[gst-devel] Two v4lsrc related problems

Thomas Kuleßa thomas.kulessa at epost.de
Thu Apr 1 07:20:05 CEST 2004

Hello all,

currently I am implementing a small image processing application on
basis of gstreamer 0.8. I have a problem with v4lsrc, I tried to figure
out for ages now without success, so I ask you now and hope someone is
willing and able to help me.

1. I defined a three element pipe inside a GstThread of the form
"v4lsrc->myfilter->xvimagesink". In principle this works, but I am not
able to change the tuner channel of the v4lsrc (it is a TV tuner card).
When I call the gst_tuner_get_channel() function after setting the
channel to e.g. S-Video, it is still on the default (TV). I tracked this
down and it seems that the ioctl call in v4l_calls.c in the v4l plugin
directory fails.
I compared my code to the specific parts in gst-record, but it seems
very similar.

2. Another problem I encountered just yesterday is that the pipe 
"videotestsrc ! myfilter ! xvimagesink" works as it is supposed, but 
"v4lsrc ! myfilter ! xvimagesink" results in a broken image. Perhaps it
has something to do with incorrect image dimensions/formats during
Obviously the error is in myfilter, but in both cases its inputs,
outputs are YUV2 buffers. 

Does anybody has an idea about these issues? I would be very glad.


Thomas Kuleßa <thomas.kulessa at epost.de>

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