After writing that email I realized that the stuff about FFmpeg could be a bit confusing, so here is some clarification:
In principle, FFmpeg runs optionally to capture and record both video and audio from inside the container, to let us "see" what happened inside. When the recording is ENABLED, the described problem does NOT happen. This led me to test what would happen if the recording is *disabled* but the container started up with a dummy FFmpeg instance that would just capture from PulseAudio and just discard the data, and that one is the "ffmpeg -f null null.out" command that I showed. BTW, this test confirmed that indeed, as long as audio is being captured from PulseAudio, the playback issue doesn't occur in Firefox. Now I've done a different test: removed the dummy FFmpeg capture, and instead modified the normal recording command. Now we compare what happens if recording either video only, or video+audio. This has the effect we can imagine: video-only recording shows the playback issue in Firefox, and video+audio recording somehow makes the issue disappear. You can see here a video+audio recording, showing correct behavior: https://www.dropbox.com/s/cf1370cta1zd5k6/firefox-pulseaudio-short-ok.mp4?dl=0 And here a video-only recording, showing the playback issue: https://www.dropbox.com/s/je9wqlw5b76u2xe/firefox-pulseaudio-short-err.mp4?dl=0 Later I tested with a longer video and this helped to explain the problem! Seems that, when the issue happens, *playback works fine in the long term but it struggles during the first 5 seconds*. We couldn't see that with the shorter test videos, because they happened to be 5 seconds long!! Here we see a video+audio recording with a longer test video, correct behavior: https://www.dropbox.com/s/j79p6lu37qsvc78/firefox-pulseaudio-long-ok.mp4?dl=0 And here a video-only recording with the larger file, playback issue happens: https://www.dropbox.com/s/p9bv11jlvx3mybu/firefox-pulseaudio-long-err.mp4?dl=0 So, how come having another process grabbing audio from PulseAudio can have such effect on the media playback in Firefox? What can be done to further troubleshoot this issue? _______________________________________________ dev-media mailing list [email protected] https://lists.mozilla.org/listinfo/dev-media
