JP2864968B2 - Data arrangement method and recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an arrangement method of digital data, and more particularly, to a data arrangement method and a recording medium suitable for transmission and recording / reproduction of a band-compressed video signal and audio signal. .

[0002]

2. Description of the Related Art FIG. 2 shows an example of an apparatus for handling band-compressed video signals. First, from the encoding side, the input digital video signal is divided by the block dividing unit 10 into blocks of a form suitable for the subsequent orthogonal transform, for example, blocks of 8 × 8 pixels. The divided signal is supplied to the next orthogonal transform unit 12, where the signal is subjected to orthogonal transform, for example, DCT, for each divided block. Due to the statistical properties of the image, the signal after DCT concentrates energy on low frequency components.

Next, the signal after the orthogonal transformation is supplied to a quantization / variable-length coding unit 14, where the dynamic range of the signal and the data amount in a certain section after quantization and variable-length coding are determined. Quantization is performed adaptively based on the original,
Variable length coding and run length coding are performed, and the data amount is reduced. Further, after the synchronization / ID / error correction code adding unit 16 adds the synchronization signal, the ID signal, and the error correction code, data transmission or recording is performed.

[0004] Next, the decoding side will be described. Data transmitted or reproduced is subjected to a synchronization / ID separation / error correction section 18 where synchronization and ID signal separation and error correction are performed. In the variable-length code decoding / inverse quantization unit 20, processing of variable-length code decoding and inverse quantization opposite to that of the quantization / variable-length encoding unit 14 is performed. Further, the inverse orthogonal transform unit 22 performs an inverse orthogonal transform process opposite to the orthogonal transform unit 12, and the block combining unit 24 performs a block combining process opposite to the block dividing unit 10.

In this case, the unit of data to be subjected to compression processing in the quantization / variable-length coding unit 14 is a block divided by the block dividing unit 10 or a macro block in which some blocks are collected. The data amount after compression processing on such an encoded block depends on the data amount of the video signal, and the data amount has a different value for each encoded block. That is, even if the block before the compression process has a fixed data amount, the data amount after compression is not always constant.

Next, a case where such compressed data is transmitted or recorded / reproduced will be considered. In this case, in order to cope with a data error, the compressed data is divided into fixed amounts, and a synchronization signal, an ID signal, an error correction code and the like are added to the fixed amount of data. That is, the size of the synchronization block, which is a delimiter of data to which an error correction code or the like is added, is usually fixed.

As described above, the amount of data after compression is not always constant between encoded blocks, whereas transmission / recording / reproduction is performed in units of synchronous blocks having a constant data amount. Therefore, the size of the encoded block after compression usually does not match the size of the synchronous block.

FIG. 3 shows such a relationship. In the figure, (A) shows coding blocks F1 and F
2, F3,... (Reduced and displayed), and each block has the same data amount. When these data are compressed, for example, a compressed block G1 shown in FIG.
~ G5. In the illustrated example, the coding block F
The degree of compression decreases in the order of 1, F5 → F3 → F2 → F4. As described above, the data amount does not always match between the compression blocks G1 to G5.

FIG. 1C shows synchronous blocks S1 to S4.
It is shown. Each of the synchronization blocks S1 to S4 has a synchronization / ID signal SI at the beginning and an error correction code SP at the end.
There is. As described above, since the data amount of the synchronous block is constant, it does not always coincide with the compressed block. According to the illustrated example, the synchronous block S1 includes the entire compressed block G1 and a part of the compressed block G2. In the synchronous block S2, the rest of the compressed block G2, all of G3,
Part of G4 is included. The synchronization block S3 includes a part of the compression block G4. Synchronous block S
4 includes the rest of the compressed block G4 and G5.

Thus, the compressed blocks G1, G2,.
Are separated from the synchronization blocks S1, S2,...
They do not always match. Next, in many cases, it is not always possible to decode the compressed data from any position of the compression blocks G1, G2,... Which are coding units, and it is necessary to be able to decode correctly from the beginning in a unit. In most cases, it does not become a meaningful signal. Therefore, when data of one synchronous block is obtained, in order to recover the original data before compression from this data,
It is necessary to recognize which position of the synchronous block is the head of the compressed group of data.

If there is one or more points in a synchronous block where decoding of compressed data can be started,
If the start point is known, it is possible to decode the compressed data using only the data of the synchronous block. But,
If the decoding start point does not exist in a certain synchronous block, it is impossible to decode the compressed data only with the data of this synchronous block, or it does not make sense to decode it. That is, meaningful decoding becomes possible when a group of compressed data including a part existing in the preceding synchronization block is continuously obtained from the head.

Furthermore, it is not always possible to accurately obtain all data to be transmitted or recorded / reproduced, and a fixed position of an original image does not always reach a fixed position after data compression. For example, data that was at 1/10 from the beginning of the entire image in the original image does not always exist at 1/10 from the beginning of the entire image after data compression. Therefore, in order to accurately reproduce the original image, a group of variable-length codes can be decoded from the compressed data to indicate the position of the signal in the original image. Must be added at regular intervals together with the start position information.

For the reasons described above, a part of the synchronous block includes a pointer indicating a start point at which meaningful information can be decoded, and a variable-length coded block corresponds to any part of the entire screen. And a block address indicating whether to perform the operation. As a block address, a block number, a frame number, or the like may be used, or a resync, a block number, a frame number, or the like inserted at an appropriate number of decoding startable points may be used.

FIG. 4A shows an example of a synchronous block having the pointer and the block address. A synchronous block S10 shown in FIG.
, The whole of G21, and a part of G22.
Then, following the beginning of the sync · ID signal SI, a pointer indicating the head position of the compression block G21, the compressed block G
Control information SA each including 21 block addresses is added.

FIG. 1B shows an example of a synchronous block having a resync in addition to the pointer and the block address. As shown in FIG.
I is followed by the rest of the compressed block G20. At the head of the next compressed block G21, control information SB including a resync signal indicating that decoding is possible from that part and the block address of the compressed block G21 is added.

Since the data arrangement is as described above, if the synchronous blocks are continuously reproduced, data can be obtained continuously from the head portion. Decryption can be performed. If the synchronized blocks are not played back continuously, using information such as the pointer and resync described above,
Decoding is performed from a decoding start possible point in the obtained synchronous block. With such a method, it is possible to decode from the earliest possible point, regardless of whether or not the synchronous blocks are continuously obtained.

[0017]

By the way, in a coding block which is a group of data to be subjected to variable length coding, important data is often gathered in a certain range at the head. For example, when DCT is performed in the orthogonal transform unit 12 and so-called zigzag scanning is performed, DCT is performed.
The transform coefficients in the low frequency region including the coefficients are located at the head of the coding block. Specifically, FIG.
In the case of the synchronous block S1 of (C), important data is collected at the head E1 of the compressed block G1, and important data is collected at the head E2 of the compressed block G2. Similarly, the compressed block G
3, G4,..., Their leading portions E3, E
Important data are gathered in 4, ...

On the other hand, in the case of special reproduction (high-speed search) in a VTR, not all data of one synchronous block is reproduced continuously. The part where the probability of obtaining data most correctly in one synchronization block is the part immediately after the synchronization / ID signal SI. However, FIG.
As shown in (C), important data is not always arranged in that part. In other words, important data is not located in a portion where the probability of obtaining correct data is high. For this reason, there is an inconvenience that special reproduction cannot be performed satisfactorily.

The present invention focuses on these points.
It is an object of the present invention to provide a data arrangement method and a recording medium capable of obtaining a good restored image even when not all data of a synchronous block can be obtained.

[0020]

In order to achieve the above object, the present invention provides a method for arranging information-compressed data in a synchronous block having a fixed data amount, which is a delimiter of data including a synchronous signal and an error correction code. In the arrangement method, if there is a point in the synchronization block at which significant decoding of the compressed data can be started, the synchronization signal is followed by the synchronization signal.
That there is a point where the meaningful decoding can start
Flag, important data in the compressed data,
Necessary data are arranged in order, and if there is no point in the synchronization block where meaningful decoding of the compressed data can be started, the meaningful decoding is started following the synchronization signal.
A flag indicating that there is no starting point, the compression
Data is arranged in order .

[0021]

According to the present invention, important data in the compressed data is arranged after the synchronization signal of the synchronization block, followed by non-important data. Generally, the portion following the synchronization signal has a high probability of obtaining correct data. Therefore, by arranging important data in that portion, a high-quality reproduced image can be obtained, for example, when a high-speed search or the like is performed.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a data arrangement method and a recording medium according to the present invention will be described below in detail with reference to the accompanying drawings. Note that the same reference numerals are used for the same components as those of the above-described related art or components corresponding to the related art.

FIG. 1 shows a data array according to this embodiment. First, a case where a point where decoding can be started is included in a synchronous block will be described with reference to FIGS. FIG. 7A shows compressed blocks G30 to G33 to which the present embodiment is applied. Among these, GI30 to GI33 are data of important parts,
GN30 to GN33 are data of non-important parts other than important parts.

As shown in FIG. 2B, the synchronous block S30
Is provided with a synchronization / ID signal SI, followed by important data blocks GI. Then, the non-important data GN30 to GN33 of the compressed blocks G30 to G33 follow, and finally the error correction code SP is arranged.

Next, FIG. 3C shows details of the important data block GI. At the beginning of this GI, a control information SC including a flag (for example, one bit following the synchronization / ID signal SI) indicating that there is a decoding start point of meaningful information and a block address of the compressed block G31.
Are arranged. Then, following this, the important data GI31, GI of the compressed blocks G31, G32, G33
32, GI33 are arranged.

That is, important data GI31, GI32, and GI33 of the compressed blocks G31, G32, and G33 included from the beginning of the synchronous block S30 are synchronized.
It is arranged immediately after the ID signal SI, followed by other insignificant data GN30, GN31, GN32, G
N33 are arranged. Note that some of the important data GI30 and the non-important data GN30 of the compressed block G30 are included in a synchronization block before the synchronization block S30 (not shown).

Next, FIG. 1D shows a case where a point where decoding can be started is not included in the synchronous block.
This example is a synchronous block S31 following the synchronous block S30 shown in (B). According to this, the important data GI33 of the compressed block G33 is already in the synchronous block S
30 and thus only a part of the non-important data GN33. At the head of the non-important data GN33, control information SD including a flag indicating that there is no point at which decoding can be started is arranged.

Next, the operation of the above embodiment will be described. As described above, of all the data, a portion having a high probability of being correctly obtained is a portion following the synchronization / ID signal SI. According to the present embodiment, the important data block GI is arranged at a position following the synchronization / ID signal SI. For this reason, if the head of each synchronous block is obtained, the important data block GI can be obtained with a very high probability. Since the important data block GI includes the important data of each compressed block as described above, it can be obtained. Specifically, in the case of DCT, D
When the C coefficient, the first order coefficient, and the second order coefficient are sub-band divisions, the low-frequency components are obtained.

On the other hand, when performing special reproduction such as a high-speed search, there is a case where the whole of the synchronous block cannot be reproduced from the beginning to the end. Also, in the case of this special reproduction, even if not all the data of the compressed block subjected to the variable length coding is obtained, only a certain range of important data is obtained, which greatly contributes to the reproduced image. Therefore, according to the present embodiment, an image of sufficient quality can be reproduced as an image at the time of high-speed search, and the quality of an image at high-speed reproduction can be improved.

The present invention is not limited to the above-described embodiment, but includes, for example, the following. (1) At the end of the important data block GI in the above embodiment, a code indicating the end of the important data block may be arranged. In this way, there is an advantage that the GI portion can be satisfactorily determined even when there is a large number of important portions in one synchronous block. (2) In the above-described embodiment, even when there are a plurality of points at which decoding of a group of meaningful data can be started, only a flag indicating that fact is set. It may be arranged following the flag.
Also in this case, similarly, there is an advantage that the important part can be determined well.

(3) Further, after the data of the important part is further extracted and arranged, a correction code relating only to the data of the important part different from the correction code SP of the synchronous block is added, so that the important part can be more stably detected. Data can be obtained. (4) In the above-described embodiment, for example, in the case of DCT, the DC coefficient, the first-order coefficient, and the second-order coefficient are regarded as important data, but these may be selected as needed. For example, a simple method such as setting the range of the first fixed number of bits in the data of the compressed block as important data may be used. (5) Various media such as a magnetic tape and an optical disk can be applied as a medium for recording the data of the arrangement in the above embodiment.

[0032]

As described above, according to the data arranging method and the recording medium of the present invention, the important part of the compressed data is arranged at the position following the synchronizing signal having a high probability of obtaining the correct data. Even if all the data of the synchronous block cannot be obtained, a good restored image can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing one embodiment of a data arrangement method according to the present invention.

FIG. 2 is a block diagram illustrating an example of an apparatus that handles compressed data.

FIG. 3 is an explanatory diagram showing a conventional data arrangement method.

FIG. 4 is an explanatory diagram showing a method of arranging control information.

[Explanation of symbols]

10: block division unit, 12: orthogonal transformation unit, 14: quantization / variable length coding unit, 16: synchronization / ID / error correction code adding unit, 18: synchronization / ID separation / error correction unit, 20: variable length Code decoding / inverse quantization unit, 22: inverse orthogonal transform unit, 2
4: Block combining unit, G30 to G33: Compressed block,
GI30 to GI33: important block, GN30 to GN3
3: Unimportant block, GI: Important data block, S3
0, S31: Synchronous block, SC, SD: Control information, S
I: Synchronization / ID signal, SP: Error correction code.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H04N 5 / 92,7 / 24 H04L 1/00 G11B 20/12

Claims (1)

(57) [Claims] 1. A data arranging method for arranging information-compressed data in a synchronous block having a fixed data amount, which is a delimiter of data including a synchronous signal and an error correction code, wherein: Some decryption
If there is capable of starting point and is continued on the synchronization signal
That there is a point where the meaningful decoding can be started.
, Important data in the compressed data,
Insignificant data is arranged in order, and meaningful decoding of the compressed data is performed during the synchronization block.
A case where start possible point does not exist, the synchronization signal
Then there is no point where the meaningful decoding can be started.
Flag indicating that no data sequence wherein the this <br/> arranging the compressed data sequentially.