[pulseaudio-discuss] Volume jumps to 100% on KDE startup in KDE 4.4.0-4.4.1

Colin Guthrie gmane at colin.guthr.ie
Sun Mar 14 16:17:34 PDT 2010

'Twas brillig, and Dwight Paige at 14/03/10 21:15 did gyre and gimble:
> On 03/14/2010 01:43 PM, Colin Guthrie wrote:
>>> I have installed the pulseaudio packages in>Main>Testing [version
>>> 1.0.21]. No problems to report so far. I wonder if there are
>>> corresponding packages in Fedora?
>> I believe the updates have already been shipped in Fedora. I don't
>> follow the updates there very closely so can't say for certain. "rpm -q
>> --changelog pulseaudio" will probably tell you more.
> I gave wrong version # for pulseaudio packages in Mandriva. It's 0.9.21.
> And Fedora pulseaudio packages are also 0.9.21. Fedora KMix [version
> 3.6-alpha2 updated from Redhat/Fedora KDE-testing repo] is indeed
> showing alsa controls currently.
> Also upon further investigation I may not have the problem I thought I had.
> I did a fresh install of Fedora 12 x86_64 formatting both / and /home
> partitions so all files would be fresh/default. Sound behavior is
> different from my original Fedora 12 install [still have that too].
> It shows the original/default volume in KMix [Master Channel] as 21%. It
> also had some channels muted like front, center, surround, and LFE which
> I had to unmute all to hear sound. This 21% volume was actually to low
> so I installed and opened pavucontrol and set Output devices to 31%
> which set KMix Master Volume to 61% which is good for me.

Just FYI, the disparity here is because the PA UIs offer volumes up to
150% (IIRC) which includes software amplification. The raw ALSA value in
Kmix does not offer this.

> Now here's one thing that seems strange to me. When I logout or reboot
> with KMix open when it plays the shutdown sound volume automatically
> lowers to 22% and I can barely hear log out sound. When I log back in
> with KMix open volume is again 61% until login sound plays when volume
> lowers automatically to 22% and when login sound finishes volume returns
> to 61%... Don't know if this is what it's supposed to do or not.

Pulseaudio expects full control over the mixer levels and what you are
seeing here is a feature called "Flat Volumes" in action. At some point
the volume of the logout sound has been saved to be 22% (perhaps not
exactly that but some value). In order to achieve that result, PA will
try whenever possible to use h/w volume adjustments rather than software.

As PA is a mixer, it will take the loudest volume of any running stream
and use that as the hardware volume and then attenuate in software any
other streams so that they are set to their relative values.

e.g. say I have a stream running at 50%, then the h/w will be set to 50%
and the stream will not be attenuated at all in software. If I then play
a second stream at 75%, the h/w volume will increase to that value and
the current running stream @50% will be attenuated in software so that
it stays at 50% overall.

So it's not exactly unusual to see the h/w volume jump around. What is
more interesting is why the logout sound is played more quietly... Can
you make sure the "System Sounds" slider in pavucontol has a sensible value?

> After a number of reboots I added Redhat/Fedora KDE repo and installed
> KDE 4.4.1 from kde-testing. And shutdown/startup sound behavior
> remained. ie. lowering automatically to 22% when startup sound started
> and after startup sound finished volume automatically changed to the 61%
> I had set.

It probably now relates to the per-application saved volumes. It's
correctly saving/restoring the volume for the logout sound.... the real
question is how/where it was set in the first place!

> At any rate my NEW Fedora install certainly has a volume level, except
> for startup/shutdown sound, that I find very usable. Will see if
> anything changes as I try more apps and tests.
> I don't know what changed in my original Fedora install to cause
> startup/shutdown volume to shoot to 100%. I'm probably just going to
> move what little data I have there to new Fedora partition and see what
> happens.

Chances are trashing your ~/.pulse folder in the existing setup will
have much the same effect as a reinstall... you may have to do the same
for the "kdm" user too if there is such a user - there is for gdm, but
don't know that much about kdm personally.

> Hope this all makes sense. Let me if it doesn't or more info or test are
> desired.

It's kinda expected behaviour in a way, so it makes sense. There are a
few unknowns relating to how the data got there in the first place but
the generally described behaviour sounds plausible enough.

If possible try and grab "pacmd ls" when the shutdown sound is playing
as it will say what "stream-restore.id" is being used for the logout
sound itself which may explain where the lower volume setting came from.



Colin Guthrie

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Open Source:
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  PulseAudio Hacker [http://www.pulseaudio.org/]
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