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STC: Enabling 16K VR streaming on mobile platforms with FoV tracking

16K VR videos are coming to ages. But it could overwhelm mobile hardware for its huge bandwidth consumption and decoding complexity. To enable 16K VR video streaming over mobile platforms, we present a novel ShiftTile-Tracking (STC) streaming system, which crops and transmits video by tracking the Field-of-View (FoV) movement of users. The video chunk is split into ShiftTiles with frame granularity, which always covers FoV areas along the FoV movement trajectory. This transforms a 360-degree VR video into a traditional planar video, which leads to huge bandwidth saving and faster decoding speed. In the system design, we mainly entail two contributions. 1) To accommodate various FoV movement trajectories with a limited number of ShiftTiles, we propose an optimal tiling algorithm by FoV trajectory clustering. 2) To be resilient to the FoV prediction errors, we propose an accuracy-sensitive streaming algorithm, which expands the FoV area if the FoV prediction errors are high. The evaluation shows that under the same real-world 4G network conditions, the proposed STC improves 0. 9dBV-PSNR, reduces 12.4% buffering ratio, and achieves 45% faster decoding speed (64 frames per second) on average compared with the state-of-the-art solutions. This enables 16K VR video streaming on current mobile platforms.