JVET-E0058 AHG8: A viewport-based pyramid projection for VR360 video streaming [P. Wang, H.-C. Lin, C.-Y. Li, Y.-H. Lee, J.-L. Lin, S.-K. Chang (MediaTek)]
(Chaired by JB and JRO.)
This contribution proposes a viewport-based pyramid projection format for VR360 video streaming. The compression efficiency among the ERP, TSP, and proposed projections is examined. In terms of the window-sized S-PSNR metrics (S-PSNR-NN and S-PSNR-I), the experimental results reportedly demonstrate that the BD-rate reduction provided by the proposed layout is considerably improved as compared to the ERP format when FOV is less than 140o, and that the proposed layout is superior to the TSP layout until FOV is 160o.
Unlike TSP, which is derived from cube projection and has 6 faces, this non-uniform projection method is directly derived from the sphere and has only 5 faces.
TSP is in the 360Lib software, but not for the metrics.
In combination with an evaluation criterion (window sized S-PSNR metric) defined in the contribution, a certain advantage is shown compared to TSP when the measurement region is narrow.
Viewport related projection formats not in central focus currently. No interest was expressed by other experts to include this as option in 360lib. No action was taken at this point.