Reducing Latency in Interactive Live Video Chat Using Dynamic Reduction Factor
YangXin Zhao, Anfu Zhou, Xiaojiang Chen · 2020
In best-effort packet networks, a buffer is commonly used to eliminate network jitter and enable smooth video playback at the expense of additional delay (i.e. jitterdelay). In this work, we examine how jitter buffer performs in the Web Real-Time Communications (WebRTC), which is the de-facto standard used in interactive multimedia applications. We collect a dataset from a live video streaming service provider, which adopts WebRTC. After an in-depth analysis of the dataset, we find that jitter buffer can dynamically adjust the jitterdelay but is too conservative, resulting in a very slow decline of jitterdelay. To address the issue, we analyze the control logic of the jitter buffer and find that the reason lies in the use of a fixed reduction factor, known as psi (ψ). We propose an enhanced jitter buffer adaptation mechanism called JTB-ψ, which dynamically adjusts ψ according to frame size and frame duration, to reasonably speed up the decline of jitterdelay. Practical testbed experiments show that JTB-ψ achieves a 41.5% lower jitterdelay and improves receiving frame rate, quantization parameter (QP) and sending bit-rate under different network conditions, compared to the fixed-ψ approach.