utils.c is getting quite crowded, and I need a new place to dump a lot of
format handling code for the ongoing rewrite. Rather than bloating this file
even more, start splitting format handling helpers off into a new file.
This also renames the existing utils.h header, which didn't really contain
anything except the SwsFormat definition anyway (the prototypes for what should
have been in utils.h are all still in the legacy swscale_internal.h).
Symbols with the sws_* prefix are exported.
Reviewed-by: Alexander Strasser <eclipse7@gmx.net>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This leverages the previously introduced color management subsystem in order
to adapt between transfer functions and color spaces, as well as for HDR tone
mapping.
Take special care to handle grayscale formats without a colorspace
gracefully.
This setting can be used to infuence the type of tone and gamut mapping used
internally when color space conversions are required. As discussed at VDD'24,
the default was set to relative colorimetric clipping, which is approximately
associative, surjective and idempotent. As such, it roundtrips well, although
it is strictly speaking not associative on out-of-gamut colors.
This interface has been designed from the ground up to serve as a new
framework for dispatching various scaling operations at a high level. This
will eventually replace the old ad-hoc system of using cascaded contexts,
as well as allowing us to plug in more dynamic scaling passes requiring
intermediate steps, such as colorspace conversions, etc.
The starter implementation merely piggybacks off the existing sws_init() and
sws_scale(), functions, though it does bring the immediate improvement of
splitting up cascaded functions and pre/post conversion functions into
separate filter passes, which allows them to e.g. be executed in parallel
even when the main scaler is required to be single threaded. Additionally,
a dedicated (multi-threaded) noop memcpy pass substantially improves
throughput of that fast path.
Follow-up commits will eventually expand this to move all of the scaling
decision logic into the graph init function, and also eliminate some of the
current special cases.
Sponsored-by: Sovereign Tech Fund
Signed-off-by: Niklas Haas <git@haasn.dev>
