Pano: Optimizing 360° Video Streaming with a Better Understanding of Quality Perception
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Streaming 360 videos requires more bandwidth than non-360 videos. This is because current solutions assume that users perceive the quality of 360 videos in the same way they perceive the quality of non-360 videos. This means the bandwidth demand must be proportional to the size of the user's field of view. However, we found several qualitydetermining factors unique to 360videos, which can help reduce the bandwidth demand. They include the moving speed of a user's viewpoint (center of the user's field of view), the recent change of video luminance, and the difference in depth-of-fields of visual objects around the viewpoint. This paper presents Pano, a 360 video streaming system that leverages the 360 video-specific factors. We make three contributions. (1) We build a new quality model for 360 videos that captures the impact of the 360 video-specific factors. (2) Pano proposes a variable-sized tiling scheme in order to strike a balance between the perceived quality and video encoding efficiency. (3) Pano proposes a new qualityadaptation logic that maximizes 360 video user-perceived quality and is readily deployable. Our evaluation (based on user study and trace analysis) shows that compared with state-of-the-art techniques, Pano can save 41-46 the perceived quality, or it can raise the perceived quality (user rating) by 25
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