Efficient fast motion estimation optimization based on the improved cross search template for H.264

Compared with previous video standards, the computational complexity of H.264/AVC is extraordinarily high due to newly adopted tools such as variable block size motion estimation. To reduce the high computational demands of H.264 coding standard, a hierarchical search strategy for ME is proposed by the deep research of the characteristics of motion estimation. This strategy consists of improved unsymmetrical cross search pattern. It predicts the motion range of the current block based on the computed RDO value character and the relation between the collocated blocks. Then based on this, variable search masks are applied in the following search steps. This scheme consists of the improved initial search point, search pattern, search range and match criterion. The experiment result shows that the method can save about 20% encode time compared to the current fast algorithms in the latest JM(Joint Model reference) software, while achieve almost the same PSNR as the full search algorithm.