Weight-based bit allocation scheme for VR videos in HEVC


Since VR videos shown on the head-mounted display (HMD) is omnidirectional, the average distortion of VR videos in all directions shall be calculated in spherical domain. Several metrics have been proposed to calculate the coding loss of VR videos in spherical domain, including S-PSNR, WS-PSNR, CPP-PSNR. The above metrics are all improved based on PSNR by creating a weight map. This paper aims to optimize the rate control scheme on HEVC mostly for WS-PSNR. According to the weight map of WS-PSNR, regions with more weights in plain are more important, thus more bits shall be allocated to the important regions. We use weight-based rate control scheme to realize the above thoughts. Weight-based rate control scheme defines bit per weight (bpw) instead of bpp. Large values of bpw indicate that the important regions deserve high bitrates, thus probably achieving better quality. Consequently, the proposed rate control scheme improves the video quality of VR videos, which leads to average gain of 2.1%, 4.3% and 1.5% of S-PSNR, WS-PSNR and CPP-PSNR.

2017 IEEE Visual Communications and Image Processing (VCIP)
Li Song
Li Song
Professor, IEEE Senior Member

Professor, Doctoral Supervisor, the Deputy Director of the Institute of Image Communication and Network Engineering of Shanghai Jiao Tong University, the Double-Appointed Professor of the Institute of Artificial Intelligence and the Collaborative Innovation Center of Future Media Network, the Deputy Secretary-General of the China Video User Experience Alliance and head of the standards group.