Research On Algorithm Based On All-intra Configuration Of AVS2 Video Coding

AVS2 (Audio Video coding Standard 2) is a new coding standard following the AVS and AVS+, formulated on June 8,2015 through four yeas effort of AVS working group. It has similar properties compared to HEVC and special coding for monitoring the scene and 3D video. AVS2 video coding standard reference code has a high complexity, it doesn’t meet the needs of real-time encoding. Therefore, it is of great significance to optimize the algorithm about AVS2 video coding.AVS2 video encoding standard has three configurations:LDP (low delay), RA (random access), and AI (all intra) which has the highest coding efficiency. Two algorithms are proposed of this thesis based on AI configuration. Firstly, study gradient direction of the pixel indicating the direction of the intra prediction mode, and the relationship of candidate modes between RMD(Rough Mode Decision, RMD) and rate-distortion optimization(Rate Distortion Optimization, RDO). A fast mode algorithm based on gradient is proposed in order to reduce alternative modes in the process of intra prediction in video coding AVS2 in this paper. The experimental results of the plurality of video sequences with resolutions from 406×240 to 2560×1600 indicate that the algorithm can effectively reduce the encoding time on average about 17%, and ensure the image quality at the same time. Secondly, aimed at the problem of a larger number of child nodes of recursive quad-tree algorithm in video coding AVS2, analyze the texture of image and encoding unit division. The simplified algorithm of quad-tree recursive seeking is proposed, based on statistical results and different conditions for different levels of the quad-tree. Simulation results of a plurality of video sequences with resolutions from 406 ×240 to 2560×1600 indicate that the coding rate increased by only 0.122%～0.3899%, PSNR declined by 0.002143～0.020714dB, and coding time reduced about 19.427%～21.785%.In the thesis, it gives an overview of international and domestic history of video compression standard, describes the key technology and innovation about AVS2 video encoding. In detail, fast algorithm about intra mode selection gradient-based and simplified algorithm about quad-tree of recursive search are discussed. The issues presented in this paper are summarized, and the future prospects in this field.