This is a complete rewrite of the math in swscale/utils.c initFilter(), using
floating point math and with a bit more polished UI and internals. I have
also included a substantial number of improvements, including a method to
numerically compute the true filter support size from the parameters, and a
more robust logic for the edge conditions. The upshot of these changes is
that the filter weight computation is now much simpler and faster, and with
fewer edge cases.
I copy/pasted the actual underlying kernel functions from libplacebo, so this
math is already quite battle-tested. I made some adjustments to the defaults
to align with the existing defaults in libswscale, for backwards compatibility.
Note that this commit introduces a lot more filter kernels than what we
actually expose; but they are cheap to carry around, don't take up binary
space, and will probably save some poor soul from incorrectly reimplementing
them in the future. Plus, I have plans to expand the list of functions down
the line, so it makes sense to just define them all, even if we don't
necessarily use them yet.
Sponsored-by: Sovereign Tech Fund
Signed-off-by: Niklas Haas <git@haasn.dev>
Another step towards a cleaner API, with a cleaner separation of purposes.
Also avoids wasting a whopping one third of the flag space on what really
shouldn't have been a flag to begin with.
I pre-emptively decided to separate the scaler selection between "scaler"
and "scaler_sub", the latter defining what's used for things like 4:2:0
subsampling.
This allows us to get rid of the awkwardly defined SWS_BICUBLIN flag, in favor
of that just being the natural consequence of using a different scaler_sub.
Lastly, I also decided to pre-emptively axe the poorly defined and
questionable SWS_X scaler, which I doubt ever saw much use. The old flag
is still available as a deprecated flag, anyhow.
Sponsored-by: Sovereign Tech Fund
Signed-off-by: Niklas Haas <git@haasn.dev>
In case we ever need to increase this number in the future.
I won't bother bumping the ABI version for this new #define, since it doesn't
affect ABI, and I'm about to bump the ABI version in a following commit.
Sponsored-by: Sovereign Tech Fund
Signed-off-by: Niklas Haas <git@haasn.dev>
This was incorrectly inferred to be a Keys spline when the documentation
was first added; but it's actually an "unwindowed" (in theory) natural
cubic spline with C2 continuity everywhere, which is a completely different
thing.
(SWS_BICUBIC is closer to being a Keys spline)
Sponsored-by: Sovereign Tech Fund
Signed-off-by: Niklas Haas <git@haasn.dev>
Allows users to test if a given hardware pixel format is supported by swscale.
This is only a rough heuristic anyways, because the actual support may
depend on the specific *combination* of frame attributes, and ultimately
is better served by the `sws_test_frame` and `sws_frame_setup()` APIs anyways.
Sponsored-by: Sovereign Tech Fund
Signed-off-by: Niklas Haas <git@haasn.dev>
The 'sws_dither' and 'alphablend' options access 'SwsDither' and
'SwsAlphaBlend' enum fields as integers. This is unsafe when the
code is compiled with -fshort-enums, as the enum size might be
smaller than an int.
Since the 'dither' and 'alpha_blend' struct members are part of the
public API, their types cannot be easily changed.
To ensure safe integer access and maintain ABI compatibility across
different compiler settings, a MAX_ENUM value is added to force the
enums to a 32-bit underlying type.
Give users and developers a way to opt in to the new format conversion code,
and more code from the swscale rewrite in general, even while development is
still ongoing.
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.
Since its introduction, this function has claimed to return 0 on success, yet
never actually did so (until the introduction of the new graph based API). It
always returned the number of scaled lines, and continues to do so.
To avoid confusion, but also avoid regressing possible clients that relied on
the existing semantics, simply update the documentation to reflect the actual
behavior. Remain ambiguous about the exact interpretation of the return value
on account of the unfortunate difference in behavior between the legacy and
new scaling APIs.
Signed-off-by: Niklas Haas <git@haasn.dev>
Sponsored-by: Sovereign Tech Fund
As part of a larger, ongoing effort to modernize and partially rewrite
libswscale, it was decided and generally agreed upon to introduce a new
public API for libswscale. This API is designed to be less stateful, more
explicitly defined, and considerably easier to use than the existing one.
Most of the API work has been already accomplished in the previous commits,
this commit merely introduces the ability to use sws_scale_frame()
dynamically, without prior sws_init_context() calls. Instead, the new API
takes frame properties from the frames themselves, and the implementation is
based on the new SwsGraph API, which we simply reinitialize as needed.
This high-level wrapper also recreates the logic that used to live inside
vf_scale for scaling interlaced frames, enabling it to be reused more easily
by end users.
Finally, this function is designed to simply copy refs directly when nothing
needs to be done, substantially improving throughput of the noop fast path.
Sponsored-by: Sovereign Tech Fund
Signed-off-by: Niklas Haas <git@haasn.dev>
Group them into an enum rather than random #defines, and document their
behavior a bit more obviously.
Of particular note, I discovered that SWS_DIRECT_BGR is not referenced
anywhere else in the code base. As such, I have moved it to the deprecated
section, alongside SWS_ERROR_DIFFUSION.
Sponsored-by: Sovereign Tech Fund
Signed-off-by: Niklas Haas <git@haasn.dev>
Following in the footsteps of the work in the previous commit, it's now
relatively straightforward to expose the options struct publicly as
SwsContext. This is a step towards making this more user friendly, as
well as following API conventions established elsewhere.
Sponsored-by: Sovereign Tech Fund
Signed-off-by: Niklas Haas <git@haasn.dev>
Replacing the old sws_isSupported* API with a more consistent family
of functions that follows the same signature and naming convention,
including a placeholder for testing the color space parameters that
we don't currently implement conversions for.
These functions also perform some extra basic sanity checking.
Sponsored-by: Sovereign Tech Fund
Signed-off-by: Niklas Haas <git@haasn.dev>
Merely a convenience wrapper around sws_freeContext(). The name change is for
parity with the other sws_* functions.
Sponsored-by: Sovereign Tech Fund
Signed-off-by: Niklas Haas <git@haasn.dev>
I want to start grouping "legacy" functions which I tend to deprecate
together, away from the new ones.
Sponsored-by: Sovereign Tech Fund
Signed-off-by: Niklas Haas <git@haasn.dev>
Slightly more convenient, especially for the upcoming refactor which will
turn SwsContext into a public struct.
Sponsored-by: Sovereign Tech Fund
Signed-off-by: Niklas Haas <git@haasn.dev>
The intention here was probably to document this as use of
conditionals does not make sense in a comment.
Fixes doxy warning:
warning: explicit link request to 'if' could not be resolved
This avoids unnecessary churn and build breakage for users, by
making sure the whole version.h is included like it has been so far,
while keeping the benefit of not needing to rebuild most files in
the ffmpeg tree on minor/micro bumps.
Signed-off-by: Martin Storsjö <martin@martin.st>
There are no known users of these functions within debian
It should be thus possible to remove these functions without recommandition of a
replacement
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
Blackfin is a painful platform to work with, no test machines are available
and the range of multimedia applications is dubious. Thus it only represents
a maintenance burden.
* qatar/master:
doxy: Define a group for libswscale documentation
Conflicts:
libavutil/avutil.h
libswscale/swscale.h
See: 18d9398143
Merged-by: Michael Niedermayer <michaelni@gmx.at>
* commit 'c1eb3e7fecdc270e03a700d61ef941600a6af491':
swscale: add support for endianness only conversion
Conflicts:
libswscale/utils.c
libswscale/version.h
Merged-by: Michael Niedermayer <michaelni@gmx.at>
