KR0129796B1 - Encoding device of moving picture - Google Patents

Abstract

The motion picture coding apparatus is composed of a memory(10) storing video signal temporarily; a bit quantity adjusting part(20) adjusting a bit resolution of the video data; a discrete cosine transforming(DCT) part(30) transforming a predicted signal obtained through a moving presumption/compensation and a differential signal between the present video signals, from a time domain to a transformation coefficient of a frequency domain; a quantum part(40) receiving a quantum transformation coefficient from the DCT part; a variable coding part(50) which codes to the signal of a short or long length depending on the frequency of occurrence of each code included in the quantum signal; a multiplex part(60) collecting the variable coded video data signals for transmitting the same to a buffer; the buffer storing temporarily the coded video data signal for transmitting to the next terminal.

Description

Video encoding device

1 is a block diagram of a video encoding apparatus according to the present invention.

2 is a view for explaining the change in the bit resolution of the image data output from the memory in accordance with the present invention.

3 is a block diagram of a conventional video encoding apparatus.

＊ Explanation of symbols on main parts of drawing

10: memory 20: bit amount control unit

30: DCT unit 40: quantization unit

50: variable length encoding unit 60: multiplexing unit

70: buffer

The present invention relates to an apparatus for encoding a video signal, and more particularly, to a video encoding apparatus suitable for improving the efficiency of encoding by adjusting the bit resolution of an input video signal.

In general, when a video signal such as a video telephone or an HDTV is to be transmitted as a digital signal, the digital data to be transmitted is compressed, that is, encoded and transmitted using a high data compression method to reduce the enormous amount of data. Done.

In encoding such a moving picture signal, the most important thing is to reduce the amount of data to be transmitted.

Therefore, encoding is performed by using spatial and temporal redundancy of image data for efficient encoding. And coding are performed by eliminating temporal redundancy of the image data by using motion compensation differential coding.

The present invention relates to the improvement of a video encoding apparatus that performs efficient compression encoding using spatial and temporal redundancy of image data.

As described above, a typical type of conventional technique for performing compression encoding of a video signal has a configuration as shown in FIG.

As shown in the figure, a conventional video encoding apparatus includes a memory 10 temporarily storing an input video signal, a motion compensated signal (prediction signal) and a current video through a motion estimation / correction means (not shown). The DCT unit 30 converts the difference signal between the signals into the conversion coefficient in the frequency domain in the time domain, and converts the conversion coefficient from the DCT unit 30 on the basis of the status signal for the data amount in the buffer 70. The quantization unit 40 to quantize, the variable length encoder 50 to encode a short or long length code according to the frequency of occurrence of each code included in the quantized signal, and the variable length coded to be transmitted to the buffer 70 And a buffer 70 for temporarily storing a video data signal and a multiplexing section 60 for temporarily transmitting the coded video data input from the multiplexing section 60 to the next stage for smooth transmission. .

In the conventional video encoding apparatus having the above-described configuration, as shown in FIG. 3, the quantization step size of the quantization unit 40 is changed or inputted based on the amount of data stored in the buffer 70. If there is much motion of the image, the amount of data input to the buffer 70 is adjusted by increasing the step size to reduce the amount of data.

However, considering that the larger the step size of the quantization in encoding, the smaller the data amount is, the lower the quality of the final reconstructed image is. The quality is improved but there is a problem that the amount of data is relatively large.

Therefore, the conventional video encoding apparatus for controlling the buffer 70 by adjusting the size of the quantization step based on the data amount of the buffer 70 as described above is finally reconstructed due to the difference in motion in units of blocks processed once. There is a deviation in image quality. That is, the conventional apparatus not only causes a blockage phenomenon in which the difference between blocks increases as the image with more movement increases, but also causes a loss of data due to congestion of the buffer, resulting in deterioration of image quality of the image to be finally restored.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems of the prior art, and an object of the present invention is to provide a video encoding apparatus capable of preventing congestion of an output side buffer or blocking of a reproduced video caused by an input reverse motion difference.

In order to achieve the above object, the present invention provides a memory for temporarily storing an input video signal, a time difference signal between a prediction signal and a current video signal obtained through motion estimation / compensation between a reconstructed previous video signal and a current input video signal. DCT unit for converting from domain to frequency-domain transform coefficient, quantizer for quantizing transform coefficient from DCT unit based on status signal of data amount in output side buffer, frequency of occurrence of each code included in quantized signal A variable length encoder that encodes a short or long coded code according to the codeword, a multiplexer that collects the variable length coded image data signal for transmission to the buffer, and a coded image data signal provided by the multiplexer. Video portion consisting of the buffer to temporarily store for transmission to the next stage An apparatus, comprising: bit amount adjusting means for adjusting a bit resolution of image data output from the memory based on the amount of data in the buffer, wherein the bit amount adjusting means increases the data amount of the buffer. And a bit resolution is reduced by reducing the number of bits of the image data output from the memory when the step size is maintained for a predetermined block by exceeding a predetermined value when the quantization step size is enlarged. To provide.

Further, in the encoding apparatus of the present invention, the bit number reduction of the image data in the bit amount adjusting means is executed once or twice depending on the size of the quantization step, and is performed in units of three frames, one bit at a time.

Other objects and various advantages of the present invention will become more apparent from the preferred embodiments of the present invention described below with reference to the accompanying drawings by those skilled in the art.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

1 is a block diagram of a video encoding apparatus according to a preferred embodiment of the present invention.

As shown in the figure, the present invention provides a bit resolution of image data output from the memory 10 in correspondence with the change in the quantization step size based on the data of the buffer 70 and the state signal next to the memory 10. It is to have a bit amount adjusting section 20 to adjust the to have the main configuration features, through this configuration to achieve the object of the present invention.

That is, the encoding apparatus of the present invention is a method of adjusting the amount of data stored in the buffer 70, as well as a method of changing the size of the quantization step, as well as reading and processing image data stored in the memory 10 (i.e., compression encoding). Before this, a method of changing the bit resolution of video data is adopted.

As an example, in the encoding apparatus of the present invention, if the amount of data stored in the buffer 70 is large, and the amount of data is to be reduced, the size of the quantization step is initially increased, but if the movement of the input image continues to increase, this causes a difference in image quality between blocks. As it becomes worse, the bit size of the input image is reduced through the bit amount adjusting unit 20 without increasing the step size continuously, thereby preventing the step size from increasing continuously.

More specifically, when the amount of data in the buffer 70 increases, the video encoding apparatus of the present invention increases the size of the step applied to the quantization unit 40 initially. At this time, if the size of the step is maintained for three blocks at least 3/4 of the maximum value, the bit resolution of the image data read from the memory 10 through the bit amount adjusting unit 20 as an example, as an example. As shown in Fig. 2 a), it is reduced from 8 bits to 7 bits.

In this state, if the video signal of three frames is processed and then the step size is not continuously reduced, as shown in FIG. 2, b), the bit resolution is reduced from 7 to 6 bits, and then 10 frames of video are displayed. After processing it will be restored. Therefore, the present invention enables efficient control of the buffer by repeatedly performing such image data processing based on the data amount of the buffer.

As described above, according to the present invention, in controlling the amount of data in the output buffer, by controlling not only the size of the quantization step but also the bit resolution of the input image, the congestion of the encoded image data stored in the output buffer and the blocking in the reproduced image Since the phenomenon can be effectively prevented, there is an effect of preventing the deterioration of the image quality of the image to be finally restored.

Claims (4)

Memory 10 for temporarily storing the input video signal, the conversion coefficient of the frequency domain in the time domain to the difference signal between the current video signal and the prediction signal obtained by the motion estimation / compensation between the reconstructed previous video signal and the current input video signal The quantization unit 40 for quantizing the transform coefficient from the DCT unit on the basis of the state signal with respect to the data amount in the output side buffer 70, for each code included in the quantized signal. A variable length encoder 50 encoding a short or long length code according to a frequency of occurrence, a multiplexing unit 60 for collecting the variable phase encoded image data signal for transmission to the buffer 70, and the multiplexing unit A video encoding apparatus comprising the buffer 70 that temporarily stores a coded image data signal provided at 60 for transmission to the next stage. The apparatus may further include bit amount adjusting means 20 for adjusting a bit resolution of image data output from the memory based on the amount of data in the buffer 70, wherein the bit amount adjusting means 20 includes: The number of bits of the image data output from the memory 10 when the step size is maintained for a predetermined block in excess of a predetermined value when the quantization step size is enlarged due to an increase in the data amount of the buffer 70. Video encoding apparatus characterized in that to reduce the bit resolution by reducing the. The video encoding apparatus of claim 2, wherein the predetermined value is 3/4 of a maximum value of the quantization step size. The video encoding apparatus according to claim 1 or 2, wherein the number of bits of the video data is reduced once or twice depending on the quantization step size, and is reduced by one bit at a time. The video encoding apparatus of claim 3, wherein the number of bits of the video data is reduced in units of three frames.