Fast merge mode decision for diamond search in High Efficiency Video Coding

This paper proposes a merge mode decision algorithm while maintaining the accuracy of a diamond search (DS) in motion estimation and compensation. In High Efficiency Video Coding (HEVC), the merge mode is used to reduce the bit rate in order to carry motion information. The rate-distortion (RD) cost of the merge mode is compared with the RD cost of the inter-prediction mode in the course of the motion estimation which can be terminated early when the merge cost is smaller than the estimated cost of the inter-prediction mode. To this end, this paper proposes a fast merge mode prediction algorithm when the DS is used for motion estimation. The main purpose of this work is to estimate the RD cost of the merge mode in advance by utilizing the distortion information of the RD cost of the motion vector prediction (MVP) so as to early terminate the motion search operation. Experimental results show that the proposed fast merge mode estimation achieves a comparable RD performance but reduces the amount of computation by 16.6% on the average when compared to the fast motion estimation with the diamond search implemented in the HM 8.0 reference software.