The OMX spec doesn't support HEVC but the OMX stack of the
zynqultrascaleplus adds it as a custom extension.
It uses the same API as the one of Android's OMX stack.
I used the H264 encoder code as a template.
https://bugzilla.gnome.org/show_bug.cgi?id=785434
This information can be useful to zynqultrascaleplus decoders. They may
use this information to reduce startup latency by configuring itself
before receiving the first frames.
We also have a custom OMX extension allowing the decoder to report the
latency. The profile/level information helps it reporting a more
accurate latency earlier.
https://bugzilla.gnome.org/show_bug.cgi?id=783114
