Adaptive Merge Candidate Selection Based on Geometric Partitioning Mode beyond Versatile Video Coding

We propose a method for adaptively selecting merge candidates for the geometric partitioning mode (GPM) in versatile video coding (VVC). The conventional GPM contributes to improved coding efficiency and subjective quality by partitioning the block into two nonrectangular partitions with motion vectors. The motion vector of the GPM is encoded as an index of the merge candidate list, but it does not consider that the GPM partitions are nonrectangular. In this paper, the distribution of merge candidates was evaluated for each GPM mode and partition, and a characteristic bias was revealed. To improve the coding efficiency of VVC, the proposed method allows GPM to select merge candidates that are specific to the partition. This method also introduces adaptive reference frame selection using template matching of adjacent samples. Following common test conditions in the Joint Video Experts Team (JVET), the experimental results showed an improvement in coding efficiency, with a bitrate savings of 0.16%, compared to the reference software for exploration experiments on enhanced compression beyond VVC capability in the JVET.