[pulseaudio-discuss] How to create a virtual microphone with source set as default monitor device?

[Sean Greenslade]

On Mon, Sep 07, 2020 at 12:31:22AM -0700, guest271314 wrote:
> > There are a couple of options. One is to simply redirect the sink input
> > once it is opened (e.g. with pavucontrol).
> 
> That option is used at
> https://github.com/guest271314/captureSystemAudio#launch_pavucontrol.
> 
> For the pavucontrol option the next goal is to embed pavucontrol in an
> HTML document.

I doubt that will be possible. Pavucontrol makes use of the native
pulseaudio APIs, which are not exposed to javascript.

> > If you really need a non-monitor source device to be present, I think
> > your best option would be module-remap-source. It shouldn't be too hard
> > to come up with a "remap" that's just a passthrough:
> >
> > https://www.freedesktop.org/wiki/Software/PulseAudio/Documentation/User/Modules/#module-remap-source
> 
> Chromium is expecting a microphone device. Currently if a monitor is
> set at command line the capture throws an exception, see
> https://bugs.chromium.org/p/chromium/issues/detail?id=931749.

After reading through those bug reports and related issue links, it's
pretty clear that this is not a use case that they are particularly
interested in supporting. May I perhaps suggest using a different
browser?  Firefox had no problem with monitor inputs last time I
checked.

> Have so far tried kernel module and null-sink without achieving
> capture of system audio.
> 
> What is the command for the remap option for this case?

No idea, I've never done it myself. The example listed in the online
docs shows a simple stereo swap, so you could presumably adapt it by
switching the channels to be non-swapped (and of course substitute your
specific master source name).

https://www.freedesktop.org/wiki/Software/PulseAudio/Documentation/User/Modules/#module-remap-source

--Sean