Hi there, for some time I've noticed a weird behaviour when using Firefox in my tests with my WebRTC gateway. Specifically, if I mute a video MediaStreamTrack in a web application, and then after some time unmute it again, it comes back delayed. It seems to happen more evidently when the bitrate of the video is low, while it's barely noticeable for higher bitrates for some reason, although it might or might not be related.
It is easily reproduceable, if you want to check it yourself: 1. open https://janus.conf.meetecho.com/echotest (simple gateway demo that just sends you back whatever you send to it) 2. use the "bandwidth" control to cap it to 128kbps (as anticipated, it seems more evident at lower bitrates: that control forces REMB feedback at 128000) 3. mute the local video track: echotest.webrtcStuff.myStream.getVideoTracks()[0].enabled=false 4. wait some time and unmute it again: echotest.webrtcStuff.myStream.getVideoTracks()[0].enabled=true 5. you'll see that video is now delayed, while audio is still ok. The demo doesn't do any RTP sequence number/timestamp overwriting, so what you get back is exactly the same as what you sent, which makes me think something goes wrong in how timestamps are computed/written in the Firefox WebRTC stack after video transmission is resumed. If I got it right, the framerate in the video changes when you disable video (IIRC you basically send a black frame at a much lower framerate), which means something might be messed up in those transitions. I've seen the issue around for a few months, and it affected Chrome too up to some time ago, so I thought it was something we were doing wrong: anyway, I've tried Chrome 50 lately and the issue is gone there, video has no delay anymore, which is making me think it might be indeed a bug in Firefox. Is there anything else I can provide to help you look into this? Thanks, Lorenzo _______________________________________________ dev-media mailing list dev-media@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-media
