[pulseaudio-discuss] Change sound via acpid

[John W]

On 12/22/15, Tanu Kaskinen <tanuk at iki.fi> wrote:
>
> It's not true that the system mode is unsupported

I've seen this link referenced a few places. Maybe it's out of date or
wrong, but definitely seems pretty clear on the point:
http://www.freedesktop.org/wiki/Software/PulseAudio/Documentation/User/WhatIsWrongWithSystemWide/

It mentions "You are using PA against the explicit recommendations of
the maintainers...".

It is good to know that PA will run as the 'pulse' user, though.

>
>> Next, I found out about the unix socket authentication options in
>> /etc/pulse/default.pa
>> ...
>
> The options aren't specific to the system mode. Without error messages,
> I don't know why it didn't work. If there are multiple users running
> pulseaudio, one problem would be all of them try to listen on the same
> socket, which will inevitably fail.

I only want to run the daemon once, but I want multiple users (in my
case, the "main" user as well as root, via the acpid script) to be
able to communicate with it to affect the audio.

You mention error messages - I would love to provide better ones. Do
you know any way to?
Perhaps a way to see what PA is getting from its configuration files,
what the final "effective config" is at the end of the process, etc?

>
> If it's sufficient to just mute one alsa sound
> card, you could use amixer to mute the hardware directly. PulseAudio
> will notice that and update its internal state accordingly. This is the
> command:
>
> amixer -c0 set Master toggle
>
> "-c0" may refer to the wrong sound card, though (and it may refer to a
> different sound card after rebooting). "-cNAME" is better, where NAME
> is the sound card name shown in brackets in /proc/asound/cards.
>

I have tried the "-c" option, and it has ... "sort of" success (:

In particular, mute works, but unmute does not.
It seems that mute will affect the "mono" as well as stereo L/R
channels, but unmute only affects mono. So the effect is that it stays
muted.

I am not at the machine right now, but can provide the full output
from that process later.

Thanks for your help
-John