| H.264/AVC is newest video coding standard of the ITU-T Video Coding Experts Group (VCEG) and the ISO/IEC Moving Picture Experts Group (MPEG), which greatly enhance compressing performance and provide a "network-friendly" video representation addressing "conversational" ( video telephony) and "non -conversational" (storage, broadcast, or streaming) applications. But the enhancement of compressing is based on rapid increasing of compute complexity, which has been the main hindrance of massive application.In this dissertation, we analyzed the decoder/encoder of H.264 carefully, then adopted various ways to optimize it. In encoder: After integrating the fast intra mode selection algorithm and fast inter mode selection algorithm adopted by H.264 standard into the reference software JM11.0, we find that above fast mode selection algorithms can not enhance encoding speed when rate distortion optimization technique method is not used. In the part of motion estimation, we used the MMX instruction in the parallel calculation of the SAD. In decoder: firstly, we adjusted the flow of the decode program,; secondly, we use the MMX and SSE2 instruction to optimize the integral transform and sub-pixel interpolation, adjusted some simple but high frequency called functions to inline asm function.In the end, the dissertation compared the performance of the optimized decoder encoder with the original. The result indicate the optimized decoder encoder have cut down the running time while maintaining the performance. |
