Abstract: Motion estimation is an important issue in H.264 video coding systems because it occupies a large amount of encoding time. So the quality of motion search algorithm affects the entire encoding efficiency directly. A novel search algorithm which utilizes an adaptive hexagon and small diamond search is proposed to enhance search efficiency. The adaptive search pattern is chosen according to the motion strength of the current block. When the block is in active motion, the hexagon search provides an efficient search means; when the block is inactive, the small diamond search is adopted. Simulation results show that this approach can speed up the search process with little effect on distortion performance compared with other adaptive approaches.

Key words: adaptive search, H.264 standard, motion estimation, Mean Absolute Difference（MAD）

摘要： H.264视频编解码标准中由于运动搜索部分占整个编码时间的权重很大，所以运动搜索算法的优劣直接影响整个编码的效率。对编码运动估计理论进行了研究，采用六边形和小菱形相结合的方法，提出了一种新的自适应快速搜索算法来改善搜索效率。自适应快速搜索算法模式由当前块运动强度来决定，当当前块处于剧烈运动时，该算法选择六边形图形搜索算法；当当前块处于缓慢运动时，该算法选择小菱形图形搜索算法。实验结果表明该算法相比其他自适应算法以及单纯使用一种搜索图形节约了搜索时间，同时率失真性能影响甚微。

关键词: 自适应搜索, H.264标准, 运动估计, 平均绝对误差