提出了一种基于方向自适应的运动估计混合模板搜索算法。该算法利用了运动矢量的时空相关性，对搜索起点进行预测，与仅利用空间相关性预测起点相比，提高了搜索的准确性；然后通过自适应阀值静止块判定技术，对静止块直接中止搜索，解决了常量阀值静止块判定技术仅适应于某种特定序列类型的缺点；最后根据运动类型自适应选择采用小菱形、六边形-小菱形或方向十字-小菱形搜索策略，解决了单一搜索策略模式下，不能兼顾视频压缩图像质量和速度的局限。实验表明，提出算法与H.264标准提供的UMHexagonS算法相比，在保证编码质量的前提下，大大降低了运动估计时间，提高了编码效率。

In this paper, a direction-based adaptive mix-pattern motion estimation search algorithm is proposed. The algorithm makes the best of spatial and temporal correlation, which improves the veracity of the search center prediction compared with the algorithms employing spatial correlation only. By employing adaptive threshold technology on static block determination, the disadvantage of const threshold technology on static block determination has been avoided. Moreover, the algorithm chooses the search strategy according to the corresponding motion type, which can balance the video quality and speed simultaneously. Experimental results show that the proposed algorithm can highly reduce the time of motion estimation ensuring the video quality compared with the UMHexagonS algorithm.