JPS62195989A - Encoding and decoding device between frames - Google Patents

Abstract

PURPOSE:To suppress the decrease in the number of frames of a transmitted animation picture and to prevent the drop in following characteristic to the movement by inserting a difference amplitude suppression circuit into the pre-stage of an adder between the frames of an encoding part and a decoding part and controlling the suppression characteristic of the amplitude value of the difference decoding block data between the frames according to a movement detection threshold every block. CONSTITUTION:A transmission data buffer 8 converts movement information nu109 and block encoding data 116 into encoding data such as a variable length code, it is stored for a fixed time, and thereafter, transmitted to a transmission path at a constant speed, the quantity 111 of storing the data in the buffer is calculated and supplied to an encoding control circuit 9. In the encoding control circuit 9, while the increase and the decrease of the quantity 111 of storing the data are monitored, the movement detection threshold Ttheta108 is supplied to the difference suppression circuit 19. The movement information nu109 and the block encoding data are decoded in a block decoding circuit 18. The difference decoding block data 112 between the frames has the amplitude value suppressed according to the movement detection threshold Ttheta non-linearly every block in the difference amplitude suppression circuit 19.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention utilizes the correlation between consecutive screens of a moving image signal [, block by block] [interframe coding in which encoding and decoding are performed while performing motion detection]. This is related to the decoding device.

[Conventional technology]

FIG. 4 is a block diagram showing the encoded configuration of a conventional interframe block encoding/decoding device.

This is an example of using adaptive vector quantization as a block encoding method. In the figure, (1) is an A/D converter, and a switch for protecting the 21-digit input image signal series.

(3) converts a raster format digital image signal sequence into blocks for each m pixels x n lines (m and n are positive integers).
A raster/block scanning conversion circuit that forms input block data (41 is a signal that differs between the input block data and the block data in the frame memory at the same position on one screen, that is, inter-frame difference block data); (5) is the subtracter that obtains the average value and amplitude component of the block data for each block (19 minutes), and obtains the normalized input vector through normalization processing.
(6) is a motion detection circuit that executes motion detection in block units using the average value, the amplitude by, and a threshold value, and outputs motion information; (7) is the normalization input; a vector quantization encoder that vector quantizes a vector and converts it into a normalized output vector index, (8)
is a transmission data buffer 5 (9) which encodes the motion information, average value, amplitude component, and normalized output vector index, respectively, stores the encoded data for a certain period of time, and sends it to the transmission path at a constant speed. ) is an encoding control circuit that controls the input frame drop motion detection threshold according to the amount of information stored in the transmission data buffer, and Ql is a coding control circuit that controls the input frame drop motion detection threshold according to the amount of information stored in the transmission data buffer. A vector quantization decoder that decodes and reproduces inter-frame difference block data, (+1) is a 71) calculator that reproduces input block data, (1 is a variable delay circuit, fi
31 is a frame memory.

Furthermore, FIG. 5 is a block diagram showing the configuration of the decoding section of the conventional frame 1) 4 block encoding/decoding system.
Encoded and 1'61 are examples using adaptive vector quantization. In the figure, (141 is a receive data buffer that receives encoded data supplied from the transmission path, performs variable length decoding, stores it for a certain period of time, and outputs it at a speed that corresponds to the decoding operation.) A block/raster scan conversion circuit, 0Q, is a D/A converter that converts input block data into raster format.

Next, the encoding/decoding operation will be explained using FIGS. 4 and 5. First, in the encoded state, input video signal (1
01) is an analog signal that is raster scanned from left to right of the screen and from top to bottom. The analog signal A
A digital signal sequence (102) is generated by the /D converter (1).
After converting to raster/block scan conversion circuit (3)
The data is divided into blocks every m pixels×n lines (m and n are positive integers) to obtain input block data (103).

The inter-frame difference block data E obtained by subtracting the block P (104) at the same block position in the frame memory j from the block data U (103)
(105) is input to the mean value separation and normalization circuit (5). In the average value separation and normalization circuit (5), the frame 1
[1] After converting the differential block data into a vector of dimension (k=mXn), perform the following calculation to obtain the intra-block average value μ.

The amplitude component σ (106) and the normalized input vector ball (1
07) is obtained.

xj=(εJ-μ)xk x=(xl, X2. ・, xk, = mXn
, 1 The obtained average value μ and amplitude component σ (106) are input to the motion detection circuit (6), and are compared with the motion detection threshold Tθ (108) determined by the encoding control circuit described later. Motion detection is performed on the block potential according to the conditions. As a result of the motion detection, motion information ν(1o9) is output from the motion detection circuit (6).

For blocks where ν=1, that is, there is movement, the following processing is performed. The normalized input vector X (1071) obtained in the mean value separation normalization circuit (5) is vector quantized by the vector quantization encoder (7),
It is converted into the index i (1)0) of the normalized output vector Y1 that minimizes distortion.

Motion information ν(1o9), average value μ when ν=1
.

The amplitude component σ(106) and the normalized output vector intex i(1)0) are each converted into encoded data using a variable length code etc. in the transmission data buffer (81) and stored for a certain period of time.The transmission data buffer (81) )
sends the encoded data to the transmission path at a constant speed, and calculates the data stored in the buffer Mm (m) and supplies it to the encoding control circuit (9). Encoding 1) 1) Control circuit (
In 9), the on/off signals (1) and 2) of the input frame drop switch, which tend to monitor increases and decreases in the data storage amount (1) 1), and the control of the motion detection threshold Tθ (IQ8) are controlled by the frame. Do it in units. An example of the control method is shown in FIG.

In addition, each data input to the transmission data buffer (8), namely motion information ν (109), average value μ and amplitude component σ (106), and normalized output vector index i (ilo”l vector quantization decoding The decoded data is decoded in the device a through the following OI control, and the inter-frame difference decoded block data'>(1)2) is reproduced.

When ν=0, g = O= (0, O, −・, O
]When ν=1 εj=σ・7ij ten μ(j=1.2.
..., k) (yl-normalized output vector corresponding to index 1) ε=[ε1. ε2. ..., εk] The obtained inter-frame differential decoding block data processing (+12
1 and the block data P (104) in the frame memory delayed for a predetermined time by the variable delay circuit α3IC, decoded reproduced block data S (1) is obtained.
5) and update the corresponding block data of 1) 5 in the frame memory. The above process is shown in the following equation.

On the other hand, in the decoding section, the motion information ν received in the reception data buffer α(4), subjected to variable length decoding and speed conversion
(109), average value μ, amplitude component σ (106), and normalized output vector index 1 (1) 0) Decoded in the same manner as above by the Id vector quantization decoder 1, and interframe difference decoded block data t (1) 2) is played. Decoded block data between frames? (1)
2) and the block data P (104) in the frame memory outputted through the variable delay circuit a4, and the decoded reproduced block data S is processed in the same manner as the encoded process.
(1) 5) is restored. Namely.

Execute. The decoded and reproduced block data S (1)3)
is converted into raster format data (1) 4) in the block/raster scan conversion circuit αS, and the D/A converter α
D/A converted by e, playback output moving image signal (1) 5
).

[The problem that the invention is trying to solve]

Since the conventional interframe coding/decoding device is configured as described above, when the motion detection threshold is large, the amplitude value of the interframe left decoding block when the motion information ν=1 and ν=0 When the error with the amplitude value is large, in the reproduced image, block-like deterioration due to the error is noticeable in adjacent parts of the block with ν=1 and the block with ν=0.

The motion detection threshold cannot be made too large because it reduces subjective quality, and as a result, the amount of encoded information increases when the motion is large, and the number of input dropouts increases. In other words, the number of frames of moving images to be transmitted is reduced.

There were problems such as a decrease in the ability to follow movements.

This invention was made in order to solve the above-mentioned problems, and it is possible to perform encoding without significantly deteriorating the subjective quality when there is a large amount of motion, and to reduce the number of frames of moving images to be transmitted. An object of the present invention is to obtain an interframe coding/decoding device that can suppress interframe coding.

[Means for solving problems]

An interframe coding/decoding device according to the present invention.

A differential amplitude suppression circuit that non-linearly suppresses the amplitude value of the inter-frame differential decoded block data in block units according to the motion detection threshold is inserted before the frame music adder in the encoded and decoding section. The nonlinear characteristics are controlled by the encoding control circuit based on the motion detection threshold and the amount of transmission data buffer storage.

In addition, a means for transmitting a motion detection threshold value is used.

[Effect]

In the frame 1j31 encoding/decoding device according to the present invention, the suppression characteristic of the width value of 1 of the inter-frame additional decoded block data is controlled by the 1-difference amplitude suppression circuit in accordance with the motion detection threshold for each block. If the value is large, the suppression width is increased, and the motion information ν=1
Since the error in the amplitude value of the inter-frame difference decoded block data of the block when ν = 0 and the block when ν = 0 is reduced, the block-like deterioration of the reproduced image is reduced even if the noise is large, and the subjective quality is improved. This is because the increase in the amount of encoded information can be suppressed without significantly reducing the amount of encoded information.

The number of frames to be transmitted increases, and as a result, the ability to follow the movement of the reproduced moving image improves. Further, when the motion is small, the above-mentioned suppression characteristic is relaxed as well as the motion detection threshold, so that the inter-frame multiplication decoded block data is faithfully restored and the subjective quality is improved.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. 1st
In FIG. 2, αη is a block encoding circuit that encodes frame m1 pressure block data into a block intensity;
0 seconds is a block decoding circuit that reproduces interframe additional decoded block data from encoded data in block units;
(1) is a differential amplitude suppression circuit that suppresses the amplitude value of the reproduced interframe differential decoded block data in a non-glandular manner. (1) to (4), +61°iRl, +91. Ql
)-(IG is the same as the conventional one shown in FIGS. 4 and 5.

The operation will be explained below. Same as the conventional one, the frame output 1 difference that can be counted by 1) ゛lock data εj (
105) is a block-by-block VC motion detection circuit (61) that detects motion and outputs IJI7I information ν (1091).Motion detection is performed using the motion detection threshold Tθ (108), for example, by the following calculation. .

For the block ν=1, block-by-block encoding is performed in the block encoding circuit αη, and the block encoded data (1) 6) is the motion information ν (109).

It is supplied to the transmission data buffer (8) together with the motion detection threshold Tθ (10B). Transmission data buffer +81
Converts the motion information ν (109) and block encoded data (1) 6) into encoded data such as variable length code, as in the conventional case. Amount of data accumulated in the buffer while sending (1) 1
) is calculated and supplied to the encoding control circuit (9). First, the motion detection threshold value (108) used in motion detection is transmitted for each encoded frame.

The encoding control circuit (9) monitors the increase/decrease in the data storage amount (1) 1) and controls the input frame drop switch on/off signals (1) 2) and the motion detection threshold Tθ (108). is performed on the frame, the motion is detected, and the threshold value Tθ (10B) is supplied to the difference suppression circuit α1, which will be described later.

The motion information ν(109) and block encoded data are decoded in a block decoding circuit αB, and interframe difference decoded block data ε(1)2) is reproduced. The inter-frame difference decoded block data g(+12) is applied to the motion detection threshold T in the encounter amplitude suppression circuit α1.

The amplitude 1 is suppressed nonlinearly in block units according to the threshold value Tθ.In other words, when the threshold value Tθ is small, the suppression width is made small, and when the threshold value Tθ is large, the suppression width is made large.Nonlinear suppression An example of the characteristics is shown in Fig. 3.The inter-frame difference decoded block data p(1)7) suppressed by the nuclear difference amplitude suppression circuit 7) is a frame delayed by a predetermined time through the variable delay circuit α in the adder a1). The corresponding block data P (added to 1041 and decoded reproduced block data 'a (1) 3) in the memory is restored, and the block data at the corresponding block position is updated.

In the decoding unit, motion information ν (109) received by the reception data buffer I, variable length decoded, and speed converted
and block encoded data (1j, 5) are decoded in the block decoding circuit 01 by the same processing as the encoded ones, and interframe difference decoded block data j (1)2) is reproduced. The inter-frame differential decoded block data ε(
1) and 2) are subjected to the nonlinear amplitude suppression processing shown in FIG. 3 in the same way as encoded ones using the motion detection threshold value Tθ (108) received through the transmission path in the running amplitude suppression circuit 4, and are suppressed. interframe difference decoded block data i
'(1)7) is obtained. The suppressed frame jJl
&min decoded block data? ' (1) 7) and the block data P (1041) in the frame memory output through the variable delay circuit are added, and the decoded reproduced block data S (1i3) is restored by the same processing as the encoded one. Decoded and reproduced block data S (1) 3) is block/raster scanning conversion circuit α! Q, D/A converter (IG
The same processing as that of the conventional one is performed through the video signal, and a reproduced output moving image signal (1) 51 is obtained.

Note that the block encoding circuit in the above embodiment.

The block decoding circuit may be constructed using a vector heir encoding encoder and a vector quantization decoding 2j as in the conventional circuit.

Further, in the motion detection circuit in the above embodiment.

We used a method to perform motion detection by comparing the sum of the absolute values of amplitudes in the inter-frame difference block with a motion detection threshold; Even if a means for softening the ratio with the threshold value is used, the effect of the above embodiment and 1-il u can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, the Shobu width suppression circuit is inserted before the adder in the encoded and decoding sections, so that when there is large movement, the subjective quality is not significantly degraded. , it is possible to perform encoding and decoding while suppressing an increase in the amount of encoded information, and it is also possible to obtain the effect of improving the ability to follow the movement of a reproduced moving image.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the encoded configuration of an interframe encoding/decoding device according to an embodiment of the present invention, and FIG. 2 is a block diagram showing the encoded configuration of an interframe encoding/decoding device according to an embodiment of the present invention. FIG. 3 is an explanatory diagram showing an example of the input/output characteristics of the differential amplitude suppression circuit of the interframe coding/decoding device according to an embodiment of the present invention, and FIG. 4 is a block diagram showing the configuration of the conventional frame m1. FIG. 5 is a block diagram showing the encoded configuration of the encoding/decoding device, and FIG. 5 is a block diagram showing the configuration of the decoding section of the conventional interframe encoding/decoding device. FIG. 6 is an explanatory diagram showing an example of an encoding control method for encoded data in a conventional interframe encoding/decoding device. In the figure, (1) is an A/D converter, and (2) is a drop-proof switch. (31 is a raster/block scan conversion circuit, (41 is a subtracter, (5) is a mean value separation normalization circuit, (6) is a motion detection circuit, (7) is a vector quantization encoder, (8) is a Transmission data buffer, (9) is encoding control circuit, ■ is vector quantization decoder, αB is /JO calculator, α is variable delay circuit. 03 is frame memory, I is reception data buffer. Block/raster scan conversion circuit, αI9 is D/
A converter, (lη is a block encoding circuit, 0& is a block decoding circuit, and α9 is a differential amplitude suppression circuit. In the figure, the same reference numerals indicate the same or equivalent parts.

Claims (3)

[Claims] (1) A frame memory that always stores at least one frame of an image signal sequence, and a raster/block scan conversion that blocks the input signal sequence every K samples (K is a positive integer) and forms input block data. a subtracter that obtains inter-frame difference block data by subtracting encoded block data of at least one frame before the input block data existing in the same position as the input block data in the frame memory; ,
Motion detection is performed on a block-by-block basis by comparing the sum of absolute values of amplitudes of samples within a block of the inter-frame difference block data with a motion detection threshold determined by the encoding control circuit described later, and whether there is motion or no motion is detected. a motion detection circuit that determines motion information; a block encoding circuit that encodes the inter-frame difference block data with motion in units of blocks as valid blocks and converts them into block encoded data;
The motion information and block encoded data are converted into appropriate code words, stored for a certain period of time, and then sent to a transmission path together with the motion detection threshold at a certain speed to determine the amount of the encoded data accumulated within a certain period of time. a transmission data buffer that calculates the encoded data, and determines the motion detection threshold and input frame drop according to the increase/decrease in the encoded data storage amount, performs feedback control of the encoding operation, and controls the motion detection threshold. An encoding control circuit that supplies the differential amplitude suppression circuit described later decodes and reproduces the inter-frame difference decoded block data with movement, and in blocks without movement, all sample values of the inter-frame difference decoded block data are treated as invalid blocks. a block decoding circuit that suppresses the amplitude value of the inter-frame difference decoded block data obtained by the block decoding circuit non-linearly based on the motion detection threshold; and an adder that adds the inter-frame difference decoded block data and the encoded block data to obtain reproduced block data, and writes the reproduced block data in the same position as the encoded block in the frame memory. an encoding unit that receives the encoded data supplied through a transmission path, stores it for a certain period of time, decodes the motion information and the block encoded data from the code word, and calculates the motion detection threshold value. a reception data buffer that separates and outputs the reproduced block data, the block decoding circuit, the differential amplitude suppression circuit, the adder, the frame memory, and the reproduced block data that is the output of the adder into a raster format signal sequence. 1. An interframe coding/decoding device comprising: a decoding unit configured with a block/raster scan conversion circuit for converting into a block/raster scan conversion circuit. (2) In the motion detection circuit, motion detection is performed by determining the average value and standard deviation value of the intra-block sample values of the inter-frame difference block data, and comparing the average value and standard deviation value with the above-mentioned motion detection threshold. action, movement,
The interframe coding/decoding device according to claim 1, characterized in that means for determining motion information without motion is used. (3) In the differential amplitude suppression circuit, the input signal, that is, the amplitude value x of the inter-frame difference decoded block data, the output signal, that is, the amplitude value y of the suppressed inter-frame difference decoded block data, and the motion detection threshold T( T is 0
above), and a (a is 1 or more), b, c (b, c are each 1 or less) are values determined by the motion detection threshold T, and n is a positive odd number. The input/output characteristics of the differential amplitude suppression circuit are expressed as y=x−bT when the absolute value of x |x| is larger than the product of c and T and x is 0 or more.
The property represented by |x| is larger than the product of c and T,
And when x is negative, the characteristic expressed as y=x+bT, as described above |
Claim 1, characterized in that means is used for controlling using the motion detection threshold so that when x| 1
) or (2).