A Fast Intra Mode Selection Algorithm Based on CU Size for Virtual Reality 360° Video

Virtual Reality (VR) 360 degrees video is spherical, and has ultra-high definition. It is time-consuming to code it using High Efficient Video Coding (HEVC) directly. In this paper, a fast intra mode selection algorithm based on Coding Unit (CU) size is proposed for VR 360 degrees video in Cubemap projection (CMP) format. A redefined mode selection strategy for two-stage Rough mode decision (RMD) is designed based on different depth CUs to reduce coding time during intra prediction process. The experimental results show that the proposed algorithm brings 27.70% saving in average coding time at the cost of only 0.8% Bjontegaard delta rate increase in All-Intra mode.