[pulseaudio-discuss] Per-app flat volume adjustment is highly unintuitive, if mathematically consistent.
lennart at poettering.net
Wed May 27 08:23:38 PDT 2009
On Wed, 27.05.09 09:13, Jud Craft (craftjml at gmail.com) wrote:
> 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.
Mate, pleas just read those mails I wrote yesterday.
> 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.
If you close ff (actually flash) PA will remember that it was at 100%
of the device 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).
Yes, PA restores flash's volume according to what it saved previously:
to 100% of the device volume.
> 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.)
PA is not storing stream volumes relative to each other but relative
to the sink's refernce volume.
Lennart Poettering Red Hat, Inc.
lennart [at] poettering [dot] net
http://0pointer.net/lennart/ GnuPG 0x1A015CC4
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