Audio Video out of sync when CPU use is high

Starting a new thread since the others about AV Sync issues were closed.

Reproduce by: Use the cpulimit Linux program to restrict Zoom’s CPU usage, and you’ll see frame drops and audio being ahead of video. This is for the latest (and earlier) Zoom clients on Linux. You can try various percentages of CPU limit and even try using the taskset Linux program.

The problem: Many of my colleagues have noticed audio being ahead of video when using the Zoom client on Linux. This is very disconcerting when viewing the recorded video later. Some profiling we did, showed that this happened because Zoom used up too much CPU and did not distribute the processing well to various cores. Only one thread seems to handle a major chunk of the processing, resulting in it not being able to process enough data and it also caused frame drops. This is on an 8 core x86 machine. From the forums, I see that AV sync issues happen on Zoom SDK too. I hope your team can improve the architecture and perhaps even use the audio and video timestamps to ensure they are in sync. I have even seen a situation where for a Zoom cloud recording, the main webcam view audio of a speaker was slightly out of sync. The smaller webcam view shown on top of the screen was a bit out of sync and an overlay webcam view of the same speaker was perfectly in sync.

Thanks for reporting this! Do you mind sharing steps to reproduce including the distro that you’re using? I’ll work to reproduce this on my end.