Based On The H.264/avc Motion Estimation Algorithm

The next-generation Video Coding Standard H.264/AVC is jointly developed by ISO/IEC Moving Picture Expert Group MPEG and ITU-T Video Coding Experts Group VCEG , which has high coding efficiency than the MPEG-4 and has been highly improved especially in the lower bit-rate that make it available for the lower broadband network video applications that requires high-quality assurance circumstances. In order to make the H.264 can be easily used in the high-real-time and low-bit-rate systems , it is necessary to improve and optimize its algorithm. After the analysis of the H.264 coding algorithm we can draw the following conclusions: motion estimation in the video compression encoding algorithm is the most important part ;the algorithm which using motion estimation algorithms and motion compensation technology can reduce and eventually eliminate temporal redundancy of video signals to improve its coding efficiency. Therefore, improving the efficiency of motion estimation algorithms to make search process faster and more efficient become the research hot spots of the H.264.This paper first discusses the basic theorys and the key technologies of H.264; then introduces several of the existing classic block-matching-based motion estimation algorithms and analyzes their advantages and disadvantages; then deeply introduces and analysis one of the core algorithms for motion estimation of the H.264 recommendation-UMHexagonS, and in order to improve the shortcomings of the algorithm-lack of real-time, carries out four aspects of its optimization, respectively, with to get the size of the dynamically generated referenced search window; to make determination of the location of the referenced search window; a small diamond-type search; a large hexagon search, finally get a new algorithm-IUMHexagonS (Improved UMHexagonS). IUMHexagonS algorithm can quickly and efficiently make the determination of the referenced windows'size and position.Throughout the search process, the improvement of the small diamond seach pattern and the large hexagonal search pattern can significantly reduce the number of search points, and can achieve a good match result.This article uses the referenced software model JM10.1 in the H.264, compiled by VC6.0, has carried out the IUMHexagonS algorithm. Compared with the simulation result with several different types test sequences of UMHexagonS and EPZS,the IUMHexagonS algorithm improved its advantages.Especially in the similar bit rate and reconstruction of image quality, the average time spend in the motion estimation process of IUMHS decreased by 27.32% and 20.26%, the average time spend in the encode process of IUMHS decreased by 26.87% and 13.46%,obviously reduces the complexity of the H.264 encoder and improves its real-time effect.