由于快速整像素搜索算法的提出和采纳,致使半像素搜索过程在整个编码过程中占用的比重更为显著。为了减小半像素搜索的计算量,提出了一种快速半像素运动矢量搜索算法。该算法是利用半像素搜索窗内的误差匹配曲面具有的单峰特性,通过比较整像素运动矢量周围4个整像素点的绝对误差和(SAD)来实现可能的最小匹配误差半像素点的预测,以排除大量不必要的计算量。实验结果表明,该算法对于各种不同运动程度和空间细节的视频序列,在保证和半像素全搜索法有相同图像质量的同时,至少可节省66%的计算量。

Half-pixel motion search is growing in importance for the whole coding process due to the adoption of fast integer pixel search algorithms.A minimal matching error direction prediction-based fast half-pixel motion vector search algorithm is proposed in this paper to reduce computation load of half-pixel search.Based on the single peak characteristic of half-pixel error matching function inside search area,the minimum matching distortion direction is predicted and possible half-pixel candidate positions with minimum matching distortion are selected based on SAD values comparison results of four integer-pixel points around integer-pixel motion vector.The experimental results reveal that,to all kinds of video sequences,the proposed algorithm can obtain almost the same video quality as that of the half-pixel full search algorithm while reducing at least 66% computation cost.