JPH0828858B2 - Multi-channel recording digital VTR - Google Patents

Description

FIELD OF THE INVENTION The present invention relates to digital VTRs, and more particularly to multi-channel recording digital VTRs having a band compressor.

2. Description of the Related Art When transmitting or recording / reproducing information, digital processing has been studied and put into practical use in order to ensure the quality of information and improve the accuracy of processing. This is also the case in the field of handling video signals, and the digital transmission, processing, and recording / reproducing of video signals are being actively studied.

Therefore, a conventional example of a digital VTR, which is one of the digital recording / reproducing apparatuses for video signals, is shown below with reference to the drawings.

FIG. 3 is a block diagram showing a conventional example of a digital VTR. In the figure, 1 is an input terminal, 2 is an analog-digital converter (hereinafter referred to as "A / D", and is also written as "A / D" in the drawing), 3 is a divider, and 5 and 8 are Recording side processor, 6
Reference numerals 9 and 9 are magnetic heads, and 10 is a magnetic tape. The video signal to be recorded is applied to the A / D 2 via the input terminal 1 and converted into digital data. The output of A / D2 is 2 in the divider 3.
It is divided into series. The two divided data strings are applied to the recording side processors 5 and 8, respectively, subjected to processing such as error correction coding and modulation, and then recorded on the magnetic tape 10 via the magnetic heads 6 and 9. Will be. In FIG. 3, only the recording side is shown, and the reproducing side, which executes almost the opposite process to the recording side, is omitted.

By the way, the divider 3 plays an important role in reducing the speed of the data recorded on each track and in improving the performance when correcting the error pixels remaining during reproduction. FIG. 4 is a pixel diagram for explaining the operation of the divider 3. In the figure, 11 is an nth line, 12 is an (n + 1) th line, and 13 to 24 are pixels. The video signal applied to the A / D 2 via the input terminal 1 is sampled by the A / D 2 and converted into a PCM value for each pixel 13-24. There are various possible methods of division by the divider 3,
For example, a method of allocating each pixel in each line and inverting the phase of each line will be described as an example. In this case, the pixels 13, 15, 17 ... Of the nth line 11 and the pixels 20, 22, 24 ... Of the (n + 1) th line 12 are applied to the recording side processor 5, Pixels 14, 16, 18 ... And (n + 1)
The pixels 19, 21, 23, ... Of the 12th line 12 are the recording side processor 8
Will be applied to.

However, FIG. 5 is a diagram showing a tape pattern.
FIG. 5 shows a tape pattern when helical scan recording is performed. In FIG. 5, 28 is a magnetic tape and 29 and 30 are tracks. The magnetic head 6 traces on the track 29, and the magnetic head 9 traces on the track 30. Therefore, the information corresponding to the pixels 13,15,17,20,22,24, ... in FIG. 4 is recorded on the track 29 on the pixels 14,16,18,19,21,23 ,.
The information corresponding to ... is recorded on track 30 respectively, and 2
A channel recording is made.

Problems to be solved by the invention By the way, it is possible to realize a high-performance VTR with almost no deterioration in image quality by digitizing and recording / reproducing a video signal, but recording on a magnetic tape. There is a tendency that the frequency bandwidth of the signal is extremely increased. This causes a problem that the tape consumption amount increases. As one measure against this, there is a band compression technique. The band compression technique is a technique for reducing the amount of data to be transmitted (or recorded) while avoiding deterioration of image quality as much as possible, and generally uses image correlation. Predictive coding (DPCM) and orthogonal transform are typical methods.

Consider the case of adopting the orthogonal transform method as band compression in a digital VTR. The orthogonal transformation also utilizes the correlation of images as described above, and the screen is divided into a plurality of small blocks, and the orthogonal transformation is applied to each block. If there is a strong correlation within this block, the energy of each sequence will be biased depending on the sequence as a result of orthogonal transformation. By utilizing this, the image quality deterioration can be avoided as much as possible and the data amount can be reduced.

On the other hand, when the division as shown in FIG. 4 is performed as a divider for reducing the frequency bandwidth of the information recorded on each track and for enabling effective modification during reproduction, the following problems occur. .

That is, assuming that the orthogonal transformers are respectively inserted between the divider 3 for performing division as shown in FIG. 4 and the recording side processors 5 and 8, it is assumed that the pixel 13 is applied to the orthogonal transformer. 1
5,17,20,22,24, ... Or the values of pixels 14,16,18,19,21,23 ,. Generally, the correlation of images tends to decrease as the pixel spacing increases (specifically, the situation is different between the composite signal and the component signal, but here, a component signal or a black and white signal is assumed to simplify the story. ), The performance of the orthogonal transformer as a compressor will be greatly reduced.

On the other hand, when an orthogonal transformer is inserted between the A / D 2 and the divider 3, the data after the orthogonal transformation does not correspond to the input pixels one-to-one, but the data after the orthogonal transformation is 1 This shows all pixels converted with all data for a block. If the divider 3 executes a division that ignores this block, an error during playback will exceed the block, and the error correction performance will be improved. Will be deteriorated.

In view of the above points, the present invention has an object to provide a multi-channel recording digital VTR capable of band compression with high efficiency and high image quality.

Means for Solving the Problems The present invention is directed to a band compressor configured by block compression coding such as orthogonal transformation, and is installed before or after the band compressor, and the data is divided into a plurality of sequences in units of the above blocks. It is provided with a divider for dividing, and the information corresponding to the plurality of series of data is recorded on different tracks respectively.

Operation With this configuration, the data of the pixel block composed of pixels that are close to each other is always applied to the block compression encoder such as the orthogonal transform, which enables highly efficient band compression. To do. On the other hand, when performing multi-channel recording, the information in the same block is recorded in the same track in the unit, so that it is possible to maintain a high retouching performance during reproduction.

EXAMPLES Examples of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention.
In the figure, 1 is an input terminal, 2 is an A / D, 3 is a divider,
4 and 7 are band compressors, 5 and 8 are recording side processors, 6 and 9 are magnetic heads, and 10 is a magnetic tape. Except for the band compressors 4 and 7, they are the same as those in FIG. 3, and detailed description thereof will be omitted. The outputs of the divider 3 are applied to the band compressors 4 and 7, respectively, to reduce the amount of data, and then introduced to the recording side processors 5 and 8.

By the way, the band compressors 4 and 7 perform block compression coding, and here, orthogonal transform is assumed. As described above, the orthogonal transform is to divide the image quality into a plurality of small blocks and perform the orthogonal transform within each block. Here, in order to simplify the description, it is assumed that the block is composed of two pixels adjacent in the horizontal direction and two pixels adjacent in the vertical direction (2 × 2), that is, a total of four pixels.

Next, further description will be given together with the pixel diagram shown in FIG. In FIG. 2, 11 is the nth line, 12 (n +
1) th line, 13 to 24 are pixels, and 25 to 27 are blocks. 11 to 24 are the same as 11 to 24 in FIG. 4, and detailed description thereof will be omitted. Band compressors 4 and 7 in FIG.
Is assumed to be a quadratic orthogonal transformer having horizontal 2 pixels and vertical 2 pixels, and 25 to 27 are blocks thereof. The pixels sampled and digitized by the A / D 2 are divided into blocks by the divider 3. That is, pixels 13, 14, 19 and 20 go to band compressor 4, pixels 15, 16, 21 and 22 go to band compressor 7,
Pixels 17, 18, 23 and 24 are divided into band compressor 4 ... Eventually, blocks 25 and 27 will be applied to band compressor 4 and block 26 to band compressor 7. Each block 25 to 27 is composed of four adjacent pixels and is applied to the band compressors 4 and 7 in units of these blocks.
Although the pixels are divided into two series, they are input to the compressors 4 and 7 as pixel blocks having extremely high correlation, so that high efficiency and high quality compression can be realized.

On the other hand, since the division is executed in units of blocks 25, 26, 27, ... Of FIG. 2, one block of data is always recorded on the magnetic tape 10 as a unit. Therefore, even if an error remains during reproduction, the image deterioration caused by the error is basically suppressed within one block. Therefore, there is a high possibility that the adjacent pixel (or adjacent block) is correctly reproduced, and the quality of error correction is also improved.

By the way, in the embodiment of the present invention, the orthogonal transform method is taken as an example of the block compression encoding, but in short, it may be the block compression encoding which divides an image into a plurality of small blocks and performs band compression in each block. For example, the present invention can be applied and is not limited to orthogonal transform. Of course, the block is not limited to the 4th order of 2 pixels in the vertical and horizontal directions as shown in FIG.

Further, in FIG. 1, two-channel recording is taken as an example for simplification of description, but the present invention is applicable to any number of channels, not limited to two channels.

Further, the divider 3 may be before or after the band compression, and the point is that the division may be performed in block units. In addition, the signals handled are not limited to black-and-white signals and component signals, and VTRs other than helical scan can be applied.

EFFECTS OF THE INVENTION As is clear from the above description, application of the present invention enables highly efficient high-quality band compression in a multi-channel recording digital VTR, reduces tape consumption, and improves error correction quality. It is possible to raise it.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a pixel diagram for explaining FIG. 1, and FIG. 3 is a digital diagram.
FIG. 4 is a block diagram showing a conventional example of a VTR, FIG. 4 is a pixel diagram for explaining FIG. 3, and FIG. 5 is a tape pattern diagram for explaining FIG. 3 ... Divider, 4, 7 ... Band compressor.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Tatsuro Shigesato 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-60-54539 (JP, A) JP-A-60-22886 (JP, A)

Claims (1)

[Claims] 1. A band compressor for dividing video signal information into a plurality of blocks, each block comprising adjacent pixels, and a block compressor provided before or after the band compressor. It has a divider that divides the data into a plurality of series in block units in compression encoding, and records each information sequence corresponding to the data of the plurality of series on different tracks. Multi-channel recording digital VTR.