A P2P-MCU Approach to Multi-Party Video Conference with WebRTC

Abstract

WebRTC enables web browsers with real-time communications capabilities via JavaScript APIs. But when the number of the participants increases, the bandwidth and CPU requirements have become a serious issue in a push based mesh network. In this paper, we propose a P2P-MCU approach for multi-party video conferencing that efficiently supports both ordinary smart mobile phones and PCs. In our approach, a MCU module is integrated into the browser to mix and transcode the video & audio streams in real time. And when the browser acts as the MCU node leaves the conference session without notice, another candidate browser can take over the control immediately, and the ongoing WebRTC conference can be seamlessly recovered with our MCU selection algorithm. In addition, our approach works under the 3G symmetric NAT networks by using some UDP hole punching method. Our P2P-MCU solution reduces 64% CPU usages and 35% bandwidth consumptions for each participant compared to the mesh-network solution in our eight-party WebRTC conference experiments. Although the P2P-MCU module may introduce some delay (<500ms), the delay is stable and perceptually almost neglectable.