H.24到AVS与MPEG2到H.264的视频转码研究.docx

ABSTRACTABSTRACT ABSTRACT ABSTRACT With the hi曲demanding for coding efficiency and video quality,the newest video coding standard H．264／AVS is developed collaboratively by the ITU-T and ISO／IEC． AVS video coding standard is developed by the Audio Video Coding Standard Working Group of China(AVS working group in short)，which was approved by the Chinese Science and Technology Department of Ministry of Information Industry． The mandate of the AVS working group is to establish the China’S national standards for compression,manipulation and digital right management in digital audio and video multimedia equipment and systems． So at least．the AVS standard will be used widely in China in several years；there is an instance need to transcode H．264 to AVS．As the video coding standard MPEG-2 has been established for long time，there are many studies about the video transcoding from MPEG-2 to H．264，including the fast transcding in pixel domain and transform domain．So in this dissertation，only focus on the cllroma transcoding in transform domain and transcoding while down-sampling at the same time for MPEG一2 to H．264 transcoder,the formula of reconstructing for chroma is given，and the algorithm of transcoding while down-sampling at the same time is proposed． In this dissertation，the video coding standards H．264／AVC、AVS and MPEG-2 are firstly introduced．Secondly,we discuss the main difference between them，and develop the algorithms used for H．264 to AVS transcoding in pixel and transform domain,include the coefficients transforming algorithm，motion vectors reconstructing and mode decision．Using the concept parallel disposing,we implement the H．264 to AVS缸anscoder to quicken the transcoding rate．For Intra trancoding of H．264 to AVS，a fast prediction mode decision is proposed，with the testing of different sequences，the algorithm call save about 56％computations；a fast fractional pel motion estimation algorithm is also proposed，the simulation results show that the proposed algorithm su