A fast CU partition algorithm based on sum of region-directional dispersion for virtual reality 360° video

Abstract

Virtual reality 360° video has an ultra-high resolution (usually 4–8 K), which takes more coding time than traditional video. Considering the degree of horizontal stretching in a different area of the ERP projected video, a fast coding unit (CU) partition algorithm based on the sum of region-directional dispersion is proposed. The relationship between the current block and its adjacent ones is measured based on the degree of horizontal stretching, and the current frame is divided into three regions. A new metric named the Sum of Region-directional Dispersion is defined to measure the complexity of the current block in different regions and directions. In the proposed algorithm, the optimal fast partition threshold is determined for each region to achieve the goal of early termination partition. Compared with the original reference software HM16.20, the proposed algorithm can reduce the time in virtual reality video coding by 38.5%, while the BD-rate only increases by 0.40%.