Error detection/correction and fault detection/recovery – Pulse or data error handling – Digital data error correction
Reexamination Certificate
2000-02-28
2001-11-06
Baker, Stephen M. (Department: 2133)
Error detection/correction and fault detection/recovery
Pulse or data error handling
Digital data error correction
C714S769000
Reexamination Certificate
active
06314542
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for recording and/or reproducing compressed video and audio signals and/or computer application data on such recording media as an optical disk.
Optical disks dedicated for reproduction of signals stored thereon have been described in detail in the Japanese literature “CD—From Audio to Personal Computer” written by Kenji Hayashi and published from Corona Ltd. on Jul. 25, 1990. Moreover, description has been given in detail of compression of video and audio signals in the Japanese literature “New Moving Picture Expert Group (MPEG) Text” written by Hiroshi Fujiwara and published from ASCII Ltd. on Aug. 1, 1994.
In the former, to add error correction codes to data beforehand continuously written on a compact disk (CD), there have been described a CD error correction method in which first and second error correction codes are added thereto and an oblique interleaving not completing in a block (block-incomplete interleaving) is carried out to convert data arrangement by changing the amount of delay in relation to the first and second correction codes for each data and a CD-ROM (read-only memory) signal recording method in which a CD for storing thereon audio signals is employed for data application.
Additionally, according to the latter, there have been described a method of compressing video and audio signals and a method of multiplexing the compressed signals. In accordance with these articles, although compressed video and audio signals are recorded on the media and computer user data is recorded thereon in a data application, there has not been described any method of efficiently recording the signals and data on the media.
SUMMARY OF THE INVENTION
As described in the “CD—From Audio to Personal Computer”, data reproduced from a compact disk of a CD player is subjected to an error correction using a first error correction (C
1
) code, an oblique block-incomplete interleaving i.e., oblique interleaving not completing in a block to transform the data arrangement by changing the amount of delay for each data, and an error correction using a second error correction (C
2
) code, thereby producing output data. In consequence, the error correcting capability is improved by the interleaving process. Furthermore, even when an error occurring in successive positions on a disk cannot be corrected, the error is dispersed in the output data since the data output order is different from the sequence of data on the disk. Therefore, for audio data, such an error can be appropriately interpolated according to data items respectively before and after the wrong data. However, when compressed video data is to be recorded on a disk, the correction using data interpolation according to the preceding and succeeding data items cannot be employed. On the contrary, if the interpolation is applied to this situation, the range of the error is disadvantageously expanded in the output data. This problem can be coped with as follows. For data recorded on a disk in a sequence of the first correction code series, an error correction is accomplished using the first correction code. An oblique block-incomplete interleaving operation is performed for the resultant data. An error correction is then carried out using the second correction code for the interleaved data after second error correction, the data is outputted in an order of the first correction code series, thereby producing data in a sequence equivalent to the time series of the original data before the encoding operation thereof. When recording the data, the encoding process is achieved in a sequence opposite to the order above. However, when the technology is adopted for a data application in a computer or the like, since the error correction is effected according to a C
2
code for a particular data block to be reproduced, it is required to reproduce the entire data of the data blocks in a range of the interleaving process. If the code length is small, the period of time to reproduce data in the range is quite small and hence the influence of the data reproduction upon the data access time is in a negligible range. However, to decrease redundancy of the code, if the code length is increased, the elongated reproduction time will exert an adverse effect on the data access time. Furthermore, video data has a large volume also in the compressed state. Consequently, to record such video data on a disk having a restricted capacity, it is required to reduce redundancy of codes representing the video data. However, when the code length employed in code correction is elongated and hence the block unit in which the correction code is completed is increased to take a valve which is several times that of the sector (2048 bytes) used as the standard data unit in computers, the data recording and reproducing operations can be accomplished only in the block unit in which the correction code is completed. In addition, another problem arises even though error correction codes are added to complete in an error block. Resultantly, when writing data of one sector on a disk available for data recording and reproducing operations, it is necessary to write data of one block including the one-sector data and dummy data. In consequence, when the data read and write operations are carried out in a smaller unit (e.g., in the unit of one sector), there arises a problem that the recording capacity is increased and there appear a large number of unused areas on the disk.
In addition, when video and/or audio signals compressed in a data stream format including a 188-byte transport packet as described in the “New MPEG Text” are recorded on a CD-ROM employed as computer data recording media, since each sector of the CD-ROM includes, e.g., 2048 bytes and the basic data capacity of the other computer data recording media is similarly represented in the unit of a power of two, if the video and/or audio signals are recorded in all user areas to increase the recording efficiency, some transport packets will be distributively written in some mutually different sectors. This disadvantageously results in complexity of the data reproducing operation. On the other hand, to simplify the data processing, if a plurality of transport packets are written in one sector and the unused data area of the sector are regarded as an invalid area, there will arise a problem of decrease in the data recording efficiency.
The above problem related to the data access efficiency had the unused recording capacity in the disk available for recording and reproducing operations can be solved as follows. Data items inputted in a time series are equally subdivided into data blocks each including an identical number of data items. Appended data is then added to each data block to configure a SYNC block to which a synchronizing code is added so as to form one sector including c SYNC blocks (c is a natural number). There is configured a correction block including p sectors. The correction block is subdivided into C
1
and C
2
data blocks to which a first error correction code and a second error correction code are respectively added, thereby recording the data items inputted in a time series with the sequence thereof kept unchanged.
The above difficulty associated with inconsistency between the processing of video and audio signal and the data application can be solved by the following process. Using c main data portions of the SYNC blocks (c is a natural number), there is formed a sector unique to the media in which the appended data is conclusive in the sector unit. The sector capacity is set to a power of two and an integral multiple of the transport stream capacity is more than the sector capacity and is less than the total of the sector capacity and appended data of p blocks.
Additionally, information indicating a position of description of a sector address is added to each SYNC block and the sector address denoting a number assigned to a sector is added according to the position describing information, which facilitates reproduction of desi
Hirabayashi Masayuki
Nagai Yutaka
Nakamura Masafumi
Takeuchi Toshifumi
Baker Stephen M.
Crowell & Moring LLP
Hitachi , Ltd.
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