中文摘要：

H.264是最新的视频编码标准,它相对于以前的视频编码标准在编码效率上有了巨大的提高.高编码效率得益于采用了一系列新的编码技术,这也导致了较高的计算复杂度.H.264运用了可变块运动估计方法,这也是H.264编码过程中最耗时的模块.提出了一种基于H.264的可变块快速运动估计算法.该算法基于以下3种策略：静止块的预测、非静止块的预测搜索和合并过程中的自适应精细搜索.试验结果证明,该算法能够将计算复杂度降低到快速全搜索运动估计算法的3%,而PSNR和码率几乎与快速全搜索算法得到的结果相当.

英文摘要：

H. 264, the latest video coding standard, achieves significant improvement in coding efficiency compared with previous standards. The high coding efficiency is based on some new techniques which also lead to high computationalcomplexity. H. 264 uses varlable-block-size motioff estimation, which is the most time-consuming module. In this paper, we propose a fast variable-block-size motion estimation algorithm for H. 264. The algorithm is based on three schemes： stationary block prediction, predictive search for non-stationary blocks and adaptive refinement search in merging process. Experimental results show that our algorithm can reduce the computational-complexity to 3% of fast full search motion estimation algorithm, with negligible PSNR loss and hit rate increase.