KR970073173A - IMPROVED IMAGE CODING SYSTEM HAVING FUNCTIONS FOR CONTROLLING GENERATED AMOUNT OF CODED BIT STREEM - Google Patents

Abstract

In an encoding system including an MC-DCT and a quantization, the present invention calculates a complexity of an image to be currently coded based on a quantization error value between a current frame input for encoding and a previous reconstructed frame, To a video encoding system having a bit generation amount adjustment function capable of adaptively adjusting a bit generation amount after coding by selectively removing a high frequency component of an input video signal using a two-dimensional discrete cosine transform according to the present invention. According to an aspect of the present invention, a quantization error value is calculated for each frame based on a pixel value difference signal between a current frame and a reconstructed previous frame, and averaged quantization error values of the calculated frame are used to calculate an average quantization error value , And calculates the quantization error values of the calculated frame Contribute quantization error calculating means for calculating the average quantization error values for a plurality of the frame set; The average quantization error value of the calculated plurality of frames is referred to as the complexity of the current frame to be encoded through the encoding means and a predetermined plurality of bandwidths for adaptively limiting the frequency pass bandwidth of the current frame inputted for encoding Control means for generating a bandwidth determination signal corresponding to an average quantization error value calculated among the signals; Discrete cosine transform means for transforming a video signal in a spatial domain for an input current frame signal into two-dimensional DCT transform coefficients in a frequency domain of an M × N block unit using a cosine function; Quantization means for quantizing a 2-dimensional DCT transform coefficient block of M × N units into a finite number of values using a quantization parameter value; Frequency selection means for determining a high-frequency passband for the quantized DCT transform coefficient blocks based on the generated bandwidth decision signal and for limiting the high-frequency passband of each quantized DCT transform coefficient block to a determined bandwidth; And restoring the original signal before coding by performing inverse quantization and inverse discrete cosine transform on each of the quantized DCT blocks with limited bandwidth, and estimating the restored bandwidth-limited frame signal as a original signal. And the image restoration means for providing the current frame signal for compensation to the encoding means. Therefore, the amount of bits generated after the encoding can be effectively controlled without increasing the step size excessively at the time of quantization in the encoding means.

Description

IMPROVED IMAGE CODING SYSTEM HAVING FUNCTIONS FOR CONTROLLING GENERATED AMOUNT OF CODED BIT STREEM

Since this is a trivial issue, I did not include the contents of the text.

FIG. 1 is a block diagram of a video encoding system having a bit generation amount adjustment function according to a preferred embodiment of the present invention. FIG. 2 is a detailed block diagram of a frequency selection block of FIG. 1. FIG. And a decision area for limiting a high frequency component determined on the basis of the complexity with respect to the 8x8 pixel block.

Claims (5)

And an error signal between predictive frames obtained through motion estimation and compensation of a current macroblock unit using the present frame and a reconstructed previous frame, through encoding means including discrete cosine transform, quantization, and entropy encoding, And generating a coded bit stream, wherein the quantization is a bit size adjustment function in which a step size is adjusted based on full state information of the bit stream stored in an output side buffer, the system comprising: A quantization error calculation unit for calculating a quantization error value for each frame based on the pixel value difference signal between the reconstructed previous frames and averaging the quantization error values of the calculated frame to calculate an average quantization error value for a plurality of predetermined frames Way; An average quantization error value of the calculated plurality of frames is referred to as a complexity of a current frame to be encoded through the encoding means and a predetermined number of frames for adaptively limiting the frequency passband bandwidth of the current frame inputted for encoding Control means for generating a bandwidth determination signal corresponding to the calculated average quantization error value among the bandwidth determination signals of the plurality of bandwidth determination means; Discrete cosine transform means for transforming a video signal of a spatial domain for the input current frame signal into two-dimensional DCT transform coefficients in a frequency domain of M × N block units using a cosine function; Quantization means for quantizing the 2-dimensional DCT transform coefficient blocks of M × N units into a finite number of values using a quantization parameter value; Frequency selection means for determining a high-frequency passband for the quantized DCT transform coefficient blocks based on the generated bandwidth decision signal, and for limiting the determined bandwidth to a high-frequency passband of each quantized DCT transform coefficient block; And restoring the original signal-restored bandwidth-limited frame signal by performing inverse quantization and inverse discrete cosine transform on each of the quantized DCT blocks having the limited bandwidth, And an image restoring unit that provides the frame signal to the encoding unit. 2. The apparatus of claim 1, wherein the predetermined bandwidth determination signal includes an average quantization error value of each of the calculated frames, an average error value of a plurality of frames transmitted per second obtained by averaging the average quantization error values of each frame, And the standard deviation of the average error value is determined by using the standard deviation of the average error value. The apparatus of claim 1 or 2, wherein the predetermined plurality of bandwidth determination signals include four bandwidth determination signals of integer values for setting different filter coefficients of the respective DCT transform coefficient blocks. Image Coding System with Emission Adjustment Function. 2. The apparatus of claim 1, wherein the discrete cosine transform unit transforms the video signal of the spatial domain of the current frame signal into two-dimensional DCT transform coefficients of 8x8 block units. Image coding system. The apparatus of claim 1 or 4, wherein the frequency selection unit maps high frequency components of the quantized DCT transform coefficient blocks to a zero value, Image coding system with bit generation amount adjustment function. ※ Note: It is disclosed by the contents of the first application.