Geometric Partitioning Merge Mode with Motion Vector Refinement

This paper describes Geometric Partitioning Merge mode with MV refinement. This extension allows more accurate MV for GPM partitions, resulting in higher coding efficiency. Four methods are studied to understand trade-off in terms of coding efficiency and complexity for different levels of refinement flexibility. Fast algorithms of the proposed methods are also described to allow manageable encoding run time options. Simulation results show that the most flexible method can achieve -0.25% and -0.51% coding gains with relative encoder run time of 129% and 133% for RA and LB test conditions, respectively. Its fast version provides -0.12% and -0.23% coding gains with relative encoder run time of 101% and 105% for RA and LB test conditions, respectively.