Can you try to run it with GST_DEBUG=3? Maybe there are some warnings that
can help debug.
Also, try to add mtu parameter to rtph264pay, and set it to 100 / 300 / 700
etc (default is 1400).
I had a similar issue in the past and it appeared to relate to the network I
was using. The mtu parameter really helped.
Thank you both for the suggestions!
I tried to add the 'h264parse' but unfortunately I got no different result
I added the debug option and got some interesting messages repeatedly,
WARNING: from element
A lot of buffers are being dropped.
Additional debug info:
gstbasesink.c(3003): gst_base_sink_is_too_late ():
There may be a timestamping problem, or this computer is too slow.