[gst-devel] v4lsrc confusion

Thomas Vander Stichele thomas at apestaart.org
Mon Dec 20 02:50:01 CET 2004


> Hi all,
> I was trying to set up a pipeline to view the video stream coming
> from my webcam (sonix based), using a V4L(1) driver. The pipeline
> I'm trying to use is
> v4lsrc -> ffmpegcolorspace -> ximagesink
> Setting this up in gst-editor gives me a dialog telling me that
> it could not set a parameter, but after dismissing this I can
> see the webcam video stream in a window.
> If I try this using gst-launch
> gst-launch v4lsrc ! ffmpegcolorspace ! ximagesink
> it gives me a similar message (from the v4lsrc module).

When reporting problems, could you please paste the actual error ? It's
more useful than a vague report on what it is, esp. when you're asking
what the error means :)

> I thought v4l does not have any property to set the framerate.

v4l by itself does not.  Two types of webcams do, however, using the
same mechanism, which is why I put it in v4lsrc for now.  (These two
kinds are the ones handled by the pwc.ko module, and the ones handled by
the quickcam.ko module).  I might move it out at a later point because
there is more camera-specific stuff handled by these modules which would
make no sense to put into v4l directly.

> I tried various combinations of setting properties sync-mode
> and autoprobe-fps, but without success.

What type of webcam do you have ?

> Another, more general thing I wonder about:
> Is it possible to have controls for v4l?
> For example, being able to control brightness, contrast,
> whiteness, color and hue.

Yes, this is exported through a GstInterface.  Read all about it in
Ronald's excellent Plugin Writers Guide, available on your favourite
GStreamer website.


Dave/Dina : future TV today ! - http://www.davedina.org/
<-*- thomas (dot) apestaart (dot) org -*->
Cause when I do
what I'm gonna do to you
Make sure
You remember my name
<-*- thomas (at) apestaart (dot) org -*->
URGent, best radio on the net - 24/7 ! - http://urgent.fm/

More information about the gstreamer-devel mailing list