Disable PulseAudio flat volumes to prevent it from pushing volume level to max

[Matthias Clasen]

On Tue, 2015-09-22 at 15:51 +0200, Lennart Poettering wrote:
> On Thu, 17.09.15 20:59, Germano Massullo (germano.massullo at gmail.com)
> wrote:
> 
> > Today I had a scary experience with the audio of my computer.
> > I was listening to music with Amarok, using my headphones... The
> > KMix
> > volume level was ~ 35%. When I logged into a video conference
> > application, the volume suddenly reached the 100%. I was shocked,
> > having
> > the maximum audio level shooted in your ears is a painful
> > experience.
> > The conference application that triggered PulseAudio pushing volume
> > to
> > maximum level probably should have never asked the system for a
> > 100%
> > audio level, but on the other hand, PulseAudio should never allow
> > an
> > application to make such sudden changes.
> > To avoid that, you have to set
> > flat-volumes = no
> > in /etc/pulse/daemon.conf
> 
> This is a non-sensical request. If an app uses the mixer APIs to set
> the volume of something to very loud, that's what happens. Flat
> volumes have nothing to do with that.
> 
> I mean, the app you are using shouldn't set the volume like this, and
> that's the key here. If you turn off flat volumes you win about
> nothing, you just work around this specific app. Soon the next app
> will come along and play the same game with the actual device volume,
> and you won *zero*.
> 
> Don't mix flat volumes with misbheaving apps. Turning off flat
> volumes
> is a hack around the broken apps at best, and completely pointless..

For better or worse, misbehaving apps are a reality that is probably
not going to go away... I think we need to have a volume control
approach that is at least somewhat tolerant against such apps and has
some safeguards.