Efective multi-frame motion estimation method for H.264

In order to achieve a high coding gain, the H.264 video coding standard allows one or more reference frames. However, this greatly increases the computational burden in proportion to the number of the searched reference frames. Therefore, we propose a method to reduce the complexity by selecting the proper reference frames. The proposed algorithm uses the optimal reference frame information in both the P16 times 16 mode and the adjacent blocks, thus decreasing any unnecessary searching process in the inter modes except for P16 times 16. Experimental results show that the proposed method considerably saves coding time with negligible quality and bit-rate difference. It can also be adopted with any of the existing motion estimation algorithms to obtain additional performance improvement.