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Re: unexpected webcam side effect

On Saturday 07 July 2007 16:17, Nigel Henry wrote:
> On Saturday 07 July 2007 14:49, Tom Horsley wrote:
> > On Sat, 7 Jul 2007 08:37:01 -0400

> > > > 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.

> > 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 list.
> 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.
> Nigel.

Ok. I've found the email about ordering multiple usb audio devices.

This was posted to LAU in March by Lars Luthman, and is his setup for 3 usb 
audio devices.

This is the relevant part of my /etc/modprobe.d/alsa-base:

alias snd-card-0 snd-emu10k1
alias snd-card-1 snd-cmipci
alias snd-card-2 snd-via82xx
alias snd-card-3 snd-usb-audio   
alias snd-card-4 snd-usb-audio
alias snd-card-5 snd-usb-audio

options snd-emu10k1 index=0
options snd-cmipci index=1
options snd-via82xx index=2
options snd-usb-audio index=3,4,5 vid=0x0c45,0x0a4d,0x17a0

As you see above on the alias lines, he has 3 usb audio devices. Obviously, if 
you only had one soundcard as card0, these three lines would number card1, 2, 
and 3.

The options line for snd-usb-audio is where the fun starts, as you need to 
find the vid's (vendor id's), and pid's (product id's) for your usb audio 

There is a list of vendor/product id's at http://www.linux-usb.org  . Just 
click on the link "USB Vendor/Device IDs list" .

It's a bit out of date, as I couldn't find any of Lars's products, but the 
vendor id's were ok. Neither could I find my Evolution MK-225C usb midi 
keyboard listed, but my omnivision webcam was listed.

You can see the vid's, pid's for your webcam by running /sbin/lsusb.

The relevant bit for my usb midi keyboard is ID 0a4d:0066 Evolution 
Electronics, Ltd.

This is all in hex, so the 0's are zero's.

If you look at Lars's options line above you will see that the vid's/pid's are 
prefixed with 0x. Someone can correct me if i'm wrong, but I believe that 
this simply states that the the following is hex.

I can't say much more as I've only the one USB audio device, but post back if 
you want more info.


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