[pulseaudio-discuss] How to control the right and left channel for a specific application using CLI ?

[Arun Raghavan]

On Tue, 3 Nov 2020, at 7:09 PM, 01ivier at labomedia.org wrote:
> Le 2020-11-03 23:49, Arun Raghavan a écrit :
> > On Tue, 3 Nov 2020, at 5:28 PM, 01ivier at labomedia.org wrote:
> >> Hello again,
> >> 
> >> I want to know if there is a way, still in command line, to control 
> >> the
> >> right and left volumes of an application.
> >> With Pulseaudio Volume Control, you can click on the lock icon related
> >> to a launched application, and two sliders appear to do so.
> >> Is it possible in CLI ?
> >> 
> >> My goal is to run two applications on the same card, but to assign 
> >> right
> >> channel for one and left for the other.
> >> 
> >> Possible complication : the output of my application is in mono and 
> >> with
> >> Pulseaudio Volume Control I don't get the two sliders if I click on 
> >> the
> >> lock icon.
> > 
> > You can use pactl to do this:
> > 
> >   pactl set-sink-input <sink input index> <volume for channel 1>
> > <volume for channel 2> ...
> > 
> > You can look up the sink input index and channel map for channel order 
> > with:
> > 
> >   pactl list sink-inputs
> > 
> > -- Arun
> 
> Hello Arun and thanks for the quick answer.
> 
> It's exactly the command I was looking for.
> Unfortunately, as I thought, it doesn't work in my case because my 
> output is in mono.
> Here's what I get:
> Failed to set volume: You tried to set volumes for 2 channels, whereas 
> channel(s) supported = 1
> 
> I can't change the output of the software.
> Is there possibly a way to create a virtual stereo output from the mono 

Yup, check out module-remap-sink: https://www.freedesktop.org/wiki/Software/PulseAudio/Documentation/User/Modules/#module-remap-sink

-- Arun