NULL caps question

Tim Müller tim at
Tue Feb 25 01:17:42 PST 2014

On Tue, 2014-02-25 at 09:42 +0100, Jorge Fernandez Monteagudo wrote:


> I would like to know how to solve a problem I have running the next pipeline:
> # gst-launch filesrc location=/home/root/video31_aac.mp4 ! qtdemux ! omx_mpeg4dec ! gpuvsink
> Setting pipeline to PAUSED ...
> Pipeline is PREROLLING ...
> Width :800, Height: 600
> (gst-launch-0.10:1518): GStreamer-CRITICAL **: gst_pad_fixate_caps: assertion `!gst_caps_is_empty (caps)' failed
> (gst-launch-0.10:1518): GStreamer-CRITICAL **: gst_pad_set_caps: assertion `caps == NULL || gst_caps_is_fixed (caps)' failed
> ** (gst-launch-0.10:1518): CRITICAL **: gst_render_bridge_set_caps: assertion `caps' failed
> I've checked the gpuvsink code and I've found the failed assert (snip)

You should check where the first CRITICAL warning comes from, that's
likely where the cause of the problem is. Run

 $ G_DEBUG=fatal_warnings gdb --args /usr/bin/gst-launch-0.10 ....

then type 'bt' when it breaks at the warning.

> Is it possible to force a caps from the command line?

You can add a capsfilter before the sink, but that's just papering over
some critical bug.

Ideally you should also try to upgrade to 1.x if possible at all. 0.10
hasn't been maintained for years now.


Tim Müller, Centricular Ltd -

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