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

[01ivier at labomedia.org]

Le 2020-11-04 01:17, Arun Raghavan a écrit :
> 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

Thank you,

Your answer is good... I just asked the wrong question... Sorry...

What could help me, in my case, is to remap the mono sink-input (the 
ouput of my application) into a stereo one, so that I could control the 
volume of each channel with set-sink-input.
Maybe I missed something but module-remap-sink doesn't like to do it.

I tried to use module-remap-source but "Name or index of the master 
source" seems to concern sink listed with "pacmd list-sinks" not "pactl 
list sink-inputs".

Is there a solution to get a stereo sink-input from a mono one ?

Thank you.

°1ivier