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

[drago01]

On Tue, Sep 22, 2015 at 12:00 AM, Owen Taylor <otaylor at redhat.com> wrote:
> On Thu, 2015-09-17 at 23:26 +0200, Germano Massullo wrote:
>> Il 17/09/2015 21:13, Andrew Lutomirski ha scritto:
>> >
>> > To clarify: did you get blasted by music or by video conference
>> > sounds?  If the music volume got louder, then it sounds like either
>> > a
>> > straight-up bug in PulseAudio (and a severe and dangerous one at
>> > that)
>> > or a serious bug in your video conference volume in which it
>> > adjusts
>> > the volume of streams other than its own.
>> >
>> > If you got blasted by video conference sounds, then I'd say it's a
>> > serious design flaw in PulseAudio.  PulseAudio should offer an
>> > easy-to-configure maximum volume (probably A-weighted power, but
>> > peak
>> > level works, too, if considerably less well) on a per-output basis
>> > with which to protect your ears.
>> >
>> > --Andy
>> I got blasted from the music because I was not making a conference, I
>> only logged into the software, so the music was the only sound I was
>> listening to. PulseAudio pushed the master audio level to 100%
>> (therefore all applications audio level changed to 100%, due flat-
>> volume setting).
>
> I'm not an expert in the subject, but I'm pretty sure this is not how
> flat volumes are supposed to work - it doesn't sound like useful
> behavior at all!
>
> Experimenting with GNOME, the model presented to the user seems to be:
>
>  - Each application's volume control separate goes from 0-100% of the
>    maximum system volume.
>  - Adjusting each application is independent
>  - Modifying the system global volume slider proportionally adjusts the
>    volume of each application
>  - The system global volume slider is always maintained to be at least
>    as much as the maximum of any application
>
>  NOTE: The system global volume slider is *not the same as the hardware
>        volume and does not represent a multiplication factor for
>        application volumes. It's just something that the user can
>        drag to change the volume of all applications.
>
> There is danger to the ears if an application assumes that 100% volume
> is a safe volume and blindly sets its volume to 100% without user
> input. But that only affects that application - one application's
> misbehavior never affects another application.
>
> It sounds like KDE ends up implementing a different model, either
> intentionally or because of bugs. It's also possible that lower level
> bugs (sound card driver, for example) might be making things misbehave.
>
> In general, the fact that pulseaudio is configurable in this area is
> going to be the source of almost infinite bug chasing, as applications
> and desktop environments are "fixed" for one setting or another. It's
> also very easy for people to stop investigating problems and say that
> "changing the setting fixed it for me." :-(

Flat volumes only make sense if we have an appropriate UI for them ...
but we do not.
Such a UI would show all volumes in relation to each other and the
system volume like windows does:
http://blog.nirsoft.net/wp-content/uploads/2011/02/volume_mixer_win7.png

What we currently have makes no sense the user has to guess what each
volume control actually does and how it affects the global volume.