Multiparty Video Conferencing

Summary

The demand for multi-party video conferencing (MPVC) has experienced tremendous growth over the last decade. However, the end-to-end encryption, which ensures the encryption between end clients, disables transcoding in the server and keeps the MPVC systems from providing adaptive bitrate for heterogeneous network bandwidth users. The current MPVC approaches try to provide the adaptive bitrate (ABR) control by deligating the bitrate control to end clients, but they face three challenges: i) the ABR algorithm needs to change the bitrate to receive promptly to guarantee the low latency while dynamically modifying the set of bitrates to send to improve the overall video quality; ii) To not break synchronization between users, the latency should not exceed the target latency shared by everyone; iii) All of those bitrate controls must consider multi-to-multi-streaming. To address these challenges, we first develop a system that shares all selectable bitrate sets with clients. Based on this system, we design SEALED, a client-side adaptive bitrate control for high video quality and synchronization. SEALED lets each client determine the target bitrate to achieve high video quality and low latency and select a bitrate close to the target bitrate. To make the selectable bitrate set closer to the target bitrate, SEALED collects bitrate requests from clients and consensus on the requests to take the most appropriate request for adjusting the bitrate set to send. SEALED also measures frame latency on each client and uses it to adjust the target bitrate to guarantee that the latency is synchronized to the target latency. 

Performance

The figure below shows that SEALED achieves better adaptability compared to existing bitrate orchestration algorithms using dynamic programming. SEALED guarantees end-to-end frame latency under 100ms, while other bitrate orchestration algorithms increase latency up to 10 seconds. This shows that SEALED enables latency-guaranteed and consensus-based streaming for Multi-party video conferencing.

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