Research On Integer Transform And Entroy Coding Of Video Coding Section Of AVS

The research of this thesis is on the video coding techniques of China's first national Audio and Video coding Standard (AVS). After introduction of the basic theory of video coding, the development and technical characteristics of two series of international video coding standards, the thesis discusses the bitstream structure, decoding process and several core techniques of video coding section of AVS. Then the major research work of this thesison the transform, quantization and entropy coding modules of AVS was presented, including:Bring out a novel combined evaluation method of transform efficiency from two aspects: energy compaction and decorrelation efficiency in a proper range of correlation coefficients of input video prediction difference data. Select several excellent 8x8 transform bases theoretically and prove the accuracy of evaluation method by video coding test.Bring out the fast transform design method of a type of transform bases and get the fast transform algorithm of the basis (4,5,3,1), which has the lowest computation complexity among good transform bases.Propose methods to solve the problems of transform non-orthogonality in the quantization module and the anomalism of Rate-Distortion curve at high bitrate part of AVS video codec and improve its efficiency.Bring out a novel entropy codec design, combining the QP range division method and dynamic choosing VLC tables according the threshold of coding levels. The design has obvious coding gain over AVS_VLC in the low bitrate coding test and has an average gain of 0.2640dB and the gain of whole QP range is close to 0.1dB. So the new design has significant improvement of AVS entropy codec in the low bitrate coding applications.Simplify the coding procedure of the ESCAPE event of transform coefficients, remove a looking-up table for the maxim run range and reduce computation complexity and the memory size that the table requires.Generally speaking, the work of this thesis has made further improvements on the transform, quantization and entropy coding techniques of the AVS video coding section.