Research and optimization of a H.264AVC motion estimation algorithm based on a 3G network

Abstract: The new video codec standard H.264/AVC is jointly developed by ISO/IEC Moving Picture Expert Group MPEG and ITU-T Video Coding Experts Group [1] [2], VCEG. It has higher coding efficiency than the MPEG-4, thus could be applied to high definition application in low bit-rate wireless environment.[3] However H.264/AVC has harsh requirement on the hardware, basically due to the complexity of the algorithms it used. And end devices, e.g. smart phones usually do not have sufficient computing capability, also it is restricted by limited battery power. As a result, it is crucial to reduce the computing complexity of H.264/AVC codec, and in the same time, keep the video quality unharmed. After the analysis of the H.264/AVC coding algorithm, it can be found that ME (motion estimation) consumes the biggest part of the computing power. So in order to adopt H.264/AVC to real-time, low bit-rate video application, it is very important to optimize ME algorithm. In this thesis, basic knowledge and key technology of H.264/AVC is introduced  in the  first  place. Then it systematically illustrate the existing block-matching ME algorithms, both the algorithm flow and different technology involved, also the pros and cons of each. In the next part, a very famous algorithm UMHexagonS, now accepted by ITU-T, is introduced in detail, and the author explain in different aspects why this algorithm could gain more efficiency over others. And on the base of the analysis, the author proposes some improvement to the UMHexagonS, taking thoughts of some classic ME algorithms into it. In the last phase of the thesis, both Subjective quality assessment experiment and objective quality assessment experiment are used to examine the performance of the improved algorithm. It has been shown by experiments that the improved ME algorithm requires less computing power than UMHexagonS, while keeping video quality at the same level. The improved algorithm could be used in a wireless environment such as a 3G network.