TCP-based application-layer protocols are increasingly applied to commercial live video streaming systems. However, in unstable mobile networks, the throughput of TCP may fluctuate rapidly due to its transmission mechanism, causing undesired playback interruption. In this paper, we propose a general application-layer rate adaptation approach to cope with the variability in TCP throughput. We analyze the transmission process and evaluate the network condition using a multi-buffer model. With information obtained in this model, an algorithm based on the Proportional-Integral-Derivative (PID) controller is proposed to dynamically adjust the video bitrate in response to the throughput change. We have implemented an experimental mobile live streaming system employing this approach and achieved a significant improvement in playback continuity and bandwidth utilization.
['Jiexi Wang', 'Shengbin Meng', 'Jun Sun', 'Zongming Quo']
A general PID-based rate adaptation approach for TCP-based live streaming over mobile networks