This introduce a library which contains a set of base classes which
handles the parsing and the state tracking for the purpose of decoding
different CODECs. Currently H264, H265 and VP9 are supported. These
bases classes are used to decode with low level decoding API like DXVA,
NVDEC, VDPAU, VAAPI and V4L2 State Less decoders. The new library is
named gstreamer-codecs-1.0 / libgstcodecs.
* Move decoding process to handle_frame
* Remove GstVideoDecoder::parse implementation
* Clarify flush/drain/finish usage
In forward playback case, have_frame() call will be followed by
handle_frame() but reverse playback is not the case.
To ensure GstVideoCodecFrame, the decoding process should be placed inside
of handle_frame(), instead of parse().
Since we don't support alignment=nal, the parse() implementation is not worth.
In order to fix broken reverse playback, let's remove the parse()
implementation and revisit it when adding alignment=nal support.
... and remove unused start, stop method from subclass.
Current implementation does not require subclass specific behavior
for the handle_frame() method.
