Red Hat Bugzilla – Bug 454534
gstreamer's v4l2src incompatible with some progressive video cameras
Last modified: 2008-11-26 12:10:55 EST
Description of problem:
v4l2src only uses V4L2_FIELD_INTERLACED which is a whole-frame capture mode (it
requests interlaced video where the two fields have already been merged
However most webcams only offer progressive video (i.e. V4L2_FIELD_NONE) and
will reject any requests for interlaced video. Other drivers will only offer
progressive and will silently 'correct' gstreamer's request for interlaced
I questioned this driver inconsistency here:
And Mauro then told me on IRC that both behaviours are correct: it's fine for
drivers to reject unsupported fields with -EINVAL, and it's also fine for
simple drivers to silently fix up the user's request.
So in order to speak to a wider number of cameras, gstreamer should tolerate
the fact that drivers may reject a request for interlaced images with -EINVAL
and should then retry for progressive (Mauro confirmed this approach is the
best we have at the moment).
This patch also allows OLPC to drop a patch that we needed to get the XO webcam
Please include my patch which has been accepted upstream:
Created attachment 311318 [details]
gstreamer-plugins-good-0.10.8-8.fc9 has been submitted as an update for Fedora 9
gstreamer-plugins-good-0.10.8-8.fc9 has been pushed to the Fedora 9 testing repository. If problems still persist, please make note of it in this bug report.
If you want to test the update, you can install it with
su -c 'yum --enablerepo=updates-testing update gstreamer-plugins-good'. You can provide feedback for this update here: http://admin.fedoraproject.org/updates/F9/FEDORA-2008-6621
Daniel can you confirm if this issue is now fixed?