Improving quality and scalability of webRTC video collaboration applications

Abstract

Remote collaboration is common nowadays in conferencing, telehealth and remote teaching applications. To support these interactive use cases, Real-Time Communication (RTC) solutions, as the open-source WebRTC framework, are generally used. WebRTC is peer-to-peer by design, which entails that each sending peer needs to encode a separate, independent stream for each receiving peer in the remote session. This approach is therefore expensive in terms of number of encoders and not able to scale well for a large number of users. To overcome this issue, a WebRTC-compliant framework is proposed in this paper, where only a limited number of encoders are used at sender-side. Consequently, each encoder can transmit to a multitude of receivers at the same time. The conference controller, a centralized Selective Forwarding Unit (SFU), dynamically forwards the most suitable stream to each of the receivers, based on their bandwidth conditions. Moreover, the controller dynamically recomputes the encoding bitrates of the sender, to follow the long-term bandwidth variations of the receivers and increase the delivered video quality. The benefits of this framework are showcased using a demo implemented using the Jitsi-Videobridge software, a Web-RTC SFU, for the controller and the Chrome browser for the peers. Particularly, we demonstrate how our framework can improve the received video quality up to 15% compared to an approach where the encoding bitrates are static and do not change over time.

Performance Improvements of Bigbluebutton for Distance Teaching

“…Byrne et al (2020) analyze performance issues of Google Hangouts and Jitsi Meet when simultaneously using several video conferencing tools. Petrangeli et al (2018) show that forwarding selective streams and dynamically adjusting bit rates on the fly lead to performance improvements of up to 15%.…”

VRComm

“…For MCUs, recent cloud developments give the opportunity to use processing on-demand, thereby allowing conferencing sessions to scale up to many hundreds or even thousands of participants [36]. For an efficient stream multiplexing without any media processing, Selective Forwarding Units (SFU) are developed, see [43] and [53]. These SFUs forward streams from one participant to all other participants, thereby alleviating the need for one participant to send out separate streams.…”

“…One drawback of a p2p based WebRTC approach for transmission is scalability [43], as multiple users can quickly elevate the (CPU/GPU) resource usage. To mitigate this, we can (optionally) deploy a Multipoint Control Unit (MCU), to aggregate streams centrally and reduce the processing burden on individual clients.…”

Federated-Access Management System and Videoconferencing Applications: Results from a Pilot Service during COVID-19 Pandemic

“…The server adopts an SFU-based WebRTC for dissemination. Compared with a multipoint control unit (MCU) model, an SFU server can accommodate more concurrent clients because it is less computationally intensive [44]. However, clients with an SFU model require a wider network bandwidth than those with an MCU model because they are likely to receive multiple media streams.…”