This adds support for slice based decoder like the Allwinner/Cedrus driver. In
order to keep things efficient, we hold the sink buffer until we reach the end
of the picture. Note that as we don't know which one is last, we lazy queue the
slices. This effectively introduces one slice latency.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/merge_requests/1268>
This code add required mechanism to try and allocate (not implemented yet)
otherwise wait for more buffers. This also comes with mechanism to terminate
the wait on flush or PAUSED_TO_READY transitions.
Use a goto to ensure that for all cases we cleanup the current picture state.
And move the src buffer allocation higher, so we don't queue a bitstream
buffer if we don't have a picture buffer to decode into.
This allow negotiating the output format through caps. Some drivers can
pipeline the decoder buffer through an image processor. This only support
colorspace conversion for now.
In some case, when downstream does not support GstVideoMeta, we need to
normalize the stride and offset of the buffer so that downstream can render
properly with a GstVideoMeta. This code is not called when GstVideoMeta is
supported downstream.
Don't let downstream cause a renegotiation at random point in time. This would
lead to spurious renegotiation and the decoder state may not be recoverable.
We now pass the controls, associated to a request, queue the bitstream, qeueue
a picture buffer to decode into and finally queue the request. This now runs
until the buffer pool is exhausted. The next step will be to dequeue.
In this patch we fill the control structure with the bitstream paramter and
copy the bitstream data into V4L2 memory. Slice paramters are only the subset
of what Hantro needs, without any support for interlaced content.
This introduces the skeleton of the H264 decoder. The plugin will list the
devices and register a subclass of the GstV4L2CodecH264Dec base class. The
subclass will pick the required specific information from the GstV4L2Device
stored in the subclass structure.
