LAPAS: Latency-Aware Playback-Adaptive Streaming

Live video streaming is one of the fastest growing applications in the mobile Internet. In addition to video quality and streaming performance, live video typically requires shorter user viewing latency or else the service quality will degrade significantly (e.g., live sports). This poses a significant challenge as latency and quality-of-experience (QoE) are inherently conflicting objectives. This work tackles this challenge by developing a novel LAPAS algorithm that employs playback rate adaptation in addition to bitrate adaptation to: (a) enable the service provider to explicitly control the tradeoff between latency and QoE; (b) reduce latency while maintaining reasonably high QoE. Extensive trace-driven simulation results showed that LAPAS can reduce latency by 21.8% to 75.1% at the same or higher QoE compared to leading algorithms. Moreover, it is the only algorithm that can achieve viewing latency shorter than 4 seconds and can work well even for latency as short as 2 seconds. Last but not least, LAPAS's performance is robust with respect to network locations, mobile operators, and time. It can be implemented entirely at the client side and is thus readily deployable in today's mobile Internet.