Qt offscreen rendering and gstreamer processing

[K nard]

Hello,

I would like to render Qt application offscreen and forward the result
to a GStreamer pipeline using hardward acceleration.

So I have tried to forward directly the opengl texture to the pipeline.
I have modify the pipeline accordingly and now I don't have any error
on log (none from Qt, none from GStreamer) but the output is a
transparent image.

My code is here : https://github.com/knard/kstream . Now it's design to
run only under EGL because the GStreamer setup is hard-coded to match
the actual Qt back-end used on my machine (EGL/Wayland).

I can provide GStreamer logs if needed but they can be quite verbose. I
don't know in which direction to search. I think I have succeed to fix
all Opengl context sharing issue and no more log are complaining they
are not able to find the texture but the result remain a transparent
window. Anyone have an idea in which direction I should dig to solve
the issue ?

Regards,