Based Fast H.264/avc Coding Mode Selection Algorithm

With the rapid development of computer technology and Multimedia technology, the video compression technique is paid more and more attention by researchers. H.264/AVC is the newest video coding international standard,which was suggested by ITU-T VCEG and ISO MPEG.It has been widely used in many applications because of its outstanding compression performance and fine networking adaptability.H.264/AVC achieves higher rate distortion performance than previous video coding standards,but the complexity increases a lot. Therefore optimizing algorithm of H.264/AVC video coding complexity is the hot topic in the world.This thesis study algorithm of full search of intra and inter mode decision and analyzes calculation complexity, then based on the existed algorithms of fast mode decision, we propose fast intra mode decision algorithm and fast mode decision algorithm of P-frame coding. Main works as follow:1.Study basis theory of video compression coding,main frame of H.264/AVC video coder and layering structure.2.Analyzes some key coding techniques of H.264/AVC in details. In order to achieve high efficiency of coding, H.264/AVC standard includes intra predi-ction,multi-references motion estimation,multi-size division and so on. This paper emphases on related technologies of intra prediction, inter prediction, transform and quantification, deblocking filter and entropy coding.3.Considering complexity of intra coding, we proposed a fast P-frame intra mode decision algorithm. In the algorithm,we firstly record some coding mode information of the coded frames, then get candidate subset of coding modes; As for current coding frame, judge temporal correlation of adjacent video frames by threshold, at the condition of strong temporal correlation, use candidate subset of coding modes to intra prediction coding. Experiment proves that it can effectively reduce the complexity of prediction mode decision.4.About P-frame coding, we proposed an adaptive threshold algorithm based ondistribution characteristics of the sum of the absolute differences(SAD) of the best inter mode and correlation among neighboring macroblocks. Firstly calculate average SAD of every coding mode of the neighboring coded frames,then confirm prejudge(Intra4x4or Intra16x16) threshold of intra coding mode; In the P-frame inter prediction phase, calculate SAD of optimal inter prediction mode, select corresponding intra prediction coding mode if it is in the inter prediction threshold interval, else select optimal inter prediction mode instead of intra prediction. Experiment proves that P-frame fast coding algorithm optimize the intra prediction coding, at the same time confirm the quality of the reconstructed image.