[pulseaudio-discuss] Per-app flat volume adjustment is highly unintuitive, if mathematically consistent.

[Jud Craft]

On Wed, May 27, 2009 at 5:07 AM, Colin Guthrie <gmane at colin.guthr.ie> wrote:
> The way I understand it, and apologies if I'm wrong here, is that Banshess
> want's 80% and it's the only app playing. In order to achieve that result,
> pulse does not scale the stream at all but sets the underlying hardware
> volume to 80% (but in dB's yada yada!). So the net result is I get sound at
> the right volume.

Right, but you did not address an important detail of my example.
Keep reading...

> Then another stream joins that wants 100% So, pulse will start scaling the
> Banshee stream to ensure it is scaled in software to 80%, and turn up the
> underlying hardware volume to 100%. Net result is that Banshee continues
> playing at the same level and sounds the same but the new stream can be
> louder.

So far so good.  When running Banshee (80%), and, say, Firefox (100%).
 Main system volume is 100%.  I am in agreement with your explanation
thus far.



Now...for the catch.

Close Firefox.  Only Banshee runs.  System volume has now dropped back
to 80% (hardware volume has been changed to 80% too), since that's
Banshee's volume.

Now, increase the system volume to 100%.  Banshee is now 100%.

Then, turn back on Firefox and play a video.  What should happen?
Since the Banshee : Firefox ratio was previously 0.8 : 1.0, my theory
was that Banshee should be pushed down to 80% and Firefox starts
playing at 100% (the system volume) again.

However, when I tried it last night, they both stayed at 100%, and I
lost the relative volume difference between them.  (This was with
flat-volumes enabled).

So when I changed Banshee to 100% when it was running alone, it
appears that Pulse forgot that Banshee-Firefox have an 0.8 : 1.0
ratio.  (Note, maybe this was a bug, and Pulse should have remembered.
 I'm not sure, since I can't tell what's intentional and what might be
a bug, since I haven't figured out what "flat volumes" mean in terms
of user volume interaction.  It didn't make sense to me that Pulse
forgot remember the ratio, but maybe that's how it's supposed to be.)