seneca-cdot / bigbluebutton Goto Github PK

Issue:

• Audio playback doesn't begin at the start of video playback (out of sync)

Observations:

• If audio is already playing before the capture starts, audio stays sync'd up with video

If ADI (Alsa Device Index) in the capture script is not set to the proper device index, ffmpeg command will fail with an "Input/Output" error. The proper ADI may vary by machine/vm.

You can find the alsa device index using pacmd list-sources and looking for the device which contains ".monitor" at the end of the name, ie:

$ pacmd list-sources
2 source(s) available.
    index: 1
	name: <alsa_output.pci-0000_00_04.0.analog-stereo.monitor>
...

The correct device index value should be placed here

Sample warning in ffmpeg output:
[mp4 @ 0x55929294b340] Non-monotonous DTS in output stream 0:1; previous: 402395, current: 399868; changing to 402396. This may result in incorrect timestamps in the output file.

This may be causing the audio/video to fall out of sync and cause stuttering in the output file/stream

In the capture.sh script, kill causes the browser to restart in safe mode in subsequent runs
See: https://github.com/Seneca-CDOT/bigbluebutton/blob/capture-meeting/labs/x11/capture.sh#L8

Suggestion:
Utilize wmctrl to gracefully close the browser window