JP3716849B2 - Data recording / reproducing method and data recording / reproducing apparatus - Google Patents

Description

  The present invention relates to an apparatus for recording and reproducing compressed video and audio signals on a medium such as an optical disk.

  The compression of video and audio signals is described in detail in “Supervised by Yonemitsu, MPEG technology, published by Trikes on December 21, 1993”. An example of an optical disk is described in detail in “Edited by Kenji Hayashi, CD-Audio to Personal Computer, July 25, 1990, Corona Publishing”.

  The former document describes a compression method of video and audio signals and a multiplexing method thereof. The latter document describes a CD signal recording format. However, it has not been described how to facilitate a search method when recording and reproducing compressed video and audio signals on a medium.

  When playing media such as video and audio signals that are compressed in the data stream format as described in "MPEG technology", the data stream is played and the pack and packet header information is determined. Thus, the boundary of the picture or the picture group can be determined. However, when recording a signal on a medium, in order to improve error tolerance, interleaving processing and error correction coding processing specific to normal media, and framing by adding a synchronization signal and sub information are performed. . For this reason, when the boundary of the picture or the group of pictures is judged by playing the data stream and judging the header information of the pack and the packet, the position of the pickup or the like that is already playing the data from the media is shifted. ing. For this reason, when searching or editing in units of pictures or groups of pictures, complicated control is required to find the position of the boundary part of the picture or group of pictures on the media. There is a problem that it takes time.

  In the present invention, in order to solve the above problem, when the pack time-series data is divided into the minimum unit of the data structure specific to the media and transmitted or recorded by the media, the minimum unit of the data structure specific to the media is used. This is achieved by describing information indicating whether there is a picture or picture group boundary in the sub-information part of the frame signal to be transmitted or recorded when media-specific framing is performed. Is done.

In the present invention, information indicating a reference time for each packet is added to the packet format compressed data, converted into a data structure unique to the recording medium, and recorded on the recording medium. When reproducing from the recording medium, the compressed data in the packet format is read, and according to the information indicating the reference time included in the read compressed data, so that the time interval between adjacent packets reproduces the interval of the reference time, The read data was rearranged in time and output.

  According to the present invention, information indicating whether the head of a certain unit of compressed video data (for example, a picture group) is included in the minimum unit of the data structure specific to the medium is stored in the medium-specific information. Transmission or recording can be performed by using an area for transmitting or recording sub information different from an area for transmitting or recording main information in the frame signal. Further, according to the present invention, it is possible to search a boundary of a certain unit of compressed video data at high speed on the medium. Furthermore, there is an effect that it is possible to configure a playback apparatus that can search a boundary between picture groups at high speed and can perform normal playback.

  FIG. 1 shows an embodiment of the present invention and shows a method for transmitting or recording information. Reference numeral 1 denotes compressed data packing processing, 2 denotes media-specific signal processing, and 3 denotes media for transmitting or recording information. 4 is compressed video data, 5 is compressed audio data, and 6 is independent data. 7, 8 and 9 are packetizing processes, and 10 is a packing process. 11 is processing for dividing the pack time-series data into media-specific data structures, 12 is media-specific signal processing such as error correction code addition and interleaving, and 13 is media-specific processing of pack time-series data. When the data structure is divided, the information extraction process indicating which component of the data structure includes the boundary of the picture group, 14 is a framing process for generating a media-specific frame signal, and 15 is a frame. A process of adding sub-information to the signal, 16 is a process of adding a synchronization signal for each frame of the frame signal.

  Hereinafter, a method of transmitting information or generating a recording signal according to the present invention will be described with reference to FIG.

  In the compressed data packing process 1, the compressed video data, the compressed audio data, and the independent data are each packetized by independently adding a packet header indicating the head of the packet. Next, each packet is time-divided, one or more packets are collected, and a pack header indicating the head of the pack and information indicating the reference time are added to form a pack. In the media-specific signal processing 2, the pack time-series data is first divided into media-specific data structures.

  At the time of the division, information extraction processing is performed to indicate which component of the data structure includes the boundary of the picture group. The time-series data of the divided packs is subjected to signal processing such as addition of an error correction code and interleaving in order to enhance error resistance according to a signal processing format unique to the media. Next, in order to transmit or record the signal-processed data, a framing process according to a frame format unique to the media is performed. In the framing process, the sub-information and the synchronization signal indicating the head of the frame are added to the data subjected to the media-specific signal processing to generate a frame signal.

  In the present invention, information indicating which component of the media-specific data structure includes the boundary of the picture group is inserted into the sub-information of the frame signal at the time of framing processing. Further, if the channel signal has a channel code unique to the medium, channel code modulation according to the modulation rule is performed. If there is no channel code, data is transmitted or recorded by the medium as it is.

  As described above, according to the present embodiment, the information indicating whether the head of a certain unit of compressed video data (for example, a picture group) is included in the minimum unit of the media-specific data structure, Transmission or recording can be performed using an area for transmitting or recording sub-information different from an area for transmitting or recording main information in a frame signal unique to the medium.

  Next, another embodiment of the present invention will be described with reference to FIG. In this embodiment, the present invention is applied to a system having a data structure and a frame format equivalent to those of a CD (compact disc), a CD-ROM, or a CD-ROM.

  In the figure, 20 indicates pack time-series data, and the boundary between B and C indicates the boundary of the picture group. The head of part C indicates the head of the data of the picture group. 21 shows a data structure specific to this medium, A is a header portion including a synchronization signal, etc., B and C are divided and applied to pack time-series data. The data is the same as the B and C parts of the data. The D part is other data including a margin part. The A, B, C, and D portions indicate the minimum unit of the data structure unique to the medium, and are defined as one block. In the present invention, the number of bytes in one block is 2352 bytes.

  Reference numeral 22 denotes a frame signal unique to the present media, SY denotes a frame synchronization signal, and SUB denotes a subcode which is sub information. Reference numeral 23 denotes a main information portion in the frame signal. In this embodiment, the total information is 32 bytes including data 24 bytes and ECC (error correction code) 8 bytes. It is assumed that one frame is composed of the frame synchronization signal, the subcode as the sub information, and the main information. Reference numeral 24 denotes the data structure of the subcode. The subcode is composed of 8 types of codes of P, Q, R, S, T, U, V, and W each having a code length of 98 bits, and 8-bit data collected from each code by 1 bit is a frame. It is inserted into the SUB part in the signal.

  Next, the recording method of this embodiment will be described. The pack time-series data is divided for each number of bytes corresponding to the number of bytes of the data portion of the block, which is the minimum unit of the data structure unique to the media, and is assigned to the data portion of each block. At the time of assignment, it is detected that the boundary between the picture group B and the picture group C exists in the block. Then, a code indicating that a boundary exists is described in, for example, a Q code in the subcode. At the same time, signal processing such as addition of media-specific error correction codes and interleaving is performed on the blocked data. When this signal processed data is framed, it is assigned to the main information portion of the frame signal.

  At the same time, the subcode is assigned to the SUB portion by the method described above. In this way, information indicating the boundary between picture groups can be described in the subcode portion of the frame signal. The frame signal thus configured is recorded on a medium such as a CD after 8-14 modulation (EFM) in which 8 bits are assigned to 14 bits, for example. As described above, according to this embodiment, the top of a picture group of compressed video data is a medium in a CD (compact disc), a CD-ROM, or a system having a data structure and a frame format equivalent to a CD-ROM. Information indicating whether it is included in a block, which is the minimum unit of a unique data structure, can be recorded using an area for recording sub-information in a frame signal unique to a medium.

  In the present embodiment, the case where information indicating that a boundary exists is described in the subcode Q has been described. However, the same effect can be obtained not only in the Q code but also in any code of P, Q, R, S, T, U, V, and W. For example, the P code has a data start flag written in the current CD. Alternatively, or in part, information indicating that a boundary exists can be described. Further, by simply describing the serial number or address at the beginning of a picture group of compressed video data instead of information indicating a boundary, a more accurate search can be performed during reproduction.

  In addition, not only the information indicating the boundary and the serial number or address of the head of the picture group of the compressed video data, but also a CRC code for detecting a reproduction error of these data is added and described at the same time. As a result, the accuracy of the information to be reproduced at the time of retrieval can be improved. When recording the information indicating the boundary, the serial number at the beginning of the compressed video data picture group, or the address in the Q code, the portion of the current CD where PMIN, PSEC, and PFRAME are described. If described instead, it is possible to detect a reproduction error using the CRC code of the Q code as it is. In addition, graphic information is described in R, S, T, U, V, and W in the current CD, but this portion can also be described in the same manner as the P code described above. it can.

  Next, another embodiment of the present invention will be described with reference to FIG. FIG. 3 shows a reproducing method according to the present invention. The data reading sections 31 and 33 are periods in which the playback device plays back data on the media, and the portion indicating the high-speed movement of the data reading position indicated by 32 is the portion on the media for high-speed search. This is a period during which the data reproduction position is moved. The playback device searches for the target position on the media while repeating the operation of reading data after performing high-speed movement of the data reading position during high-speed search.

  In the present invention, in this data reading section, the beginning of a unit of data (for example, a picture group) of compressed video data described in the sub-information in the frame signal unique to the medium is unique to the medium. Information indicating whether or not it is included in the minimum unit of the data structure can be determined, and based on this information, a boundary of data of a certain unit of compressed video data can be searched at high speed on the medium. . As described above, according to the present embodiment, there is an effect that a boundary of data of a certain unit of compressed video data can be searched at high speed on the medium.

  Next, another embodiment of the present invention will be described with reference to FIG. FIG. 4 shows a reproduction method according to the present invention. In this embodiment, the reproduction method of the present invention is applied to a CD (compact disk), CD-ROM, or system having a data structure and frame format equivalent to those of a CD-ROM. In the figure, elements having the same numbers as those in FIGS. 2 and 3 indicate the same elements.

  Similar to the embodiment shown in FIG. 3, the playback device performs a high-speed search by moving the pickup at a high speed, moving the data reading position, and then reading the data on the disk. Search for the target position on the media. The frame signal reproduced from the disc in the data reading section is the same signal as the frame signal shown in FIG.

  As for the subcodes, those described in 8 bits in each frame over 98 frames are collected, and 8 codes of P, Q, R, S, T, U, V, W of 98 bits per code are collected. Are reproduced. Playing back information indicating whether or not the head of a picture group of compressed video data described in any of the subcodes is included in a block that is a minimum unit of a media-specific data structure, By determining the boundary of the picture group, the boundary of the picture group can be searched at high speed. As described above, according to the present embodiment, there is an effect that a boundary of data of a certain unit of compressed video data can be searched at high speed on the medium.

  Next, another embodiment of the present invention will be described with reference to FIG. FIG. 5 shows a reproducing apparatus according to the present invention. In this embodiment, the playback apparatus of the present invention is applied to a system having a data structure and a frame format equivalent to those of a CD (compact disc), CD-ROM, or CD-ROM. In FIG. 5, 51 is an optical disk, 52 is a signal processing unit specific to the medium, 53 is a subcode determination unit, 54 is a pickup control unit, 55 is a pickup, 56 is a memory, 57 is a write address generation unit for the memory, 58 Is an address comparator, 59 is an address comparator, 60 is an output time adjustment unit for time-series data of packs, 61 is a reference clock, and 62 is a clock specific to the medium.

  First, the operation during high-speed search will be described. During the high-speed search, the frame signal reproduced from the disk 51 is input to the media-specific signal processing unit 52 during the data reading period, and the subcode and main information are separated based on the synchronization signal in the frame signal. To do. The subcode is input to the subcode determination unit 53, where it is determined whether or not it is a picture group boundary. If it is not the boundary of the picture group, the pickup is moved at high speed via the pickup control unit, and the determination by the subcode is repeated. If it is a picture group boundary, playback is performed. In this way, a search can be performed on a picture group basis.

  Next, the operation at the time of reproduction after the search is completed will be described. The reproduced frame signal is input to a media-specific signal processing unit 52, and after subcode and main information are separated based on a synchronization signal in the frame signal, the main information is error-corrected and deinterleaved. The block structure data, which is a data structure unique to the media, is reproduced. The block structure data is temporarily stored in the memory 56 in accordance with a media-specific clock and a write address generated based on the reference clock. The data stored in the memory is read according to a read address generated based on the reference clock, and input to the pack time-series data output time adjustment unit 60.

  The write address and read address of the memory are always compared by the comparator 59, and when the write address value is separated from the read address value by a certain value or more, the pickup 55 is controlled via the pickup control unit 54 to pause the reproduction. . When the pack is connected to the output of this playback device by constantly increasing the data reading speed from the disc than the data transmission rate of the pack time-series data and performing the playback control described above. Excess or deficiency of data with the series data decoding device can be absorbed.

  The data read from the memory is corrected on the time axis in the pack time-series data output time adjustment unit. 63 shows the correction on the time axis of the time series data of the pack. In the pack time-series data output time adjustment unit, the time interval of the heads of adjacent packs becomes equal to the difference in the reference time according to the reference time described for each pack of data read from the memory. The time axis is corrected as follows. Since the amount of data in one pack varies from pack to pack, output is performed at the maximum data transfer rate in the time series data of the pack. For packs with a small amount of data in one pack, Pack invalid data before the beginning of the pack. As described above, according to the present embodiment, there is an effect that it is possible to configure a playback apparatus that can search a boundary between picture groups at high speed and can perform normal playback.

The figure which shows the transmission or recording method of the information by this invention. The figure which shows the recording method of the information by this invention. The figure which shows the reproduction | regeneration method of the information by this invention. The figure which shows the reproduction | regeneration method of the information by this invention. The figure which shows the reproducing | regenerating apparatus of the information by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Packing process part of compression data, 2 ... Signal processing part peculiar to media, 3 ... Media, 13 ... Extraction part of information which shows the boundary of a picture group, 15 ... Sub information addition part 51 ... Optical disc, 52 ... Media-specific signal processing unit, 53 ... subcode determination unit, 54 ... pickup control unit, 55 ... pickup, 56 ... memory,
60: Output time adjustment unit for pack time-series data, 63: Pack time-series data

Claims (4)

Add information indicating the reference time to the compressed data in packet format,
Convert to a data structure specific to the recording medium, record it on the recording medium,
When reproducing from the recording medium, the compressed data in the packet format is read, and according to information indicating the reference time included in the read compressed data , the time interval between the adjacent compressed data becomes equal to the difference in the reference time A method of recording and reproducing data, wherein the compressed data read out are rearranged in time and output. 2. The data recording / reproducing method according to claim 1, wherein the compressed data in the packet format includes a data stream of a compressed video signal and a data stream of a compressed audio signal. In a data recording / reproducing apparatus for recording / reproducing packet format compressed data on a recording medium,
Data processing means for adding information indicating a reference time to the compressed data in the packet format and converting the information into a data structure unique to the recording medium;
Recording means for recording the compressed data converted by the data processing means on a recording medium;
Reproducing means for reproducing the compressed data from the recording medium;
Storage means for temporarily storing the compressed data reproduced by the reproduction means;
The compressed data in the packet format is read from the storage means, and read according to the information indicating the reference time included in the read compressed data so that the time interval between the adjacent compressed data is equal to the difference in the reference time Time axis adjustment means for rearranging and outputting the compressed data; and
A data recording / reproducing apparatus comprising: 4. The data recording / reproducing apparatus according to claim 3, wherein the compressed data in the packet format includes a data stream of a compressed video signal and a data stream of a compressed audio signal.

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