[Bug 677516] New: [PATCH 0.10.31] v4l2src: ignore double framerates

[GStreamer (bugzilla.gnome.org)]

https://bugzilla.gnome.org/show_bug.cgi?id=677516
  GStreamer | gst-plugins-good | 0.10.31

           Summary: [PATCH 0.10.31] v4l2src: ignore double framerates
    Classification: Platform
           Product: GStreamer
           Version: 0.10.31
        OS/Version: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: Normal
         Component: gst-plugins-good
        AssignedTo: gstreamer-bugs at lists.freedesktop.org
        ReportedBy: jwrdegoede at fedoraproject.org
         QAContact: gstreamer-bugs at lists.freedesktop.org
     GNOME version: ---


Created an attachment (id=215696)
 View: https://bugzilla.gnome.org/attachment.cgi?id=215696
 Review: https://bugzilla.gnome.org/review?bug=677516&attachment=215696

[PATCH 0.10.31] v4l2src: ignore double framerates

Hi,

We (Fedora) have received bugreports from multiple users that cheese is not
working on thinkpad x121e models. Since a friend of mine has such a model I
booted a Fedora livecd there and managed to reproduce the issue. The problem is
that gstreamer hangs deep inside the gstreamer core when doing caps negotation,
this seems to be triggered by the /dev/video# node for the camera reporting the
same frameinterval 4 times.

The underlying cause of the reporting the same interval 4 times, is the USB
descriptors of the camera reporting it can do 27.5xxx fps 4 times with 4
different frame interval values each differing only 0.1 microseconds from each
other. The uvc kernel driver then translates this to the device having 4
framerates of each 27.5 fps, and this confuses gstreamer.

I've not debugged the actual hang in the capabilities negotiation code, instead
I've opted to modify the v4l2src to detect a device reporting the same
framerate multiple times and to ignore the double reported rates. I've tested
this and it fixes the problem on the x121e laptop I've access too. A patch for
this is attached.

Regards,

Hans

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