Dynamic magnetic information storage or retrieval – General processing of a digital signal – Data in specific format
Reexamination Certificate
1998-08-11
2001-02-20
Kim, W. Chris (Department: 2651)
Dynamic magnetic information storage or retrieval
General processing of a digital signal
Data in specific format
C369S059160
Reexamination Certificate
active
06191903
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a recording medium, data transmission apparatus, data receiver, and optical disk unit, and is particularly applicable to a system which transmits video data and other data or records them on an optical disk in a predetermined block unit. This invention permits each frame to be easily and correctly located by providing unique combinations for at least contiguous synchronization patterns or contiguous synchronization patterns with one synchronization pattern interleaved therebetween.
2. Description of Related Art
In a conventional optical disk unit, on the basis of synchronization patterns inserted between contiguous pieces of data, a clock out of synchronization is corrected so that the data can be correctly reproduced. Further, the optical disk unit is constructed so that the use of a combination of a plurality of types of synchronization patterns, which are fewer than the number of frames constituting one sector, helps to effectively avoid an increase in redundancy due to the synchronization patterns as well as to locate the frames on the basis of the result of reproducing the synchronization patterns.
Namely, a DVD (Digital Versatile Disc), an optical disk unit of this sort, for example, transforms video signals and audio signals successively inputted into digital signals to produce digital video signals and digital audio signals. Further, the optical disk unit subjects the digital video signals to data compression in accordance with a format defined in MPEG (Moving Picture Experts Group) and multiplexes them with the digital audio signals similarly subjected to data compression (hereinafter, the multiplexed data is called AV data), and then performs a scramble process.
Further, as shown in
FIG. 15
, after adding identification data indicating an address and other data to the AV data, the optical disk unit splits the AV data in a predetermined block unit, adds an error correction code, preamble, postamble, etc. to each block, generating one cluster of data from the data of these blocks. By this process, the optical disk unit records and reproduces AV data on and from an optical disk in units of error correction blocks consisting of one cluster. In
FIG. 15
, the number of frames is represented by the symbol Fr.
Further, the optical disk unit forms 16 sectors of data from one cluster of data, and as shown in
FIG. 16
, forms 26 sync frames of data from data of each sector. Each sync frame is formed with synchronization patterns SY
0
to SY
7
assigned to AV data or other data formed in units of 91 bytes.
In these DVDs, eight types of synchronization patterns SY
0
to SY
7
(hereinafter, referred to as first to eighth synchronization patterns) are successively assigned to the sync frames in a predetermined order. Namely, each sector begins with the first synchronization pattern SY
0
to indicate the start of the sector, followed by the first sync frame consisting of ID data and other data. In the sector, the sixth synchronization pattern SY
5
follows to form a sync frame with AV data and other data.
Further, the sector has the remaining 24 frames divided into three blocks, which have even frames assigned sixth, seventh, and eight synchronization patterns SY
5
, SY
6
, and SY
7
, respectively. The odd frames of each block are assigned second to fifth synchronization patterns SY
1
, SY
2
, SY
3
, and SY
4
in this order.
With this arrangement, in a DVD, the synchronization patterns SY
5
, SY
6
, and SY
7
of even frames help to distinguish among the first block, middle block, and last block of each sector, and the synchronization patterns SY
0
to SY
4
of odd frames help to identify a frame in each block, thereby making it possible to restore the data to be successively reproduced.
By this arrangement, in an optical disk unit of this sort, there are cases where data is reproduced from middle frames of a sector by a seek operation. Also, middle frames may not be correctly reproduced because of the occurrence of an out-of-synchronization condition due to a damage. To provide against such a circumstance, when data is to be reproduced from middle frames of a sector based on the result of reproducing synchronization patterns, the optical disk unit is constructed so that reproduction results can be outputted by correctly placing the data of frames successively reproduced even when the middle frames cannot be correctly reproduced.
Meanwhile, when the synchronization patterns SY
0
to SY
7
are assigned in this way, as shown by the arrow A, when data of a third frame of each sector is reproduced from data of a second frame, the sixth and second synchronization patterns SY
5
and SY
1
are contiguous. Also, as shown by the arrow B, when data of an eleventh frame is reproduced from data of a tenth frame, similarly, the sixth and second patterns SY
5
and SY
1
are contiguous.
Accordingly, in an arrangement of the synchronization patterns, when the sixth and second synchronization patterns SY
5
and SY
1
are contiguous, it is difficult to locate a frame from the sixth and second synchronization patterns SY
5
and SY
1
alone; eventually, it is difficult to correctly determine a frame until a synchronization pattern which follows is detected. Namely, it takes a long time to correctly locate a frame.
When the synchronization pattern of an odd frame of synchronization patterns that are contiguous in a stream of even, odd, and even frames could not be correctly reproduced, it can be determined which of the first, middle, and last blocks of a sector the frame exists in, but it is difficult to determine the specific location of the frame within the block; also in this case, it is difficult to correctly identify the frame until a synchronization pattern which follows is detected.
Namely, for example, if the second synchronization pattern SY
1
cannot be correctly reproduced when the sixth, second, and sixth synchronization patterns SY
5
, SY
1
, and SY
5
are contiguous, in
FIG. 16
, it is difficult to locate a specific sector in one of the following cases: when the sixth, second, and sixth synchronization patterns SY
5
, SY
1
, and SY
5
are contiguous, when the sixth, third, and sixth synchronization patterns SY
5
, SY
2
, and SY
5
are contiguous, when the sixth, fourth, and sixth synchronization patterns SY
5
, SY
3
, and SY
5
are contiguous, and when the sixth, fifth, and sixth synchronization patterns SY
5
, SY
4
, and SY
5
are contiguous.
Even when three contiguous synchronization patterns can be detected, if any of them is incorrectly detected, eventually, no correct frame can be located; also in this case, it is difficult to correctly identify the frame until a synchronization pattern which follows is detected.
In this case, one possible method is to assign a unique synchronization pattern to each sync frame, but this requires that the bit length of the synchronization pattern be longer accordingly, posing a problem in that redundancy is increased because of the synchronization patterns.
SUMMARY OF THE INVENTION
This invention has been made in consideration of the above-mentioned problems, and it is an object of this invention to offer a recording medium, data transmission apparatus, data receiver, and optical disk unit which permit frames to be easily and correctly located.
According to the invention to solve the above-mentioned problems, in a recording medium, data transmission apparatus, and optical disk unit, identification patterns that are fewer in type than the number of frames constituting one block are successively assigned to frames in such a manner that, when contiguous frames are arbitrarily selected in each block, a combination of identification patterns assigned to the contiguous frames is different from combinations of identification patterns assigned to any other contiguous frames in the block.
At this time, the identification patterns are assigned in such a manner that, when three contiguous frames are arbitrarily selected, a combination of the identification patterns assigned to the
Fujimoto Kensuke
Mawatari Hideki
Shigenobu Masahiro
Kim W. Chris
Limbach & Limbach LLP
Sony Corporation
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