Research And Improvement Of Fast Motion Estimation Algorithm In H.264

H.264/AVC is the latest video coding standard developed by the Internation al Organization for Standardization (ISO) and the International Telecommunicati on Union (ITU). This standard can support network strongly, and to some extent, can improve the coding efficiency, and therefore has been widely recognized in the industry. However, the new standard is the highest complexity currently, because it added many new encoding modules which based on traditional modules. The design of H.264/AVC is based on conventional block-based motion-compensated hybrid video coding concepts, but with some important differences relative to prior standards:enhanced motion-prediction capability; a small block-size exact-match transform; adaptive in-loop de-blocking filter; enhanced entropy coding methods. Selecting the best coding mode among those prediction modes contributes mainly to the high coding efficiency of H.264/AVC. In order to decide the best coding mode, the Rate-Distortion Optimization (RDO) method is used. The RDO method improves the coding efficiency significantly. However, this relies on a substantial increase in the complex structure of the encoder to achieve. Therefore, improving its key algorithm to meet the needs of real-time critical is very important.Motion estimation is the key technology of video compression, which dominates the performance of compression and the time for calculating. Motion estimation and motion compensation can reduce the large amount of temporal redundancy exists between frames of video sequences, which leads to high compression. Especially in H.264, due to some new modules, such as the motion estimation with variable block size, and higher precision motion vector, etc, the motion estimation has seventy of the amount of the computation. The research on looking for an algorithm which can get an effective and accurate motion vector quickly becomes a hot topic at present.As the premise of the cost of saving time, this paper do deep exploration based on the H.264/AVC coding standard of motion estimation module in the practical application of the direction for the movement. First of all, the paper introduces the technology of video CODEC, including inter-prediction, intra prediction, integer DCT transform, entropy encoding and so on. The history of the existing video compression standards is introduced. Then, UMHexagonS, the H.264/AVC recommended core algorithm of motion estimation is analyzed in depth. Aimed at improving the lack of search algorithm, some aspects of it were improved, which are decision in the original search point, the dynamically generation of efficient search range, improved full search pattern in small region and the improved searching method of hexagon. On platform of JM10.1reference software, compiled by VS2008, the optimized algorithm is realized. The results of experiment show the performance of new algorithms are much better than original algorithm in real-time, code efficiency has improved greatly with little changes on image quality.