一种用于H.264的改进UMHexagonS算法

在运动估计中,H.264以增加的编码复杂性为代价获得了非常好的性能.基于对现有文献的研究,提出了一种改进的UMHexagonS算法.首先,在UMHexagonS的非对称十字交叉搜索中增加了8个搜索点,以改善算法在垂直方向上运动的适应性;其次,为提高编码效率,将UMHexagonS算法的小矩形窗口全搜索分为两个步骤;然后,在UMHexagonS的非均匀多层次六边形网格搜索中采用了一种并行算法,进一步提高算法的运动估计性能;最后,采用三点搜索法来替代小菱形搜索,原始的小菱形搜索只作为满足提前终止最佳情况的跳转对象.仿真表明,相比于UMHexagonS算法,提出的改进算法在视频压缩编码速度和重建图像的质量都具有更好的性能.

A Novel Improved UMHexagonS for H.264

The standard H.264 gains a very excellent performance at the expense of an increased encoding complexity, in particular for motion estimation. In this paper, a novel improved UMHexagonS algorithm based on the study of the existing literature is proposed. First, eight points are added to the unsymmetric-cross search of UMHexagonS to improve the adaptability of its movement in the vertical direction. Second, the small rectangular window search is divided into two steps to enhance the coding efficiency. Then, a parallel algorithm for uneven multi-hexagon-grid search of UMHexagonS is set up to further improve the performance of the algorithm for motion estimation. Last, three search points is used to replace the small diamond search which in this paper is just a jump object for the most satisfied early-termination. Simulations shows that improved algorithm has a better performance in the terms of reducing motion estimation time, improving the speed of video coding compression and guaranteeing the quality of reconstructed image, comparing with UMHexagonS algorithm.