JPH01231583A - Picture coding device with variable bit rate - Google Patents

Abstract

PURPOSE:To avoid the deterioration of the picture quality due to the change of a transmission rate by controlling adaptively the space image resolution or the time image resolution in accordance with the shift value of an input screen in case the transmission bit rate is limited and the occupation rate of a buffer memory is increased. CONSTITUTION:A controller 3 applies adaptively the control signal to an encoder 1 for thinning or frame omitting action in accordance with the shift value of an input picture detected by a shift detector 2 as long as the occupation rate of a buffer memory 4 exceeds its threshold value when the transmission bit rate instructed from the transmission line side is smaller than the threshold level. Therefore the thinning process is carried out to lower the space image resolution against the large shift value in case the transmission bit rate is kept at a low level. While the frames are omitted to lower the time image resolution against the small shift value. Thus it is possible to reduce the quantity of produced information and to secure the visually stable picture quality.

Description

[Detailed Description of the Invention] [Summary] Regarding the motion compensation means for the transmission screen (variable bin tray with ITFF) - image encoding device, it is possible to suppress deterioration of image quality as much as possible even if the transmission bin tray 1 is limited. The purpose is to provide a motion amount detector that detects the motion amount of the input screen from the input screen and the previous screen from the encoder, and a motion amount detector that detects the amount of movement of the input screen from the input screen and the previous screen from the encoder, and a motion amount detector that detects the amount of motion of the input screen, and a motion amount detector that detects the amount of motion of the input screen, and a motion amount detector that detects the amount of motion of the input screen, and a motion amount detector that detects the amount of movement of the input screen from the input screen and the previous screen from the encoder. 'A (a controller that adaptively applies a thinning processing signal or a frame-dropping signal to the encoder according to the amount of motion when the amount of motion exceeds 1);

[Industrial Field of Application] The present invention relates to a variable focus rate image encoding device, and more particularly to a variable focus rate image encoding device equipped with motion compensation means for a transmission screen.

If the bit rate of the digital signal transmitted from the image encoding device is constant (for example, 768 Kh/s), the capacity of the encoder (not shown) used in the encoding device is finite. Second (if the delay time is infinite, the delay time will also be infinite).If the amount of generated information increases, it is necessary to reduce the amount of generated information and transmit it by reducing the amount of starization. Therefore, the quality of the decoded image on the receiving side deteriorates. For this reason, it is desirable that the transmission bit rate be variable depending on the amount of information generated.

[Conventional technology]

Net 1-1 when realizing such variable pin rate transmission
As an example of a work configuration, in the case of a network in which a large number of terminals 101 are connected to a backbone line 100, as shown in FIG. Line 1. OO and each terminal 1
．． A possible method is to make the bit rate of the line between the two lines variable and the total sum of each line constant.

In this way, even if the amount of information generated by the terminal 101 increases, the bit rate can be increased accordingly, so that information that is generated in bursts due to the nature of the instantaneous screen can be transmitted as is. This eliminates the need to degrade the image quality of the received image, unlike fixed focus rate encoding.

[Problem to be solved by the invention]

A terminal equipped with such a variable bit rate 1-image encoding device is in competition with other information sources in terms of the amount of transmitted information, and it is not always possible to obtain the requested bit rate. In such a case, if the bin route is increased and the bit rate exceeds the specified bit rate of the backbone line, the transmitted data will be lost and the image quality will deteriorate significantly.

Therefore, it is an object of the present invention to realize a variable bit rate image encoding device that can suppress deterioration of image quality as much as possible even when the transmission rate is changed.

[Means to solve the problem]

In order to achieve the above object, the variable Pino-1-Heley-1 image encoding device according to the present invention has the following functions: As conceptually shown in FIG. The motion amount detector 2 detects the amount of motion, and when the bit rate instructed from the transmission line side is less than the threshold value and 644 ri of the buffer memory 4 exceeds the threshold value, the motion amount detector 2 detects the amount of motion. A controller 37 is provided which adaptively provides a thinning signal or a frame dropping signal.

[For production]

According to the variable bit rate image encoding device of the present invention shown in FIG. 1, when the transmission focus rate instructed from the transmission path becomes less than the threshold, the memory occupancy of the buffer memory 4 exceeds the threshold. In this case, the controller 3 adaptively provides a control signal for thinning or dropping frames to the encoder 1 according to the amount of motion of the input image detected by the motion detector 2.

As a result, for example, when the transmission bit rate is limited to a low value, if the amount of motion is large, a thinning process is performed to reduce the spatial resolution, and if the amount of movement is small, frame dropping is performed to reduce the temporal resolution. The amount of generated information can be suppressed and visually stable image quality can be maintained.

〔Example〕

Embodiments of the variable bin/rate image encoding device according to the present invention will be described below.

FIG. 2 shows an embodiment of the variable bin Lu I-image encoding device of the present invention shown in FIG. The encoder 12 encodes the predicted picture, and the predicted picture is stored in the frame memory [3] and used for the next predictive operation. Reference numeral 14 denotes a sub-sampler (preprocessor), which calculates the relative movement of the input screen to the previous screen from the output of the sub-sampler 14 (which may also be input as shown by the dotted line) and the predicted screen in the frame memory 14. The compensator 2I detects motion in block units in the form of motion hectors, and the motion amount calculator 22 outputs a motion amount M obtained by multiplying this motion hector by one molecule A per frame. The motion vector output from the motion compensator 21 is sent to the variable delay device 15, which delays the predicted picture in the frame memory 13 by the motion vector, and transmits the difference from the input picture. The encoder 1 in FIG. 1 includes a quantizer 11, an encoder 12, a frame memory 13, a sampler 14,
The motion detector 2 includes a motion compensator 21 and a motion amount calculator 22.

Further, the controller 3 receives the motion liM from the motion amount calculator 22.
, the occupancy O of the buffer memory 4, and the transmission hit rate 1-R from the transmission line interface (not shown) are input, and a thinning processing signal is given to the sub sampler 14.
A frame-dropping signal is given to the encoder 12, and the quantization characteristics are not controlled in order to keep the S/N ratio of reproduced image quality constant.

The controller 3 is given in advance a threshold value Th for the amount of movement M, a threshold value Tho for the occupancy amount O of the buffer memory 4, and a threshold value T h R for the transmission pinot tray 1.R.
is being given.

Next, the operation of the controller 3 in this embodiment will be explained.

First, when the transmission bin tray 1-R commanded from the transmission path ink face is larger than the threshold value T h R, that is, when there is no restriction on the transmission pinot I rail, no control is performed to reduce the resolution, and the sub-side non-plaster 14 outputs all pixels, and a J encoder 12 encodes all frames.

Next, when the transmission bin 1-ray 1-R becomes smaller than the threshold 'r h , that is, when a limit is imposed on the bit rate, the occupied space O of the buffer memory 4 is set to the threshold T h o When o>Tho, the amount of information generated is reduced. When 0 < T h +1, there is room in the buffer memory 4, so it is possible to wait for the transmission rate 1-R to become larger.

For this reason, first compare the amount of motion M with its threshold Th, 4,
When M>ThM, it is determined that the movement is large, and in consideration of the fact that the spatial resolution of human vision decreases when the movement is large, a control signal is sent to the subsampler 14 to perform pixel thinning processing. give.

On the other hand, if M≦Th, it can be determined that the movement is small, so when the movement is small, human visual perception 2. If the resolution is lowered, the image quality will deteriorate or become noticeable, so all pixels are output to the Zabu sampler 14. The encoder 12 is controlled so as to not encode the next frame, that is, to drop frames.

〔Effect of the invention〕

As described above, according to the variable via trade image encoding device according to the present invention, if the occupancy rate of the buffer memory is high when the transmission focus rate is limited, the image encoding device is adapted according to the amount of human screen movement. Since the spatial resolution or temporal resolution is controlled automatically, changes in image quality due to changes in the transmission beam 1- can be made visually less noticeable.

[Brief explanation of the drawing]

FIG. 1 is a principle block diagram of a variable bit rate image encoding device according to the present invention, FIG. 2 is a block diagram showing an embodiment of a variable bit rate image encoding device according to the present invention, and FIG. 3 is a block diagram showing a variable bit rate image encoding device according to the present invention. FIG. 1 shows an example of a configuration of a network to which a rate image encoding device is applied. 1... Encoder, 2... Motion amount detector, 3... Controller, 4...・Buffer memory. In the figures, the same reference numerals indicate the same or corresponding parts. Master

Claims (1)

[Claims] A motion amount detector (2) that detects the motion amount of the input screen from the input screen and the previous screen from the encoder (1), and a motion amount detector (2) that detects the amount of motion of the input screen from the input screen and the previous screen from the encoder (1), and a motion amount detector (2) that detects the amount of movement of the input screen from the input screen and the previous screen from the encoder (1), and a motion amount detector (2) that detects the amount of movement of the input screen from the input screen and the previous screen from the encoder (1). and a controller (3) that adaptively applies a thinning processing signal or a frame dropping signal to the encoder (1) according to the amount of motion when the amount of occupancy of the buffer memory (4) exceeds a threshold value. A variable bit rate image encoding device comprising: .