Re: [gentoo-user] BTTV Mini-HOWTO -- how do I use multiple inputs?

[Nick Rout]

On Mon, 28 Nov 2005 23:09:31 -0800
"Daevid Vincent" <daevid@××××××.com> wrote:

> > > If I try to take a picture:
> > >
> > > /usr/bin/v4lctl -c /dev/video0 snap jpeg 320x240
> > > /home/dae51d/public_html/nokia_cam.jpg
> > > /usr/bin/v4lctl -c /dev/video1 snap jpeg 320x240
> > > /home/dae51d/public_html/ittybitty_cam.jpg
> > >
> > > Then the first one works fine, but the second one is failing with:
> > >
> > > v4l2: open /dev/video1: No such device
> > > v4l2: open /dev/video1: No such device
> > > v4l: open /dev/video1: No such device
> > > no grabber device available
> >
> > yes, you probably have one bttv device with a number of inputs. you
> > need to switch inputs. they are usually called TV, Composite, S-Video
> > etc. If there is more than one composite they might be called
> > Composite-1, Composite-2 etc
> >
> > On the other hand they may be audio inputs? 4 composite inputs is
> > rather excessive I would have thought.
>
> The PCI card looks kind of like this one:
> http://www.hauppauge.com/pages/products/data_impactvcb.html
> But it has 3 RCA Inputs and and S-VIDEO input (see bottom of page)
>
> > By the way which package does v4lctl come in?
>
> # equery belongs v4lctl
> [ Searching for file(s) v4lctl in *... ]
> media-tv/xawtv-3.94-r1 (/usr/bin/v4lctl)
>
> > ok it is part of xawtv. just refreshing myself, you can see a list of
> > available parameters with
> >
> > v4lctl -c /dev/video0 list
>
> attribute  | type   | current | default | comment
> -----------+--------+---------+---------+-----------------------------------
> --
> norm       | choice | PAL     | PAL     | PAL NTSC SECAM PAL-Nc PAL-M PAL-N
> NTSC-JP PAL-60
> input      | choice | Televis | Televis | Television Composite1 S-Video
> Composite3
> audio mode | choice | mono    | mono    | mono stereo lang1 lang2
> bright     | int    |   32768 |   32768 | range is 0 => 65535
> contrast   | int    |   32768 |   32768 | range is 0 => 65535
> color      | int    |   32768 |   32768 | range is 0 => 65535
> hue        | int    |   32768 |   32768 | range is 0 => 65535
> mute       | bool   | off     | off     |
> chroma agc | bool   | off     | off     |
> combfilter | bool   | off     | off     |
> automute   | bool   | on      | off     |
> luma decim | bool   | off     | off     |
> agc crush  | bool   | on      | off     |
> vcr hack   | bool   | off     | off     |
> whitecrush | int    |     207 |     207 | range is 0 => 255
> whitecrush | int    |     127 |     127 | range is 0 => 255
>
> So this doesn't mention anything about the inputs.

Read again, it says you have inputs called "Television, Composite1,
S-Video and Composite3".

Do not confuse your video device with the card's input.

You get one video device, and unless you have another v4l device
present it certainly will be /dev/video0

You get a number of inputs to that device, which controls what is seen
on /dev/video0. 

I note that on your device there are 4 physical composite inputs, but
only two compsite inputs are exposed by the driver. This may be because
no-one ever wrote the bttv driver expecting a card with 4 composite
inputs, or it may be because the kernel has not recognised the card
properly and has set up the driver wrong.


Take a look at the kernel documentation in Documentation/videoforlinux,
in particular CARDLSIST.bttv. If you can find your card number you can
add it to your module loading line as is well documented for these
cards.


>
> I would have thought they would be /dev/video0 ... Video2
>
> Since the way that I take a snap with one camera attached to the card is
> like this:
> /usr/bin/v4lctl -c /dev/video0 snap jpeg 320x240
> /home/dae51d/public_html/nokia_cam.jpg
>
> Notice the "-c /dev/video0"
>
>
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