Streaming 360° videos demands excessive bandwidth. Tile-based streaming and super-resolution are two widely studied approaches to alleviate bandwidth shortage and enhance user experience in such real-time video streaming systems. The former prioritizes the transmission of a fraction of the 360° video according to the user viewport, while the latter enhances the streamed video in higher resolutions through computations. However, these two approaches bring substantial complexity and computation overhead and thus suffer from resource bottlenecks due to the constrained mobile hardware. This paper proposes TBSR, a practical mobile 360° video streaming system that incorporates in-time super-resolution with tile-based streaming on commodity mobile devices. We present the designs of three key mechanisms, including a rate adaptation method with macro tile grouping to reduce decoding computations, a decoding and SR scheduler for different types of tasks to achieve the best cost efficiency, and the workload adjustment method to control the amount of tasks given the available capabilities. We further implement the TBSR prototype. Our performance evaluation shows that TBSR outperforms the existing methods, improving QoE quality by up to 32% and bandwidth savings by 26%.

Today’s multimedia applications usually organize the contents into data blocks with different deadlines and priorities. Meeting/missing the deadline for different data blocks may contribute/hurt the user experience to different degrees. With the goal of optimizing real-time multimedia communications, the transmission control scheme needs to make two challenging decisions: the proper sending rate and the best data block to send under dynamic network conditions. In this paper, we propose a delay-sensitive and priority-aware transmission control scheme with two modules, namely, rate control and block selection. The rate control module constantly monitors the network condition and adjusts the sending rate accordingly. The block selection module classifies the blocks based on whether they are estimated to be delivered before deadline and then ranks them according to their effective priority scores. The extensive simulation results demonstrate the superiority of our proposed scheme over the other representative baseline approaches.