[gst-devel] Troubles with GStreamer

Stefan Kost ensonic at hora-obscura.de
Mon Jun 21 17:28:50 CEST 2010

On 18.06.2010 17:12, Wes Miller wrote:
> I have a mixed bag of related problems all of which showed up together.  Can
> someone help me with my first problem so I can see if the others are real?
> To start, I had a stable, working gstreamer and plugins on my Fedora 12 box. 
> I wrote and have been using a program that gst_parse_launch()-es two
> (separate threads) simple video recorder pipeline (mjpeg camera saved to
> matroska file and tee'd off to an appsink where I save off some of the
> metadata).  These pipe run 1 minute then are stopped, torn down (unrefed,
> etc), rebuilt and re-gst_parse_launched()-ed.  The only difference is a new
> output filename for each iteration. The location property of the filesink is
> set outside the gst_parse_launch().  And, FWIW, this is run in Qt and
> doesn't seem to need a g_main_loop to execute.  I reuse the same instance of
> gstreamer.
> Last week I ran yum update and noticed that i got new gstreamer updates.  I
> also yum installed gst-ffmpeg and yum updated gst-rtsp.  I was going to
> start work on a new project where I needed rtsp streams.  I reran my
> existing project and that's where all my troubles started.
> It runs through the first iteration with no problems.  On the second pass I
> get a bunch of GST_CRITICAL messages like these:
> (<unknown>:7048): GStreamer-CRITICAL **: gst_pad_new_from_template:
> assertion `GST_IS_PAD_TEMPLATE (templ)' failed

G_DEBUG="fatal_warnings" gdb --args ./your-app --your-args

and get a "backtrace" in gdb. It's also a good idea from time to time to
sanity check your installation (e.g. cehck if there are leftover plugins
etc. /usr/lib/gstreamer0.10/ having files that don't belong to a package)

> (<unknown>:7048): GLib-GObject-CRITICAL **: g_object_unref: assertion
> `G_IS_OBJECT (object)' failed
> (<unknown>:7048): GStreamer-CRITICAL **: gst_pad_set_event_function:
> assertion `GST_IS_PAD (pad)' failed
> (<unknown>:7048): GStreamer-CRITICAL **: gst_element_add_pad: assertion
> `GST_IS_PAD (pad)' failed
> (<unknown>:7048): GStreamer-CRITICAL **: gst_object_ref: assertion `object
> != NULL' failed
> (<unknown>:7048): GStreamer-CRITICAL **: gst_caps_can_intersect: assertion
> `GST_IS_CAPS (caps2)' failed
> (<unknown>:7048): GStreamer-CRITICAL **: gst_pad_push_event: assertion
> `GST_IS_PAD (pad)' failed
> I don't know how to trace a gst_parse_launch(0-ed stream so giving me that
> information may be a good starting point.
> One other detail, not sure it'll be any help, I added a videorate element
> into my pipeline and it stopped working even before I got all those updates. 
> Relevant?  Cause?
> Thanks,
> Wes

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