To improve decorrelation between components, we offset the dither matrix
slightly for each component. This is currently done by adding a hard-coded
offset of {0, 3, 2, 5} to each of the four components, respectively.
However, this represents a serious challenge when re-ordering SwsDitherOp
past a swizzle, or when splitting an SwsOpList into multiple sub-operations
(e.g. for decoupling luma from subsampled chroma when they are independent).
To fix this on a fundamental level, we have to keep track of the offset per
channel as part of the SwsDitherOp metadata, and respect those values at
runtime.
This commit merely adds the metadata; the update to the underlying backends
will come in a follow-up commit. The FATE change is merely due to the
added offsets in the op list print-out.
This function uses ff_sws_pixel_type_size to switch on the
size of the provided type. However, ff_sws_pixel_type_size returns
a size in bytes (from sizeof()), not a size in bits. Therefore,
this would previously never return the right thing but always
hit the av_unreachable() below.
As the function is entirely unused, just remove it.
This fixes compilation with MSVC 2026 18.0 when targeting ARM64,
which previously hit an internal compiler error [1].
[1] https://developercommunity.visualstudio.com/t/Internal-Compiler-Error-targeting-ARM64-/10962922
This covers most 8-bit and 16-bit ops, and some 32-bit ops. It also covers all
floating point operations. While this is not yet 100% coverage, it's good
enough for the vast majority of formats out there.
Of special note is the packed shuffle fast path, which uses pshufb at vector
sizes up to AVX512.
Provides a generic fast path for any operation list that can be decomposed
into a series of memcpy and memset operations.
25% faster than the x86 backend for yuv444p -> yuva444p
33% faster than the x86 backend for gray -> yuvj444p
This will serve as a reference for the SIMD backends to come. That said,
with auto-vectorization enabled, the performance of this is not atrocious.
It easily beats the old C code and sometimes even the old SIMD.
In theory, we can dramatically speed it up by using GCC vectors instead of
arrays, but the performance gains from this are too dependent on exact GCC
versions and flags, so it practice it's not a substitute for a SIMD
implementation.
This handles the low-level execution of an op list, and integration into
the SwsGraph infrastructure. To handle frames with insufficient padding in
the stride (or a width smaller than one block size), we use a fallback loop
that pads the last column of pixels using `memcpy` into an appropriately
sized buffer.
See docs/swscale-v2.txt for an in-depth introduction to the new approach.
This commit merely introduces the ops definitions and boilerplate functions.
The subsequent commits will flesh out the underlying implementation.
