QoS improvements for MCU-ru

MCU-ru is a popular video conference system, improved from Multipoint Control Unit (MCU) open source. Users can send their video streams to MCU server and the system compresses all received video streams into one mixed multiple-view stream and sends back to all users. This method allows users with modest Internet bandwidth to video conference. Although the system works well in many countries, the quality of video conferencing can be significantly reduced when the available bandwidth is not stable, such as peak usage times. This article focuses on the improvement of the problem mentioned above by a simple approach: for a chosen codec when a client receives the mixed stream from MCU server by RTP, RTCP sends the quality feedback of the communication session to MCU server as well as in the reverse direction. As a result, both the client and server would have enough information to adjust the frame-per-second (FPS) and video resolution to optimize the usage of the available network bandwidth. We have run the system through multiple test scenarios and found that this method shows promising results in reducing bandwidth consumption. Lastly, an added feature of the design allows users to switch between mixed stream and specific stream, which gives participants of the video conferences more options.