H.264运动估计UMHexagonS算法的优化与改进

针对H.264中UMHexagonS算法存在的不足，提出了一种改进的快速运动估计算法。改进算法根据起始预测运动矢量成为最佳点的可能性大小对起始预测运动矢量的检测顺序进行了优化，提高了编码效率；设计了一种改进的5×5螺旋全搜索模板，减少了5×5螺旋全搜索模板的搜索点数；增加了一种针对亚宏块的提前终止策略，进一步减少了运动估计带来的运算量。实验结果表明，改进算法在基本保持UMHexagonS算法编码性能的同时，有效减少了运动估计时间，提高了编码效率，并且可适用于不同运动强度的视频序列。

Optimization and Improvement of Motion Estimation UMHexagonS Algorithm in H.264

Aiming at the existing problem of UMHexagonS algorithm in H.264, an improved fast motion estimation algorithm is proposed. The algorithm enhances the coding efficiency by optimizing the detection sequence of initial prediction motion vector(MV) according to the possibility of initial prediction MV becoming the best point, then an improved 5×5 spiral global search pattern is designed to reduce the search points of pattern, and an early termination technique for sub-macro block is proposed for further reducing the computation of motion estimation. The experimental results show that, with only negligible change of encoding performance, the improved algorithm can effectively reduce the motion estimation time and enhance the coding efficiency, and it can suit for video sequence of different motion intensities.