Tile-based Rate Assignment for 360-Degree Video based on Spatio-Temporal Activity Metrics

Tile-based video systems have recently emerged as a viable solution to overcome the challenges of 360-degree video. For instance, the HEVC based viewport-dependent profile of MPEG OMAF allows serving clients independently coded tiles of the 360-degree video at varying resolution to enhance fidelity within the actual user viewport. During streaming, the client constantly adapts its tile selection and feeds a single merged bitstream to the video decoder. This paper addresses the open issue of rate assignment in a distributed encoding system in such a multi-resolution tiled streaming scenario. A model for tile rate assignment based on the spatio-temporal activity of the video is presented to reduce variance of the quality distribution and experimental results are reported.