H.264作为新一代的视频标准,对基于块匹配法的运动估计做了新的改进。运动估计是视频编码过程中极其重要的一个环节,它的算法效率对整个编码效率有很大的影响。针对H.264标准中提出的1/4像素精度的运动估计,对其基本算法以及几种快速算法进行分析比较,并在此基础上提出了一种快速的矢量合成算法。实验结果证明,这种算法在提高搜索速度的同时,也保证了图像质量。

As a new video coding standard,H.264 has an enhanced motion estimation method based on block matching that each partition in an inter-coded macroblock is predicted from an area of the same size in a reference picture,the offset between the two areas(the motion vector) has 1/4-pel resolution(for the luma component).Sub-pixel motion compensation can provide significantly better compression performance than integer-pixel compensation,at the expense of increased complexity.Quarter-pixel accuracy outperforms half-pixel accuracy.Motion estimation,whose efficiency has great effect to the whole coding efficiency,is an important part during the video coding process.In this paper,we compare the basic algorithm and some fast algorithms of 1/4-pel accuracy motion estimation,then put forward a fast algorithm which use composite vector.Experiments show that this algorithm is effective.