[alsa-devel] Question about "control names"

Juergen Beisert jbe at pengutronix.de
Fri May 23 12:01:41 CEST 2008

On Friday 23 May 2008 11:36, Clemens Ladisch wrote:
> Juergen Beisert wrote:
> > I'm playing with the control names of my "snd_kcontrol_new" controls.
> > When I'm using "PCM Playback Switch" and "PCM Playback Volume" alsamixer
> > shows me a slider with a switch at its bottom. That's what I expected.
> > But when I'm using a second set ("line in" to "line out" bypass), with
> > "Line Bypass Capture Switch" and "Line Bypass Capture Volume" control
> > names, its confusing (BTW: "Line Bypass Capture Volume" is of type
> This may be caused by the control type.  Why is the volume "enumerated"?

Its not linear. Its defined in dB and has some "holes" in it.
When I change it to SNDRV_CTL_ELEM_TYPE_INTEGER I see the slider in the 
[Capture] screen, and also something at its bottom, but I can't switch 

<Line Byp>

This I see in the [Playback] screen now with identical code but "PCM Playback 
Switch" and "PCM Playback Volume" as control names.

  │  │ 

If I change the "Line Bypass Capture ..." control names to "CD Playback ..." 
the control looks like the PCM one above.

Seems "Line Bypass Capture" is something alsamixer can't handle. Is there a 
better control name for such a feature? I can route "Line In" through a 
amplifier to "Line Out".


Dipl.-Ing. Juergen Beisert | http://www.pengutronix.de
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