Question about "control names"

Question about "control names"

[Juergen Beisert]

Hi,

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 
SNDRV_CTL_ELEM_TYPE_ENUMERATED).

The "Line Bypass Capture Volume" control is shown on the [Playback] page with 
the name "Line Byp" and the default value. I can walk through the enumerated 
values. But the "Line Bypass Capture Switch" is shown on the [Capture] page 
in alsamixer as:

  L    R
  CAPTUR

<Line Byp>

What does it mean? Problem of alsamixer or the name of this set?

Juergen
-- 
Dipl.-Ing. Juergen Beisert | http://www.pengutronix.de
 Pengutronix - Linux Solutions for Science and Industry
    Handelsregister: Amtsgericht Hildesheim, HRA 2686
         Vertretung Sued/Muenchen, Germany
   Phone: +49-8766-939 228 |  Fax: +49-5121-206917-9

Re: Question about "control names"

[Juergen Beisert]

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
> > SNDRV_CTL_ELEM_TYPE_ENUMERATED).
>
> 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 
anything:


   │▒▒│ 
   │▒▒│ 
   └──┘
  ------
     7
<Line Byp>

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

  │  │ 
  ├──┤ 
  │MM│ 
  └──┘ 
  0<>0 
  PCM 

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".

Juergen

-- 
Dipl.-Ing. Juergen Beisert | http://www.pengutronix.de
 Pengutronix - Linux Solutions for Science and Industry
    Handelsregister: Amtsgericht Hildesheim, HRA 2686
         Vertretung Sued/Muenchen, Germany
   Phone: +49-8766-939 228 |  Fax: +49-5121-206917-9
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Re: Question about "control names"

[Mark Brown]

On Fri, May 23, 2008 at 12:01:41PM +0200, Juergen Beisert wrote:
> On Friday 23 May 2008 11:36, Clemens Ladisch wrote:
> > Juergen Beisert wrote:

> > > names, its confusing (BTW: "Line Bypass Capture Volume" is of type
> > > SNDRV_CTL_ELEM_TYPE_ENUMERATED).

> > 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 
> anything:

Couldn't this be covered by providing TLV ranges for it?

Re: Question about "control names"

[Clemens Ladisch]

Juergen Beisert wrote:
> 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
> > > SNDRV_CTL_ELEM_TYPE_ENUMERATED).
> >
> > This may be caused by the control type.  Why is the volume "enumerated"?
>
> Its not linear.

The only requirement for volume slider is that they are somewhat
monotonic.

An enumerated control won't be considered a volume slider.

> Its defined in dB and has some "holes" in it.

This doesn't matter; this can described, too.

What is the exact mapping?

> 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
> anything:
>
>
>    │▒▒│
>    │▒▒│
>    └──┘
>   ------
>      7
> <Line Byp>

The "------" indicates that this can be enabled for recording.
Doesn't the space key work?


Regards,
Clemens
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