[gstreamer-bugs] [Bug 591451] New: PATCH: v4l2 plugin causes hanging stream when VIDIOC_G_PARM is not supported

[GStreamer (bugzilla.gnome.org)]

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  GStreamer | gst-plugins-good | Ver: 0.10.15
           Summary: PATCH: v4l2 plugin causes hanging stream when
                    VIDIOC_G_PARM is not supported
           Product: GStreamer
           Version: 0.10.15
          Platform: Other
        OS/Version: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: Normal
         Component: gst-plugins-good
        AssignedTo: gstreamer-bugs at lists.sourceforge.net
        ReportedBy: jwrdegoede at fedoraproject.org
         QAContact: gstreamer-bugs at lists.sourceforge.net
     GNOME version: Unspecified
   GNOME milestone: Unspecified


Hi,

I've been debugging this:
https://bugzilla.redhat.com/show_bug.cgi?id=467961

A little (and yes it still happens with up2date everything), the problem is
that the pwc driver does not support the VIDIOC_G_PARM call, which
results in gv4l2src_calls.c: st_v4l2src_set_capture() not setting v4l2src->
fps_n / fps_d, so they stay 0.

However gstv4l2src.c: gst_v4l2src_create() calls gst_util_uint64_scale_int()
using v4l2src->fps_n / fps_d unconditionally.

This causes cheese, which uses the following pipeline:
v4l2src name=video_source device=/dev/video1 ! capsfilter name=capsfilter
caps=video/x-raw-rgb,width=640,height=480,framerate=15/1;video/x-raw-yuv,width=640,height=480,framerate=15/1
! identity

To hang, while filling the terminal it was started from with:
(cheese:5273): GStreamer-CRITICAL **: gst_util_uint64_scale_int: assertion
`denom > 0' failed

(cheese:5273): GStreamer-CRITICAL **: gst_util_uint64_scale_int: assertion
`denom > 0' failed

(cheese:5273): GStreamer-CRITICAL **: gst_util_uint64_scale_int: assertion
`denom > 0' failed

The attached patch fixes this by making the substraction of the latency from
the timestamp conditional.


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