[toast0]

At least the WebRTC library (not sure about browser integration) can do some a/v sync. RTP audio and video both have timestamps; but of course they have different frequencies and epochs. RTCP sender reports include an RTP time and an NTP time, so you can correlate them.

Personally, I'm not thrilled with how webrtc modulates playback to try to synchronize the two streams, so the SFU I work with doesn't send NTP timestamps in the sender reports or we just don't send sender reports; I can't recall the details atm. Part of the problem may be that our SFU always send audio immediately, but video gets buffered and paced.

For 1:1 calls not using the SFU, a/v sync seems to work and was not controversial when we enabled it.