Pano: Optimizing 360° Video Streaming with a Better Understanding of Quality Perception
This work addresses bandwidth efficiency for 360° video streaming users, representing an incremental improvement by refining quality models and adaptation logic.
The paper tackles the high bandwidth requirements of 360° video streaming by identifying unique quality-determining factors specific to 360° videos, such as viewpoint speed and luminance changes, and presents Pano, a system that uses these factors to optimize streaming. The results show that Pano saves 41-46% bandwidth without quality loss or improves perceived quality by 25%-142% at the same bandwidth compared to state-of-the-art methods.
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 360°videos, 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% bandwidth without any drop in the perceived quality, or it can raise the perceived quality (user rating) by 25%-142% without using more bandwidth.