. When the length of the I picture data is calculated, the control device 8 records the I-picture data length I-picture length in the entry point storage device 33 and adds an entry packet later. The drive device 10 is supplied with the value of I-picture length and recorded.

  Further, the end position I-picture END sector-No. Of the pack in which the data of the I picture is multiplexed is obtained as follows. The control device 8 multiplexes the data with the algorithm shown in FIG. 5 according to the data amounts M4 and M5 stored in the code buffer 4 and the code buffer 5. Here, the control device 8 is shown in FIG. Apart from the processing described in the algorithm, it is determined for each pack whether the video data of that pack includes the end point of the I picture. When the end point of the I picture data is included in the pack, the control device 8 records the position of the pack in the entry point storage device 33. When recording in the entry point storage device 33, it is stored so as to correspond to the data written in the entry packet multiplexed just before the I picture.

  The pack position I-picture END sector-No., Which is recorded in the entry point storage device 33 and includes the end position of the I-picture data, is added to the entry packet as in the I-picture data length I-piturelength. Is performed, the value is supplied to the drive device 10 and recorded. At this time, the I-picture END sector-No. Is given to the driving device 10 by the relative distance from the position of the pack where multiplexing of the data of the I picture is started, that is, the position of the pack where the entry packet is multiplexed. Written.

  Next, an example of a multiplexed data decoding apparatus that performs a high-speed search using the I-picture END sector-No. Written in the entry packet in this way will be described with reference to FIG. A video decoder based on ISO11172 (MPEG) has a video code buffer in the decoder in order to guarantee a decoding operation even for a bit stream having a different amount of data for each picture. The bit stream that has entered the video decoder 25 is temporarily stored in the video code buffer and then decoded at a necessary timing.

  Conventionally, in order to continuously reproduce I pictures, the control device 24 monitors whether or not the decoding of the I picture by the video decoder 25 has been completed, and after confirming the completion of the decoding, issues a search command for the next I picture. 10 was performed. If the video decoder 25 has a video code buffer at this time, when the decoding unit of the video decoder 25 finishes decoding the I picture, it is multiplexed in the video code buffer of the video decoder 25 following the I picture. The P and B picture data are stored, and these data are being read from the driving device 10 even though they are not decoded. In many cases, the search speed is governed by the time for reading data from the driving device 10 rather than the time required for decoding by the video decoder 25. Therefore, the search speed decreases due to unnecessary loading of P and B pictures. .

  By using the I-picture END sector-No. Information written in the entry packet, the amount of useless P and B picture reading is minimized, and the I picture data to be displayed next is video decoder. 25 can be read in advance in the video code buffer in 25, so that a higher speed search operation can be realized in the multiplexed data demultiplexer in which the search speed is governed by the read speed from the driving device 10.

  During the search operation, the control device 24 instructs the drive device 10 to perform a search based on the information recorded in the entry point storage device 41. The driving apparatus 10 sends the multiplexed bit stream from the designated position to the header separation circuit 22. When an entry packet is detected in the transmitted multiplexed bit stream, the header separation circuit generates an interrupt to notify the controller 24 of this. In response to this interruption, the control device 24 reads the current read position information from the drive device 10 and records it in the entry point storage device 41 as the current entry point position.

  At the same time, the control device 24 extracts the entry point position information written in the entry packet from the header separation circuit and records it in the entry point storage device. At this time, information written in the entry packet at a relative position from the pack position at the beginning of the current entry point, such as I-picture END sector-No. The relative position information is converted into absolute position information by adding the relative position information to the position information of the current entry point read from 10 and recorded in the entry point storage device 41, and recorded in the entry point storage device 41. To do.

  As the driving device 10 continues to supply the multiplexed bit stream to the header separation circuit 22, the read position information of the driving device 10 increases with time. The control device 24 reads the read position information from the drive device 10 at a constant cycle, and compares it with the I-picture END sector-No. Converted to the absolute position information stored in the entry point storage device 41. At this time, when the read position information obtained from the driving apparatus 10 exceeds the I-picture END sector-No., The necessary I picture has been read, and the P, B pictures, etc. following the I picture have been read. It is determined that unnecessary data is loaded, and immediately instructs the drive device 10 to perform a search for reading the next I picture.

  Also, the size I-picture length of the I picture data written in the entry packet and the pack position I-picture END sector-No. In which the end of the I picture data is multiplexed are written. An example of a multiplexed data decoding apparatus capable of performing a search at a more constant search speed will be described with reference to FIG. In the multiplexed data decoding apparatus shown in FIG. 2, when the search operation is started, the control apparatus 24 uses the position information of the entry point stored in the entry packet storage apparatus 41 to store the I picture data. The leading pack is read from the driving device 10. Entry packets are always multiplexed in the read pack, so the data length of the I-picture and the pack to be read are read from the I-picture length and I-picture END sector-No. The quantity can be read out.

  The control device 24 determines whether or not the I-picture length and I-picture END sector-No. Written in the entry packet exceed a certain threshold and how many I-pictures exceeding the threshold continue. To do. When a certain number of I-pictures whose data amount exceeds the threshold value continues for a certain number of times, it takes time to read data from the driving device 10 and to perform decoding processing by the video decoder 25, and the search speed is slow. Since it can be estimated, the delay is corrected by temporarily stopping decoding of the I picture or changing the entry point to be selected among the entry points from -3 to +3. The decoding of the I picture is stopped by instructing the driving device 10 to search for the next entry point before the data is supplied to the video decoder 25 and the audio decoder 26. The change of the position of the entry point to be selected is realized by causing the drive device 10 to search the entry point that performs a search at a higher speed than the search that has been performed so far when searching for the next I picture. For example, if a search using entry_packet_ + 2 is performed, the search is temporarily changed to a search using entry_packet_ + 3.

  According to the above procedure, when the search speed is temporarily lowered, the search operation immediately after is temporarily omitted or speeded up, and a search closer to a constant speed can be realized. Further, the format of the entry packet is as shown in FIG. 16, and not only the I-picture length and I-picture END sector-No. Related to the I picture following the entry packet but also from entry_packet_-3 to entry_packet_ + 3 The I-picture length and I-picture END sector-No. Relating to the I picture following the indicated entry packet can be recorded in the entry packet. That is, I-picture length_-3 to I-picture length_ + 3 and I-picture END sector-No ._- 3 to I-picture END sector-No ._ + 3 are written in the entry packet.

  Thus, when a new I picture is read, the control device can know the length of the I picture and the end position on the drive device before reading the entry packet multiplexed immediately before the I picture. Therefore, a faster search can be realized. The entry packet is in the format shown in FIG. 16, and the video stream number and Video stream-No. Can be recorded. Up to 16 video data are allowed to be multiplexed in the multiplexed bit stream defined in ISO11172 (MPEG). When a plurality of video streams are multiplexed into one multiplexed bit stream and it is considered that a search operation is performed for two or more multiplexed video streams, the entry point position differs depending on each video stream. , It is necessary to record entry point information for each bitstream.

  In the conventional entry packet format, only the entry packet for one video stream can be multiplexed, but the video stream-No. Information is recorded in the entry packet, and the entry packet for each video stream is multiplexed. This enables the decoding device to select an entry packet for a necessary video stream, and realizes a search operation for any video stream even in multiplexed data in which a plurality of video streams are multiplexed. it can.

  In the multiplexing apparatus shown in FIG. 17, there are n video encoders 1, video entry point detection circuit 31, I picture end point detection circuit 51, and n code buffers 4 and 5, respectively. In the case of such a multiplexing device, the control device 8 switches the video or audio bit stream stored in each code buffer by the switching circuit 62 and supplies it to the header addition circuit to add the video packet header or audio packet header, Recording is performed on the driving device 10 in pack units.

  If the pack to be recorded in the driving apparatus 10 includes an I picture of any video stream, the entry packet is multiplexed immediately before the I picture. At this time, the control device 8 supplies to the entry point generation circuit 32 which video stream the entry packet is for, and records it in the Video stream-No. Of the entry packet.

  In the multiplexed data decoding apparatus shown in FIG. 2, the control device 24 reads the video stream-No. Of the entry packet from the header separation circuit 22, and when the value matches the video stream number to be searched, The entry point information recorded in the entry packet is stored in the entry point storage device 41. If they do not match, the entry point information is discarded. By providing an entry packet for each video stream to be multiplexed in this way and including an identifier indicating which video stream corresponds to the entry packet, the search operation can be realized in all the multiplexed video streams.

  The entry packet has a format as shown in FIG. 16, and a copy management flag and a copy management flag can be recorded. Copy Management Flag realizes the same function as SCMS (Serial Copy Management System) used in CDs (compact discs) and DATs (digital audio tapes), and does not match the intention of the creator of the multiplexed data. Is a flag that specifies that is impossible.

  In the data multiplexing apparatus shown in FIG. 1, the control apparatus 8 instructs the entry packet generation circuit 32 for a bit stream to be prohibited from being copied, and sets a value indicating copy prohibition in the Copy Management Flag of the entry packet to be generated. Set. In the data decoding apparatus shown in FIG. 2, the control apparatus 8 reads the copy management flag of the entry packet from the header separation circuit 22, and if the value indicating copy prohibition is set here, the video stream is treated as copy prohibition. . For a video stream treated as copy-prohibited, the decoding apparatus prevents the bit stream data from being output to the external output terminal when the decoding apparatus is provided with an external output terminal, or transmits it when outputting externally. A value indicating copy prohibition is set in the bit stream copy prohibition area to notify the destination device that the bitstream is copy prohibited.

  The Copy Management Flag can record not only information indicating whether copying is prohibited, but also information on the number of times copying is permitted. As a result, it is possible to create a duplicate by copying the bitstream, but it is possible to prohibit duplication based on the duplicate, that is, duplication by grandchild copy. As described above, it is possible to clearly indicate to the decoding device or a device connected thereto a bit stream that is desired to be prohibited from being copied due to reasons such as copyright claims.

  When performing the search operation, the decoding apparatus continuously displays I pictures using the entry packet information. In this case, pictures that are not temporally continuous are displayed. In this way, when an image that is not temporally continuous is viewed for a certain period of time or more, the eyes may become extremely tired. Therefore, as shown in the multiplexed data decoding device shown in FIG. 18, the control device 24 can send a luminance control signal to the video decoder 25, and the luminance of the display screen is lowered during the search to reduce eye fatigue. Can be measured. When the control device 24 is instructed by a main control device (not shown) and enters a search operation, the control device 24 sends a control signal for reducing the luminance to the video decoder 25. When the video decoder 25 receives the luminance control signal, the video decoder 25 reduces the luminance of the display screen and darkens the display screen. When the search operation is completed, the control device 24 sends a control signal for returning the luminance to normal. The video decoder 25 returns the luminance of the display screen to a normal state by the signal.

  Accordingly, while the search operation is performed and a temporally discontinuous image is displayed, the brightness of the display image can be reduced, and eye fatigue during the search operation can be reduced.

It is a block diagram which shows the structure of one Example of the data coding apparatus of this invention. It is a block diagram which shows the structure of one Example of the data decoding apparatus of this invention. It is a figure which shows the format of a pack among the data formats of the disk driven by the drive device 10 of the Example of FIG. 1 and FIG. FIG. 4 is a diagram for explaining a format of an entry packet in FIG. 3. It is a flowchart explaining operation | movement of the Example of FIG. It is a block diagram which shows the structure of an example of the conventional data encoding apparatus. It is a block diagram which shows the structure of an example of the conventional data decoding apparatus. It is a figure explaining the format of the bit stream in the example of FIG. 6 and FIG. It is a figure explaining stream ID of FIG. FIG. 7 is a flowchart explaining the operation of the example of FIG. 6. FIG. It is a figure explaining the bit stream in the disk driven by the drive device 10 of FIG. 6 and FIG. It is a figure explaining the format in the bit stream of an entry packet. It is a figure explaining the other format in the bit stream of an entry packet. It is a figure explaining other formats in the bit stream of an entry packet. It is a block diagram which shows the structure of an example of the multiplexing apparatus for recording data in an entry packet. It is a figure explaining other formats in the bit stream of an entry packet. It is a block diagram which shows the structure of an example of the multiplexing apparatus for recording data in an entry packet. It is a block diagram which shows the structure of an example of the multiplexed data decoding apparatus which enables brightness | luminance control. It is a figure explaining other formats in the bit stream of an entry packet.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Video encoder 2 Audio encoder 3 Multiplexer 4, 5 Code buffer 6 Switching circuit 7 Header addition circuit 8 Control device 9 Multiplexing system clock generation circuit 10 Drive device 21 Separation device 22 Header separation circuit 23 Switching circuit 24 Control device 25 Video Decoder 26 Audio decoder 31 Video entry point detection circuit 32 Entry packet generation circuits 33 and 41 Entry point storage device

Claims (5)

In a recording medium mounted on a playback device and controlled to be read based on recorded address information,
A bit stream in which a moving image is encoded into an intra-frame encoded picture and an inter-frame encoded picture is recorded,
An entry packet having an area for recording position information of a plurality of discretely selected intra-frame encoded pictures selected for access according to a search speed is arranged in front of the intra-frame encoded pictures in the bitstream. Has been
A recording medium , wherein position information of a plurality of discretely selected intra-frame coded pictures for access depending on a search speed is recorded in the entry packet . The recording medium according to claim 1,
The entry packet has an area for recording position information of at least adjacent forward and backward intra-frame coded pictures. The recording medium according to claim 1,
The recording medium, wherein the entry packet has an area for recording position information of an intra-frame coded picture selected such that an adjacent distance increases as the distance increases. The recording medium according to claim 1,
The entry packet has an area for recording information indicating how far the intra-frame coded picture is located, together with position information of the intra-frame coded picture. The recording medium according to claim 1,
The bitstream is composed of one or more packs in which intra-frame coded pictures and inter-frame coded pictures are arranged,
In each of the packs, the entry packet is arranged before an intra-frame coded picture.

Images