When I try to do video chatting in Firefox (using Jitsi Meet) it apparently selects the first available Input Source as my microphone which is always invalid. The one selected is "Monitor of HDMI Output" and that one is silent.
Normally I open
pavucontrol and select the correct Input Source "Mic Input" in the Recording tab for the Firefox application. However, sometimes this does not work. Also, from within Firefox the Mic source is often not selectable / the selection has no effect. I need to select within
Can I disable or blacklist the Pulse Audio channel "Monitor of HDMI Output" as a valid input/recording source for Firefox? Perhaps within Firefox itself?
If this source were hidden I would expect Firefox to behave much better within Jitsi Meet.
The inability to select sound inputs in Firefox is a bug:
Also, this comment in this bug
suggests that an audio input device cannot be changed while a different is active. This would explain why you cannot select the correct device once the wrong one has been selected.
However, this is at best an explanation, neither a workaround or a solution.