Open-Loop Rate Control for adaptive video streaming

Dynamic video streaming performs video rate selection based on streaming client's throughput estimate. In practice, the accuracy of the estimated throughput is limited due to feedback delay and unawareness of the dynamics of the underlying HTTP/TCP transport layer. Furthermore, state-of-the-art rate selection methods inherently introduce a two-fold quantization error, as will be detailed in this paper. As a result, streaming adaptation is often erroneous and causes client buffer instability. In this paper, we present Open-Loop rAte Control (OLAC), an adaptive streaming architecture designed to support low-latency streaming applications. The key components of our architecture are a server-side simulation of the streaming client's buffer, which provides a low-delay feedback for the video rate selection, and a hybrid adaptation logic based on throughput and buffer information, which stabilizes the adaptive response to dynamics of transport and application layers. We evaluate the performance of OLAC in wireless streaming scenarios by comparing it against two well-known streaming architectures, QAC and vlc-plugin DASH. The results show that our approach achieves at least 10% higher average quality and at least 73% lower rebuffering duration - achieving zero rebuffering duration in most scenarios - for dynamic live streaming with buffering delays as low as two seconds.