Fast multi reference frame motion estimation for high efficiency video coding

In this paper, a fast multi reference frame motion estimation algorithm is proposed to reduce the computational complexity for high efficiency video coding (HEVC). Firstly, according to the reference frame distribution, we define the motion complexity for a frame. Based on the motion complexity, an initial reference frame set (RFS) is constructed to reduce the number of the reference frame for motion estimation. Then for each prediction unit (PU), the average distortion per pixel together with the motion vector difference (MVD) in the first reference frame is employed to shrink the RFS in order to early terminate the motion estimation process. In addition, to enhance the robustness of the proposed scheme, an expansion method for RFS is proposed to guarantee the video quality. Experimental results demonstrate that the proposed scheme can significantly save the encoding time. For Low Delay testing configuration, over 30% of time saving can be achieved on average with ignorable performance loss.