JP2650590B2 - Recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording apparatus used for recording or transmitting a video signal with high efficiency encoding.

[0002]

2. Description of the Related Art As a method for reducing the data amount of a video signal, a method using high efficiency coding is known. High-efficiency coding is a coding method that removes the redundancy of a video signal to reduce the amount of data.

As a high-efficiency encoding method, a method is often used in which adjacent pixels are collected to form a block, and each block is compressed using an orthogonal transform or the like. A block that performs this orthogonal transformation is called an orthogonal transformation block. In order to improve the compression efficiency, the orthogonally transformed data is usually coded for each orthogonal transform block using variable length coding and recorded or transmitted.

[0004]

However, since the above configuration uses variable length coding, if an error occurs during recording and reproduction, the variable length code cannot be decoded.
There was a problem that could not be reproduced. On the other hand, there has been proposed a method of recording address information indicating which orthogonal transformation block the data around the data is for every predetermined recording data period. According to this method, even if the code synchronization of the variable length code is lost due to a transmission path error, the code synchronization and the orthogonal transform block synchronization can be restored using the address information.

However, in order to record the address information, it is necessary to record data that is not related to the video information, so that the compression efficiency of the high-efficiency coding is deteriorated. Further, in order to execute high-speed reproduction with a VTR or the like, it is desirable that the position of recorded data and the position of data on the screen have a one-to-one correspondence, but since variable-length coding is used, , The relationship between the recording position and the position on the screen becomes undefined. For this reason, the image quality during high-speed reproduction is greatly deteriorated.

An object of the present invention is to solve the problem of such a conventional recording apparatus using variable-length coding.

[0007]

SUMMARY OF THE INVENTION The present invention is directed to orthogonal transform means for collecting a plurality of adjacent pixels of an input video signal to form an orthogonal transform block and performing orthogonal transform, and the orthogonal transformed image. A variable-length coding unit for performing variable-length coding on a signal for each orthogonal transform block, collecting a certain number of the orthogonal transform blocks to form a macroblock, and recording each macroblock based on a specific format. A recording device that secures a macroblock recording area of a specific length for recording each macroblock, and for each of a plurality of orthogonal transform blocks included in the macroblock, each orthogonal transform block. Divides the macroblock recording area so as to secure an orthogonal transformation block recording area of a specific length, and for each of the orthogonal transformation blocks, The code words in order of visually important code word for click, the orthogonal transform block recording area for the orthogonal transform block, and critical data recording means for recording to the orthogonal transform block recording area that is filled,
When important data is recorded in the important data recording unit in all the orthogonal transformation block recording areas in the macroblock recording area for a certain macroblock, the important data recording unit records the orthogonal transformation block recording area. The data of the orthogonal transform block that could not be recorded is regarded as non-important data, and the non-important data is arranged for each orthogonal transform block in the macroblock in the order of the non-important data belonging to the visually important orthogonal transform block. Macroblock non-important data generating means for generating important data; and non-important data in macroblock units generated by the macroblock non-important data generating means. When the data was recorded, the important data was recorded A non-important data recording unit in the macro block for recording until the remaining area is filled in order from the beginning of the non-important data in the macro block unit; and the important data recording unit and the non-intra macro data for all the macro blocks. When the data in each macroblock is recorded in the macroblock recording area by the important data recording means, the data of the macroblock that has not yet been recorded by the important data recording means and the non-important data recording means in the macroblock is stored in the important data recording means. Residual data for macroblocks, residual data generating means for collecting residual data of a plurality of macroblocks in the order of macroblocks to generate residual data of a plurality of macroblocks, and residual data generated by the residual data generating means, The important data recording means and the macro block Characterized in that it comprises a residual data recording means for critical data and macroblock in a non-critical data using the clock in the non-critical data recording means for recording on the remaining area when recorded.

[0008]

According to the recording apparatus of the present invention, the important data of each macroblock and the orthogonal transform block included therein are recorded at fixed and fixed positions (macroblock recording area and orthogonal transform block recording area). Therefore, even if an error occurs in the transmission path, important data of each orthogonal transform block can be reproduced independently of the error.

[0009] In addition, insignificant data which could not be recorded in each orthogonal transform block recording area, data relating to an important orthogonal transform block among them can be recorded in the same macroblock recording area. Therefore, in a macroblock recording area where no transmission path error has occurred, data included in an important orthogonal transform block among non-important data included in the macroblock can be reproduced.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments. Here, an example in which the present invention is applied to a TV signal transmitted by the 525/60 system will be described. In this embodiment, the video signal is independently encoded and recorded for each frame with high efficiency, and the luminance signal of one frame is composed of 720 horizontal pixels and 4 vertical pixels.
It is assumed that it is composed of 80 lines. Further, the orthogonal transformation block is constituted by data composed of 64 pixels of 8 horizontal pixels and 8 vertical lines. As a result, the number of orthogonal transform blocks of the luminance signal per frame becomes 5,400.

Next, two color difference signals (RY signal and BY signal)
A signal) includes pixels included in the same area on the screen as the orthogonal transform block of four adjacent luminance signals, and constitutes one orthogonal transform block. Also, an orthogonal transform block of four luminance signals at the same position on the screen and one RY
A total of 6 signal blocks and one BY signal block
The orthogonal transform blocks are collectively referred to as one macroblock. Therefore, one frame is composed of 1350 macroblocks.

FIG. 1 is a block diagram of one embodiment of the present invention. In FIG. 1, 1 is an input unit, 2 is an orthogonal transform unit, 3 is a variable length coding unit, 4 is a classification unit, 5 is an important data recording unit,
6 is an insignificant data memory unit, 7 is an insignificant data recording unit,
8 is an output unit.

Video data input from the input unit 1 in units of macroblocks is subjected to orthogonal transformation by the orthogonal transformation unit 2 for each orthogonal transformation block included in the macroblock. Normally, a discrete cosine transform (DCT) is used as the orthogonal transform, but other methods such as a wavelet are also applicable.

The data orthogonally transformed by the orthogonal transformation block unit 2 is subjected to variable length encoding by the variable length encoding unit 3 for each orthogonal transformation block. As a result, data is converted into a different data amount for each orthogonal transform block.

The orthogonally transformed data is recorded based on a specific recording format. FIG. 2 shows a recording format for a macro block according to the present embodiment. In FIG. 2, 75 bytes of a macroblock recording area are allocated to one macroblock. The orthogonal transform block of luminance signal (Y0, Y1, Y2, Y3 in FIG. 2) has 15 bytes each, and the orthogonal transform block of chrominance signal (RY, BY in FIG. 2) has 7 bytes each. A conversion block recording area is allocated.

In the example shown in FIG. 2, all the macroblock recording areas are divided into orthogonal transformation block recording areas included in the macroblock, but the macroblock recording areas do not belong to the orthogonal transformation block recording area. It is also possible to secure

In this embodiment, there are 1350 macroblock recording areas per frame as shown in FIG. By recording the macro block and the orthogonal transform block at the fixed recording positions in this manner, the effects of transmission path errors are small, and recording suitable for high-speed reproduction can be performed.

The data of the orthogonal transform block, which has been variable-length coded by the variable-length coding unit 3 in FIG. 1, is separated by the classification unit 4 into important data and non-important data. Here, important data and insignificant data will be described first.

In each orthogonal transform block, auxiliary data necessary for decoding the orthogonal transform block first becomes important data. As other important data, the code amount representing the lowest frequency is sequentially added to the data amount of the auxiliary data, and the code word data up to the data amount recordable in the orthogonal transformation block recording area in FIG. Is also important data. If the amount of recordable data is satisfied in the middle of the last code word, the data up to the middle of the code word is important data (important data can be defined for each code word).
Conversely, codeword data that is not defined as important data (data representing a relatively high frequency that cannot be recorded in the orthogonal transformation block recording area) is regarded as non-important data.

Although the distortion of the component representing the low frequency band is easily detected visually, the distortion of the high frequency component is hardly detected. Therefore, by classifying important data and insignificant data using the method described above,
Even when only important data is reproduced, it is possible to reduce image quality deterioration. In the example of FIG. 2, the orthogonal transformation block recording area for the luminance signal is larger than the orthogonal transformation block recording area for the chrominance signal. As a result, it becomes possible to increase the amount of important data of a visually important luminance signal, and it is possible to further reduce the deterioration in image quality when only important data is reproduced.

The important data classified by the classifying unit 4 in FIG. 1 as described above is sequentially recorded in the important data recording unit 5 for each orthogonal transform block from the front of the orthogonal transform block recording area in accordance with the recording format of FIG. Be recorded. Unimportant data is saved until the important data is recorded in the non-important data memory unit 6. The insignificant data collected in the insignificant data memory unit 6 is recorded in the insignificant data recording unit 7 in the macroblock recording area, which is not recorded in the important data recording unit 5 but remains. However, since the data is variable-length coded, insignificant data is not always recorded in the same macroblock recording area as described later. After the insignificant data is recorded in this way, it is output to the output unit 8 for each macroblock recording area.

Next, a method of recording insignificant data will be described with reference to FIG. First, FIG. 3A shows a state of a macro block recording area in which important data is recorded by the important data recording unit 5 in FIG. In FIG. 3A, since the data amount of the orthogonal transform blocks Y1 and Y3 is small, even if all data is recorded in the orthogonal transform block recording area, an empty area still occurs. On the other hand, since the data amount of the orthogonal transformation blocks Y0, Y2, RY, and BY is larger than the orthogonal transformation block recording area, data that cannot be recorded occurs. These unrecordable data are the above-mentioned insignificant data.

FIG. 3B shows the insignificant data memory 6 of FIG.
3A shows insignificant data for the macroblock shown in FIG. As shown in FIG. 3B, in the present embodiment, the insignificant data is arranged in order from the insignificant data for the preceding orthogonal transform block in the macroblock recording area. In the present embodiment, as in the format of the macroblock recording area in FIG. 2, the most visually important luminance signal is placed before the most important RY signal, and the least important BY signal is placed next to the luminance signal. Is placed last. For this reason, as shown in FIG. 3B, the non-important data for the macroblock is arranged in the order of visually important orthogonal transform blocks.

FIG. 3C shows the non-important data recording section 7 shown in FIG.
Indicates the result of recording insignificant data of the same macroblock. Here, the free area of the orthogonal transformation block recording area of Y1 and Y3 in FIG.
The insignificant data for this macroblock obtained in FIG. 3B is recorded from the beginning. In FIG. 3C, Y0 and
All the unimportant data for Y1 and a part of the unimportant data for RY will be recorded. Therefore, when reproducing only the data in the macroblock recording area due to a transmission path error or high-speed reproduction, it is possible to reproduce all the data of the luminance signal and the important data of the color difference signal included in the macroblock. Become. That is, most visually important data can be reproduced only from this macroblock recording area. In this way, by arranging the insignificant data for the macroblock in the order of the more important orthogonal transform blocks (the luminance signal, the RY signal,
By arranging the signals in order, it is possible to reduce the effects of transmission path errors and to improve the high-speed reproduction image quality.

FIG. 3D is an explanatory diagram of a method of recording data that has not been recorded yet after recording insignificant data for the same macroblock in FIG. 3C (hereinafter referred to as residual data). The residual data for the macroblock in FIG. 3A is the insignificant data of RY and BY as shown in FIG. The residual data and the residual data of other macroblocks are combined to form residual data for a plurality of macroblocks. In FIG. 3D, M _n-1 indicates the residual data for the macro block before the current macro block, and M _{n + 1} indicates the residual data for the macro block after the current macro block (the current macro block). The residual data is _Mn ).

The residual data for a plurality of macroblocks as shown in FIG. 3D is recorded in a macroblock recording area in which a vacant area still exists after all the insignificant data in the same macroblock are recorded. Therefore, since the residual data is not recorded in the same macroblock, there is a possibility that the data cannot be reproduced when a transmission path error occurs or during high-speed reproduction. The recording of the residual data is also executed by the non-critical data recording unit 7 in FIG.

As described above, the recording apparatus of the present invention has been described using the embodiment. By using the present invention as described above, the effect of transmission path errors can be reduced, and improvement in high-speed reproduction image quality can be realized.

In this embodiment, the recording format for a specific video signal is shown, but the present invention is applicable to any other video signal and recording format. Further, in the embodiment, a video signal composed of a luminance signal and a color difference signal has been described, but the present invention is also applicable to a composite signal, an RGB signal, and other image signals and audio signals.

The configuration for realizing the present invention can be various configurations other than the embodiment of FIG. 1, and can be realized by software on a computer.

[0030]

As described above, according to the recording apparatus of the present invention, the important data of each macroblock and the orthogonal transformation block included therein are fixed at fixed positions (the macroblock recording area and the orthogonal transformation block recording area). Since the data is recorded, even if an error occurs in the transmission path, the important data of each orthogonal transform block can be reproduced independently of the error.

In addition, even for insignificant data that could not be recorded in each orthogonal transform block recording area, data relating to an important orthogonal transform block can be recorded in the same macroblock recording area, so that no transmission path error has occurred. In the macroblock recording area, data included in an important orthogonal transform block among non-important data included in the macroblock can be reproduced. For example, recording a luminance signal in a macroblock in preference to a chrominance signal on a recording format (enlarge an orthogonal transformation block recording area for a luminance signal and record it in the front of the macroblock recording area). Accordingly, even when only the data in the macroblock can be used, the image quality degradation can be concentrated only on the high frequency component of the color difference signal. This makes it possible to minimize substantial image quality degradation.

The present invention can solve the disadvantages of the high-efficiency coding apparatus using variable-length coding with a relatively simple configuration, so that its practical effect is very large.

[Brief description of the drawings]

FIG. 1 is a block diagram of a recording apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a macro block recording area and an orthogonal transform block recording area of an embodiment of the recording apparatus of the present invention.

FIG. 3 is a diagram illustrating a method for recording insignificant data according to an embodiment of the recording apparatus of the present invention.

[Explanation of symbols]

 2 Orthogonal transformation unit 3 Variable length coding unit 4 Classification unit 5 Important data recording unit 6 Non-important data memory unit 7 Non-important data recording unit

Claims (4)

(57) [Claims] An orthogonal transformation means for collecting a plurality of adjacent pixels of an input video signal to form an orthogonal transformation block and performing orthogonal transformation, and changing the orthogonally transformed video signal for each orthogonal transformation block. A variable-length encoding means for performing long encoding, a recording apparatus that collects a certain number of the orthogonal transform blocks to form macroblocks and records each macroblock based on a specific format, A macroblock recording area of a specific length for recording a macroblock is secured, and for a plurality of orthogonal transform blocks included in the macroblock, each orthogonal transform block has an orthogonal transform of a specific length. The macroblock recording area is divided so as to secure a block recording area, and for each of the orthogonal transform blocks, a codeword for the orthogonal transform block is visually determined. Important data recording means for recording in the orthogonal transform block recording area for the orthogonal transform block in the order of upper important code words until the orthogonal transform block recording area is filled; When important data is recorded in all the orthogonal transformation block recording areas in the area by the important data recording means, the data of the orthogonal transformation blocks that could not be recorded in the orthogonal transformation block recording area by the important data recording means are unwritten. Macroblock non-significant data generation for generating the non-significant data in macroblock units by arranging the non-significant data in the order of non-significant data belonging to a visually important orthogonal transform block in the macroblock for each orthogonal transform block as important data Means for generating the macroblock insignificant data generating means. When the important data is recorded by the important data recording means in the macro block recording area in the macro block recording area, the non-important data in the macro block A macroblock non-important data recording means for recording until the remaining area is filled in order from the beginning of important data; and an important data recording means and an intra-macroblock non-important data recording means for all macroblocks. When data in a macroblock is recorded in the macroblock recording area, data of a macroblock that has not been recorded by the important data recording means and the non-important data recording means in the macroblock is regarded as residual data for the macroblock. , The residual data of a plurality of macroblocks Data generating means for generating residual data of a plurality of macroblocks; and transmitting the residual data generated by the residual data generating means to important data and macro data by the important data recording means and the non-important data recording means in the macroblock. A recording apparatus comprising: a residual data recording unit that records in an area remaining when non-important data in a block is recorded. 2. The recording apparatus according to claim 1, wherein the important data recording means records the code words for low-frequency components in code words orthogonally transformed in the orthogonal transformation block recording area in order. . 3. An input signal comprising: a luminance signal; a first color difference signal which is a difference signal between a signal representing red and the luminance signal; and a second color difference signal which is a difference signal between a signal representing blue and the luminance signal. 2. The recording apparatus according to claim 1, wherein when composed of three types of signals, the macroblock is composed of orthogonal transform blocks for the three types of signals included in the same area on the screen. 4. The non-important data recording means in a macro block, wherein the orthogonal transformation block recording area for the luminance signal is the first.
And when the non-important data in the macro block is larger than the orthogonal transform block recording area for the second color difference signal, the non-important data for the luminance signal, the non-important data for the first color difference signal, and the non-important data for the second color difference signal. 4. The recording apparatus according to claim 3, wherein the recording is performed in the order of data.