Re: Webcam

From: Tim McCoy (tmccoy_at_hotPOP.com)
Date: 01/08/05


Date: Sat, 08 Jan 2005 14:43:24 +1100

On Fri, 07 Jan 2005 10:16:29 +0000, John Stolz wrote:

> I have a Philips 740 webcam which seems to work fine when I use
> camstream, but when I try and runxawtv (3.93) I get the
> following error:
>
> This is xawtv-3.93, running on Linux/i686 (2.6.8.1-12mdk)
> /dev/video0 [v4l]: no overlay support
> v4l-conf had some trouble, trying to continue anyway
> ioctl: VIDIOCMCAPTURE(frame=0;height=120;width=160;format=7):
> Invalid argument
> ioctl: VIDIOCMCAPTURE(frame=0;height=288;width=352;format=15):
> No such file or directory
> ioctl: VIDIOCMCAPTURE(frame=0;height=288;width=352;format=15):
> No such file or directory
>
> using the -remote option in xawtv gets me:
>
> This is xawtv-3.93, running on Linux/i686 (2.6.8.1-12mdk)
> ioctl: VIDIOCMCAPTURE(frame=0;height=120;width=160;format=7):
> Invalid argument
> ioctl: VIDIOCMCAPTURE(frame=0;height=288;width=352;format=15):
> No such file or directory
> ioctl: VIDIOCMCAPTURE(frame=0;height=288;width=352;format=15):
> No such file or directory
>
> I have a Dell latitude with an ATI Rage mobility graphics chip.
> The video device is present (/dev/video -> /dev/video0) and the
> hardware is recognised (everything works fine in camstream)
> I'm on Mandrake 10.1. official, kernel 2.6.8.1-12mdk.
> I'd be grateful to be pointed in the right direction.

Nice timing - we've been playing with these issues for a Holiday project
lately.

The Philips webcams use the "pwc" kernel driver. This (until recent
kernels) gives 288x352 images. Most of these cams are capable of 640x480,
which is only available using the "pwcx" driver - a binary decompression
module. Unfortunately, its active development has been abandoned. But if
you're comfortable compiling a custom kernel, you'll do well with 2.6.4,
using a patch thats available here.

http://www.smcc.demon.nl/webcam/

The issue with XAWTV is that it generally tries to get max res without
playing nicely. So you'll need to change a few params to keep it back to
288x353, or get "pwcx" working.

With an app such as "camorama", you'll probably find you won't be able to
get the "larger" sized image, which is basically the problem xawtv has.

Cheers

Tim

PS: the binary pwcx functionality has apparently now been built into the
standard pwcx driver, so a VERY recent kernel (>= 2.6.9) may resolve
things entirely, without the need to patch and twiddle.

-- 
"Linux... because rebooting is for adding new hardware!"
http://home.swiftdsl.com.au/~tmccoy
MSN: timsy_01@hotmail.com
ICQ: 160341067


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