[pulseaudio-discuss] module-switch-on-connect: handling virtual sinks

[Georg Chini]

On 11.11.2017 05:28, Михаил Новоселов, Думалогия wrote:
> Hello,
>
> PulseEffects, an application, that can apply different effects or 
> equalize both input and output sound, cannot work properly when 
> module-switch-on-connect is on. PulseEffects creates a virtual sinks, 
> but PulseAudio's module-switch-on-connect makes it a default sinks 
> automatically what severely breaks the logic of PulseEffect's work.
>
> Please see https://github.com/wwmm/pulseeffects/issues/99
>
> 1) Can we specify that the created sink is a virtual one?
> 2) Maybe there are other ways to prevent module-switch-on-connect from 
> making a newly created virtual device a default one?
>
> I wrote the script Dumacast https://github.com/mikhailnov/dumacast 
> (first of all for my company's (Dumalogiya, http://думалогия.рф) 
> internal usage), and starting with the newest version of Ubuntu, where 
> module-switch-on-connect is on, I ran into the same troubles. My 
> script 
> https://github.com/mikhailnov/dumacast/blob/master/usr/bin/dumacast 
> creates virtual sinks via pactl (lines 135-149), and they are also 
> made default and break the logic of how the script works. I currently 
> have no idea how to handle it without unloading module-switch-on-connect.
>
> I tried both Ubuntu's 17.10 default PulseAudio and built from dEbian 
> sources PulseAudio 11, the situation is the same with them both.
>
> What can be done?
>
Do you really need module-switch-on-connect? If not, you could just 
check with
"pactl list modules short" if the module is loaded and unload it prior 
to starting
your application. You can also remove it from default.pa, so that it 
never gets
loaded.

If you need module-switch-on-connect, a command line switch could be added
to the module so that it ignores virtual sinks. The default behavior 
however can
not be changed, because other applications might rely on the current setup.

Regards
              Georg