JP2006253966A - Coded data recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coded data recording apparatus capable of reproduction without disturbance of an image when recording media are each independently reproduced in division recording in which coded data generated by using a motion image coding system including an intra-picture coding and inter-picture prediction coding are divided into a plurality of recording media. <P>SOLUTION: The coded data are stored in a first GOP buffer 4 per GOP, the coded data are re-coded by a re-coder 5 using only the coded data in the GOP so that inter-picture prediction coding can be decoded to generate re-coded data, and the re-coded data are stored in a second GOP buffer 6 per GOP. If an idle capacity of the recording medium is larger than the coded data amount stored in the buffer 4, the coded data are read from the buffer 4 and recorded, and if smaller, the recording medium is replaced by another recording medium and re-coded data are read from the buffer 6 and recorded. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an encoded data recording apparatus that divides and records encoded data generated using a moving image encoding system including intra-picture encoding and inter-picture predictive encoding into a plurality of recording media.

  As a moving picture coding system, there is a motion compensation predictive coding such as a system based on ISO / IEC13818-2 (hereinafter referred to as MPEG-2 video).

  With this encoding method, for example, a standard moving picture digital video signal of 216 Mbps can be encoded from 3 Mbps to 6 Mbps, and the recording medium and the transmission medium can be efficiently used for recording and transmitting the encoded data. Can be used for

  Then, by recording the encoded data encoded by a method compliant with MPEG-2 video on a recording medium, it is possible to reproduce and display a moving image later. As the recording medium, various digitally recordable recording media such as a semiconductor memory, an optical disk, a magnetic tape, and a hard disk are used. Among them, the optical disc is excellent in portability, cost, convenience, and the like.

  However, optical disks generally have a smaller storage capacity than magnetic tapes and hard disks, and recording time is shorter when compared with moving image encoded data having the same encoding rate.

  For this reason, when a long-time moving image is recorded on a single optical disc, the encoding rate needs to be lowered. As a result, when the recorded encoded data is reproduced, the quality of the reproduced image is deteriorated.

  Therefore, there is a conventional recording / reproducing apparatus using an optical disk changer. For example, as disclosed in Patent Document 1, there is a technique that enables recording and reproduction for a long time by replacing with another optical disk having a free space in the changer when there is no free space on the optical disk.

  However, when reproducing the encoded data divided and recorded on a plurality of optical disks, the encoded data recorded and divided is sequentially read and reproduced while exchanging the optical disk as necessary based on the management information. The recording / reproducing of the encoded data is temporarily stopped by exchanging the optical disk.

  Therefore, the recording / reproducing apparatus disclosed in Patent Document 1 or Patent Document 2 performs continuous recording / reproduction by using a buffer memory.

As described above, long-time moving image encoded data can be recorded and reproduced without lowering the encoding rate and degrading the image quality of the reproduced image.
JP 2000-30413 A JP 2001-6285 A

  However, in the continuous recording by the conventional optical disk changer as disclosed in Patent Document 1, when there is no free space in the optical disk being recorded, the optical disk is replaced in the middle of the encoded data and the recording is continued. For this reason, the encoded data recorded on each optical disc is divided regardless of the syntax of the encoded data.

  As a result, when the encoded data recorded on each optical disc is reproduced independently, the encoded data is interrupted in the middle of the syntax, and the encoded data starts from the middle of the syntax. There is a problem in that the decoded data cannot be correctly decoded and the reproduced image is greatly disturbed.

  In addition, when the encoded data recorded on each optical disk is reproduced independently, if decoding of inter-picture prediction that requires encoded data recorded on another optical disk is included, correct decoding of the encoded data is performed. There was a problem that the image could not be reproduced and the reproduced image was greatly disturbed.

  Therefore, the present invention provides an independent recording medium for divided recording in which encoded data generated using a moving picture encoding method including intra-picture encoding and inter-picture predictive encoding is divided into a plurality of recording media. It is an object of the present invention to provide an encoded data recording apparatus that can reproduce an image without disturbance even when it is reproduced.

  The encoded data recording apparatus of the present invention uses a plurality of pieces of encoded data generated using a moving image encoding method including intra-picture encoding and inter-picture predictive encoding, and once recorded on a first recording medium. In the coded data recording apparatus for dividing and recording on the second recording medium, reading means for reading the coded data from the first recording medium, and divided coding obtained by dividing the read coded data Of the data, the first divided encoded data, which is the divided encoded data immediately after the one division point, is regenerated so that no other divided encoded data is required in inter-picture predictive decoding. And recording means for encoding the first divided re-encoded data and recording the first divided re-encoded data on one second recording medium.

  The encoded data recording apparatus of the present invention includes a reading means for reading encoded data from the first recording medium, and time for one division point among the divided encoded data obtained by dividing the read encoded data. Thus, the first divided re-encoded data is re-encoded so that the other divided encoded data is not required in the inter-picture predictive decoding, and the first divided re-encoded data is obtained. And recording means for recording the first divided re-encoded data on one second recording medium, so that when the encoded data is divided and recorded on a plurality of recording media, a plurality of The encoded data recorded on the recording medium can be divided with the GOP as a boundary. When the encoded data recorded on each recording medium is reproduced independently, the encoded data is interrupted in the middle of the syntax. Without , It is possible to prevent large disturbance of the reproduced image by the encoded data is decoded without starting in the middle of the syntax.

  In addition, it is possible to prevent a large image disturbance caused by failure to correctly decode a picture that requires encoded data divided and recorded on another recording medium for decoding of inter-picture prediction.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(About MPEG-2 video encoded data)
First, MPEG-2 video encoded data will be described with reference to FIG. FIG. 1 is a diagram showing a configuration example of MPEG-2 video encoded data.

  In MPEG-2 video, as a picture type of screen data generated by compressing and encoding an original screen, an I picture (I-picture) to be encoded as intra-picture encoding, and a previous reference picture in the picture display order are displayed. A motion-compensated predictive coded picture (P-picture) to be coded as a motion-compensated predictive-coded picture (inter-picture predictive coded picture) used, and a reference picture immediately before and after in the picture display order ( There is a B picture (B-picture) to be encoded as an inter-picture predictive encoded picture.

  Here, the reference picture is a picture encoded as an I picture or a P picture.

  As shown in FIG. 1A, in MPEG-2 video, generally, encoded data is composed of a plurality of GOPs (Group of Pictures). Each GOP starts with a sequence header (Sequence Header), followed by a sequence extension part (Sequence Extension) and a GOP header (GOP Header).

  After that, for example, as shown in FIG. 1 (b), the structure continues with I picture, P picture, B picture, B picture, and as shown in FIG. 1 (c), it continues with I picture, B picture, B picture, P picture. There is a configuration.

  In the configuration shown in FIG. 1B, the picture in the immediately preceding GOP can be decoded without being used as a reference picture.

  In the configuration shown in FIG. 1C, a case where decoding is possible without using a picture in the immediately preceding GOP as a reference picture, and a case where decoding is necessary using a picture in the immediately preceding GOP as a reference picture. There are two ways.

  Specifically, with the configuration shown in FIG. 1C, two B pictures 1a and 1b between an I picture and a P picture can be encoded using the picture in the immediately preceding GOP as a reference picture. it can.

  In general, from the viewpoint of encoding efficiency, there are many cases where encoding is performed using a picture in the immediately preceding GOP as a reference picture, but encoding is performed without using a picture in the immediately preceding GOP as a reference picture at the time of encoding. There is also.

  Information such as an image size, a frame rate, an aspect ratio, and a bit rate is described in the sequence header. In the sequence extension section, information such as a profile level representing a standard standard of encoded data, a progressive condition, and a color difference thinning condition is described.

  FIG. 1D shows a specific configuration of the GOP header. In the GOP header, four syntax elements are described.

  The first is 32-bit group_start_code, and a fixed value is determined as an international standard.

  Second, it is a 25-bit time_code, which describes the time code for the first picture to be displayed in the GOP.

  Third, 1-bit closed_gop, and the value of this element being 1 indicates that decoding is possible without using the picture in the immediately preceding GOP as a reference picture. Thereby, for example, when a GOP of different encoded data is connected by editing, it is possible to inform the editor that the value of broken_link described later does not have to be 1.

  This is particularly effective when the two B pictures 1a and 1b between the I picture and the P picture are encoded without using the picture in the immediately preceding GOP as a reference picture with the configuration shown in FIG. Become.

  That is, by setting closed_gop to 1, it is possible to avoid setting the value of broken_link, which will be described later, at the time of editing, and to prevent the display of the two B pictures 1a and 1b from being lost as a result at the time of decoding. it can.

  Fourth, 1-bit broken_link, and when the value of this element is 1, the two B pictures 1a and 1b between the I picture and the P picture cannot be correctly decoded with the configuration shown in FIG. 1C. Indicates that there is sex.

  This is used, for example, to prevent a large disturbance of the image due to the fact that the two B pictures 1a and 1b, which may have been encoded using the picture in the immediately preceding GOP as a reference picture by editing or the like, cannot be decoded correctly.

  In general, in the MPEG-2 decoder, when broken_link is 1, two B pictures 1a and 1b are reproduced without being displayed.

(Example)
Next, an embodiment of the encoded data recording apparatus of the present invention will be described with reference to FIG. Hereinafter, a case will be described in which a system compliant with MPEG-2 video is used for encoding moving images and an optical disk is used as a recording medium. FIG. 2 is a block diagram showing an encoded data recording apparatus according to an embodiment of the present invention.

  As shown in FIG. 2, the encoded data recording apparatus of the present embodiment stores an encoder 2 that encodes a moving image signal to generate encoded data, and encoded data generated by the encoder 2. The accumulator 3, the first GOP buffer 4 that stores the encoded data read from the accumulator 3 in GOP units, and the moving image data generated by decoding the encoded data read from the accumulator 3 is re-encoded. A re-encoder 5 for generating re-encoded data, a second GOP buffer 6 for storing the re-encoded data generated by the re-encoder 5 in GOP units, and a recording from the recording controller 10 An optical disc recorder 8 that reads out the encoded data or re-encoded data from the first GOP buffer 4 or the second GOP buffer 6 via the switch 7 in accordance with the start instruction and records the data on the optical disc, and the light from the recording controller 10 It comprises an optical disc exchange 9 to replace the optical disk, and a recording controller 10 for controlling the switch 7 and the optical disc recorder 8 and the optical disk exchange 9 by disk exchange command.

  The re-encoder 5 includes a decoder 5a and an encoder 5b. The switch 7 has ports 7a, 7b, and 7c. When the port 7b-7a is connected by a switch switching signal from the recording controller 10, the second GOP buffer 6 and the optical disk recorder 8 are connected. When the ports 7c-7a are connected, the first GOP buffer 4 and the optical disk recorder 8 are connected.

  Next, the operation of the encoded data recording apparatus of this embodiment will be described. First, a moving image signal is input to the encoder 2 and is encoded with a configuration as shown in FIG.

  The encoded data generated by the encoder 2 is temporarily stored in the storage 3. The accumulator 3 is composed of a hard disk, for example. Moreover, you may comprise with magnetic tape, a semiconductor memory, an optical disk, an optical hologram memory, etc. others.

  Then, the encoded data is read from the accumulator 3 in GOP units and transferred to the first GOP buffer 4, while the re-encoded data is generated by the re-encoder 5 in GOP units to generate the second GOP buffer 6. Forward to. At this time, the transfer to the second GOP buffer 6 is performed by deleting the previous GOP re-encoded data.

  The re-encoder 5 includes a decoder 5a and an encoder 5b. The decoder 5a decodes encoded data for 1 GOP and supplies a moving image signal for 1 GOP to the encoder 5b. Then, the encoder 5b performs encoding so that inter-picture prediction encoding can be decoded using only encoded data in the GOP.

  As described above, the first GOP buffer 4 and the second GOP buffer 6 store encoded data and re-encoded data for one GOP for moving images in the same period.

  The recording controller 10 compares the free recording capacity of the optical disk in the optical disk recorder 8 with the encoded data amount for 1 GOP stored in the first GOP buffer 4.

  If the free space on the optical disk is larger, the recording controller 10 outputs a recording start instruction to the optical disk recorder 8 and encodes 1 GOP stored in the first GOP buffer 4. Data is read and recorded on the optical disc.

  When the free space on the optical disk is smaller, the recording controller 10 outputs a recording stop instruction to the optical disk recorder 8 to stop the recording operation, and after the optical disk recorder 8 stops the recording operation, the optical disk An optical disk replacement instruction is output to the recorder 8 and the optical disk switch 9 to replace the optical disk with sufficient free space.

  After the replacement of the optical disk, the recording controller 10 outputs a switching signal to the switch 7 and switches so as to connect the ports 7b-7a of the switch 7. First, the recording controller 10 outputs a recording start instruction to the optical disk recorder 8 and outputs the second signal. The re-encoded data for 1 GOP stored in the GOP buffer 6 is read and recorded on the optical disc. Thereafter, the port 7c-7a of the switch 7 is switched to be connected so that the subsequent GOP encoded data and subsequent data are read from the first GOP buffer 4 and recorded on the optical disk.

  As described above, according to the encoded data recording apparatus of the present embodiment, the encoded data is stored in the first GOP buffer 4 in units of GOP, and the moving image generated by decoding the encoded data with the re-encoder 5. The image data is encoded using only the encoded data in the GOP so that the inter-picture predictive encoding can be decoded to generate re-encoded data, and the re-encoded data is stored in the second GOP buffer 6 in units of GOP. When the free space of the optical disk is larger than the amount of encoded data stored in the first GOP buffer 4, the encoded data stored in the first GOP buffer 4 is read and recorded on the optical disk, If the free space of the optical disk is smaller than the amount of encoded data stored in the first GOP buffer 4, the optical disk switch 9 replaces the optical disk with another optical disk, and The switch 7 is switched to read the re-encoded data stored in the second GOP buffer 6 and record it on another optical disk by the optical disk recorder 8. When recording divided into optical disks, the encoded data recorded on a plurality of optical disks by the optical disk recorder 8 can be divided with GOP as a boundary, and the encoded data recorded on each optical disk can be independently When reproduced, the encoded data can be decoded without being interrupted in the middle of the syntax, and the encoded data can be decoded without starting in the middle of the syntax, thereby preventing a large disturbance in the reproduced image. Can do.

  In addition, it is possible to prevent a large image disturbance caused by failure to correctly decode a picture that requires encoded data divided and recorded on another optical disk for decoding of inter-picture prediction.

  In the present embodiment, MPEG-2 video has been described as an example of a moving picture coding method. However, if the moving picture coding method includes at least inter-picture predictive coding, for example, ISO / IEC11172-2 is used. Other encoding methods such as (MPEG-1 video), ISO / IEC14496-2 (MPEG-4 visual), and ISO / IEC14496-10 (MPEG-4 AVC) may be used.

  Further, although an optical disk has been described as an example of the recording medium, other recording media such as an optical hologram memory, a semiconductor memory, a magnetic tape, and a hard disk may be used.

  The present invention relates to a recording apparatus that divides and records encoded data generated using a moving image encoding method including at least inter-picture predictive encoding into a plurality of recording media, for example, recording by an optical disc changer. Applicable to equipment.

It is a figure which shows the structural example of MPEG-2 video coding data. It is a block diagram which shows the encoding data recording device of the Example of this invention.

Explanation of symbols

2 Encoder 3 Accumulator 4 First GOP buffer 5 Re-encoder 5a Decoder 5b Encoder 6 Second GOP buffer 7 Switch 8 Optical disk recorder 9 Optical disk switch 10 Recording controller

Claims (1)

Coded data generated using a moving picture coding system including intra-picture coding and inter-picture predictive coding and once recorded on a first recording medium is divided into a plurality of second recording media. In the encoded data recording device for recording,
Reading means for reading the encoded data from the first recording medium;
Among the divided coded data obtained by dividing the read coded data, the first divided coded data which is the divided coded data immediately after the one division point is inter-picture predictive decoded. Re-encoding without obtaining other divided encoded data to obtain first divided re-encoded data, and recording the first divided re-encoded data on one second recording medium An encoded data recording apparatus comprising: a recording unit.

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