[alsa-devel] alsactl adds volume controls?

[David Henningsson]

2010-08-30 10:01, Takashi Iwai skrev:
> At Sat, 28 Aug 2010 06:58:20 +0800,
> Raymond Yau wrote:
>>
>> 2010/8/28 David Henningsson <david.henningsson at canonical.com>
>>
>>> 2010-08-27 17:43, Clemens Ladisch skrev:
>>>> David Henningsson wrote:
>>>>> So I've discovered that my sound card has a "PCM Playback Volume"
>>>>> control, but changing that control does not alter the volume.
>>>>>
>>>>> Interestingly enough, this control does not come from the HDA parser, it
>>>>> is added by alsactl at boot time...!
>>>>
>>>> This control was created by the software volume plugin.  When not using
>>>> this plugin, the control does not have any effect.
>>>>
>>>> To get rid of it, delete its entry from /etc/asound.state.
>>>
>>> Hmm, I wonder if this is an Ubuntu-specific bug then? Because when I run
>>> Maverick (the upcoming Ubuntu release) from a Live-CD, the "PCM Playback
>>> Volume" control is still there (and there is no asound.state, neither in
>>> /etc or in /var/lib/alsa).
>>> When I use the plughw interface, the "PCM Playback Volume" does not
>>> affect volume output. Should I use another device string to test the
>>> softvol plugin, to see if it's there or not?
>>>
>>
>> The softvol plugin it is defined in "front" device in
>> /usr/share/alsa/cards/HDA-Intel.conf
>>
>> reason is some HDA codec does not has any hardware volume control (analog)
>>
>> this user-defined control only effective when the application use "front"
>> device
> 
> Hm, but if PA opens the device with SND_PCM_NO_SOFTVOL flag, the
> softvol should be skipped.

But that does not apply to the mixer controls as well, does it? I think
we still have a problem with PA assuming that it can change the PCM
volume control to change the output volume.


-- 
David Henningsson, Canonical Ltd.
http://launchpad.net/~diwic