JPS63108879A - Video encoding transmission equipment - Google Patents

Abstract

PURPOSE:To transmit a video of high picture quality irrespective of the move ment of the video by variably controlling the information speed of an encoding output in time, measuring the movement of an input video and controlling the picture quality of the movement. CONSTITUTION:A video signal inputted to an input terminal 10 is applied to a video encoding part 1 and a movement detection part 4. The movement detec tion part 4 calculates the quantity of movement from a video code of a preced ing frame and a video signal of a current frame and outputs the value to a comparing part 5. The comparating part 5 compares the output of the movement detection part 4 with a threshold set by a control part 6, outputs a frame speed control signal to the video encoding part 1 from the compared result and controls a frame speed in the video encoding part 1. The video encoding part 1 controls the frame speed according to a frame speed control signal from the comparing part 5, executes a variable length encoding, temporarily stores in a buffer 2 and supplies to a burst forming part 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is used for encoding and transmitting video information. In particular, the present invention relates to an encoding and transmitting device that transmits high-quality video information with a small amount of information.

[Conventional technology]

Conventional high-efficiency coding methods can be roughly classified into predictive coding methods and transform coding methods. These encoding systems always output codes at a constant information rate. On the other hand, when video information is encoded, the amount of generated information varies depending on the motion of the video. That is, the more active the movement of the video, the more the amount of generated information increases.

In conventional video encoding and transmission devices, a buffer of a certain size is used to absorb deviations in the amount of generated information. That is, the encoding parameters are changed depending on the amount of buffer occupancy, and high-quality encoding is realized while keeping the information rate of the encoded output constant.

Examples of such devices include R.F.Dubliny Peace, J.O. Lim, "Exchange of Spatial and Temporal Resolution - Silane in Television Coding", Bell System. Technical Journal Vol. 50 No. 1 (197
January 1st) pages 191 to 200 (R, FJ, P
ease SJ, O, Limbs rEx-chan
ge of 5 pacial and tem
polar Re5solution 1nTele
vision Coding J, B, S, T, J,
50.1, pp191-200 (1971-1)) describes a coding/transmission device that maintains temporal resolution at the expense of spatial resolution in moving parts, and maintains spatial resolution at the expense of temporal resolution in stationary parts. It has been stated. With this device, it is possible to improve image quality at a constant information rate by taking advantage of the fact that human visual characteristics deteriorate in moving parts, and the resolution of moving objects decreases due to the accumulation effect of the image pickup tube. can.

[Problem that the invention seeks to solve]

However, if moving parts are divided into stationary parts, this movement can be followed by the eye when the movement is slow, and the deterioration in human visual characteristics is smaller than the deterioration in image quality. As imaging devices develop, it is thought that it will be possible to input moving objects without causing too much blur. For this reason, in conventional video encoding and transmission devices, it is unavoidable that the image quality deteriorates in moving parts under certain conditions.Therefore, there is a drawback that the image quality changes greatly over time depending on the motion status of the input video. be.

This drawback can be solved by using a buffer with a larger capacity, but this increases the processing delay and is not practical in terms of transmission.

Momentary deterioration in image quality poses a major problem from a human visual perspective. In other words, even if the average image quality numerically determined from the average information rate is good, if there is instantaneous deterioration in image quality, human vision is often unsatisfactory.

However, conventional video encoding and transmission apparatuses have the disadvantage that temporal fluctuations in image quality cannot be avoided unless the information rate is increased.

In addition, a method that equivalently transmits the encoded output of one information source at a variable speed by giving a constant speed to multiple information sources as a whole and using a large buffer that is variably divided; For example, TA S I (t
ime assignment 5peech
1interpola-tion), DSI,
(Digital 5peech 1interpola
tion) and the like are known. However, it has not been possible to variably control the information rate of encoded output for each information source.

SUMMARY OF THE INVENTION The present invention aims to solve the above-mentioned problems and to provide a video encoding and transmission device that transmits high-quality video regardless of the degree of motion in the video without increasing the average information rate. .

[Means for solving problems]

A video encoding and transmitting device according to the present invention includes a video encoding section that encodes an input video signal, and a sending means that transmits the encoded output of the video encoding section. The present invention is characterized by comprising a motion detecting means for detecting the degree of motion in an input video signal, and an information speed control means for controlling the output information speed of the video encoding section in accordance with the output of the motion detecting means.

The sending means includes a buffer for temporarily storing the encoded output of the video encoding section, and a means for reading the encoded output stored in the buffer at a speed lower than a preset maximum information speed, and controls the information speed. The means includes means for reducing the output information rate of the video encoding section when the amount of code stored in the buffer is greater than the amount read out.

The information rate control means includes means for keeping the average output information rate in a predetermined time interval within a predetermined range; - The motion detection means responds to small movements that do not feel unnatural even if the movement is stopped; a first threshold;
The information rate control means is configured to use a second threshold corresponding to high-speed movement that exceeds the ability of human vision to follow the movement, and the information rate control means is configured to use a second threshold that corresponds to a movement that is faster than the first threshold. means for controlling the frame rate output by the video encoding section to a low speed when the frame rate is smaller than the second threshold value or when the frame rate is higher than the second threshold; and means for performing variable length encoding without changing the frame rate.

[For production]

The video encoding/transmission device of the present invention variably sets the information rate of the encoded output, keeps the average information rate sent to the wire within a predetermined time constant, and reduces the information rate when the video is active. It is something that increases. This makes it possible to transmit high-quality video regardless of the degree of video movement.
The overall quality relative to the average information rate can be improved.

〔Example〕

FIG. 1 shows a block diagram of a video encoding and transmitting apparatus according to an embodiment of the present invention.

A video signal from an imaging device is supplied to the video input terminal 10. The maximum information rate input terminal 12 receives from the cable a setting value for the maximum information rate that can be transmitted to this network. The average information rate input terminal 13 receives from the network a set value of the average information rate that can be transmitted to this network.

The video input terminal 10 is connected to the video encoder 1 and the motion detector 4.
connected to. The maximum information rate input terminal 12 is connected to the burst creation section 3. Average information rate input terminal 13 is connected to control section 6 .

The motion detection section 4 and the control section 6 are connected to the comparison section 5.

The comparison section 5 is connected to the video encoding section 1.

Video encoder 1 is connected to buffer 2 . buffer 2
The output thereof is connected to the burst creation section 3, and the information regarding the occupancy is connected to the burst creation section 3 and the control section 6. The burst creation section 3 is connected to the network via a burst data output terminal 11.

The motion detection section 4 calculates the amount of motion from the video signal of the previous frame and the video signal of the current frame, and outputs the value to the comparison section 5. The comparison unit 5 compares the amount of motion from the motion detection unit 4 with a threshold value set by the control unit 6, and outputs a frame rate control signal to the video encoding unit 1 based on the comparison result,
The frame rate in the video encoding unit 1 is controlled.

The comparator 5 uses two values as threshold values.

As the first threshold, set a value that corresponds to small movements that do not feel too unnatural even if you stop moving.
As the second threshold value, a value corresponding to high-speed movement that exceeds the ability of human vision to follow movement is set. As a result, if the motion of the input video is smaller than the first threshold and larger than the second threshold,
A control signal is sent to lower the frame rate, and in a range between the two thresholds, a control signal is sent to perform variable length encoding without changing the frame rate.

The video encoder 1 controls the frame rate according to the frame rate control signal from the comparator 5 and performs variable length encoding. A buffer 2 temporarily stores the encoded output of the video encoder 1. The burst creation unit 3 reads out the encoded output stored in the buffer 2 according to the amount of occupancy supplied from the buffer 2, converts it into a burst, and outputs it. At this time, the burst sending interval is controlled according to the occupied amount of buffer 2,
Adjust so that the amount of storage in buffer 2 is constant.

A maximum information rate setting value is further input to the burst creation unit 3, and the burst sending interval is adjusted so as not to exceed this maximum information rate.

The control unit 6 normally determines the average image quality of the motion corresponding to the set value of the average information rate, and sets a threshold value corresponding to this in the comparison unit 5. That is, the threshold value is set so that the average speed observed at a predetermined time interval falls within a certain standard with respect to the set value of the average information speed.

When the encoded output of the video encoder 1 is extremely large with respect to the set value of the maximum information rate, the occupancy rate of the buffer 2 increases. At this time, the buffer 2 outputs an information generation suppression signal to the control unit 6. Based on this signal, the control section 6 changes the threshold value of the comparison section 5. However, due to the swarm effect of the network, the maximum information rate can be set several times higher than the average information rate, and the probability that the threshold value will need to be changed is extremely small.

FIG. 2 shows a block diagram of an example of the motion detection section 4. As shown in FIG.

The input video signal is supplied to a frame memory 21 and a screen dividing section 22. The frame memory 21 and the screen division section 22 each include motion vector detection sections 23-1 to 23-1.
23-n. Motion vector detection unit 23-1~
23-n is connected to the maximum motion detection section 24.

The screen dividing unit 22 divides the screen of the video signal into n blocks, and the motion vector detecting units 23-1 to 23-1 respectively divide the divided current frame video signal and the previous frame video stored in the frame memory 21 into n blocks. The signals are compared and the most matching direction is output as motion vector information. The maximum motion detection unit 24 detects the maximum motion vector from the motion vector information of each block, and outputs this as the amount of motion in this frame.

FIG. 3 is a flowchart of the operation of the motion vector detection units 23-1 to 23-n.

The vector detection units 23-1 to 23-n translate each input block in parallel, and calculate the difference from the previous frame at each position. The direction and distance moved during one frame, that is, the movement vector, can be detected from the position where the residual energy is minimum. This movement vector indicates a motion vector.

Regarding detection of a motion vector, the only question is whether the maximum value exceeds a threshold value, and a rough calculation that allows detection of a motion amount approximately equal to the threshold value is sufficient.

Therefore, motion detection can be performed after lowering the resolution of the original video signal, and processing can be performed with a smaller amount of calculation compared to normal motion vector detection.

〔Effect of the invention〕

As explained above, the video encoding and transmitting device of the present invention includes:
The information rate of the encoded output is temporally variably controlled, the motion of the input video is measured, and the image quality related to that motion is controlled.

This has the effect that video transmission can be performed with high image quality regardless of the degree of movement in the video. Furthermore, the frame rate does not decrease due to movement, and the overall image quality relative to the average information rate can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a video encoding and transmitting apparatus according to an embodiment of the present invention, and FIG. 2 is a block diagram of an example of a motion detection section. FIG. 3 is a flowchart of the operation of the motion vector detection section. l...Video encoding unit, 2...Buffer, 3...Burst creation unit, 4...Motion detection unit, 5...Comparison unit,
6... Vibration damping section, 10... Video input terminal, 11...
Burst data output terminal, 12... Maximum information rate input terminal, 13... Average information rate input terminal, 21... Frame memory, 22... Screen division unit, 23-1 to 23
-n...Motion vector detection unit 24...Maximum motion detection unit. , :Do・Pa/Example Figure 1

Claims (4)

[Claims] (1) In a video encoding and transmitting device equipped with a video encoding unit that encodes an input video signal and a transmission means that transmits the encoded output of the video encoding unit to a network, the degree of movement in the input video signal is determined. What is claimed is: 1. A video encoding and transmitting device comprising: motion detection means for detecting motion detection means; and information rate control means for controlling an output information rate of the video encoding section according to an output of the motion detection means. (2) The sending means includes a buffer for temporarily storing the encoded output of the video encoding section, and means for reading the encoded output stored in the buffer at a speed lower than a preset maximum information speed, The video encoding system according to claim 1, wherein the information rate control means includes means for reducing the output information rate of the video encoding section when the amount of code stored in the buffer is greater than the amount read out. Transmission device. (3) The video encoding and transmission apparatus according to claim (1), wherein the information rate control means includes means for keeping the average output information rate at a predetermined time interval within a predetermined range. (4) The motion detection means has a first threshold that corresponds to small movements that do not feel unnatural even if the movement is stopped, and high-speed movements that exceed the human visual ability to follow the movement. and a second threshold value corresponding to means for controlling the frame rate output by the encoder to a low speed; and means for executing variable length encoding without changing the frame rate output from the video encoder in a range between the two thresholds. A video encoding and transmitting device according to claim (1).