[AG-TECH] WebCam

Piers O'Hanlon p.ohanlon at cs.ucl.ac.uk
Thu Jun 8 08:30:39 CDT 2006

Hi Doug,

Great to hear you're working on the code.

> My code is more or less based on video/grabber-v4l2.cpp from SVN UCL
> vic. The main issue the SVN code is that it only supports the YUYV pixel
> format and not YUV420 common with webcams. Ideally I want to get it to
> support all the pixel formats that the V4L version did.
Yes this true - it's something I've been meaning to fix (there was
some code from MASH that did a slighly better job).

> There were other issues with incorrectly initialised ioctl arguments
> with the PWC V4L2 driver and capture size.
Ah ok.

> > There are still a number of drivers in the kernel (including some for
> > webcams) that are still video4linux version one only - Now all video
> > capture devices are listed as /dev/video - one has to open the devices
> > and see which ones can be opened with V4L1 or V4L2 - thus the UCL
> > version compiles both drivers.
> I'm currently compiling both, but the AGTk sets the VIC_DEVICE env
> variable to let AG vic know which capture device it should use.
> So in grabber-v4l2.cpp I currently have:
>   #ifdef HAVE_V4L2
>           const char *myDev = getenv("VIC_DEVICE");
> and grabber-video4linux.cpp I have a ifndef version of the above.
> Another approach may need to be used instead of the VIC_DEVICE env
> variable, e.g. using the so called vic device nickname.
oh ok - I guess another way would be to pass and device as a common
line argument - or pick it up from the resources - like the most of
the other config stuff.

> > We are in the process having the AG features ported into the UCL
> > version of vic - either by ANL or by UCL, we also plan to integrate
> > work from NCHC vic - under our SUMOVER project - as mentioned by me at
> > the recent AG retreat.
> >
> > We would welcome any developer work on vic - we are keen to bring on
> > board any active developers and potentially provide commit access to
> > the SVN repository.
> I was actually going to contact you guys about merging my Mac TCL/Tk
> Aqua AG vic port (in ANL's CVS) to UCL vic, but haven't gotten around to
> it yet.
This would be great - we'd like to have the aqua stuff and It would
also be good to wrap in the video capture code for OSX (do have a link
to the src of that grabber?)

We can create an SVN account on our subversion repository if you would like.

Thanks alot,


> Cheers,
> Doug.

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