codecalpha is a new plugin introduced to support VP8/VP9 alpha as
defined in the WebM and Matroska specifications. It splits the stream
into two streams, one for the alpha and one for the actual content,
then it decodes them separately with vpxdec and finally combine the
results as A420 or AV12 (i.e. YUV + an extra alpha plane).
The workflow above is setup by means of a bin, gstcodecalphabin.
This patch simulates the same workflow into the v4l2codecs namespace,
thus using the new v4l2 stateless decoders for hardware acceleration.
This is so we can register the new alpha decode elements only if the
hardware produces formats we support, i.e. I420 or NV12 for now.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/merge_requests/2272>
This adds a non-thread safe refcount to the GstV4l2Request. This will
allow holding on more then one request in order to implement render
delay. This is made non-thread safe for speed as we know this will all
happen on the same streaming thread.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/merge_requests/1881>
Starting from this patch, all queue and dequeue operation happening
on V4L2 is now abstracted with the request. Buffers are dequeued
automatically when pending requests are marked done and only 1 in-flight
request is now used.
Along with fixing issues with request not being reused with slice
decoders, this change reduces the memory footprint by allocating only
two bitstream buffers.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/merge_requests/1881>
The Cedrus driver would otherwise choose 1KB buffer, which is too small.
This follows what some drivers do, which is simply to use the size a
packed raw image would have. Specifications do not really guaranty any minimum
compression ratio.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/merge_requests/1268>
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 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.
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.
This is a GstObject which will be used to hold on media and video device file
descriptor and provide abstracted ioctl calls with these descriptor. At the
moment this helper contains just enough to enumerate the supported format.
This part will be used by the plugin to register the CODEC specific elements..
