Avs Reduced Resolution Transcoding Research And Implementation Of The Parallel Environment

Audio Video coding Standard (AVS), independently developed and owned by China, has high coding efficiency and low patent fee. Current video programs mostly are compressed with high resolution ratio, such as digital video broadcasting and DVD video. Obviously, it's not cost-efficient to recompress low detail video stream for devices whose demand on resolution ratio is lower. This thesis, with the video coding standard of AVS, studied transcoding stream from high resolution ratio to low resolution ratio.The task this thesis accomplished includes three parts:1. Studied the parallelism of video transcoding and actualized serial and parallel transcoding by using multi-thread technology.2. Analyzed three dominating MV mapping algorithms and tested their performances in AVS reducing resolution ratio transcoding. Then, according to the test results, chosen AMR arithmetic and added SAD adjudging to be MV reuse algorithm of this thesis. Then using the property of AVS encoder and the picture information of source stream, presented an algorithm for fast choice of 8x8 block's encoding mode of B frame.3. Found out the matrix transforming process for AVS transform and inverse transform and deduced the down sampling formula in transform domain of AVS. Analyzed video transcoding frames and used the best frame design a P frame motion compensation transcoding structure. With this structure, the video quality increased 2.22dB and the video distortion diminished evidently.The test result indicates that the transcoding scheme of this thesis can reduce 70.24% of the transcoding time while video quality descend 0.90dB and bit rate increases 0.003%. Finally, using VC2005, this thesis finished a time and frequency domain transcoder with UI in x86 platform.