Optimization Of AVS-M Video Encoding Algorithm On DM642

Along with the development of computer and the increasement of networkbandwidth, people's lives are full of multimedia applications such as digital TV ,video conference, streaming media and so on. Because of huge volume, rawmultimedia data should be encoded before being stored or transmission. Digitalaudio and video codec technology is the foundation of multimedia applications.AVS-M is the seven part of the AVS audio and video codec standard proposedby our country.The purpose of this issue is to realize a real-time video encoder on DM642.Inthis paper, I do some research on basic principles of video encoding and technicalpoints of AVS-M, bring with some corresponding improved algorithm. In part ofintra frame encoding, I optimized the algorithm of choosing the best predictedmethod for a sub-macro block, reducing the number of judgement . In part of interframe encoding, I propose to treat the reference frame number of the first sub blockdivided from the macro block which is being encoding as the reference framenumber of the other sub blocks get from the same macro block. According to thestatistics features of the inter frame encoding result that the percentage of INTRAmode of the macro block is very small, this paper put forward to omit the INTRAmode in inter frame encoding. In motion estimation, I chose SAD as the selectioncriteria of motion vector instead of SSD. Experiments show that with these methodsthe speed of the video encoder is increased while the encoding quality is in thescope of accepted. Then some optimization is done based on DM642 platform. Adirected graph is used to model the call relations of the C language functions in theencoding system and a evaluation methods is proposed to measure the contributionof a C language function when optimized. This evaluation method has some valueon the choosing of C language functions to be optimized. Some common way toimprove the performance of a system on DM642 is introduced , along with which isthe work I did.Test shows that the video encoder been optimized could encode CIF frame realtime.It's speed is about 21 frame per second when encoding CIF video frame. Thework finished in this paper has some meaning for the application of AVS-M.