AVS-M中基于准零块检测的快速率失真算法

Fast rate-distortion algorithm based on quasi-zero-block detection in AVS-M

一个4×4块在变换、量化后各元素的绝对值和若不大于1,称该块为“近似零块”或“准零块”,AVS-M编码时就认为该4×4块的残差全为零,对该块的变换、量化、反量化、反变换运算都是没有必要的,在实际的低码率应用中,一般有70%-90%的4×4块变换、量化后为准零块。提出一种准零块的检测方法,只额外增加对非准零块各元素平方和(SSD)的计算,减少了率失真中的70%-90%变换、量化、反量化、反变换运算,编码性能基本不变。

A 4×4-block is named near-zero-block or quasi-zero-block if sum of absolute value of it does not exceed one after transform and quantization.Computation for transform,quantization,inverse transform,inverse quantization and block reconstruction of this blocks are not needed.There are about 70%-90% near-zero-blocks in nature video coding.In this paper,a near-zero-block detection rule is carried out.The method adds computation for Square Sum of Distortion of non-zero blocks,but it can omit about 70%-90% computation for transform,quantization,inverse transform,inverse quantization and reconstruction with little video quality degradation.