AVS视频标准中块变换系数熵编码器的优化设计

文章研究了我国的国家音视频编码标准AVS视频部分的块变换系数熵编码技术，介绍了AVS当前的块变换系数熵编码器AVS_VLC的编码流程，分析了AVS_VLC在不同码率段(即不同的QP段)存在编码性能差异且与变换、量化模块不匹配等问题，提出了一种结合QP分段机制和VLC子表切换机制的熵编码器设计方法，即将编码器划分为多个码率段分别设计基于VLC子表切换机制的熵编码器。视频测试的结果表明本文设计的熵编码器在划分的3个码率段性能均优于AVS_VLC，QCIF序列测试结果平均有0．1548dB的增益，而且在低码率OP分段的性能较AVS_VLC有明显优势，平均增益达到0．3211dB，更适合于在低码率无线通信环境下应用。

Optimized Design of Entropy Encoder of Block Transform Coefficients of AVS Video Coding Standard

This paper discusses the entropy coding technique of block transform coefficients of the video section of National Audio and Video Coding Standard of China. First, the coding procedure of current entropy encoder (AVS_VLC) of AVS is introduced. Then the problems existed in AVS_VLC such as differences of coding efficiency at different bit rates and mismatching with transform and quantization modules are analyzed. The paper proposed a new entropy encoder design combining mechanisms of QP range division and VLC sub tables switch. The new entropy encoder has high efficiency over AVS_VLC at all 3 bit rate sections and has an average gain of 0.1548dB at QCIF sequence test. The gain at low bit rate section is 0.3211dB, which is most significant. So the new entropy encoder has more advantages over AVS_VLC in the low bit rate wireless communication applications.