Adaptive Bitrate Algorithm For 360-Degree Video Streaming

In recent years,360-degree video has become more and more popular.Compared with traditional videos,360-degree videos can bring users a more immersive viewing experience.In a 360-degree video streaming system,the performance of the adaptive bitrate(ABR)algorithm affects the user’s quality of experience(Qo E)directly.On the one hand,existing algorithms rarely consider the significant difference in storage size across tiles within the same bitrate level,resulting in sub-optimal bitrate allocation results.On the other hand,under dynamic network conditions,video freezing and bitrate switching occur frequently.Therefore,designing a more efficient 360-degree video adaptive bitrate algorithm is of great significance for improving user’s Qo E.Adaptive bitrate algorithms that ignore the difference in storage size between tiles at the same bitrate level will cause large tiles to occupy more network bandwidth without obtaining greater quality gain.Small tiles have greater potential for quality improvement,but the quality is low due to insufficient network bandwidth.Therefore,this thesis proposes a method called Tile-Size Aware Bitrate Allocation for Adaptive 360°Video Streaming(TSA).By carefully reducing the bitrate of large tiles,TSA greatly improves the quality of more small tiles without reducing the quality of large tiles too much,thereby improving the overall quality of the video.Experimental results show that TSA can effectively improve video quality and user’s Qo E.Under network conditions with fluctuating bandwidth,360-degree videos frequently experience freezing and bitrate switching.To address this problem,this thesis proposes an Adaptive Bitrate Algorithm for360-Degree Video Streaming Using Playback Rate Control Mechanism(PRC).PRC is based on deep reinforcement learning technology.When the network bandwidth decreases,by appropriately reducing the video playback rate,PRC can not only slow down the speed of data consumption in the buffer,but also give the following video chunks a chance to transmit at higher bitrate.Experimental results show that PRC can effectively reduce video freezing and bitrate switching.