Starting from Linux v5.11, the V4L2 stateless H.264 uAPI is updated and stable. Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/merge_requests/1624>
Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/merge_requests/1268>
Most of the features we need are very early or not expose yet in the uAPI. Using an internal copy ensure that we everything we need is defined avoiding to add load of checks and conditionnal code.