[pulseaudio-tickets] [Bug 81777] Can't change optical-out volume on Terratec Aureon DualUSB

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=81777

--- Comment #11 from Tanu Kaskinen <tanuk at iki.fi> ---
(In reply to main.haarp from comment #9)
> (In reply to Tanu Kaskinen from comment #3)
> > (In reply to comment #2)
> > > Interestingly, if I set ignore_dB=1 then PA falls back to software-mixing
> > > only. That actually seems like a simpler workaround ten yours, Tanu :P
> > 
> > That shouldn't happen... ignore_dB=1 should have the opposite effect:
> > software volume should get disabled for the device.
> I swear that it reverts to exclusive software-mixing. Maybe it's because PA
> on this machine is quite old? (Debian stable has PA 2.0)

It sounds unlikely that the behaviour would have changed that way. I'll have to
test this myself when I get time.

> (In reply to Tanu Kaskinen from comment #6)
> > Main, could you test if muting the Speaker mixer element has any effect when
> > using digital output? I don't have hardware to test the digital output
> > myself.
> I can confirm that muting works on the optical out.

Hmm, PA seems to do software mute always, even when there's hardware mute
available, so the test didn't prove anything. Sorry for wasting your time. If
you could make another test with optical output, that'd be nice (but it's not
super important):

1) Run "pasuspender -- bash". This will start a new shell, and as long as the
shell is running, PA won't access the alsa devices.

2) Run "aplay -D plughw:Device /usr/share/sounds/alsa/Front_Center.wav". It
should produce sound (assuming that the Speaker element is not muted).

3) Run "amixer -c Device sset Speaker off" to mute the Speaker element.

4) Run "aplay -D plughw:Device /usr/share/sounds/alsa/Front_Center.wav".

5) Run "amixer -c Device sset Speaker on" to unmute the Speaker element.

6) Exit the shell that was started in step 1.

Was there sound in step 4?

The reason why I'm so interested in this is that I should document the mute
behaviour in the configuration file. I could write there that it's unconfirmed
whether the hardware mute works with the optical output, but it would be much
nicer to know the real behaviour.

> > I wrote a patch that should fix this bug. Instead of using two profiles for
> > selecting between analog and digital, I decided to just disable hardware
> > volume control in both modes, because requiring the user to select the
> > profile manually wouldn't really be very user-friendly.
> Cool, thanks!
> Wouldn't it suffice to make software mixing the default? Users who use the
> analog output may then still switch to hardware then (and get lower CPU
> usage I suppose)

Yes, we could do that, but I have difficulty to make the profile naming user
friendly. There would be three output profiles (plus combinations with inputs)
to choose from:

Off
On (with software volume)
On (with hardware volume when using analog output and broken volume when using
optical output)

Especially the third option name is far too long, and I don't think most users
have any idea anyway about what difference it makes to their life whether the
volume is "software" or "hardware". I feel that complicating the UI isn't
really worth the small performance benefit of hardware volume.

By the way, this bug probably won't be fixed in 6.0 unfortunately. The fix has
the side effect of making the default volume 100% for this card, which I think
is not acceptable, and altering the default volume logic is a bit complicated,
so we decided to postpone fiddling with that until the next release. I've made
a note for myself to get back to this bug right after the release.

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