JPH03214989A - Motion compensated predictive interframe coding device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a motion compensated predictive interframe coding device for television control signals.

2. Description of the Related Art In recent years, with the development of video encoding technology, video telephones, video conference systems, CD4LOM. f digital VT
A motion-compensated predictive interframe coding device has been developed as a high-efficiency coding device for color video images used in R and the like. For example, see Multidimensional Signal Processing of rTV Images J by Takahiko Fukinuki (
Published November 15, 1988, Nikkan Kogyo Shimbun, No. 7
A motion compensated predictive interframe coding device is known, which is described in Chapter 1, High Efficiency Coding, pp2t3-pI) 291).

In a motion compensated predictive interframe coding device, the generated code I is used in order to realize video coding at a constant frame rate.
If there are many prediction errors or pixel values of the input television signal, the quantization step size is increased to limit the amount of code generated.

As a conventional method for determining the quantization step size, C.
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A motion-compensated predictive interframe coding device is known, which is described in RSION:June, g+1gBg'').

Hereinafter, a conventional motion compensation predictive interframe coding device will be described with reference to FIG. In Figure 2, 51
Reference numeral 53 indicates an input terminal to which an input TV control signal is input; 53 indicates a motion vector calculation unit that compares the image signal of the encoded block of the current frame with the reproduced image signal of the previous frame to calculate the motion vector of the encoded block; 54 indicates the current frame; 58 is a motion compensation prediction unit that performs motion compensation prediction on the reproduced image signal of the previous frame; and 58 is a motion compensation prediction unit that performs motion compensation prediction on the reproduced image signal of the previous frame, and performs intraframe encoding or interframe encoding of the block to be encoded. 62 is an in-loop filter unit that performs two-dimensional low-pass filter processing on the motion-compensated prediction signal; 64 calculates the difference between the original signal and the prediction signal of the encoded block to calculate the prediction error; A prediction error calculation unit 66 selects a signal to be orthogonally transformed and a signal to be used for calculating a reproduced image based on a coding method selection signal. 68 is an orthogonal transformer that orthogonally transforms the signal to be orthogonally transformed. 70 is a quantization unit that quantizes orthogonal transform coefficients, 73 is a quantization step size calculation unit that calculates a doji conversion step size, 74 is a code memory unit that temporarily stores transmission frames, and 76 //i quantized an inverse orthogonal transform unit that performs inverse orthogonal transform on orthogonal transform coefficients, 78
8 is a reproduced image calculation unit that calculates a reproduced image of the current frame;
2 is a prediction error encoding unit that encodes the prediction error through channel coding; 8
Reference numeral 4 designates a motion vector encoding unit that encodes a motion vector through a channel, 86 a multiplexer unit that configures a transmission frame from a prediction code and a motion vector code, and 89 an output terminal that outputs a transmission signal.

The operation of the above configuration will be explained below. The television signal is converted into a digital signal by an analog-to-digital conversion circuit (not shown) and divided into blocks of M pixels in the horizontal direction and N lines in the vertical direction.
It is input as an input television signal 52 from an input terminal 51 .

The motion vector calculation section 53 compares the input television signal 52 with the reproduced television signal 55 of the previous frame stored in the image memory section 54, calculates the motion of the encoded block as a motion vector, and generates a motion vector signal 56. Output to. At the same time, the motion vector calculation unit 53 uses the evaluation value at the time of motion vector calculation to determine whether motion compensation prediction is valid or invalid for the encoded block, and outputs the result as a motion compensation prediction control signal to the motion vector signal 56. . Therefore, the motion vector signal 56 has a motion vector and a motion compensated prediction signal superimposed thereon.

The motion compensation prediction unit 58 (1) performs motion compensation prediction on the reproduced television signal 55 of the previous frame using a motion vector when the motion compensation prediction control signal instructs to enable motion compensation prediction; If the compensation prediction control signal instructs invalidation of motion compensation prediction, the reproduced television signal 55 of the previous frame is output as is as a motion compensation prediction signal 59.

The inter-frame/intra-frame determination unit 60 compares the input television signal 52 and the motion compensation prediction signal 59 in units of blocks, determines the effectiveness of the motion compensation prediction, and if the effectiveness of the motion compensation prediction is small, the corresponding block If the effectiveness of motion compensation prediction is high, it is determined that interframe coding is effective for the corresponding bronch, and the result is output as a coding method selection signal 6l. By switching the encoding method between the intra-frame encoding method and the inter-frame encoding method on a block-by-block basis, the following improvements can be made compared to the case where encoding is performed using only the inter-frame encoding method. (1) When a scene change occurs, intra-frame encoding is selected, so the image quality after a scene change can be improved. (2) When a large movement of a moving object occurs,
A background area hidden behind a moving object appears, and in this case, intra-frame encoding is selected, thereby improving image quality.

In addition, in the storage media encoding method used for CD-ROMs, etc., in order to realize the editing function and reverse playback function of the reproduced image, a frame in which all blocks are intra-frame encoded at a fixed frame period (this frame is , [refresh frame (referred to as 3refreshprame) J)], and the insertion of the refresh frame can be realized by providing the motion compensated predictive interframe coding device with an intraframe coding function.

The in-loop filter section 62 performs two-dimensional low-pass filter processing on the encoded block subjected to motion compensation prediction using the motion vector, and calculates a prediction signal 63. The prediction error calculation unit 64 calculates the difference between the input television signal 52 of the encoded block and the prediction signal 63, and outputs the result as a prediction error signal 65.

The switch unit 66 (1) selects the input television signal 52 as the signal 67 to be orthogonally transformed when the encoding method selection signal 61 selects intraframe encoding;
) If the encoding method selection signal 61 selects interframe encoding, the prediction error signal 65 is selected as the signal 67 to be orthogonally transformed.

The orthogonal transform unit 68 performs orthogonal transform on the signal 67 to be orthogonally transformed, removes high correlation between neighboring pixels of the signal 67 to be orthogonally transformed, and calculates orthogonal transform coefficients 69. As the orthogonal transform method, in many cases, discrete cosine transform is used, which has high transform efficiency and can be implemented in hardware.

, the quantization unit 70 quantizes the orthogonal transform coefficient 69 using the quantization step size 7l, and the orthogonal transform quantization coefficient 7
Calculate 2.

The quantization step size calculation unit 73 calculates the quantization step size 7l from the residual code amount 75 in the code memory unit 74 using the method shown below.

The method for calculating the quantized stenopsize 71 in this conventional example will be described below.

In this conventional example, the input television control signal has a size of 352 pixels in the horizontal direction and 288 lines in the vertical direction, as shown in FIG. [Macro block
Block) J and tail. ) is divided into two parts. The quantization step size Qb is calculated from the equation shown in equation (l) at the start of quantization with a period of 0 macroblocks.

Qb= 2 x INT (Bcont÷2009) +
2.-(1) However, in equation (1), it is defined as follows.

(aJ INT(*) is a function that truncates the fraction below the decimal point.

Example: INT[1.5]-1, INT(1.3)=1
, INT[:1.6:] = 1 (bJBcont indicates the remaining code amount in the code memory section 74.

(cl q is an encoding rate parameter, and has a relationship with the encoding rate V as shown in equation (2).

V= q x 64 kbit/sec
-- -42) Example: V = 64 kbit /
When sec, Q=1.

As is clear from equation (1), the residual code amount Bcont
As the number increases, the number of generated codes with a large quantization step size Qb is restricted, and video signal encoding at a constant frame rate can be realized. For example, ■ childization step size Q
When calculating b, the residual code Bcont = 7QQ b
When it is, the quantization step size Qb=8, and when the residual code amount Bcont=6100 bits, the quantization step size Qb=62.

However, from the first macroblock to the (n-1)th macroblock, quantization is performed with a predetermined quantization step size Qb.

For example, when V=64bit/see(q=1) (7), Qb=32.

In this conventional example, the calculation period n of the quantization step size Qb
Here, n=12.

The inverse orthogonal transform unit 76 performs inverse orthogonal transform on the orthogonal transform quantization coefficient 72 and calculates an orthogonally transformed signal 77 containing a quantization error.

The switch unit 66 (1) selects the numerical value "O" signal 80 as the reproduced image calculation signal 79 when the encoding method selection signal 61 selects intraframe encoding, and (2) selects the encoding method selection signal. If the signal 6l selects interframe coding, the predicted signal 63 is selected as the reproduced image calculation signal 79.

Reproduction image calculation unit 78 adds the orthogonally transformed signal 77 containing fi quantization error and the reproduction image calculation signal 79 to calculate the reproduction image 81 of the encoded block.

The image memory 44 stores the reproduced image signal 81 of the current frame and outputs the reproduced image signal 55 of the previous frame. The prediction error encoding unit 82 encodes the orthogonal transform Doji conversion coefficient 72, the quantization step size 71, and the encoding method selection signal 6l, and calculates the prediction error code 83. The quantization step size 7l is encoded only when the value of the quantization step size 71 changes, that is, once every n macroblocks.

The motion vector encoding unit 84 encodes the motion vector 56,
A motion vector code 85 is calculated. Multiplexer section 86
calculates a transmission frame 87 in a predetermined format from the prediction error code 83 and the motion vector code 85.

The code memory unit 74 temporarily stores the transmission frame 87,
It is output from an output terminal 89 as a transmission code 88 in synchronization with a clock signal input from an external source (not shown). At the same time, the code memory unit 74 calculates the amount of codes remaining in the memory as the remaining code amount 75.

Problems to be Solved by the Invention However, in the above configuration, the quantization step size Q
Since the block period (n macroblock period in the conventional example) for which b calculates the quantization step size is fixed, the same quantization occurs between consecutive n blocks regardless of the characteristics of the input television signal. conversion step size Qb
The orthogonal transform coefficients quantized by are quantized. In other words, within consecutive blocks belonging to the same quantization step size period, a block with a fine pattern to be intra-frame encoded has the same quantization step size Q as other blocks.
There is a problem in that the image quality of blocks having minute intra-frame encoded patterns is degraded because they are quantized by b. In other words, by quantizing the orthogonal transform coefficients generated from intra-frame encoded blocks with fine patterns using a large quantization step size, the fineness of the original image is lost, resulting in flat blocks. "distortion" occurred, which was visually recognized as a major deterioration in image quality. On the other hand, in order to reduce the amount of code generated by encoding the quantization step size, the number of consecutive blocks to be quantized with the same quantization step size must be greater than a certain value (in the conventional example, n macroblocks). So,
The quantization step size is calculated for each block and cannot be changed.

In view of the above-mentioned problems, it is an object of the present invention to maintain the fineness of the original image and improve the image quality as a result.

Means for Solving the Problems In order to achieve the above object, the technical solution of the present invention is as follows:
A/D converts television signals from analog to digital
a converting means, a blocking means for dividing one frame or one field of the digitized input television signal into blocks of a predetermined size, and a moving means for calculating a motion vector representing the movement of the television image for each block. a vector detection means; a motion compensation determination means for determining whether motion compensation prediction is to be performed using the motion vector for each block; a motion compensation prediction means for calculating a value; an error calculation means for calculating a difference between a pixel value of an input television signal and a predicted pixel value as a prediction error value; and a motion compensation prediction means for calculating a prediction error value as a prediction error value. a coding method determining means for determining whether to perform a coding method, and a signal to be orthogonally transformed based on the intra-frame coding/inter-frame coding judgment result for each block as a pixel value of an input television signal or a prediction error value; orthogonal transform means for orthogonally transforming pixel values or prediction error values of an input television signal to calculate orthogonal transform coefficients; and a first quantizer for calculating a first quantization step size from the generated code amount. an encoding step size determining means, an average/variance calculation means for calculating the average and variance of pixel values for each block of the input television signal, and a block to be intra-frame encoded that classifies the blocks based on the average and variance. A second quantization step size is calculated from the first quantization step size for each class, and for blocks to be interframe encoded, a second quantization step size is calculated using the first quantization step size as the second quantization step size. 2 quantization step size determination means; quantization means for quantizing orthogonal transform coefficients using the second quantization step size and calculating genoized orthogonal transform coefficients; information on the first quantization step size and quantization classification; and an encoding means for encoding the quantum-optimized orthogonal transform coefficients; an inverse quantization means for calculating a quantum sign, and a motion-compensated prediction of a pixel value to be used when calculating a reproduced pixel value based on the inter-frame coding/intra-frame coding determination result;
A switching means for switching between the I pixel value and the numerical value "0", an image reproducing means for calculating the reproduced image from the predicted pixel value or the numerical value "0" and the inverse quantization signal, and an image storage for accumulating the reproduced image. The above object is achieved by a motion compensated predictive interframe encoding device comprising a motion vector encoding means and a motion vector encoding means for encoding a motion vector.

It is considered that the precision of each block of the input television signal can be determined by the variance 02 of pixel values within the block. For example, the variance σ2 of a block with a fine turn is considered to be smaller than the variance σ2 of a coarse coblock with sharp changes in pixel values. It is thought that it will become smaller.

Furthermore, even if a block has a small variance, if the average value of pixel values is smaller than a certain value, it can be said that the block is visually hardly noticeable even if the precision is high.

Therefore, according to the present invention, with the above configuration, the precision of each block of the input television signal is measured by the variance σ2,
For consecutive blocks that are quantized using the same standard first quantization step size, that have minute images that are intra-frame encoded, and that have an average pixel value that is greater than or equal to a certain value, the above-mentioned The quantization step size of 1 is
The second block is made smaller in proportion to the precision of the corresponding block.
By quantizing orthogonal transform coefficients with a quantization step size of , it is possible to limit the amount of generated code and improve the image quality of a block containing a detailed image.

EXAMPLE A first example of the present invention will be described below with reference to FIG. FIG. 1 is a block diagram of a motion compensation predictive interframe coding apparatus in a first embodiment of the present invention. In Figure 1, 1 is an input terminal into which an input television signal is input, 3 is an encoding process for the current frame, and the video signal of the current frame is compared with the reproduced image signal of the previous frame to calculate the motion vector of the encoded block and motion compensation. a motion vector calculation unit that calculates a predictive control signal; 4 an image memory unit that stores the reproduced image signals of the current frame and the previous frame; 7 a motion compensation prediction unit that performs motion compensation prediction for the reproduced image signal of the previous frame; 9Fi; An inter-frame/intra-frame determining unit that determines whether a block to be encoded is to be inter-frame encoded or intra-frame encoded, 1
1 is an in-loop filter unit that performs two-dimensional low-pass filter processing on a motion-compensated prediction signal; 13 is a prediction error calculation unit that calculates a prediction error by calculating the difference between the original signal and the prediction signal of the encoded block; l5 is a code A switch unit selects a signal to be orthogonally transformed and a signal to be used to calculate a reproduced image according to a conversion method selection signal; l7 is an orthogonal transform unit that performs orthogonal transform; l9 is a quantizer that converts the orthogonal transform coefficients;
1 is a 21st childization step size calculation unit that calculates the second quantization step size, 22 is a first quantization size calculation unit that calculates the first quantization step size, and 25 is the average of the input TV screen signal. 30 is an inverse orthogonal transform unit that performs inverse orthogonal transform on quantized orthogonal transform coefficients; 34 is an inverse orthogonal transform unit that performs inverse orthogonal transform on quantized orthogonal transform coefficients; 36 is a prediction error encoding unit that encodes the encoding method selection signal, prediction error, first quantization step size, and quantization class information through a channel; 38 encodes a motion vector through a channel. 4o is a multiplexer unit that configures a transmission frame from a prediction code and a motion vector code, and 43 is an output terminal that outputs a transmission signal.

The operation of the above configuration will be explained below.

The television signal is converted from analog to digital by a signal processing unit not shown in FIG.
It is divided into blocks of N lines in the vertical direction, and is inputted as an input TV Jimin signal 2 from an input terminal 1. Next, the motion vector calculation section 3 compares the input television signal 2 with the reproduced image 5 of the previous frame read out from the image memory section 4, calculates a motion vector, and outputs it as a motion vector signal 6.

At the same time, the motion vector calculation unit 3 uses the evaluation value at the time of motion vector calculation to determine whether motion compensation prediction for the encoded block is valid or invalid, and outputs the result as motion compensation prediction control information to the motion vector signal 6. do.

The motion compensation prediction unit 7 performs motion compensation prediction using the motion vector when performing motion compensation prediction using the motion vector signal 6 on the reproduced image 5 of the previous frame at the same position as the encoded block, and does nothing when not performing motion compensation prediction. , the motion compensated prediction signal 8
Output as .

The inter-frame and intra-frame determination unit 9 compares the input television signal 2 and the motion compensation prediction signal 8 in block units,
The effectiveness of motion-compensated prediction is determined, and if the effectiveness of motion-compensated prediction is low, it is determined whether intra-frame coding is effective for the block concerned, and if the effectiveness of motion-compensated prediction is high, inter-frame coding is performed for the block. is determined to be valid, and outputs the result as an encoding method selection signal 10.

Furthermore, in the case of an encoding apparatus that requires insertion of a refresh frame, the intra-frame/inter-frame determining unit 9 outputs an encoding method selection signal 1o so as to perform intra-frame encoding on all blocks at a constant frame period.

The in-loop filter section 11 performs in-loop filter processing, which is two-dimensional low-pass filter processing, on the motion compensation prediction signal 8 when the encoded block is a block to be predicted with motion compensation, and in other cases, performs in-loop filter processing on the motion compensation prediction signal 8. It is output as the predicted signal 12 without being processed.

The prediction error calculation unit 13 performs a difference calculation between the input television signal 2 of the encoded block and the prediction signal l2, and outputs the result as a prediction error signal 14.

Switch unit 15/ri, (1) Encoding method selection signal 10
selects intraframe encoding, selects the input television control signal 2 as the signal l6 to be orthogonally transformed, and (
2) When the encoding method selection signal 10 selects interframe encoding, the prediction error signal l4 is selected as the signal l6 to be orthogonally transformed.

The orthogonal transform unit 17 performs orthogonal transform on the signal l6 to be orthogonally transformed, removes high correlation between neighboring pixels of the signal l6 to be orthogonally transformed, and calculates orthogonal transform coefficients 18. As the orthogonal transform method, in many cases, discrete cosine transform is used, which has high transform efficiency and can be implemented in hardware.

The quantization unit l9 quantizes the orthogonal transform coefficients 18 with a second quantization step size of 20. The method for calculating the second quantized stenopsize 20 will be described below.

(1) When the block to be encoded is an intra-frame encoded block, the 21st childization step size calculation unit 2l calculates the residual code amount 2 The first quantization step size calculated is output as the second quantization step size.

(2) When the block to be encoded is an interframe encoded block, calculate the average and variance of the pixel values of the encoded block using the method shown below, classify the corresponding block based on the calculated average and variance, A second quantization step size to be used in actual quantization is calculated for each class from the reference l-th unichild step size.

■The average/variance value calculation unit 25 calculates the average value μ and variance σ2 of the pixel values of the input television signal 2 of the encoded block to the (
3) and (4) and output as an average signal 44 and a variance signal 26. The average μ is used to determine whether to change the first step size depending on the precision of the block.

The variance σ takes a small value in a block where the input television signal 2 has high precision, and a large value in a block where the incoming television signal 2 has low precision.

However, equations (3) and (4) are defined as follows.

(a) M indicates the number of pixels in the horizontal direction of the block.

(b) N indicates the number of vertical lines in the block.

(C) P(i.j) is the address within the block (i.j)
indicates the pixel value of

(2) The second quantization step size calculation unit 21 calculates the second quantization step size 20 based on the average signal 44 and variance signal 26 of the encoded blocks and the first quantization step size 24.
and quantization class information 27 is calculated. The first quantization step size 24 is calculated by the first quantization step size calculation section 22 from the code residual amount 23 in the code memory section 28 using the method described in the conventional example.

The second quantization stenobe size calculation unit 2l calculates an average signal 44, a variance signal 26, and
and four predetermined threshold values thl, th2, th3,
th4 is compared, each block is divided into four quantization classes, and the first quantization step size is 2 depending on the doji class.
4, the second quantization step size 20 is calculated. However, the first quantization step size is Qb, and the second quantization step size is Qstep.

■ If O≦σ2(thl and μ)th4, Qst
ep Class = 1 Qs tep = ” Qb 4 ■ If thl≦02<th2 and μ>th4, Qst
ep Class = 2 Qstep = : Qb ■ Qst if th2≦σ2<th3 and μ)th4
ep Class = 3 Qstep = ”, Qb ■ Qstep if th3≦σ2 and μ)th4
Class = 4 Qstep = Qb By doing the above, the second quantization step size 20 of the block to be intra-frame encoded is such that the average value of the pixel values of the input television signal 2 is greater than or equal to a certain value,
In addition, for blocks with high precision, the size is smaller than the first quantization stem size 24.

The quantization unit l9 quantizes the orthogonal transform coefficients 14 with a second quantization step size 20, and calculates orthogonal transform quantized coefficients 29. The inverse orthogonal transform unit 30 converts orthogonal transform quantization coefficients 2
9 is subjected to inverse orthogonal transformation, and a signal 3l including a quantization error is calculated.

The switch section 16 (1) selects the numerical value "0" signal 33 as the reproduced image calculation signal 32 when the encoding method selection signal 10 selects intraframe encoding, and (2) selects the encoding method. When the signal 10 selects interframe coding, the predicted signal 12 is selected as the reproduced image calculation signal 32.

Reproduction image calculation unit 34 Signal 3 containing tri quantization error
1 and the reproduced image calculation signal 32 to calculate the reproduced image 35 of the encoded block. The image memory 4 stores the reproduced image signal 35 of the current frame and outputs the reproduced image signal 5 of the previous frame.

The prediction error encoding unit 36 includes an encoding method selection signal 10, a first quantization step size 24, and quantization class information 27.
, the orthogonal transform quantization coefficient 25 is encoded, and the prediction error code 3 is
Calculate 7.

The motion vector encoding unit 38 encodes the motion vector signal 6 of the block subjected to motion compensation prediction and calculates a motion vector code 39.

The multiplexer unit 40 calculates a transmission frame 41 in a predetermined format from the prediction error code 37 and the motion vector code 39.

The code memory unit 28//i transmission frame 41 is temporarily stored and output as a transmission code 42 from an output terminal 43 in synchronization with a clock signal input from an external device (not shown). At the same time, the code memory section 28 calculates the amount of codes remaining in the memory as the remaining code amount 23.

As is clear from the above description, according to this embodiment, in a group of consecutive blocks belonging to the same quantization stenobe size, if the block is intra-frame encoded and the average value of pixel values is greater than a certain value, the block The second quantization step size is smaller than the first reference quantization step size in proportion to the precision of
Since the second quantization step size is calculated and the orthogonal transform coefficients are quantized using the second quantization step size, the image quality of the entire image can be improved without impairing the precision of the image.

In the above explanation, the variance value 26 calculated by the mean/variance value calculation unit 25 is defined by equation (3), or it may be defined by other measurement scales as long as the variance can measure the fineness of the input television signal 2. But that's fine. For example, since the size of a block (horizontal pixel number 2M, vertical line number: N) is generally a fixed value, Fi is a numerical value D shown in equation (5) as a measure that is easy to calculate. However, P(i.j) represents the pixel value of the intra-block address (i.j), and μ represents the average pixel value of the block.

Further, in the above description, whether or not to change the first quantization step size is determined based on the average value of pixel values, but other measures expressing the characteristics of the entire pixel values may be used.

Furthermore, in the above description, the quantization stepsize size is divided into four classes, but other number of classes may be used.

In addition, in the above explanation, the first quantization step size, which is the standard, is divided into equal parts for each classification to determine the second quantization step size, but the second quantization step size is determined for blocks with small variance. Any other method may be used as long as it is calculated so that the value is small.

Effects of the Invention As described above, the effects of the present invention include measuring the characteristics related to the precision of the input television signal of the block to be intra-frame encoded, and quantizing consecutive blocks with the same quantization step size. By reducing the quantization step size for intraframe-encoded blocks whose average value is greater than a certain value and which have a delicate pattern, the amount of generated code is limited and the amount of code contained in the original image is reduced. Since video encoding can be performed without sacrificing precision, image quality can be improved, and the effect is significant.

In particular, the image quality improvement effect of the Refrenoche frame is remarkable.

[Brief explanation of drawings]

FIG. 1 is a block wiring diagram of a motion compensated predictive interframe coding device according to an embodiment of the present invention, FIG. 2 is a block wiring diagram of a conventional motion compensated predictive interframe coding device, and FIG.
The figure is a conceptual diagram showing the relationship between an image and a macroblock in a conventional example. 1, 5l... Input terminal, 3, 53... Motion vector calculation section, 4, 54... Image memory section, 7, 58... Motion compensation prediction section, 9, 60... Intra-frame/inter-frame determination Section, 11, 62... In-loop filter section, 13, 64.
...Prediction error calculation unit, l5, 66...Switch unit, l
7, 68・Orthogonal transformation section, l9, 70... quantization section, 2
l...Second quantization step size calculation unit, 22, 59.
...First quantization step size calculation section, 25 - Average/variance value calculation section, 28, 74... Code memory section, 30,
76... Inverse orthogonal transform unit, 34, 78... Reproduction image calculation unit, 36, 82... Prediction error encoding unit, 38, 84
Motion vector encoding unit, 41, 86...Multiplexer unit, 43, 89... Output terminal.

Claims (1)

[Claims] A/D converts television signals from analog to digital
a converting means, a blocking means for dividing one frame or one field of the digitized input television signal into blocks of a predetermined size, and a moving means for calculating a motion vector representing the movement of the television image for each block. a vector detection means; a motion compensation determination means for determining whether motion compensation prediction is to be performed using the motion vector for each block; a motion compensation prediction means for calculating a value; an error calculation means for calculating a difference between a pixel value of an input television signal and a predicted pixel value as a prediction error value; a coding method determining means for determining whether to perform a coding method, and a signal to be orthogonally transformed based on the intra-frame coding/inter-frame coding judgment result for each block as a pixel value of an input television signal or a prediction error value; orthogonal transform means for orthogonally transforming pixel values or prediction error values of an input television signal to calculate orthogonal transform coefficients; and a first quantizer for calculating a first quantization step size from the generated code amount. an encoding step size determination means, an average/variance calculation means for calculating the average and variance of pixel values for each block of the input television signal, and a block to be intra-frame encoded that classifies the blocks based on the average and variance. A second quantization step size is calculated from the first quantization step size for each class, and for blocks to be interframe encoded, a second quantization step size is calculated using the first quantization step size as the second quantization step size. 2 quantization step size determination means, quantization means for quantizing orthogonal transform coefficients using the second quantization step size and calculating quantized orthogonal transform coefficients, and intra-frame encoding or inter-frame encoding. an encoding means for encoding the information, the first quantization step size and the quantization classification information, and the quantized orthogonal transform coefficients; Inverse quantization means for calculating a signal and whether the pixel value to be used when calculating the reproduced pixel value is a motion compensated predicted pixel value or a numerical value "0" based on the interframe coding/intraframe coding determination result. A switching means for switching,
The image reproducing means calculates a reproduced image from a predicted pixel value or numerical value "0" and a dequantized signal, an image storage means stores the reproduced image, and a motion vector encoding means encodes a motion vector. Motion compensated predictive interframe coding device.