[sane-devel] Video4linux

Henning Meier-Geinitz henning@meier-geinitz.de
Tue, 10 Jun 2003 20:22:32 +0200


On Tue, Jun 10, 2003 at 02:29:48PM +0200, Novak Levente wrote:
> Recently, the videodev2.h thread reminded me an old problem with the
> video4linux (or is it v4l?) backend.

The backend is called "v4l".

> That is, only the first "scan"
> produces a (more or less) correct image, while the others have the
> succesive scanlines badly shifted. Is it normal?

If I remeber correctly, it didn't happen with my card the last time I

> Can it be avoided?
> I know I can use other software (like XawTV) to take snapshots, but if
> there is such a SANE backend, it should work correctly.

The code of v4l suffers severe bitrot. The TODO mentions:

  * v4l:
     - Geometry support is missing
     - Frequency setting is missing
     - check if v4lctl distributed with xawtv can be used
     - Use #define _LINUX_TIME_H 1 just before including videodev.h or  videodev2.h to avoid
       trouble if /usr/include/linux is a link.
     - Add v4l updates from Martin Palm, see
     - compilation seems to break when video4linux version 2 is installed?       

Martin Palm worked on the v4l backend but I haven't heard from him for
quite some time. YOu can try the code in the above mentioned archive
but I don't remember if it really works.

You could bug Martin Palm or Julien Blache (who also wanted/wants to
work on v4l) a bit :-)
> Also, a v4l2 backend would be welcome too.

Yes, please go ahead and write it :-)

There is an old v4l2 backend but I guess that's a different version 2.