Efficient motion estimation using a modified early termination algorithm in H.264

In the H.264 video coding standard, 7 modes {16 x 16, 16 x 8, 8 x 16, 8 x 8, 8 x 4, 4 x 8, 4 x 4} are used to enhance the coding efficiency. The motion vector estimation with 7 modes may require huge computing time. Thus, several efficient ME schemes have been proposed to reduce the complexity of ME module in H.264. In this paper, we propose a ME scheme using a modified early termination technique to speed up the motion vector estimation procedure while maintaining high image quality. We demonstrate the effectiveness of the proposed method by computer simulation. In the simulation results, the CPU time consumed by the proposed scheme is much less than that of the conventional scheme while the encoded video quality remains unchanged. This is due to the fact that the proposed scheme searches MVs from the smallest block mode to the largest block mode, and utilizes the correlation between neighbor MVs. Furthermore, the process of the proposed ME scheme can bypass to the next mode when the MVs of a mode are highly correlated with each other, while the conventional schemes can not skip to other modes.