360° Video Coding Based on Projection Format Adaptation and Spherical Neighboring Relationship

作     者：Hanhart, Philippe Xiu, Xiaoyu He, Yuwen Ye, Yan 

作者机构：InterDigital Commun Inc San Diego CA 92121 USA Alibaba Grp US Sunnyvale CA 94085 USA 

出 版 物：《IEEE JOURNAL ON EMERGING AND SELECTED TOPICS IN CIRCUITS AND SYSTEMS》 (IEEE J. Emerg. Sel. Top. Circuits Syst.)

年 卷 期：2019年第9卷第1期

页      面：71-83页

核心收录：

学科分类：0808[工学-电气工程] 08[工学] 

主　　题：360 degrees video video coding cubemap projection geometry padding HEVC 

摘      要：This paper describes a 360 degrees video coding scheme submitted in response to the joint call for proposal on video compression for capability beyond HEVC issued by ITU-T SG16 Q.6 (VCEG) and ISO/IEC JTCUSC29/WG11 (MPEG) in October 2017. The proposed coding scheme uses projection format adaptation and spherical neighboring relationship to improve coding efficiency. A hybrid angular cubemap projection format is used to adapt the sampling within each face. The faces are packed in an adaptive manner, and the frame packing configuration is updated at regular intervals. Geometry padding of reference photographs is used to improve inter prediction. For intra-/inter-prediction and in-loop filters, processes are modified to avoid utilizing wrong neighbors in the frame packed photograph. Finally, post-filtering is used to reduce artifacts at face discontinuities. Experimental results are presented to demonstrate the superior compression efficiency achieved by the proposed 360 degrees video coding scheme. Based on the end-to-end weighted-to-spherically uniform PSNR metric, it achieves average bit rate savings of 33.9% and 13.5% over the HM and joint exploration model anchors, respectively, encoded in the padded equirectangular projection format.