JP2953704B2 - Digital video signal recording and reproducing method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital video signal recording method and a reproducing method for recording or reproducing a digital video signal such as a digital VTR with high efficiency coding on a medium.

2. Description of the Related Art As a conventional digital video signal recording and reproducing apparatus, there is, for example, a rotary head type digital VTR which directly records pixel data without performing high-efficiency encoding (band compression).

FIG. 4 is a block diagram of this conventional digital video signal recording and reproducing apparatus, wherein 1 is a first error correction encoder, 2 is a shuffling memory, 3 is a second error correction encoder, Is a magnetic tape, 5 is a second error corrector, 6 is a deshuffling memory, and 7 is a first error corrector.

In the conventional digital video signal recording and reproducing apparatus configured as described above, at the time of recording, the digital video signal is input to the first error correction encoder 1, where an error correction code is added and the digital video signal is stored in the shuffling memory 2. Written. In the reading of the shuffling memory 2, the order of the digital video signals is read out by changing the order in units of pixels, and the read out signals are based on the pixel order rearranged by the second error correction encoder 3. The error correction code is added again and recorded on the magnetic tape 4.
At the time of reproduction, the detected signal is subjected to error correction by the second error corrector 5 and written to the deshuffling memory 6. The deshuffling memory 6 performs a pixel rearrangement reverse to the pixel rearrangement in the shuffling memory 2 at the time of recording, and restores the pixel order. Thereafter, the reproduced signal is again subjected to error correction by the first error corrector 7, and is output as a digital video signal.

The reason why the pixel order is rearranged by shuffling is not only the problem of error correction efficiency, but also to make it easy to view a high-speed playback image of a digital VTR. digital
In high-speed reproduction of a VTR, the head of the rotating drum crosses the track recorded on the tape diagonally as shown in FIG. For this reason, the detectable signal is located at discrete locations with respect to the recording pattern. digital
The VTR composes a high-speed playback screen using only detected pixels, but when shuffling is applied, the detected pixels are scattered throughout the screen, which has the effect of preventing unnatural cuts on the screen. .

However, when considering a digital VTR using high-efficiency coding, pixels on the screen are divided into rectangles as shown in FIG. 3, and the rectangular units are variable after orthogonal transformation. The amount of information is compressed by a method of performing long coding, collecting a fixed number of pieces of information in rectangular units, and forming fixed-length blocks. However, when digital recording is performed by shuffling the rectangular unit, the image at the time of high-speed reproduction becomes mosaic-like, which is very difficult to see, unlike shuffling in pixel units. However, if video information in rectangular units is recorded in the same order without shuffling, the rectangular units in each fixed-length block will be adjacent to each other on the screen, resulting in a bias in the amount of information and high efficiency. There was a problem that the coding efficiency was not improved.

SUMMARY OF THE INVENTION In view of the foregoing, it is an object of the present invention to provide a digital video signal recording and reproducing method that achieves both easy viewing of video during high-speed reproduction and high efficiency coding efficiency.

Means for Solving the Problems The present invention divides a screen into a predetermined number of regions, further divides the region into rectangular units, and encodes each of the plurality of rectangular units at positions apart from each other on the screen with a high efficiency code. A fixed length block formed by collecting the information and recording the fixed length block data on a recording medium, wherein the rectangular unit is transferred from one of the areas to the other end for each of the areas. Are arranged such that the rectangular units are adjacent to each other, and when the rectangular units are recorded on the recording medium, the rectangular units belonging to the same area are arranged on the recording medium in the order of the order. This is a digital video signal recording method.

Operation With this configuration, at least in the same area,
A rectangular unit adjacent on the screen is arranged at a close position (near) on the magnetic tape. For this reason, when a plurality of rectangular units in the same area can be reproduced at the same time during high-speed reproduction, adjacent rectangular units on the screen can be reproduced simultaneously.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a digital video signal recording and reproducing apparatus according to an embodiment of the present invention. The present embodiment is a rotary head type digital VTR that divides a screen into rectangular units, encodes the data with high efficiency, and records the encoded data on a magnetic tape. In FIG. 1, 11 is a formatter, 12 is a rearrangement memory, 13 is an orthogonal transformer, 14 is a variable length encoder, 15 is a blocker, 16 is an error correction encoder, 17 is a magnetic tape,
Reference numeral 18 denotes an error corrector, 19 denotes a variable length code decoder, 20 denotes an inverse orthogonal transformer, 21 denotes a rearrangement memory, and 22 denotes a deformatter.

The operation of the digital video signal recording / reproducing apparatus of the present embodiment configured as described above will be described below.

At the time of recording, the digital video signal is formatted by the formatter 11 into pixel data on a screen in a rectangular unit.
It is input to the sorting memory 12. FIG. 2 is a diagram showing how a rectangular unit is divided on a screen, and the whole rectangle represents one screen. In this embodiment, as shown in FIG. 2, the screen is divided into six areas, and these areas are called A, B, C, D, E, and F, respectively. Each area is further divided into rectangular units, and the rectangular units in each area are sequentially numbered as A1, A2, A3,.... In the rearrangement memory 12, the video signals are A1, B1, C1, D1, E1, F1, A2, B2, C2, D2, E2, F2,.
・ Rearrange them so that they are taken out one by one from each area. The video signal of each rectangular unit is input to an orthogonal transformer 13, where it is orthogonally transformed and coded using a Hadamard transform or a cosine transform technique, and then a variable length coder.
At 14, variable length coding is performed according to the information amount of each rectangular unit. In variable length coding, the amount of data is determined according to the amount of information in a rectangular unit, and high efficiency coding is performed by reducing the amount of data as a whole. Orthogonal transformation is a means for that. Although the code length of each rectangular unit of information is variable, the blocker 15 collects a plurality of rectangular unit information to form a fixed-length block. In the present embodiment, one fixed-length block is formed by six rectangular units of A1, B1, C1, D1, E1, and F1, and another one is formed by six rectangular units of A2, B2, C2, D2, E2, and F2. One fixed length block is formed.

By doing so, the positions of the respective rectangular units in one block on the screen are apart from each other, but the corresponding rectangular units of the adjacent blocks are also adjacent to each other on the screen. Accordingly, the information amount of each fixed-length block is less likely to be biased, so that the efficiency of variable-length coding can be improved. How to maintain the continuity of data on the screen between adjacent fixed-length blocks to ensure the visibility of the screen during high-speed reproduction will be described later. The block data is added with an error correction code by an error correction encoder 16 and is digitally recorded on a magnetic tape 17.

During playback, digital signals are detected from the magnetic tape,
An error corrector 18 corrects an error generated in the tape head system. Since the recording signal is variable-length coded, the code compressed by the variable-length code decoder 19 is restored. At this time, since one fixed-length block is composed of six rectangular units, frame synchronization may be performed in units of these blocks.
The decoded signal is converted back to a digital video signal by the inverse orthogonal transformer 20. At this point, since the signals are rearranged in units of rectangles, the input / output addresses of the memory are controlled by the rearrangement memory 21 so that the data rearrangement is reverse to that of the recording side. Sorted signal is deformatter
By means of 22, a reproduced digital signal is output in the same line order as the video signal.

During high-speed playback of a digital VTR, the head moves over a plurality of tracks on the magnetic tape as shown in FIG. Since data is continuously recorded on each track in block units, signals can be captured to some extent continuously even during high-speed reproduction. In the present embodiment, two corresponding rectangular units included in two continuous blocks are located at continuous positions on the screen, so that a certain degree of screen continuity can be realized even during high-speed playback. Mosaic of the screen can be avoided.

As described above, according to the present embodiment, a plurality of rectangular units included in one fixed-length block are located at positions separated from each other on the screen. The information amount is hardly biased, and the compression efficiency is improved. Furthermore, two rectangular units corresponding to each other included in two blocks adjacent to each other on the recording medium are also adjacent to each other on the screen, so that the continuity of the screen can be secured in high-speed reproduction of the digital VTR, and it is visually easy to see. A high-speed playback screen can be obtained.

In this embodiment, the orthogonal transform is used as the compression means. However, any other method may be used as long as it encodes the screen in a rectangular unit. Further, although a rotary head type digital VTR is used as a recording method, a disk type may be used.

Effect of the Invention As described above, according to the present invention, the efficiency of high-efficiency encoding of a video signal and the image quality in high-speed reproduction from a recording medium can be compatible, and the practical effect is large.

[Brief description of the drawings]

FIG. 1 is a block diagram of a digital video signal recording and reproducing apparatus according to an embodiment of the present invention, FIG. 2 is an explanatory view of screen division in the embodiment, FIG. 3 is a front view for explaining a rectangular unit, FIG. FIG. 4 is a block diagram of a conventional digital video signal recording and reproducing apparatus, and FIG. 5 is a tape pattern diagram in high-speed reproduction. 1 ... first error correction encoder, 2 ... shuffling memory, 3 ... second error correction encoder, 4 ... magnetic tape,
5: second error corrector, 6: deshuffling memory,
7: first error corrector, 11: formatter, 12: rearrangement memory, 13: orthogonal transformer, 14: variable length encoder, 15: blocker, 16: error correction code , 17
... magnetic tape, 18 ... error corrector, 19 ... variable length code decoder, 20 ... inverse orthogonal transformer, 21 ... sorting memory,
22 …… deformatter.

Continuation of the front page (56) References JP-A-2-76490 (JP, A) JP-A-1-240088 (JP, A) JP-A-62-229984 (JP, A) JP-A-2-58986 (JP) , A)

Claims (1)

(57) [Claims] 1. A screen is divided into a predetermined number of regions, the regions are further divided into rectangular units, and each of a plurality of rectangular units located at positions separated from each other on the screen is efficiently coded. A fixed-length block formed by collecting the information of (1) and (2), and recording the fixed-length-blocked data on a recording medium, wherein the rectangular unit is adjacent to one end of the area for each of the areas. A digital video signal characterized in that the rectangular units are ranked in such a manner that, when the rectangular units are recorded on the recording medium, the rectangular units belonging to the same area are arranged in the order of the ranking. Recording method.