JPH06284412A - Picture signal coding method and picture signal coder, picture signal decoding method and picture signal decoder and picture signal recording medium - Google Patents

Abstract

PURPOSE:To reduce a transmission quantity by sending a weighting coefficient of a waiting matrix as a difference from a coefficient at one preceding time. CONSTITUTION:A coder 1 separates an input video signal into a luminance signal and a chrominance signal at a Y/C separation circuit 11, they are ADD- converted by A/D converters 12, 13 and the result is stored in a frame memory 14. A frame format signal in the memory 14 is converted into a block format signal by a conversion circuit 17 and fed to an encoder 18. The encoder 18 encodes the signal by using a first weighting coefficient of a weighting matrix as complete M-bit data and by using a succeeding weighting coefficient being a difference from one-preceding weighting coefficient as N-bit data (N<=M).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention records a moving image signal on a recording medium such as a magneto-optical disk or a magnetic tape,
It can be played back and displayed on a display, etc., video conferencing systems, video telephone systems, broadcasting equipment, etc.
An image signal encoding method, an image signal encoding device, and an image signal suitable for use when transmitting a moving image signal from a transmitting side to a receiving side via a transmission path and receiving and displaying the moving image signal on the receiving side. The present invention relates to a decoding method, an image signal decoding device, and an image signal recording medium.

[0002]

2. Description of the Related Art In a system for transmitting a moving image signal to a remote place such as a video conference system or a video telephone system, for example, the line correlation or inter-frame correlation of a video signal is used in order to efficiently use a transmission path. Is used to compress and code an image signal.

That is, an image signal is subjected to, for example, DCT (discrete cosine transform) processing and then quantized using a predetermined weighting matrix. The weighting matrix is composed of weighting coefficients arranged in a matrix of 8 × 8 because the DCT process is usually performed in macroblock units of 8 × 8 pixels. By multiplying the DCT coefficient by this weighting coefficient and quantizing, more efficient coding becomes possible.

This weighting matrix may be changed as necessary on the encoder side in order to control the amount of information and the image quality. When dequantizing the transmitted data on the decoder side, the same weighting matrix as that used on the encoder side is required. Therefore, when the weighting matrix is changed, this weighting matrix is also transmitted from the encoder side to the decoder side.

[0005]

By the way, there are two types of weighting matrices, one for intra macroblocks and one for inter macroblocks. Each weighting matrix is 64 (= 8 × 8)
If the weighting coefficients are represented by 8-bit data and the weighting matrix for intra and inter is transmitted, a total data amount of 1024 (= 8 × 64 × 2) bits is transmitted. Becomes Therefore, if the weighting matrix is changed frequently, there is a problem that the original image data cannot be transmitted by that much.

However, in the case of compressing and transmitting an image signal in, for example, television broadcasting, in order to receive a predetermined channel at an arbitrary time and surely dequantize the received data, the weighting is performed. The matrix must be detectable at any time. For this purpose, the weighting matrix is preferably transmitted relatively frequently.

The present invention has been made in view of such a situation, and it is possible to reduce the transmission amount of the weighting matrix.

[0008]

According to a first aspect of the present invention, there is provided an image signal encoding method, wherein an image signal is encoded using a predetermined predicted image signal, a predetermined operation is performed on the encoded signal, and the operation is performed by the operation. In an image signal coding method in which the obtained signal is quantized using a predetermined weighting matrix and the quantized signal is variable length coded, the first weighting coefficient of the weighting matrix is transmitted as complete M-bit data. The subsequent weighting coefficient is characterized by calculating a difference from the preceding weighting coefficient and transmitting the difference as N-bit data smaller than M bits.

Each weighting coefficient of the weighting matrix can be transmitted in the order of zigzag scanning, horizontal scanning, or vertical scanning. Also, the bit precision of the difference can be transmitted. Furthermore, this difference can be transmitted, for example, as a variable length code of the zero run system.

The image signal encoding method according to claim 8 is
An image signal is encoded using a predetermined predicted image signal, a predetermined operation is performed on the encoded signal, the signal obtained by the operation is quantized using a predetermined weighting matrix, and the quantized signal is changed. An image signal coding method for long coding is characterized in that a difference between each weighting coefficient of a weighting matrix and a default value is calculated, and the difference is coded and transmitted.

This difference can be encoded and transmitted in a fixed length of N bits, or can be encoded and transmitted by the zero run method.

These image signal encoding methods can be applied to an image signal encoding device.

An image signal decoding method according to a twelfth aspect of the present invention is to decode a variable length coded image signal, dequantize the decoded signal using a predetermined weighting matrix transmitted, The weighting transmitted in the image signal decoding method in which the inversely quantized signal is subjected to a predetermined operation opposite to the case at the time of encoding, and the calculated signal is decoded using a predetermined predicted image signal. The first weighting factor of the matrix is the complete M
It is characterized in that it is decoded as bit data, and the subsequent weighting coefficient is decoded by adding it to the weighting coefficient immediately before.

The weighting coefficients can be arranged in the order of zigzag scanning, in the horizontal direction, or in the vertical direction to generate the weighting matrix. Further, the bit precision of the weighting coefficient subsequent to the first weighting coefficient can be specified by decoding the transmitted bit precision.

According to a seventeenth aspect of the present invention, there is provided an image signal decoding method, wherein a variable length coded image signal is decoded, the decoded signal is inversely quantized using a predetermined weighting matrix transmitted, The weighting transmitted in the image signal decoding method in which the inversely quantized signal is subjected to a predetermined operation opposite to the case at the time of encoding, and the calculated signal is decoded using a predetermined predicted image signal. A feature is that a weighting matrix is generated by adding the difference between the matrix and the default value to the default value.

These image signal decoding methods can be applied to an image signal decoding device.

Data can be recorded on the image signal recording medium by using the above-mentioned image signal encoding method.

[0018]

In the image signal coding method of the present invention, the weighting coefficient is transmitted as a difference from the preceding weighting coefficient or as a difference from a predetermined default value. Therefore, the amount of data required to transmit the weighting matrix can be reduced.

Therefore, the image signal can be rapidly dequantized by adding the difference to the preceding weighting coefficient or a predetermined default value.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Image signals are coded using line correlation and frame correlation.

By using the line correlation, the image signal can be compressed by, for example, DCT (discrete cosine transform) processing.

Further, by utilizing the inter-frame correlation, the image signal can be further compressed and encoded. For example, as shown in FIG. 1, when frame images PC1, PC2, and PC3 are generated at times t1, t2, and t3, respectively, the difference between the image signals of the frame images PC1 and PC2 is calculated to generate PC12. Also, the difference between the frame images PC2 and PC3 is calculated to generate PC23. Normally, the images of frames that are temporally adjacent do not have such a large change, so when the difference between the two is calculated, the difference signal has a small value. Therefore, if this difference signal is encoded, the code amount can be compressed.

However, the original image cannot be restored by transmitting only the difference signal. Therefore, the image of each frame is set to any one of three types of pictures of I picture, P picture, and B picture,
The image signal is compressed and encoded.

That is, as shown in FIG. 2, for example, image signals of 17 frames from frames F1 to F17 are set as a group of pictures, which is one unit of processing. Then, the image signal of the first frame F1 is encoded as an I picture, and the second frame F2 is a B picture.
The third frame F3 is processed as a P picture. Hereinafter, the fourth and subsequent frames F4 to F17 are alternately processed as a B picture or a P picture.

As the image signal of the I picture, the image signal for one frame is transmitted as it is. On the other hand, as the image signal of the P picture, basically, as shown in FIG.
As shown in (A), the difference from the image signal of the I picture or P picture preceding it in time is transmitted. Further, as the image signal of the B picture, basically, as shown in FIG. 2B, a difference from the average value of both the temporally preceding frame and the temporally following frame is obtained, and the difference is encoded. Turn into.

FIG. 3 shows the principle of the method of encoding a moving image signal in this way. As shown in the figure,
Since the first frame F1 is processed as an I picture, it is directly transmitted to the transmission path as the transmission data F1X (intra-picture coding). On the other hand, the second frame F
2 is processed as a B picture, the difference between the frame F1 temporally preceding and the average value of the frame F3 temporally following is calculated, and the difference is calculated as the transmission data F2.
Transmitted as X.

However, there are four types of processing as the B picture, which will be described in more detail. The first process is to transmit the data of the original frame F2 as it is as the transmission data F2X (SP1) (intra coding), which is the same process as in the I picture. The second processing is to calculate the difference from the frame F3 that is temporally later and transmit the difference (SP2) (backward predictive coding). The third process is to transmit a difference (SP3) from the temporally preceding frame F1 (forward predictive coding). Further, the fourth process is to generate a difference (SP4) between the average value of the frame F1 preceding in time and the average value of the frame F3 following, and transmit this as the transmission data F2X (bidirectional predictive coding). .

Of these four methods, the method that minimizes the amount of transmitted data is adopted.

When transmitting the difference data, the motion vector x1 between the image of the frame (prediction image) for which the difference is to be calculated (motion vector between the frames F1 and F2) (in the case of forward prediction). , Or x2 (frame F
The motion vector between 3 and F2) (for backward prediction) or both x1 and x2 (for bidirectional prediction) are transmitted with the difference data.

In the frame F3 of the P picture, the frame F1 temporally preceding is used as a predicted image to calculate a difference signal (SP3) from the frame and a motion vector x3, which is transmitted as transmission data F3X. (Forward predictive coding). Alternatively, the data of the original frame F3 is directly transmitted as the transmission data F3X (S
P1) (intra coding). As in the case of the B picture, whichever method is used for transmission is selected so that less transmission data is transmitted.

FIG. 4 shows an example of the configuration of an apparatus which encodes and transmits a moving image signal based on the above-mentioned principle, and decodes this. The encoding device 1 encodes the input video signal and transmits it to the recording medium 3 as a transmission path. Then, the decryption device 2 uses the recording medium 3
It reproduces the signal recorded in, decodes it, and outputs it.

In the encoding apparatus 1, the input video signal is input to the pre-processing circuit 11, where the luminance signal and the color signal (color difference signal in this example) are separated, and the A / D converter 12 respectively. , 13 for A / D conversion. The video signal converted into a digital signal by A / D conversion by the A / D converters 12 and 13 is supplied to and stored in the frame memory 14. The frame memory 14 stores the luminance signal in the luminance signal frame memory 15 and the color difference signal in the color difference signal frame memory 16, respectively.

The format conversion circuit 17 converts the frame format signal stored in the frame memory 14 into
Convert to block format signal. That is, as shown in FIG. 5, the video signal stored in the frame memory 14 is frame format data in which V lines of H dots per line are collected. The format conversion circuit 17 converts this 1-frame signal into 16
A line is used as a unit to divide into M slices. Then, each slice is divided into M macroblocks. Each macroblock is composed of a luminance signal corresponding to 16 × 16 pixels (dots), and this luminance signal further includes a block Y [1] in units of 8 × 8 dots.
To Y [4]. Then, this 16 × 16 dot luminance signal includes an 8 × 8 dot Cb signal and an 8 × 8 dot Cb signal.
An 8-dot Cr signal is supported.

The data converted into the block format in this way is supplied from the format conversion circuit 17 to the encoder 18, where it is encoded. The details will be described later with reference to FIG.

The signal encoded by the encoder 18 is output to the transmission path as a bit stream and recorded on the recording medium 3, for example.

The data reproduced from the recording medium 3 is supplied to the decoder 31 of the decoding device 2 and decoded.
Details of the decoder 31 will be described later with reference to FIG.

The data decoded by the decoder 31 is input to the format conversion circuit 32 and converted from the block format to the frame format. Then, the luminance signal of the frame format is supplied to and stored in the luminance signal frame memory 34 of the frame memory 33, and the color difference signal is supplied to and stored in the color difference signal frame memory 35. The luminance signal and the color difference signal read from the luminance signal frame memory 34 and the color difference signal frame memory 35 are D / A converted by the D / A converters 36 and 37, respectively.
A-converted, supplied to the post-processing circuit 38, and combined.
Then, it is output and displayed on a display (not shown) such as a CRT.

Next, a configuration example of the encoder 18 will be described with reference to FIG.

The image data to be encoded is input to the motion vector detection circuit 50 in macroblock units.
The motion vector detection circuit 50 converts the image data of each frame into I in accordance with a preset predetermined sequence.
Process as a picture, P picture, or B picture. Images of each frame that are sequentially input are
Which of I, P, and B pictures is to be processed is predetermined (for example, as shown in FIG. 2, the group of pictures composed of the frames F1 to F17 is I, B, P, or B, P, ... B, P).

The image data of a frame (for example, frame F1) processed as an I picture is transmitted from the motion vector detection circuit 50 to the front original image portion 51a of the frame memory 51.
The image data of the frame (for example, frame F2) that is transferred and stored in the reference original image section 51b is the image data of the frame (for example, frame F3) that is transferred and stored in the reference original image portion 51b. , And is transferred to and stored in the rear original image portion 51c.

Further, at the next timing, B
When an image of a frame to be processed as a picture (frame F4) or P picture (frame F5) is input, the image data of the first P picture (frame F3) stored in the backward original image portion 51c until then is It is transferred to the front original image portion 51a, and the next B picture (frame F
The image data of 4) is stored (overwritten) in the reference original image portion 51b, and the image data of the next P picture (frame F5) is stored (overwritten) in the backward original image portion 51c. Such an operation is sequentially repeated.

The signal of each picture stored in the frame memory 51 is read therefrom, and the prediction mode switching circuit 52 performs frame prediction mode processing or field prediction mode processing. Furthermore, under the control of the prediction determination circuit 54, the calculation unit 53 performs calculation of intra-picture prediction, forward prediction, backward prediction, or bidirectional prediction. Which of these processes is to be performed is determined in accordance with the prediction error signal (difference between the reference image to be processed and the predicted image corresponding thereto). Therefore, the motion vector detection circuit 50 generates the sum of absolute values (or the sum of squares) of the prediction error signal used for this determination.

Here, the frame prediction mode and the field prediction mode in the prediction mode switching circuit 52 will be described.

When the frame prediction mode is set, the prediction mode switching circuit 52 supplies the four luminance blocks Y supplied from the motion vector detection circuit 50.
[1] to Y [4] are directly output to the arithmetic unit 53 in the subsequent stage. That is, in this case, as shown in FIG. 7A, the data of the odd field (first field) line and the data of the even field (second field) are mixed in each luminance block. It is in the state of doing. In this frame prediction mode, prediction is performed in units of four luminance blocks (macro blocks), and one motion vector is associated with each of the four luminance blocks.

On the other hand, the prediction mode switching circuit 5
In the field prediction mode, 2 indicates a signal input from the motion vector detection circuit 50 in the configuration shown in FIG. 7A as a luminance block among four luminance blocks as shown in FIG. 7B. For example, Y [1] and Y [2] are formed only by dots of lines in an odd field, and the other two luminance blocks Y [3] and Y [4] are formed by data of lines in an even field. And outputs it to the calculation unit 53. In this case, two luminance blocks Y
One motion vector corresponds to [1] and Y [2], and another one motion vector corresponds to the other two luminance blocks Y [3] and Y [4]. To be done.

The motion vector detection circuit 50 outputs the sum of absolute values of prediction errors in the frame prediction mode and the sum of absolute values of prediction errors in the field prediction mode to the prediction mode switching circuit 52. Prediction mode switching circuit 5
2 compares the absolute value sums of the prediction errors in the frame prediction mode and the field prediction mode, performs a process corresponding to the prediction mode having the smaller value, and outputs the data to the arithmetic unit 53.

However, such processing is actually performed by the motion vector detection circuit 50. That is, the motion vector detection circuit 50 outputs a signal having a configuration corresponding to the determined mode to the prediction mode switching circuit 52, and the prediction mode switching circuit 52 outputs the signal as it is to the arithmetic unit 53 in the subsequent stage.

In the frame prediction mode, the color difference signal is supplied to the arithmetic unit 53 in a state in which line data of odd fields and line data of even fields are mixed, as shown in FIG. 7 (A). To be done. In the field prediction mode, as shown in FIG. 7B, the upper half (4 lines) of each color difference block Cb, Cr is an odd field corresponding to the luminance blocks Y [1], Y [2]. The color difference signal is used, and the lower half (4 lines) is the luminance block Y.
Color difference signals of even fields corresponding to [3] and Y [4] are set.

Further, the motion vector detection circuit 50 uses the intra-picture prediction in the prediction determination circuit 54 as follows.
A sum of absolute values of prediction errors for determining whether to perform forward prediction, backward prediction, or bidirectional prediction is generated.

That is, the sum ΣAij of the signals Aij of the macroblocks of the reference image is used as the sum of absolute values of the prediction errors of the intra-picture prediction.
The difference between the absolute value | ΣAij | of the macroblock and the sum Σ | Aij | of the absolute value | Aij | of the macroblock signal Aij is calculated. Also, as the sum of absolute values of the prediction errors of the forward prediction, the sum Σ | Aij− of the absolute value | Aij−Bij | of the difference Aij−Bij between the signal Aij of the macroblock of the reference image and the signal Bij of the macroblock of the predicted image. Bij |
Ask for. Further, the sum of absolute values of the prediction errors of the backward prediction and the bidirectional prediction is also obtained in the same manner as in the case of forward prediction (the predicted image is changed to a predicted image different from that in forward prediction).

The sum of these absolute values is supplied to the prediction judgment circuit 54. The prediction determination circuit 54 selects the smallest sum of absolute values of prediction errors of forward prediction, backward prediction, and bidirectional prediction as the sum of absolute values of prediction errors of inter prediction. Furthermore, the sum of absolute values of the prediction error of this inter-prediction and the sum of absolute values of the prediction error of intra-picture prediction are compared,
The smaller one is selected, and the mode corresponding to the selected sum of absolute values is selected as the prediction mode. That is, if the sum of absolute values of prediction errors in intra-picture prediction is smaller, the intra-picture prediction mode is set. If the sum of absolute values of prediction errors in inter prediction is smaller, the mode in which the corresponding sum of absolute values is the smallest is set among the forward prediction, backward prediction, and bidirectional prediction modes.

In this way, the motion vector detection circuit 50
Supplies the signal of the macroblock of the reference image to the arithmetic unit 53 via the prediction mode switching circuit 52 in a configuration corresponding to the mode selected by the prediction mode switching circuit 52 among the frame or field prediction modes. Of the four prediction modes, the prediction determination circuit 54
The motion vector between the prediction image and the reference image corresponding to the prediction mode selected by is detected, and the variable length coding circuit 5
8 and the motion compensation circuit 64. As described above, the motion vector that minimizes the sum of absolute values of the corresponding prediction errors is selected.

The prediction determination circuit 54 uses the intra-frame (image) prediction mode (mode without motion compensation) as the prediction mode when the motion vector detection circuit 50 is reading the image data of the I picture from the front original image portion 51a. ) Is set, and the switch 53d of the calculation unit 53 is switched to the contact a side. As a result, the image data of the I picture is DCT
It is input to the mode switching circuit 55.

As shown in FIG. 8 (A) or (B), the DCT mode switching circuit 55 allows the data of four luminance blocks to be mixed with odd field lines and even field lines (frame DCT). mode),
Or, the separated state (field DCT mode),
And output to the DCT circuit 56.

That is, the DCT mode switching circuit 55 is
Mixed data of odd field and even field D
Comparing the coding efficiency in the case of CT processing and the coding efficiency in the case of DCT processing in the separated state,
Select a mode with good coding efficiency.

For example, as shown in FIG. 8 (A), the input signal has a structure in which lines of an odd field and an even field are mixed, and a signal of a line of an odd field and a line of an even field which are vertically adjacent to each other. The difference between the signals is calculated, and the sum of the absolute values (or the sum of squares) is calculated. As shown in FIG. 8B, the input signal has a structure in which the lines of the odd field and the even field are separated, and the difference between the signals of the lines of the odd fields vertically adjacent to each other and the line of the even field are separated. The difference between the signals is calculated, and the sum (or sum of squares) of the absolute values of each is calculated. Further, both (sum of absolute values) are compared, and the DCT mode corresponding to a smaller value is set. That is, if the former is smaller, the frame DCT mode is set, and if the latter is smaller, the field DCT mode is set.

Then, the data having the structure corresponding to the selected DCT mode is output to the DCT circuit 56, and the DCT flag indicating the selected DCT mode is output to the variable length coding circuit 58 and the motion compensation circuit 64.

The prediction mode in the prediction mode switching circuit 52 (FIG. 7) and the DCT mode switching circuit 55.
As is clear by comparing the DCT modes in FIG. 8 (FIG. 8), the data structures in both modes of the luminance block are substantially the same.

When the frame prediction mode (a mode in which odd lines and even lines are mixed) is selected in the prediction mode switching circuit 52, the frame DCT mode (in which odd lines and even lines are mixed) is also selected in the DCT mode switching circuit 55. If the field prediction mode (a mode in which the data in the odd field and the data in the even field are separated) is selected in the prediction mode switching circuit 52, the field in the DCT mode switching circuit 55 is high. There is a high possibility that the DCT mode (mode in which the data of the odd field and the data of the even field are separated) is selected.

However, this is not always the case, and the prediction mode switching circuit 52 determines the mode so that the sum of the absolute values of the prediction errors becomes small, and the DCT mode switching circuit 55 encodes the mode. The mode is determined so that the efficiency is good.

The I-picture image data output from the DCT mode switching circuit 55 is input to the DCT circuit 56, subjected to DCT (discrete cosine transform) processing, and converted into DCT coefficients. This DCT coefficient is input to the quantization circuit 57, quantized in a quantization step corresponding to the data storage amount (buffer storage amount) of the transmission buffer 59, and then,
It is input to the variable length coding circuit 58.

The variable length coding circuit 58 is a quantization circuit 57.
In accordance with the supplied quantization step (scale), the image data (in this case, I picture data) supplied from the quantization circuit 57 is converted into a variable length code such as a Huffman code and transmitted. Output to the buffer 59.

In the variable length coding circuit 58, a quantization step (scale) is set by the quantization circuit 57, and a prediction mode (intra-picture prediction, forward prediction, backward prediction, or bidirectional prediction is set by the prediction determination circuit 54. Mode indicating whether or not the motion vector is detected by the motion vector detection circuit 50,
A prediction flag (a flag indicating whether the frame prediction mode or the field prediction mode has been set) from the prediction mode switching circuit 52, and a DCT flag (either the frame DCT mode or the field DCT mode set by the DCT mode switching circuit 55 are set Has been input, and these are also variable length coded.

The transmission buffer 59 temporarily stores the input data and stores the data corresponding to the storage amount in the quantizing circuit 57.
Output to.

The transmission buffer 59 increases the quantization scale of the quantization circuit 57 by the quantization control signal when the remaining data amount increases to the allowable upper limit value.
The amount of quantized data is reduced. On the contrary, when the data remaining amount decreases to the allowable lower limit value, the transmission buffer 59 uses the quantization control signal to quantize circuit 57.
The data amount of the quantized data is increased by reducing the quantization scale of. In this way, overflow or underflow of the transmission buffer 59 is prevented.

Then, the data accumulated in the transmission buffer 59 is read out at a predetermined timing, outputted to the transmission path, and recorded in the recording medium 3, for example.

On the other hand, the I picture data output from the quantization circuit 57 is input to the inverse quantization circuit 60 and inversely quantized in accordance with the quantization step supplied from the quantization circuit 57. The output of the inverse quantization circuit 60 is IDCT
After being input to the (inverse DCT) circuit 61 and subjected to inverse DCT processing, it is supplied to and stored in the forward predicted image portion 63a of the frame memory 63 via the calculator 62.

When the motion vector detection circuit 50 processes the sequentially input image data of each frame as, for example, I, B, P, B, P, B ... Pictures, it is input first. After processing the image data of another frame as an I picture, before processing the image of the next input frame as a B picture, the image data of the next input frame is processed as a P picture. This is because a B picture is accompanied by backward prediction and cannot be decoded unless a P picture as a backward predicted image is prepared in advance.

Then, the motion vector detection circuit 50 starts the processing of the image data of the P picture stored in the backward original image portion 51c after the processing of the I picture. Then, as in the case described above, the sum of absolute values of the inter-frame difference (prediction error) in macroblock units is supplied from the motion vector detection circuit 50 to the prediction mode switching circuit 52 and the prediction determination circuit 54. Prediction mode switching circuit 52
And the prediction determination circuit 54 sets the frame / field prediction mode, or the prediction mode of intra-picture prediction, forward prediction, backward prediction, or bidirectional prediction in accordance with the sum of the absolute values of the prediction errors of the macroblock of the P picture. To do.

When the intra-frame prediction mode is set, the arithmetic unit 53 switches the switch 53d to the contact a side as described above. Therefore, this data is similar to the I picture data in that the DCT mode switching circuit 55, the DCT
It is transmitted to the transmission line via the circuit 56, the quantization circuit 57, the variable length coding circuit 58, and the transmission buffer 59. Further, this data is supplied to and stored in the backward prediction image section 63b of the frame memory 63 via the inverse quantization circuit 60, the IDCT circuit 61, and the computing unit 62.

In the forward prediction mode, the switch 53d is switched to the contact b, and the image data (in this case, the I picture image) stored in the forward prediction image portion 63a of the frame memory 63 is read out to move. The compensation circuit 64 compensates for the motion vector output from the motion vector detection circuit 50. That is, when the prediction determination circuit 54 instructs the motion compensation circuit 64 to set the forward prediction mode, the motion compensation circuit 64 sets the read address of the forward predicted image portion 63a to the position of the macroblock currently output by the motion vector detection circuit 50. Read data by shifting from the corresponding position by the amount corresponding to the motion vector,
Generate predicted image data.

The predicted image data output from the motion compensation circuit 64 is supplied to the calculator 53a. Calculator 53a
Subtracts the predicted image data corresponding to this macroblock supplied from the motion compensation circuit 64 from the data of the macroblock of the reference image supplied from the prediction mode switching circuit 52, and outputs the difference (prediction error). To do. This difference data is the DCT mode switching circuit 55, DC
T circuit 56, quantization circuit 57, variable length coding circuit 58,
It is transmitted to the transmission line via the transmission buffer 59. Also,
This difference data is stored in the inverse quantization circuit 60 and the IDCT circuit 6
It is locally decoded by 1 and input to the calculator 62.

The same data as the predicted image data supplied to the calculator 53a is also supplied to the calculator 62. The calculator 62 adds the predicted image data output by the motion compensation circuit 64 to the difference data output by the IDCT circuit 61. As a result, the image data of the original (decoded) P picture is obtained. The image data of the P picture is supplied to and stored in the backward predicted image portion 63b of the frame memory 63.

In this way, the motion vector detection circuit 50 executes the process of the B picture after the data of the I picture and the P picture are stored in the forward predicted image portion 63a and the backward predicted image portion 63b, respectively. The prediction mode switching circuit 52 and the prediction determination circuit 54 correspond to the magnitude of the sum of absolute values of inter-frame differences in macroblock units,
The frame / field mode is set, and the prediction mode is set to either the intra-frame prediction mode, the forward prediction mode, the backward prediction mode, or the bidirectional prediction mode.

As described above, the switch 53d is switched to the contact point a or b in the intra-frame prediction mode or the forward prediction mode. At this time, the same processing as in the P picture is performed and the data is transmitted.

On the other hand, when the backward prediction mode or the bidirectional prediction mode is set, the switch 53d is switched to the contact c or d, respectively.

In the backward prediction mode in which the switch 53d is switched to the contact point c, the image (in this case, P picture image) data stored in the backward predicted image section 63b is read out and the motion compensation circuit 64 is read. Thus, motion compensation is performed corresponding to the motion vector output by the motion vector detection circuit 50. That is, when the prediction determination circuit 54 instructs the motion compensation circuit 64 to set the backward prediction mode,
The read address of the backward predicted image portion 63b is shifted from the position corresponding to the position of the macro block currently output by the motion vector detection circuit 50 by the amount corresponding to the motion vector, and the data is read to generate predicted image data.

The predicted image data output from the motion compensation circuit 64 is supplied to the calculator 53b. Calculator 53b
Subtracts the predicted image data supplied from the motion compensation circuit 64 from the macroblock data of the reference image supplied from the prediction mode switching circuit 52, and outputs the difference. This difference data is stored in the DCT mode switching circuit 5
5, the DCT circuit 56, the quantization circuit 57, the variable length coding circuit 58, and the transmission buffer 59.

In the bidirectional prediction mode in which the switch 53d is switched to the contact point d, the image data (in this case, the I picture image) stored in the forward predicted image portion 63a and the backward predicted image portion 63b are stored. The image data (in this case, the image of the P picture) being read is read out, and the motion compensation circuit 64 causes the motion vector detection circuit 5
Motion compensation is performed according to the motion vector output by 0.
That is, the motion compensation circuit 64, when the bidirectional prediction mode setting is instructed by the prediction determination circuit 54, the motion vector detection circuit 50 now outputs the read addresses of the forward predicted image portion 63a and the backward predicted image portion 63b. The data is read out by shifting the amount corresponding to the motion vector (in this case, there are two for the forward prediction image and the backward prediction image) from the position corresponding to the position of the existing macroblock, and the prediction image data is generated. To do.

The predicted image data output from the motion compensation circuit 64 is supplied to the calculator 53c. Calculator 53c
Subtracts the average value of the predicted image data supplied from the motion compensation circuit 64 from the macroblock data of the reference image supplied from the motion vector detection circuit 50, and outputs the difference. This difference data is transmitted to the transmission line via the DCT mode switching circuit 55, the DCT circuit 56, the quantization circuit 57, the variable length coding circuit 58, and the transmission buffer 59.

The B picture image is not stored in the frame memory 63 because it is not used as a predicted image of another image.

In the frame memory 63, the forward predictive image portion 63a and the backward predictive image portion 63b are bank-switched as necessary, and a predetermined reference image
The one stored in one or the other can be switched and output as the forward prediction image or the backward prediction image.

In the above description, the luminance block is mainly described, but the same applies to the color difference block in FIG.
The macroblocks shown in FIG. 8 are processed as a unit and transmitted. The motion vector used for processing the color difference block is obtained by halving the motion vector of the corresponding luminance block in each of the vertical direction and the horizontal direction.

Next, FIG. 9 is a block diagram showing the structure of an example of the decoder 31 shown in FIG. Transmission line (recording medium 3)
The coded image data transmitted via the receiver is received by a receiving circuit (not shown), reproduced by a reproducing device, temporarily stored in the receiving buffer 81, and then, the variable length decoding circuit 82 of the decoding circuit 90. Is supplied to. Variable length decoding circuit 82
Performs variable length decoding of the data supplied from the reception buffer 81, and outputs the motion vector, the prediction mode, the prediction flag and the DCT flag to the motion compensation circuit 87, and the quantization step to the dequantization circuit 83. At the same time, the decoded image data is output to the inverse quantization circuit 83.

The inverse quantization circuit 83 is used in the variable length decoding circuit 8
The image data supplied from No. 2 is inversely quantized according to the quantization step supplied from the variable length decoding circuit 82, and output to the IDCT circuit 84. The data (DCT coefficient) output from the inverse quantization circuit 83 is the IDCT circuit 8
In step 4, inverse DCT processing is performed and the result is supplied to the calculator 85.

When the image data supplied from the IDCT circuit 84 is I-picture data, the image data is output from the arithmetic unit 85 and is subsequently input to the arithmetic unit 85 (P or B-picture data). Is generated and supplied to the forward prediction image unit 86a of the frame memory 86 to be stored therein. Further, this data is output to the format conversion circuit 32 (FIG. 4).

When the image data supplied from the IDCT circuit 84 is P picture data in which the image data one frame before is the predicted image data, and is the data in the forward prediction mode, the forward prediction of the frame memory 86 is performed. The image data of one frame before (image data of I picture) stored in the image portion 86a is read out, and the motion compensation circuit 8
At 7, motion compensation corresponding to the motion vector output from the variable length decoding circuit 82 is performed. Then, in the calculator 85, the image data (difference data) supplied from the IDCT circuit 84 is added and output. The added data, that is, the decoded P picture data is
In order to generate predictive image data of image data (B-picture or P-picture data) input later to the calculator 85, it is supplied and stored in the backward predictive image section 86b of the frame memory 86.

Even in the case of P-picture data, the intra-picture prediction mode data is stored in the backward-prediction image section 86b as it is without any special processing by the calculator 85, like the I-picture data.

Since this P picture is an image to be displayed next to the next B picture, it is not yet output to the format conversion circuit 32 at this time (as described above, the P input after the B picture is input). Pictures have been processed and transmitted before B pictures).

When the image data supplied from the IDCT circuit 84 is B picture data, it is stored in the forward predicted image portion 86a of the frame memory 86 in accordance with the prediction mode supplied from the variable length decoding circuit 82. Has been I
The image data of the picture (in the case of the forward prediction mode), the image data of the P picture stored in the backward prediction image portion 86b (in the case of the backward prediction mode), or both image data (in the case of bidirectional prediction mode) The motion compensation circuit 87 reads out and performs motion compensation corresponding to the motion vector output from the variable length decoding circuit 82,
A predicted image is generated. However, when motion compensation is not required (in the case of the intra-picture prediction mode), the predicted picture is not generated.

The data which has been motion-compensated by the motion compensation circuit 87 in this way is sent to the IDC in the calculator 85.
It is added to the output of the T circuit 84. This addition output is output to the format conversion circuit 32.

However, since this addition output is B picture data and is not used for generating a predicted image of another image, it is not stored in the frame memory 86.

After the B picture image is output, the P picture image data stored in the backward predicted image section 86b is read out, and the arithmetic unit 85 is passed through the motion compensation circuit 87.
To the format conversion circuit 32. However, at this time, motion compensation is not performed.

The decoder 31 includes a prediction mode switching circuit 52 and a DCT in the encoder 18 of FIG.
Although the circuits corresponding to the mode switching circuit 55 are not shown, the processing corresponding to these circuits, that is, the configuration in which the signals of the lines in the odd field and the even field are separated is necessary for the original mixed configuration. The motion compensation circuit 87 executes the process of returning.

Further, although the processing of the luminance signal has been described above, the processing of the color difference signal is performed in the same manner.
However, in this case, the motion vector used for the luminance signal is halved in the vertical and horizontal directions.

Next, the quantization circuit 57 and the inverse quantization circuit 6
The weighting matrix used at the time of quantization or dequantization at 0 and 83 will be described.
In these circuits, a waiting matrix as shown in FIG. 10 is prepared. FIG. 10 (A)
Is a weighting matrix for intra macroblocks, and FIG. 10B is a weighting matrix for inter macroblocks.

The quantizing circuit 57 of the encoder 18 is provided with a quantizing weighting matrix circuit 102 as shown in FIG. 11, and the quantizing weighting matrix circuit 102 is provided for intra and inter shown in FIG. 2 weighting matrices are stored. The weighting coefficient (8 bits) of the weighting matrix is supplied to the quantizing circuit 57. Further, the quantization characteristic circuit 103 generates the quantization characteristic QUANT (9 bits) according to the feedback data corresponding to the data storage amount in the transmission buffer 59, and the quantization characteristic QUANT (9 bits) is supplied to the quantization circuit 57. The quantization circuit 57, for the 12-bit DCT coefficient 101 supplied from the DCT circuit 56, weights these weighting coefficients Weighting (i, j) and the quantization characteristic QUA.
The calculation according to the following equation is performed corresponding to NT.

In the intra mode, this calculation is performed as follows. That is, the quantization level QAC (i, j) of the AC component output from the quantization circuit 57 is calculated by the following equation. QAC (i, j) = 8 × (Coeff (i, j) + sign (Coeff (i, j)) / (QUANT × Weighting (i, j)) However, Coeff (i, j) is from the DCT circuit 56. Represents the data at the position (i, j) of the output DCT coefficient,
sign (Coeff (i, j)) represents the polarity of the DCT coefficient (that is, +1 when the coefficient is positive and −1 when the coefficient is negative). Further, the weighting coefficient We at this time
The value in FIG. 10A is used as the lighting (i, j).

The quantization level QAC (i, j) is −
Clipped to fall in the range of 255 to +255.

Unlike the AC component, the DC component of the quantization level is calculated by the following equation. QDC = Coeff (0,0) / 8

This quantization level QDC and QAC
(I, j) is supplied to the variable length coding circuit 58, variable length coded and transmitted.

On the other hand, in the inter mode, the calculation in the quantization circuit 57 is performed as shown in the following equation. QAC (i, j) = ac (i, j) / (2 × QUANT) (when QUANT is an odd number) = (ac (i, j) +1) / (2 × QUANT) (QUANT is an even number, and ac (i, j) is negative) = (ac (i, j) -1) / (2 * QUANT) (when QUANT is an even number and ac (i, j) is positive)

However, ac (i, j) is expressed by the following equation. ac (i, j) = 8 × Coeff (i, j) / Weighting (i, j)

Weighting coefficient We in this case
The value in FIG. 10B is used as the lighting (i, j).

On the encoder 18 side, the weighting matrix is changed as necessary to control the amount of information and the image quality. Since the same weighting matrix is required on the decoder 31 side as well, when the weighting matrix is changed, the weighting matrix is transmitted to the decoder 31.

FIG. 12 shows a configuration example for transmitting a weighting matrix in the quantization weighting matrix circuit 102. As shown in the figure, the quantization weighting matrix circuit 102 is
It has a table 201 in which a weighting matrix is stored, a register 202, and a subtractor 203. The table 201 stores a predetermined weighting matrix as needed.

When transmitting this weighting matrix, the weighting matrix having 64 weighting coefficients to be transmitted is zigzag scanned as shown in FIG. 13, for example. In FIG. 13, the numbers indicate the scanning order. As a result, each weighting coefficient of the weighting matrix shown in FIG. 10 is read from the table 201 in the order shown in FIG.

Each weighting coefficient of the weighting matrix is composed of M bits (for example, 8 bits) as described above. The register 202 latches the M-bit first weighting coefficient read from the table 201. Then, the latched first weighting coefficient is used as data 205 without changing the M bits.
As the first output.

Next, when the second M-bit weighting coefficient is read from the table 201, this weighting coefficient is supplied to the subtracter 203. The subtractor 203 is also supplied with the first M-bit weighting coefficient stored in the register 202. The subtractor 203 subtracts the first weighting coefficient from the second weighting coefficient, and outputs the difference data as N-bit data 204 smaller than M bits.

In this way, the data related to the weighting matrix output from the quantization weighting matrix circuit 102 is supplied to the variable length coding circuit 58, variable length coded and transmitted. The bit stream in this case is as shown in FIG.

In FIG. 14, (i, j) is shown in FIG.
The weighting coefficient at the position (i, j) of the weighting matrix shown in FIG. As shown in the figure, the first weighting coefficient Weighting
(0,0) (weighting coefficient corresponding to the DC component of the DCT coefficient) is transmitted in M bits, and the other DCT
The coefficient corresponding to the AC component of the coefficient is transmitted with an accuracy of N bits smaller than M bits. Therefore, the amount of transmission can be reduced as compared with the case where all the weighting coefficients are transmitted with M bits.

The bit precision (N) of the differential data to be transmitted need not be transmitted from the encoder side to the decoder side if it is fixed in advance on the decoder side and the encoder side, but if necessary. When it is changed, it is necessary to transmit from the encoder side to the decoder side. In this case, the bit precision flag 206 is multiplexed with the differential data in the bit stream and transmitted.

The inverse quantizing circuit 83 of the decoder 31 (similarly to the inverse quantizing circuit 60 of the encoder 18), the quantizing weighting matrix circuit 112, as shown in FIG.
And a quantization characteristic circuit 113.

Quantization weighting matrix circuit 1
12 is a register 302, as shown in FIG.
It is composed of a table 303 and an adder 305.
The register 302 stores the transmitted M-bit first weighting coefficient 301, supplies it to the table 303 as it is, and stores it. Next, the second N
When the bit difference data 304 is input to the adder 305, the adder 305 adds the M-bit first weighting coefficient stored in the register 302 to this difference data, and outputs the M-bit data as the M-bit register 302.
Output to. The register 302 stores this data,
Further, it is supplied to the table 303 and stored. The above operation is sequentially repeated, and the weighting matrix is generated in the table 303 in the order of zigzag scanning.

When the bit precision flag 306 of N-bit difference data is supplied, the precision of the N-bit data input to the adder 305 is adjusted according to this flag.

As described above, the weighting coefficient Weighting (i, of the weighting matrix stored in the quantization weighting matrix circuit 112).
j) is supplied to the inverse quantization circuit 83. In addition, the quantization characteristic circuit 113 has a 5-bit quantization characteristic QU corresponding to the quantization characteristic decoded by the variable length decoding circuit 82.
ANT is generated and supplied to the inverse quantization circuit 83. The inverse quantization circuit 83 is supplied with the variable length decoding circuit 82 from the 9
The bit quantization level 111 is calculated according to these data as shown in the following equation.

That is, in the case of the intra mode (the weighting matrix shown in FIG. 10A is used), the reproduction value rec output from the inverse quantization circuit 83.
(I, j) is calculated by the following equation. rec (i, j) = QUANT × QAC (i, j) × Weighting (i, j) / 8

However, when rec (i, j) is even and positive, the following equation is calculated. rec (i, j) = rec (i, j) -1 When rec (i, j) is even and negative, the following equation is calculated. rec (i, j) = rec (i, j) +1

That is, the reproduction value rec (i, j) is set to an odd number. As a result, variations in the IDCT circuit 84 can be suppressed.

Furthermore, when QAC (i, j) is 0, rec (i, j) is 0.

The DC component of the reproduced value is exceptionally processed as follows. rec (0,0) = 8 × QDC

The reproduction value rec (i, j) is clipped so as to fall within the range of -2048 to +2047.

In the inter mode (the weighting matrix shown in FIG. 10B is used), the following calculation is performed. That is, QAC
When (i, j) is positive, it is calculated by the following equation. rec (i, j) = (2 × QAC (i, j) +1) × QUANT × Weighting (i, j) / 16

Further, when QAC (i, j) is negative, it is calculated by the following equation. rec (i, j) = (2 * QAC (i, j) -1) * QUANT * Weighting (i, j) / 16

When rec (i, j) is even and positive, the following equation is calculated. rec (i, j) = rec (i, j) -1

Furthermore, rec (i, j) is an even number,
And if it is negative, the following equation is calculated. rec (i, j) = rec (i, j) +1

Furthermore, when QAC (i, j) is 0, rec (i, j) is 0.

As the difference data, it is possible to assign a variable length code according to the frequency of occurrence of transmission data. Table 1 shows an example of the variable-length code in the case where the N-bit difference data is signed 5-bit data (the polarity is 1 bit and the remaining 4 bits are absolute bits).

[0129]

[Table 1]

As shown in this table, the variable length code (VLC
The code is short in the vicinity of 0, and becomes longer as the absolute value thereof becomes larger. Since the difference data often has a value near the absolute value of 0,
By performing such allocation, the transmission data can be reduced.

Alternatively, as in the case of coefficient data, it is possible to perform coding and transmission by a two-dimensional variable length code in which the number of consecutive 0s (zero run) and the value (level) immediately after that are combined. .

FIG. 17 and FIG. 18 show another scanning order for transmitting 64 weighting matrices or difference data thereof. In the embodiment of FIG. 17, scanning is performed horizontally from left to right and from top to bottom. The data at the beginning of each row is M bits, but the subsequent data adjacent in the horizontal direction is N bits of data. And after the rightmost data is transmitted,
Next, move to the line below it, and the first data at the left end is
It is transmitted as M-bit data, and the following data is
It is transmitted as N-bit data. The same operation is repeated thereafter.

As shown in FIG. 10, regarding each data of the weighting matrix, when attention is paid to each row, in each row, the data at the left end tends to be small and the data at the right end tend to become large. Then, when the scan order shifts from the rightmost data to the leftmost data of the next lower row, the difference becomes relatively large. So, in this case,
Since the value at the left end of the data is smaller than that at the difference data, the left end data of each row is not transmitted as N bit difference data, but the original M bit data itself. Is transmitted.

In the embodiment shown in FIG. 18, the scanning direction is set to the vertical direction. As shown in the weighting matrix of FIG. 10, the weighting coefficient in each column tends to gradually increase from top to bottom. When the scan order is moved from the left column to the right column adjacent thereto, the difference between the data on the bottom of the left column and the data on the top of the right column is It may be larger than the top data of. Therefore, as in the case of FIG. 17, the head data of each column is transmitted as it is as M-bit data, and the data following it is transmitted as N-bit difference data.

FIG. 19 shows another example of encoding.
In this embodiment, default values for the weighting matrix are prepared in advance. When the default value is desired to be changed, the changed (transmitted) weighting matrix is prepared on the decoder side. Then, the difference from the weighting matrix to be transmitted is calculated, and this difference is encoded and transmitted.

Normally, each weighting coefficient of the weighting matrix to be transmitted rarely changes significantly from the weighting coefficient of the weighting matrix as the default. Therefore, the difference data of the corresponding weighting coefficient is often 0. In this embodiment, of the 64 corresponding coefficient weighting difference data, 56 pieces of data are 0 and only the remaining 8 pieces are data having a level other than 0. Therefore, if this data is transmitted at the run level by, for example, a zigzag scan, the data becomes (21,
2), (12,3), (0,3), (0,6), (0,
5), (9, 2), (0, 5) and (0, 5).

The encoded data can be recorded on a disc as a recording medium. FIG. 20 shows a method of manufacturing such a disc. That is, for example, a master disk made of glass or the like is prepared, and a recording material made of photoresist or the like is applied onto the master disk. As a result, a recording master is produced. On the other hand, as described above, the bit stream including the high-resolution image data and the low-resolution image data is once recorded on a magnetic tape or the like according to a predetermined format, and software is produced.

This software is edited as necessary to generate a signal of a format to be recorded on the optical disc. Then, in response to this recording signal, the laser beam is modulated,
This laser beam is irradiated onto the photoresist on the master. As a result, the photoresist on the master is exposed according to the recording signal.

Then, this master is developed to make pits appear on the master. The master thus prepared is subjected to a process such as electroforming to manufacture a metal master in which the pits on the glass master are transferred. A metal stamper is further manufactured from this metal master and used as a molding die.

A material such as PMMA (acrylic) or PC (polycarbonate) is injected into this molding die by, for example, injection or the like to be solidified. Alternatively, 2P (ultraviolet curable resin) or the like is applied on the metal stamper and then irradiated with ultraviolet rays to be cured. This allows
The pits on the metal stamper can be transferred onto a replica made of resin.

On the replica thus generated,
The reflective film is formed by vapor deposition or sputtering. Alternatively, it is formed by spin coating.

Then, the inner and outer diameters of this disc are processed, and necessary treatments such as laminating two discs are performed. Further, a label is attached, a hub is attached, and the label is inserted into the cartridge. In this way, the optical disc is completed.

[0143]

As described above, according to the image signal coding method of the first aspect, the weighting coefficient of the weighting matrix is transmitted as a difference from the preceding weighting coefficient. Can be made smaller.

Further, according to the image signal coding method of the second, third or fourth aspect, since the weighting coefficient is zigzag-scanned or is scanned in the horizontal or vertical direction and transmitted, the weighting coefficient is transmitted. It is possible to reduce the difference between and to transmit.

According to the image signal decoding method of the fifth aspect, since the differential bit precision is transmitted, it is possible to change the differential bit precision as necessary.

According to the image signal coding method of the sixth aspect, since the difference is variable length coded and transmitted, the transmission amount can be further reduced.

According to the image signal coding method of the seventh aspect, since the difference is transmitted by the zero run method, the data amount can be surely reduced.

According to the image signal coding method of the eighth aspect, since the difference between each weighting coefficient of the weighting matrix and the default value is transmitted, most of the difference can be set to 0, The amount of transmitted data can be reduced.

According to the image signal coding method of the ninth aspect, since the difference is transmitted with a fixed length of N bits, the configuration can be simplified.

According to the image signal coding method of the tenth aspect, since the difference is transmitted by the zero run method, the transmission amount can be further suppressed.

According to the image signal coding apparatus of the eleventh aspect, since the image signal coding method of any one of the first to tenth aspects is used, the weighting of the weighting matrix is performed with a smaller amount of data. It becomes possible to realize an apparatus capable of transmitting coefficients.

According to the image signal decoding method of the twelfth aspect, since the transmitted weighting coefficient is decoded by adding it to the preceding weighting coefficient, it is transmitted with a small transmission amount. From the data
It is possible to reliably decode the original weighting coefficient.

According to the image signal decoding method of the thirteenth to fifteenth aspects, the weighting matrix transmitted is arranged in a zigzag scan order, a horizontal direction order, or a vertical direction order to obtain a weighting matrix. Is generated, the weighting matrix can be surely generated.

According to the image signal decoding method of the sixteenth aspect, since the bit precision of the weighting coefficient is set in correspondence with the transmitted bit precision, the bit precision of the weighting coefficient is changed. Also, it becomes possible to reliably obtain the original weighting coefficient.

According to the image signal decoding method of the seventeenth aspect, since the weighting matrix is generated by adding the transmitted data to the default value, the weighting matrix can be generated quickly and surely. It becomes possible to do.

According to the image signal decoding apparatus of the eighteenth aspect, since the image signal decoding method of any one of the twelfth to seventeenth aspects is used, the data can be surely decoded. Possible devices can be realized.

According to the image signal recording medium of the nineteenth aspect, data is recorded by using the image signal encoding method according to any one of the first to tenth aspects, so that the capacity is limited. It becomes possible to record much information in.

[Brief description of drawings]

FIG. 1 is a diagram showing the principle of high efficiency encoding.

FIG. 2 is a diagram illustrating a picture type.

FIG. 3 is a diagram showing the principle of a moving image signal encoding method.

FIG. 4 is a block diagram showing a configuration example of a moving image encoding device and a decoding device.

FIG. 5 is a diagram illustrating a structure of image data.

6 is a block diagram showing a configuration example of an encoder 18 of FIG.

7 is a diagram illustrating a prediction mode in the prediction mode switching circuit 52 of FIG.

8 is a diagram illustrating a frame / field DCT mode in the DCT mode switching circuit 55 of FIG.

9 is a block diagram showing a configuration example of a decoder 31 of FIG.

FIG. 10 is a diagram illustrating a weighting matrix.

11 is a diagram showing a more detailed configuration of the quantization circuit 57 of FIG.

12 is a block diagram showing a configuration example of a quantization weighting matrix circuit 102 of FIG.

FIG. 13 is a diagram illustrating zigzag scanning.

FIG. 14 is a diagram illustrating an order of transmitting a weighting matrix by zigzag scanning.

15 is a diagram showing a more detailed configuration of the inverse quantization circuit 83 of FIG.

16 is a block diagram showing a more detailed configuration of the quantization weighting matrix circuit 112 of FIG.

FIG. 17 is a diagram for explaining the operation of scanning the weighting matrix in the horizontal direction.

FIG. 18 is a diagram illustrating an operation of vertically scanning a weighting matrix.

FIG. 19 is a diagram illustrating an operation of transmitting a weighting matrix as a difference from a default value.

FIG. 20 is a diagram illustrating a disc manufacturing method.

[Explanation of symbols]

1 Encoding Device 2 Decoding Device 3 Recording Medium 12, 13 A / D Converter 14 Frame Memory 15 Luminance Signal Frame Memory 16 Color Difference Signal Frame Memory 17 Format Conversion Circuit 18 Encoder 31 Decoder 32 Format Conversion Circuit 33 Frame Memory 34 Luminance Signal Frame memory 35 Color difference signal frame memory 36, 37 D / A converter 50 Motion vector detection circuit 51 Frame memory 52 Prediction mode switching circuit 53 Calculator 54 Prediction determination circuit 55 DCT mode switching circuit 56 DCT circuit 57 Quantization circuit 58 Variable length Encoding circuit 59 Transmission buffer 60 Inverse quantization circuit 61 IDCT circuit 62 Operator 63 Frame memory 64 Motion compensation circuit 81 Reception buffer 82 Variable length decoding circuit 83 Inverse quantization circuit 84 IDCT circuit 85 arithmetic unit 86 frame memory 87 motion compensation circuit 102, 112 quantization weighting matrix circuit 103, 113 quantization characteristic circuit 201 table 202 register 303 table

Claims (19)

[Claims] 1. An image signal is encoded using a predetermined predicted image signal, a predetermined operation is performed on the encoded signal, and the signal obtained by the operation is quantized using a predetermined weighting matrix, In the image signal coding method for variable-length coding a coded signal, the first weighting coefficient of the weighting matrix is transmitted as complete M-bit data, and the subsequent weighting coefficient is the weighting coefficient from the preceding weighting coefficient. An image signal encoding method, wherein a difference is calculated, and the difference is transmitted as N-bit data smaller than the M-bit. 2. The image signal encoding method according to claim 1, wherein each weighting coefficient of the weighting matrix is transmitted in a zigzag scan order. 3. The image signal encoding method according to claim 1, wherein each weighting coefficient of the weighting matrix is sequentially scanned in the horizontal direction and transmitted. 4. The image signal encoding method according to claim 1, wherein each weighting coefficient of the weighting matrix is sequentially scanned in the vertical direction and transmitted. 5. The image signal coding method according to claim 1, wherein the bit precision of the difference is transmitted. 6. The image signal coding method according to claim 1, wherein the difference is variable length coded and transmitted. 7. The image signal coding method according to claim 6, wherein the difference is transmitted as a number of consecutive zeros and a level following the number. 8. An image signal is encoded using a predetermined predicted image signal, a predetermined operation is performed on the encoded signal, and the signal obtained by the operation is quantized using a predetermined weighting matrix, An image signal coding method for variable length coding a coded signal, wherein a difference between each weighting coefficient of the weighting matrix and a default value is calculated, and the difference is coded and transmitted. Method. 9. The image signal encoding method according to claim 8, wherein the difference is encoded into a fixed length of N bits and transmitted. 10. The difference is the number of consecutive zeros,
9. The image signal coding method according to claim 8, wherein the signal is transmitted as a subsequent level. 11. An image signal encoding apparatus using the image signal encoding method according to any one of claims 1 to 10. 12. A variable-length coded image signal is decoded, the decoded signal is inversely quantized using a predetermined weighting matrix transmitted, and an inversely quantized signal is obtained by encoding. In an image signal decoding method of performing a predetermined operation which is the reverse of the above, and decoding the calculated signal using a predetermined predicted image signal, the first weighting coefficient of the transmitted weighting matrix is set to a complete M An image signal decoding method characterized in that decoding is performed as bit data, and the subsequent weighting coefficient is decoded by adding it to the preceding weighting coefficient. 13. The image signal decoding method according to claim 12, wherein the weighting coefficients are arranged in a zigzag scan order to generate the weighting matrix. 14. The image signal decoding method according to claim 12, wherein the weighting coefficients are sequentially arranged in a horizontal direction to generate the weighting matrix. 15. The image signal decoding method according to claim 12, wherein the weighting coefficients are arranged in order in the vertical direction to generate the weighting matrix. 16. The bit precision of a weighting coefficient following the first weighting coefficient is determined by decoding the transmitted bit precision.
16. The image signal decoding method according to any one of 2 to 15. 17. A variable-length coded image signal is decoded, the decoded signal is inversely quantized using a predetermined weighting matrix transmitted, and an inversely quantized signal is obtained at the time of encoding. In the image signal decoding method of performing a predetermined calculation opposite to the case and decoding the calculated signal using a predetermined prediction image signal, the difference between the transmitted weighting matrix and the default value is An image signal decoding method, wherein the weighting matrix is generated by adding the weighting matrix to a default value. 18. An image signal decoding apparatus using the image signal decoding method according to any one of claims 12 to 17. 19. An image signal recording medium, wherein data is recorded using the image signal encoding method according to any one of claims 1 to 10.