Improvement And Optimization Of H.264Inter Prediction And Estimation Based On DSP

As the most widespread use of video encoding standard,H.264has higher performance than H.263and MPEG-4.Because of using several powerful coding methods it improves the compression efficiency,under the same reconstructionvideo quality,H.264can save50%bit-stream compared with H.263and MPEG-4. While high compression efficiency also brings an extremely large number ofcomputations,which has an influence on real time video coding.How to reduce the calculated amount of H.264is nowadays a research hotspot.As a digital signal processor designed by TI,DM6437is an efficient and cheap chip that is thesuitable platform for H.264coding.In the course of missile guidance,DSP in missile compresses the pictures from infrared video camera according to the instructions of flight control computer,then translates the outcome to computer on theground,which is worthy of research.This paper firstly introduces the background of the research project andrecommends the key modules of H.264.Because inter prediction is the most timeconsuming part in H264,then a improved fast mode decision algorithm is introduced. Main of the work is following: researching on the code of H.264interprediction in JM10.2; using single-step debug to analyse the flow path of codeand finding that inter prediction is the most time-consuming; introducing a improved fast mode decision algorithm to reduce computation time that contains thepriority prediction of SKIP mode,using threshold to end motion estimation of8x8even more smaller pixel lumps and selective inter mode decision; researching optimizion of H.264compression in DM6437like as loop unrolling,linear assembly, memory allocation,using cache and EDMA.The experiment in PC indicts that the improved algorithm can reduce70%of the coding time with a little influence on image quality compared with the algorithm of JM10.2. The compression coding is realized in DM6437. The coding rate of QCIF is75fps in DM6437,and30fps with CIF.