[gst-devel] GStreamer Capture Problems

Greg Logan greg.logan at usask.ca
Tue Jul 20 00:39:30 CEST 2010

I have been using v4lsrc to capture from a Epiphan VGA2USB
<http://www.epiphan.com/products/frame-grabbers/vga2usb/>  device. For
the most part the pipeline works well, but on the rare occasion the
v4lsrc element will throw a "Could not synchronize on resource" error.
Afterwards I am unable to capture from the card again until I reload the
drivers for it. When I try to start the pipeline again without reloading
the drivers I get an "Internal data flow error" from the v4lsrc element.
 So my first question is, what does the synchronize on resource error mean?

The device drivers do not support the use of the v4l2src element so I am
stuck between finding a solution from the Epiphan driver end of things
or finding a solution on the GStreamer end of things. Is there any
recommended solution to this problem through GStreamer?

A separate issue is the fact that if the VGA2USB device does not have a
VGA signal when the GStreamer pipeline starts the v4lsrc element will
throw a "Could not synchronize on resource" error and the pipeline will
not start. The drivers for Mac OS X and Windows provide blank frames
when there is no VGA signal, but the Linux drivers do not. Is there a
way to potentially catch this error and insert just a static image until
a VGA signal is detected and then dynamically switch to using the VGA

I'm considering using input-selector or a similar feature (multiqueue)?
 The input selector seems really difficult to manage, anyone know of
some good examples using this element?


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