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From: Elimar Riesebieter on 3 Apr 2010 15:10
* Stephen Powell [100403 13:08 -0400]
> On Sat, 3 Apr 2010 12:17:44 -0400 (EDT), Oscar Corte wrote:
[...]
> > About point [6], I checked again and there is only one column shown.
>
> That can't be right. What's the output of

The udev system recoognized a usb webcam as an audio device
(snd-usb-audio) and it becomes soundcard 0 in ALSA's card devices.

alsamixer by default uses soundcard 0. See alsamixer(1). Webcams
don't have a mixer device.

In /usr/share/doc/alsa-base/README.Debian.gz is described how to set
the priorities of sound devices. To check how much sound devices the
system provides just

$ cat /proc/asound/cards

Elimar
Debian ALSA Maintainers Team

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From: Stephen Powell on 3 Apr 2010 19:10
On Sat, 3 Apr 2010 15:00:11 -0400 (EDT), Elimar Riesebieter wrote:
> Stephen Powell wrote:
>> That can't be right. What's the output of amixer?
>
> The udev system recoognized a usb webcam as an audio device
> (snd-usb-audio) and it becomes soundcard 0 in ALSA's card devices.
>
> alsamixer by default uses soundcard 0. See alsamixer(1). Webcams
> don't have a mixer device.

Aha! Good catch. I missed that. And now the obvious question is,
"Why?" Why does udev think that that a webcam is a sound card?
Isn't the right solution to this problem to prevent a webcam
from being misidentified as a sound card? Changing the priorities
of multiple sound cards makes sense if there really are multiple
sound cards, but if there's really only one then why not try to prevent
the misidentification in the first place?

--
.''`. Stephen Powell <zlinuxman(a)wowway.com>
: :' :
`. `'`
`-


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From: Elimar Riesebieter on 3 Apr 2010 19:40
* Stephen Powell [100403 19:06 -0400]
> On Sat, 3 Apr 2010 15:00:11 -0400 (EDT), Elimar Riesebieter wrote:
> > Stephen Powell wrote:
> >> That can't be right. What's the output of amixer?
> >
> > The udev system recoognized a usb webcam as an audio device
> > (snd-usb-audio) and it becomes soundcard 0 in ALSA's card devices.
> >
> > alsamixer by default uses soundcard 0. See alsamixer(1). Webcams
> > don't have a mixer device.
>
> Aha! Good catch. I missed that. And now the obvious question is,
> "Why?" Why does udev think that that a webcam is a sound card?
> Isn't the right solution to this problem to prevent a webcam
> from being misidentified as a sound card?

Will be fixed next upload of alsa-base.
There is already a bug:

http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=574593
http://svn.debian.org/wsvn/pkg-alsa/?op=rss&rev=2385&sc=1&isdir=1

> Changing the priorities of multiple sound cards makes sense if
> there really are multiple sound cards, but if there's really only
> one then why not try to prevent the misidentification in the first
> place?

It is just sorted by the order of the bus check while booting.

Elimar


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From: Ron Johnson on 3 Apr 2010 20:00
On 2010-04-03 18:38, Elimar Riesebieter wrote:
> * Stephen Powell [100403 19:06 -0400]
>> On Sat, 3 Apr 2010 15:00:11 -0400 (EDT), Elimar Riesebieter wrote:
>>> Stephen Powell wrote:
>>>> That can't be right. What's the output of amixer?
>>> The udev system recoognized a usb webcam as an audio device
>>> (snd-usb-audio) and it becomes soundcard 0 in ALSA's card devices.
>>>
>>> alsamixer by default uses soundcard 0. See alsamixer(1). Webcams
>>> don't have a mixer device.
>> Aha! Good catch. I missed that. And now the obvious question is,
>> "Why?" Why does udev think that that a webcam is a sound card?
>> Isn't the right solution to this problem to prevent a webcam
>> from being misidentified as a sound card?
>
> Will be fixed next upload of alsa-base.
> There is already a bug:
>
> http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=574593
> http://svn.debian.org/wsvn/pkg-alsa/?op=rss&rev=2385&sc=1&isdir=1

That doesn't answer why udev thinks webcam is an audio card.

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or the timid." Dwight Eisenhower


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From: Elimar Riesebieter on 3 Apr 2010 20:20
* Ron Johnson [100403 18:55 -0500]
> On 2010-04-03 18:38, Elimar Riesebieter wrote:
> >* Stephen Powell [100403 19:06 -0400]
> >>On Sat, 3 Apr 2010 15:00:11 -0400 (EDT), Elimar Riesebieter wrote:
> >>>Stephen Powell wrote:
> >>>>That can't be right. What's the output of amixer?
> >>>The udev system recoognized a usb webcam as an audio device
> >>>(snd-usb-audio) and it becomes soundcard 0 in ALSA's card devices.
> >>>
> >>>alsamixer by default uses soundcard 0. See alsamixer(1). Webcams
> >>>don't have a mixer device.
[...]>
> That doesn't answer why udev thinks webcam is an audio card.

Are there webcams with an intergrated microphne flying around? This
woulb be useful for ekiga (skype), isn't it?

Eöimar

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Alles was viel bedacht wird ist bedenklich!;-)
Friedrich Nietzsche


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