Spherical Position Dependent Rate-Distortion Optimization for 360-degree Video Coding

Abstract

360-degree video in spherical format cannot be well handled by the conventional video coding tools. Currently, most of the 360-degree video coding methods first project the spherical video content onto a 2-dimensional plane and then compress the projected video using a conventional video codec. However, the projection conversion process will cause an irreversible conversion error, which indicates that the reconstruction quality of the projected video cannot fully represent that of the spherical video. In view of this, this paper proposes a spherical position dependent rate-distortion optimization (RDO) approach for 360-degree video coding. During the RDO process, spherical reconstruction quality is taken into consideration and calculated according to the spherical position of the pixels in each coding unit (CU). Furthermore, the Lagrangian multiplier and quantization parameter are adjusted accordingly. The proposed method is implemented on HEVC reference software HM-16.7. Experimental results show that the proposed method can achieve better coding performance, compared with HM-16.7.