omxh264dec - Failed to negotiate RGBA for EGLImage

[horai]

Dear all,

I am trying to code RTSP client in C following this:
http://gstreamer-devel.966125.n4.nabble.com/Simple-RTSP-Pipeline-Works-with-gst-launch-But-Not-with-API-td4678108.html
It is a rewritten pipeline to C language for Raspberry PI taking advantage
of omxh264dec codec which should use GPU acceleration for video decoding:
gst-launch-1.0 rtspsrc location="rtsp://192.168.1.2:8554/test" latency=40 !
rtph264depay ! h264parse ! omxh264dec ! videoconvert ! fbdevsink
device=/dev/fb0

It is a bit more complicated thanks to sink being a clutterActor interacting
with GTK (clutter-gtk + clutter-gst), just for hardware accelerated
videosink to X11. 
I don't want to use fbdevsink due to GTK widgets as I want to use as a GUI
together with video.
Actually, that all works fine and also the video runs quite fine, but I am
experiencing random lags and random freezes, sometimes really annoying.
(capturing the same video on desktop is pretty fine, so network is probably
not of a problem)
I was wondering what the problem might be and came across one error which
made me suspicious that hardware acceleration is not working, actually even
the CPU usage varies above 60% and together with X11 consumes 80% of CPU.
Thanks to GST_DEBUG=3 I got this error:
omxvideodec
gstomxvideodec.c:974:gst_omx_video_dec_reconfigure_output_port:<omxh264dec-omxh264dec0>
Failed to negotiate RGBA for EGLImage
The problem is also described here: 
https://bugzilla.gnome.org/show_bug.cgi?id=767801

I tried many ways to get rid of it and lower the CPU usage following advice
given by contributors, but I was not able to get it working, moreover
changing videodriver makes no difference and compiled C program and all kind
of pipelines using omxh264dec are yielding this error.
Could anyone be so kind to explain me this issue and does it really effect
hardware decompression or is there any solution for this problem? 
I am not telling I am fully right as together with this error probably
unrelated to decoding, but maybe could also affect video output speed:

 FIXME                default
gstutils.c:3826:gst_pad_create_stream_id_internal:<fakesrc0:src> Creating
random stream-id, consider implementing a deterministic way of creating a
stream-id
Progress: (request) Sending PLAY request
Progress: (request) Sending PLAY request
Progress: (request) Sent PLAY request
0:00:01.291350354  1037 0xb1e0e660 FIXME        rtpjitterbuffer
gstrtpjitterbuffer.c:1488:gst_jitter_buffer_sink_parse_caps:<rtpjitterbuffer0>
Unsupported timestamp reference clock
0:00:01.295135325  1037 0xb1e0e660 FIXME        rtpjitterbuffer
gstrtpjitterbuffer.c:1496:gst_jitter_buffer_sink_parse_caps:<rtpjitterbuffer0>
Unsupported media clock

SYSTEM:
Raspberry Pi Zero running Raspbian 9
gstreamer1.0-omx				install
gstreamer1.0-omx-rpi				install
gstreamer1.0-omx-rpi-config			install





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