[alsa-devel] Verifying mixer dB data/Invalid dB data from USB cards, especially Aureon 5.1 MkII

[Clemens Ladisch]

Lennart Poettering wrote:
> On Tue, 23.02.10 11:08, Clemens Ladisch (clemens at ladisch.de) wrote:
> > Lennart Poettering wrote:
> > > Unfortunately there is no way from the simple mixer to the lower level
> > > mixer.
> > 
> > From the check_unplugged function in alsa-utils/alsamixer/mixer_widget.c:
> > 
> > 	err = snd_mixer_get_hctl(mixer, mixer_device_name, &hctl);
> > 	if (err >= 0)
> > 		ctl = snd_hctl_ctl(hctl);
> 
> But that still doesn't give me a hint which snd_ctl_eleme_t belongs to
> which snd_mixer_eleme_t, does it?

Not really; the point of the simple mixer interface is to abstract away
some of the ctl naming conventions.

> > > It would be great if the smixer would include some API that gives me a
> > > hint to which device/subdevice a specific snd_mixer_elem_t belongs to.
> > 
> > Often, there is no 1:1 correspondence between mixer elements and PCM
> > devices.  Only mixer controls with interface PCM (not MIXER) have (sub-)
> > device numbers, and at the moment this is used only for controls that
> > are associated with the streams of hardware-mixing-capable cards.
> 
> Which are not that many, right? Not HDA at least?

No, most recent hardware was designed for software mixing.  Only the
snd-emu10k1, snd-via82xx and snd-ymfpci drivers implement such controls.


Regards,
Clemens