Re: Handling multiple video devices

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On Wednesday 07 March 2007, Nigel Henry wrote:
> On Wednesday 07 March 2007 21:13, Anne Wilson wrote:
> > I have three video devices that may be in use at any time on this box. 
> > One is a pci video-capture card, so always present.  The other two are
> > webcam and usb tv tuner.  The problem is that every package that can
> > handle either the webcam or the tv tuner looks for video0.
> >
> > tvtime's menu has an entry for changing the input, and I thought that
> > should do it, but absolutely nothing happens if I click on that.  I
> > haven't had any more luck with amsn + webcam either - as long as it gets
> > video0 it is happy, but it won't talk to anything else.
> >
> > There must be some way to configure these to talk to video*.  I've had
> > some luck with getting udev to track the webcam connection, so if I could
> > point amsn to /dev/webcam, that would be solved.  Similarly I could build
> > a rule for the tuner, but it's no good if I can't get the software to use
> > it.
> >
> > Has anyone managed this sort of situation?
> >
> > Anne
>
> Hi Anne. This probably going to be a totally useless reply, but, how are
> the 3 devices setup at the moment? I think you have Xawtv. Try running
> xawtv -hwscan to see how the video devices are setup in /dev.
>
> With xawtv I can specify which device to use when I launch it. For example
> my TV tuner card uses /dev/video0, so that is just launched as xawtv. If I
> want to use xawtv to access the webcam, I set the command on the desktop
> launcher as, xawtv -device /dev/video1, and then get the webcam showing on
> xawtv. I don't know much about TVtime, but it may be worth launching it
> specifying the device it should use.
>
> Amsn is a problem, as it just looks in /dev/video. If you mess with udev,
> and create symlinks (/dev/webcam)  Amsn is totally lost. Can't see the wood
> for the trees.
>
> My TVtuner card uses /dev/video0, and the webcam (ov511) uses /dev/video1,
> except on FC5 with the 2.6.18 kernel, where it's a bit hit and miss in
> which order they are loaded. I've used the webcam using /dev/video1 while
> talking to you on Amsn, so I don't think there is a problem with Amsn, as
> long as it can find a webcam device in /dev/video, whether that's
> /dev/video0, 1, 2, or 3.
>
> I don't if this is any help, but on FC2 the USB webcam was being
> given /dev/video0, and the TVtuner card wasn't being loaded. The TVtuner
> card should be loaded as /dev/video0, and the webcam as /dev/video1, but
> that was an FC2 problem. USB starts early in the boot process, and USB
> devices were loaded before PCI stuff.
>
> This is what I did on FC2 in /etc/rc.d/rc.local  to fix it.
>
> /sbin/modprobe -r ov511    (remove webcam using /dev/video0)
>
> /sbin/modprobe tda9887 port2=0 pal=I   (load TVtuner card to /dev/video0)
> /sbin/modprobe bttv tuner=38 automute=0  (more TVcard stuff)
> #install bttv /sbin/modprobe tda9887 port2=0 pal=I; /sbin/modprobe
> --ignore-install bttv
>
> /sbin/modprobe ov511 force-palette=15   (load webcam to /dev/video1)
>
> It may be worth trying something like this. I don't think there is a
> problem with the webcam, so that can be loaded last, as Amsn is just
> looking in /dev/video for a webcam device. The TVtuner card I don't know
> about, but may be worth loading this first so that it grabs /dev/video0,
> especially as you have problems with TVtime. Load the driver for the PCI
> video-capture card second, and the driver for the webcam third.
>
> If all 3 drivers are already loaded you will have to do a modprobe -r for
> each one in /etc/rc.d/rc.local before modprobing them in the order you want
> to have them loaded.
>
> Personally I think this is a bit of a hack, but it has worked to get the
> TVtuner card, and the webcam driver loaded in the correct order on FC2.
>
Thanks, both Nigel and Sander.  I haven't had time to look into this any 
further today, but I'll take another look at it tomorrow.

Anne



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