Fast adaptive code rate control method

Abstract

The invention discloses a fast adaptive code rate control method which comprises the following steps of: coding the current image by use of the quantization coefficient obtained by the previous code rate control; storing the intermediate result of the coding; comparing the code rate calculated according to the size of the current coded frame and the size of the previous N-1 frames of the current coded frame with the target code rate; adjusting the quantization coefficient according to the comparison result; if the current coding code rate exceeds the threshold, adjusting the quantization coefficient of the previous N frames, and adjusting the quantization coefficient according to the difference between the coding result of each frame and the target code rate; recoding the N frames by use of the adjusted quantization coefficient by use of the intermediate result of the coded frame before; and calculating the quantization coefficient of the next frame by use of the bit number after the recoding of the N frames and the quantization coefficient when calculating the quantization coefficient in next code rate control. The method disclosed by the invention has the advantages of fast response to the screen change in a complicated scene, fast change of the coding type, fast recovery and stable code rate.

Description

technical field [0001] The invention provides a fast self-adaptive code rate control method, in particular to a coding method for making self-adaptive adjustment according to pre-coded results and actual code rate requirements by using reserved pre-coding information, and belongs to the field of video coding. Background technique [0002] The principles and steps of video encoding are as follows: [0003] 1. Intra-frame coding: [0004] 1) Transformation, according to a fixed division (such as 8x8 pixels), the coefficients in the transformed matrix represent the frequency distribution of the image before transformation, in which the high-frequency part is concentrated in the upper left corner, and the low-frequency part is concentrated in the lower right corner; [0005] 2) Quantization, using quantization coefficients for quantization (for example, dividing the transformation matrix coefficient by the quantization coefficient, this process is called quantization), so that ...

AI Technical Summary

Problems solved by technology

[0015] The characteristics of the traditional bit rate control method are as follows: the advantage is that the bit rate can be kept stable when the video scene changes little (the proportion of the changed details in the image is small); the disadvantage is that when the video scene changes greatly, the bit rate It will suddenly become larger or smaller, and it takes a long time to return to a stable state again. Generally, it takes at least one encoding unit (0.5 seconds to 1 second of encoding frames) to restore stability. In scenes with drastic changes or frequent switching ( For example, when advertising), the bit rate may be out of control (the actual encoding bit rate exceeds the target bit rate by more than double and lasts for more than 1 second)

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