Abstract: H.264 is the latest international video coding standard，it supports high accurate subpel motion estimation.When the fast integer motion estimation is used，the computational load of subpel motion estimation may be the bottleneck of motion estimation.According to the monotonically increasing match criteria around the location of the optimal motion vector a fast fractional motion estimation algorithm based on the group error is presented.Simulation results show that it can save the search points of subpel motion estimation efficiently with very low rate distortion loss.

摘要： H.264是最新一代的视频编码标准，它支持高精度分数像素运动估计。当在整数运动估计中采用快速算法后，分数像素的运动估计可能成为制约快速运动估计算法性能的瓶颈。根据匹配准则的目标函数在最优运动矢量的附近都是单调递增这一假设，提出一种基于分组误差的快速分数像素运动估计算法。实验结果表明该算法不但能够有效降低分数像素运动估计的计算量，而且还能保持较小的率失真性能损失。