Research And Implementation Of Several Key Optimization Technologies In H.264 Video Coding

H.264 video coding standard is the new international video coding standard approved on May, 2003. Many new technologies such as 1/4 or 1/8 sub-pixel motion estimation, multiple reference frames, deblocking filter, enhanced entropy coding, small block integer transform and so on are adopted in H.264 to improve the coding efficiency of H.264 while all these technologies increase the complexity of H.264 encoder thus restrict its real time application. Excellent coding effect of H.264 has a great attraction to the market and a fast coding algorithm and its implementation are the precondition and guarantee for the market application of H.264, so the optimization of H.264 coding has a great theoretical significance and applicable value.First in this paper we deeply analyse the new standard and its syntax structure to grasp the coding framework as a whole. Then tests and analysis are made on the different configured parameter sets which affect the coding efficiency apparently and a parameter set for real time coding is gotten with less influence on its coding effect. Second, several mainstream motion search algorithms are analysed and implemented and comparison is made between them, finally the diamond search algorithm is chosen to be integrated into the encoder. Additionally, the coarse-grained search process in DS algorithm is improved to reduce its computation size. Third, through the analysis of the time consumption of different module, we get the bottleneck of the encoder, namely the mode decision module which affects the real time coding effect greatly. So through the statistical analysis of the real testing results, the time-consuming mode decision module is optimized and a biased fast mode decision algorithm is proposed to speed up the common mode searching process through a biased search order and early termination strategy thus speeds up the whole encoder. Finally, the variable length coding and arithmetical coding are compared and analysed and the VLC which consumes less time is chosen as the research object. Through the analysis of the UVLC, a quotient-residue variable lengh coding scheme is proposed which conforms to the distribution of the syntax value in real video coding and its average code length is shorter. Through the real test, its coding efficiency is higher than that in the standard.