JP2656899B2 - Digital video data processing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for processing video data in a home digital VTR for compressing digital video data using a RAM, and more particularly to a high-speed reproduction and an error concealment. )
And a method for shuffling data for the purpose of the present invention.

[0002]

2. Description of the Related Art A digital VTR for recording and reproducing video data in a digital manner has an advantage that it can provide various functions as compared with a conventional analog VTR, but the amount of data to be processed is large. Face a burgeoning problem. In this digital VTR, in order to perform recording and playback using a current analog VTR video tape, the amount of data recorded on the tape must be reduced. For this reason, video data is compressed. .

In the process of recording the compressed video data on a recording medium, reading the data from the recording medium, and reproducing the video, the error occurrence rate is higher than the recording and reproducing process of the data that has not been compressed. Become. An error correction code is added to the compressed data to compensate for this disadvantage.
It is already known to add an (error correction code) so that errors generated can be calibrated.

FIG. 4 schematically shows only the configuration of a system related to recording in a system for processing video data in accordance with such a method. Before explaining this, a method of calibrating an error will be described. Will be briefly described first. In a system that records compressed video data on a medium and then reproduces the video, as a typical method for protecting data from random errors and burst errors generated during the data recording or reproduction process, A method using two error correction codes is illustrated in FIG.

An inner code (inner code) which is one of error correction codes is additional information for detecting and correcting a random error, and an outer code (outer code) which is another one is a burst code. This is additional information for error detection and correction. Such a data structure in which additional information is superimposed on pure video information is called a product code block structure. Such a product code block structure enables an error to be corrected at the time of reproduction when an error occurs in a data recording process.

A conventional video data processing system will be described with reference to FIG. An analog video signal corresponding to one frame is converted to an AD converter (Analog to Digital Converte).
r) 10, for example, 720 pixels × 480
The digital data having a structure corresponding to the line image (see FIG. 6) is sampled and provided to the data compression unit 20. The data compression unit 20 is the 16 pi shown in the example in FIG.
Data (usually 16 × 16 bytes) related to a unit pixel block composed of xel × 16 lines is compressed to 32-byte data.

FIG. 7 schematically shows the structure of the data compression section 20. The data compression process will be described more specifically with reference to FIG. The data compression unit 20 includes a frame memory 21, a control unit 22, and a compression algorithm processing unit 23. The frame memory 21 stores digital video data for one frame provided from the AD converter 10 for a predetermined time, and the control unit 22 performs various control processes required for the compression process, and performs compression. Algorithm processing unit 23
Is the frame memory 2 according to the instruction of the control unit 22.
1 to a unit pixel block (16 pixels × 16 li)
ne) (usually 16 × 1
6 bytes), and then compresses the data into 32-byte data according to a predetermined compression algorithm and outputs the data.

The data compressed as described above is sequentially provided to the memory 30 and stored. The unit block compressed data having a size of 32 bytes sequentially provided from the data compressing unit 20 is stored in the memory 30 as shown in FIG.
32 bytes are recorded in the horizontal (row) direction, and 45 bytes are recorded in the vertical (column) direction.

Therefore, the memory 30 must have a storage capacity of at least 32 bytes × 45 × 30 or more. The reason is 16 × 16 corresponding to one frame.
The number of unit pixel blocks (see FIG. 6) is 1350 (= 3
(0 × 45). Therefore, if data having a size of 32 bytes × 45 (see FIG. 8) is regarded as one block, the memory 30 has 30 blocks. That is, one frame of data is composed of 30 data blocks (32 bytes × 45).

As described above, the data recorded in the memory 30 is provided to the first encoding unit 40 for reading 45 bytes at a time in the vertical direction and adding an external code. The encoding unit 40 provides the memory 50 with the 4-byte external code additional information superimposed on the 45-byte data read from the memory 30 as shown in FIG.

In a VTR system for compressing video data, adding an error correction code to the video data, and recording and reproducing the data on a recording medium, the VTR system is used for high-speed reproduction or for preventing pixel reduction due to an error that has occurred. Error Concealment
shuffling of data to perform operations such as cealment, etc. (here, shuffling does not record data sequentially, but a high-speed reproduction algorithm or an error concealment algorithm, etc., to improve image quality) Recording data in the format specified by
Is performed.

The above-mentioned memory 50 is for performing such shuffling. In the second memory 50, the 49-byte data to which the external code additional information (see FIG. 9) is added by the first
It is stored twice to form one data block. The data provided from the encoding unit 40 is composed of 49 × 32 data blocks formed in this way, for a total of 3 data blocks.
Repeat the same method until there are no more
Stored in

FIG. 10 is a block diagram showing the configuration of the 1 provided by the encoding unit 40.
This shows a state in which data for a frame is stored in the memory 50. The data stored in this way is 1
EB1, EB1, 3EB1, ..., 30EB1, 1EB
2,2EB2, ..., 30EB2,1EB3, ..., 30E
B45, 1P1, 2P1, 2P2, ..., 30P1, 1P
2,..., 30P4 and read in the second encoding unit 60
Provided to The second encoding unit 60 adds the 4-byte internal code additional information to the 32-byte data provided from the memory 50 as shown in FIG. 11, and then records the data on the tape 70 in a predetermined format. At this time, the data of one frame processed by the second encoding unit 60 is as shown in FIG.
, And these are divided into six tracks and recorded on the tape 70 as shown in FIG.

[0014]

Conventionally, data compression and shuffling are performed separately, so that at least 36 data compression and shuffling are performed separately.
Memory 50 having a storage capacity of × 49 × 30 bytes or more
However, there is a problem that a huge cost is required for the configuration of the memory.

It is an object of the present invention to provide a data processing method capable of significantly reducing the amount of memory required in configuring a system in order to make up for such an economic disadvantage.

[0016]

In order to achieve the above object, a data processing method according to the present invention uses a memory to record an analog video signal in a digital system on a recording medium and reproduce the video. In a method of processing a signal digitally, a first plurality (eg, 480)
Each line is composed of a second plurality (for example, 720) of image data. The analog video signal for one frame is converted into digital video data, and the first memory for compression processing is formed. A digital image data stored in the first memory 21 by a third plurality (16 bytes) of pixel data in a line direction by a fourth plurality (for example, 16).
For each data of the unit pixel block (= 16 × 16 bytes) corresponding to the line, the data is adjacent to the line vertically (downward in FIG. 6) and sequentially in the line direction (left to right in FIG. 6). A second stage in which the shuffling process is repeated and read, and the read data of each unit pixel block is compressed to a predetermined information amount (32 bytes) to obtain a unit block (for example, 1 EB1). A third step of storing a unit block for one frame in the second memory 30; reading compressed data of a single unit block from the second memory 30; Each of the data blocks (for example, 49 × 32 bytes in FIG. 2) is created by adding external code additional information (for example, 1P1 to 1P4) for the third memory 50.
And sequentially reading the data blocks stored in the third memory 50 in the line direction (from left to right in FIG. 2) and adding internal code additional information for error correction. And a sixth step of recording the product code block on a recording medium, wherein the fourth, fifth, and sixth steps are repeatedly performed on data for one frame. It is characterized by doing.

Further, according to the present invention, each formed product code block is recorded on each track of the recording medium, and
One frame of data is recorded on the same number of tracks (for example, 6) as product code blocks.

[0018]

According to the present invention, when digitally compressing video information,
In a system using a memory, when data is recorded and reproduced, especially when reproducing at high speed or error concealment (Erro
When an operation such as (r Concealment) is performed, data shuffling performed to obtain good image quality is performed using the memory 21 of the data compression unit without using a separate memory.

[0019]

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now be described in detail with reference to the attached drawings. The hardware configuration of a system for realizing the present invention is the same as the conventional configuration (see FIG. 4) except for the following two items. The difference between the prior art and the present invention in the configuration is that the configuration of the data compression unit 20 is different.

As described above, the conventional data compression section 20 has the configuration as shown in FIG. 7, but the configuration of the data compression section according to the present invention is as shown in FIG. Looking closely at the configuration of the compression unit according to the present invention, it is the same as the conventional configuration except that the second control unit 22 'is added to the conventional compression unit (FIG. 7). The second control unit 22 'is a data compression unit 2
0 performs a function of causing shuffling to be performed. That is, the control unit 22 'controls the writing / reading operation of the memory so that data shuffling for improving image quality is performed using the frame memory 21 used only for data compression in the related art.

Another difference in the configuration according to the present invention is as follows.
That is, the memory 50 has a storage capacity reduced to several tenths compared to the conventional technology. A description will now be given of how the data processing of the present invention, which can significantly reduce the capacity of the memory 50, is performed.

The analog video data is converted to digital data by the AD converter 10 and provided to the data compression unit 20. As described above, one frame of data provided from the AD converter 10 is stored in the frame memory 21 of FIG. 1 in a structure as shown in FIG. The data stored in the frame memory 21 is controlled by the second control unit 22 ', and 1EB1, 2EB1, 3EB1,.
30EB1, 1EB2, 2EB2, ..., 29EB45,
The data is read in the order of 30EB45 and provided to the compression algorithm processing unit 23.

The compression algorithm processing unit 23 compresses the unit block data (for example, 1 EB1) read from the memory 21 according to an instruction from the first control unit 22 into 32-byte data, and then stores the data in the memory 30 in order. At this time, the storage structure of the data stored in the memory 30 is the additional information (1P1, 1P2,..., 30P4) in FIG.
The part from which is removed has the same structure as the conventional one. The first encoding unit 40 converts data from the first block into data of 45 bytes in the vertical direction (unit block) out of data of a total of 30 blocks stored in the memory 30 with the above structure.
The data is read out at a time, and 4-byte additional information (external code) is added as shown in FIG. Therefore, the memory 50 need only have a storage capacity capable of storing 49 × 32 bytes (data blocks) necessary to form the minimum product code block structure.

The second encoding unit 60 sequentially reads out the data of 49.times.32 bytes stored in the memory 50 by 32 bytes in the horizontal direction, and adds 4 bytes of additional information (internal code) as shown in FIG. Are overlapped to form a product code block, and the tape 70 is formatted in a format as shown in FIG.
To record. Next, by repeating the above processing for the second block, the third block,..., The 30th block stored in the memory 30, 1
The data processing for the frame is completed.

When FIG. 13 and FIG. 3 are compared with each other, it can be seen that the processing of the video data according to the present invention can obtain the same result as the prior art. That is, one frame of data is divided into six tracks and recorded on the tape.

[0026]

According to the present invention, since the data shuffling for improving the image quality is performed in the data compression process, the storage capacity of the third memory 50 for the internal coding is reduced to the product code block. Can be reduced to the minimum data amount, which is a data block used for the operation. Therefore, the storage capacity of the third memory 50 for internal coding is reduced to 1 /
It can be reduced to about 30 and has a very great economic advantage.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a data compression unit according to the present invention.

FIG. 2 is a diagram illustrating a storage structure of data stored in a memory 50 according to the present invention.

FIG. 3 is a diagram showing a tape format according to the present invention.

FIG. 4 is a block diagram schematically illustrating a configuration of a system for compressing and shuffling video data in a general digital VTR.

FIG. 5 shows a product code block (produc
FIG. 4 is a diagram illustrating a structure of a t code block).

FIG. 6 is a diagram showing a sampling structure of digital data corresponding to video data of one frame.

FIG. 7 is a diagram illustrating a configuration of a data compression unit in FIG. 4;

FIG. 8 is a diagram showing a data structure in a case where data of a size of 16 × 720 composed of 45 unit blocks (16 × 16 bytes) in FIG. 6 is compressed.

FIG. 9 is a diagram showing a state in which external code additional information for error correction is added in the column direction in FIG. 8;

FIG. 10 is a diagram showing a structure in which compressed data is stored in a memory 50 for shuffling in FIG. 4;

FIG. 11 is a diagram showing a state in which internal code additional information for error correction is added to data in a memory 50 in a row direction.

FIG. 12 is a diagram showing a product code block for one frame.

FIG. 13 is a diagram showing a tape format according to the related art.

[Explanation of symbols]

 Reference Signs List 10 AD converter 20 Data compression unit 30, 50 Memory 40, 60 Error correction encoding unit 70 Video tape

Claims (2)

(57) [Claims] 1. A method of processing an image signal by a digital method using a memory to record an analog image signal on a recording medium in a digital method and reproduce the image, wherein one frame is constituted by the first plurality of lines. Each line is composed of a second plurality of image data, and a first step of converting the analog video signal for one frame into digital video data and sequentially storing the digital video data in the first memory 21 for compression processing; 1 digital video data stored in the memory 21
The shuffling process is repeated by reading the unit pixel block data of the third plurality of pixel data in the line direction and the unit pixel block of the fourth plurality of lines in the line direction and sequentially adjacent to the line direction. A second step of outputting, and compressing the read data of each unit pixel block to a predetermined information amount to obtain a unit block, and
A third step of storing the unit blocks of the frame in the second memory 30; reading out the compressed data of a single unit block from the second memory 30; To create each data block by adding the external code additional information of
And the steps of: storing the data block stored in the third memory 50;
A fifth step of sequentially reading in the line direction and adding internal code additional information for error correction to create a product code block; and a sixth step of recording the product code block on a recording medium. A digital video data processing method, wherein the fifth and sixth steps are repeatedly performed on data of one frame. 2. The product code block formed is recorded on each track of the recording medium, and data for one frame is recorded on the same number of tracks as the product code block. The digital video data processing method according to the above.