Re: unexpected webcam side effect

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On Saturday 07 July 2007 14:49, Tom Horsley wrote:
> On Sat, 7 Jul 2007 08:37:01 -0400
> Tom Horsley <[email protected]> wrote:
> > > It's worth a try Tom. Just rename snd-usb-audio.ko back to it's
> > > original name, add the 2 lines to /etc/modprobe.conf, plug in the
> > > webcam, and reboot.
> >
> > Thanks, I'll certainly give it a try. It does seem to be some kind of
> > ordering issue since I can plugin the webcam after booting and have
> > things work.
> And it does indeed work! Thanks. I think I see why things were so
> confusing as well. Fedora had already put these lines in
> modprobe.conf:
> alias snd-card-0 snd-intel8x0
> options snd-card-0 index=0
> options snd-intel8x0 index=0
> but I guess by the time it saw them, the usb was already using card0
> so it failed utterly rather than simply winding up as card1.

Precisely. I'm using FC2 at the mo, but have just looked at /etc/modprobe.conf 
for FC6 on the same machine, and see that I've added the 2 lines for 
snd-usb-audio there too. I do know though, that FC4, and FC5 had resolved 
this USB problem. There, modprobe.conf just showed the entries for the 
soundcard, with no reference to snd-usb-audio, and yet the soundcard was set 
as card0, and my usb midi keyboard as card1. It may be kernel related, or 
something to do with udev, that kernels later than 2.6.15 are using.

F7 is booted up on the other machine at the mo, but I'll boot up FC5 later on, 
and check it out with the pre udev kernel, and one of the post udev kernels, 
just to see if there is any difference in the way that the USB, and 
snd-usb-audio is being handled.

Whether the problem can be correctly described as a bug I don't know. It may 
be more of a configuration thing, but is a bit strange that the problem was 
resolved on FC4, and FC5, but then has returned.

I think I'd post the fix to the bug report, and close it.

> I'm wondering what would happen if I had two different USB audio
> devices plugged in though :-).

Well I've got 2 devices on the USB, but only one, my usb midi keyboard is 
audio related. The other one is a webcam, and is a cheapo one with no 
integrated mike. That just uses /dev/video1.

If you have more than 1 USB audio device that you want to connect, the syntax 
is a bit different for the 2 snd-usb-audio lines in /etc/modprobe.conf. This 
has been discussed a bit on the alsa-user list. I've got an email lying 
around with the details, and will try and find it and post the details to the 

Anyway. I'm glad your problem is fixed, and perhaps if Antti is reading this 
thread still, it may fix his problem with the usb headphones.


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