[pulseaudio-discuss] How to combine microphone audio and music from application to pipe to video conference

[Sean Greenslade]

On Sat, May 23, 2020 at 11:49:54AM -0400, Samir Parikh wrote:
> Ok, I'm back after researching and trying some things a bit more.
> 
> Sean Greenslade wrote on 5/16/20 1:23 AM:
> > This is definitely possible entirely within pulseaudio. I'll go over the
> > basic concepts here, then show an example.
> ...
> > Now you can begin playing music, and in the Playback tab of pavucontrol
> > move the music playback to the VirtualMixer.
> 
> I got this far in following your instructions but got stumped on that last
> part about moving the music playback to the VirtualMixer.  This screenshot
> shows my options for where to direct the Rhythmbox output:
> https://imgur.com/a/PRCYV3B
> 
> If I select VirtualMixer, playback of the music continues but I can no
> longer hear it.  Is there a way for me to also hear it through my own
> speakers/headset?

This is possible, but adds some complexity to the setup. To hopefully
make this easier to follow, I've made a little flowchart of all the
components:

https://dumbpic.link/manu/2020-05-23_pulse_diagram_mic_mix_with_mon.png

Remember that pulseaudio draws a distinction between sources and sinks,
and normally doesn't allow you to route a source to sink or vice-versa.
So source components have a rounded face, and sink components have a
pointed face.

Certain endpoints are "exclusive," meaning that they can only have one
thing connected to or from it. These points have a grey shading to
indicate that property.

Modules with a thick border are real hardware. Modules with a thin
border are software. The dotted line around "auto monitor" refers to the
fact that it is auto-created when a virtual sink is created.

The thick lines connecting modules are the routings within Pulse. These
routings can all be modified in realtime within pavucontrol.

Hopefully this makes enough sense to help you to augment your script.
For comparison, here's the flowchart for my original suggestion that
does not let you monitor the music:

https://dumbpic.link/manu/2020-05-23_pulse_diagram_mic_mix.png

--Sean