The decoder will reinit the hwaccel upon pixfmt/dimension changes,
so we can remove the f->use32bit and is_rgb variants of all shaders.
This speeds up init time.
We have no use for 14-bit pixel formats for now, so remove support for gray14,
which was broken due to the LSB padding issue.
Similarly YUVA at 10/12 bit was broken for the same reason.
This commit also makes it possible for the encoder to choose a different
quantization table on a per-slice basis, as well as adding this capability
to the decoder.
Also, this commit fully fixes decoding of context=1 encoded files.
This reduces the intermediate VRAM used for RGB decoding by a
factor of 100x for 6k video.
This also speeds the decoder up by 16% for 4k RGB24 and 31% for 6k video.
This is equivalent to what the software decoder does, but with less pointers.
This patch adds a fully-featured level 3 and 4 decoder for FFv1,
supporting Golomb and all Range coding variants, all pixel formats,
and all features, except for the newly added floating-point formats.
On a 6000 Ada, for 3840x2160 bgr0 content at 50Mbps (standard desktop
recording), it is able to do 400fps.
An Alder Lake with 24 threads can barely do 100fps.
