Use of subframe API from videodecoder base class.
This subframe allows to decode subframe instead of
waiting for a whole frame.
The subframe uses the same frame over the whole
subframe passing process and will wait
for a signal to know the last subframe.
In this implementation it will use
GST_VIDEO_BUFFER_FLAG_MARKER as the
end of batch of subframes.
This implement subframe mode negotation for the Zynq based on caps
negotation. This mode can be combined with low-latency mode, in order to
reach the lowest possible latency (assuming the stream is within the
low-latency constraints for the HW).
... ! video/x-h264,alignment=nal ! omxh264dec ! ...
Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-omx/-/merge_requests/49>
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
The decoder only requires to receive one frame per buffer which is
already enforced with 'alignment=au'. There is no need to require to
have a parser upstream.
Allow to run "encode ! decode" pipeline without having a parser.
https://bugzilla.gnome.org/show_bug.cgi?id=784344
The omxvideodecoder class only checks some of the caps parameters but if
other fields change such as h264 profile and/or level it wouldn't trigger a
reconfiguration.
https://bugzilla.gnome.org/show_bug.cgi?id=752376
