For certain types of filters where the intermediate sum of coefficients
can go above the fixed-point equivalent of 1.0 in the middle of a filter,
the sum of a 31-bit calculation can overflow in both directions and can
thus not be represented in a 32-bit signed or unsigned integer. To work
around this, we subtract 0x40000000 from a signed integer base, so that
we're halfway signed/unsigned, which makes it fit even if it overflows.
After the filter finishes, we add the scaled bias back after a shift.
We use the same trick for 16-bit bpc YUV output routines.
Signed-off-by: Mans Rullgard <mans@mansr.com>
As old bits are shifted out of the accumulator, they cause signed
overflows when they reach the end. Making the variable unsigned fixes
this.
Signed-off-by: Mans Rullgard <mans@mansr.com>
This was removed erroneously in
046f081b46. This define still is
necessary for getting MAP_ANONYMOUS defined on linux/glibc,
despite the define reshuffling done in that commit.
Without MAP_ANONYMOUS defined, the mprotect calls for setting the
generated mmx2 scaler code pages executable are left out, causing
crashes if that codepath is chosen.
This patch fixes scaling from 192x144 to 320x240 with
-sws_flags fast_bilinear, which crashes on linux at the
moment.
Signed-off-by: Martin Storsjö <martin@martin.st>
Although gcc guarantees 16 byte stack alignment, threads under WinXP
don't appear to be guaranteed to start stack aligned. So fix the
alignment.
Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>
Altivec does unaligned reads from this buffer in
hscale_altivec_real(), and can thus read up to 16 bytes beyond
the end of the buffer. Therefore, add an extra 16 bytes of
padding at the end of the conversion buffer.
This fixes fate-lavfi-pixfmts_scale on AltiVec-enabled builds
under valgrind.
Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>
Use uintptr_t instead of plain int. Without this change, the
comparisons will come out wrong for pointers in certain ranges.
Fixes random failures on ppc64. Also fixes some compiler warnings.
Signed-off-by: Mans Rullgard <mans@mansr.com>
SSE-optimized hScale() scales up to 4 pixels at once, so we need to
allocate up to 3 padding pixels to prevent overreads. This fixes
valgrind errors in various swscale-tests on fate.
Speed: from 3.9x to 9.6x speed improvement over C, and some small
(up to 15%) speed improvements over existing MMX code (particularly
for bigger filters).
This allows using more specific implementations for chroma/luma, e.g.
we can make assumptions on filterSize being constant, thus avoiding
that test at runtime.
It just does that part in scalar form, I doubt using a vector store
over 2 array would speed it up particularly.
The function should be written to not use a scratch buffer.
The logged information is possibly false, and it tends to be outdated
after each change since the logging code needs to be manually updated.
Simplify and prevent confusing wrong debug messages.
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
Also remove the unnecessary isSupportedIn/Out macros.
Make the code more compact/readable, and simplify the access to
lsws-specific pixel format information.
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
When converting RGB format to RGB format with the same bits per sample,
unscaled path performs conversion on the whole buffer at once. For
non-multiple-of-16 BGR24 to RGB24 conversion it means that padding at the
end of line will be converted too. Since it may be of arbitrary length
(e.g. 8 bytes), operating on the whole buffer produces obviously wrong
results.
Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>
ptrdiff_t can be 4 bytes, which leads to the next element being 4-byte
aligned and thus at a different offset than intended. Forcing 8-byte
alignment forces equal offset of dither16/32 on x86-32 and x86-64.
Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>
We operated on 31-bits, but with e.g. lanczos scaling, values can
add up to beyond 0x80000000, thus leading to output of zeroes. Drop
one bit of precision fixes this.
Remove unused variables "flags" and "dstFormat" in yuv2packed1,
merge source rows per plane for yuv2packed[12], and make every
source argument int16_t (some where invalidly set to uint16_t).
This prevents stack pollution and is part of the Great Evil Plan
to simplify swscale.
This will likely lead to a considerable performance boost,
since it removes a branch from the inner loop. Part of the
Great Evil Plan to simplify swscale.
On architectures such as x86 (both 32 bit and 64bit), the stack element
size is fixed, which maintains alignment. Here, this change does not
break anything. However, we also support also other architectures where
this property is not maintained and therefore, applications will crash
horribly.
This change effectively forces all applications to be recompiled against
libswscale.
This is part of the Great Evil Plan to simplify swscale. Note that
you'll see some code duplication between the output functions for
different RGB variants, and even between packed-YUV and RGB
variants. This is intentional because it improves readability.
Inline functions are easier to read, maintain, modify and test,
which justifies the slightly increased source size. This patch
also adds support for non-native endianness RGB15/16 and fixes
isSupportedOutput() to no longer claim that we support writing
non-native RGB565/555/444.
