This uses Stein's binary GCD algorithm:
https://en.wikipedia.org/wiki/Binary_GCD_algorithm
to get a roughly 4x speedup over Euclidean GCD on standard architectures
with a compiler intrinsic for ctzll, and a roughly 2x speedup otherwise.
At the moment, the compiler intrinsic is used on GCC and Clang due to
its easy availability.
Quick note regarding overflow: yes, subtractions on int64_t can, but the
llabs takes care of that. The llabs is also guaranteed to be safe, with
no annoying INT64_MIN business since INT64_MIN being a power of 2, is
shifted down before being sent to llabs.
The binary GCD needs ff_ctzll, an extension of ff_ctz for long long (int64_t). On
GCC, this is provided by a built-in. On Microsoft, there is a
BitScanForward64 analog of BitScanForward that should work; but I can't confirm.
Apparently it is not available on 32 bit builds; so this may or may not
work correctly. On Intel, per the documentation there is only an
intrinsic for _bit_scan_forward and people have posted on forums
regarding _bit_scan_forward64, but often their documentation is
woeful. Again, I don't have it, so I can't test.
As such, to be safe, for now only the GCC/Clang intrinsic is added, the rest
use a compiled version based on the De-Bruijn method of Leiserson et al:
http://supertech.csail.mit.edu/papers/debruijn.pdf.
Tested with FATE, sample benchmark (x86-64, GCC 5.2.0, Haswell)
with a START_TIMER and STOP_TIMER in libavutil/rationsl.c, followed by a
make fate.
aac-am00_88.err:
builtin:
714 decicycles in av_gcd, 4095 runs, 1 skips
de-bruijn:
1440 decicycles in av_gcd, 4096 runs, 0 skips
previous:
2889 decicycles in av_gcd, 4096 runs, 0 skips
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
Proper names should be capitalized in all user facing API as far as
possible. The option names themselves have not been changed since:
1. We consistently keep option names in lower case.
2. Changing them would break existing scripts.
3. I suspect that we want to be similar to Sox and its relevant options.
The converse is also true: improper names should not be capitalized
generally.
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
During a build, a lot of *.o.-hash files are created - had not noticed
this as they are usually dumped in tmpfs on Linux. However, they
sometimes are present during a long build in the project directory, making it
annoying to commit while the project is being built.
These have been observed with Clang, -fsanitize-undefined on Arch Linux,
though other configurations may also generate such temporaries.
The solution here is on lines with the Linux kernel's .gitignore:
https://github.com/torvalds/linux/blob/master/.gitignore.
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
Proper names should be capitalized in all user facing API as far as
possible. The option names themselves have not been changed since:
1. We consistently keep option names in lower case.
2. Changing them would break existing scripts.
The converse is also true: improper names should not be capitalized
generally.
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This should fix the undefined behavior reported in:
https://trac.ffmpeg.org/ticket/4727.
I can reproduce this at runtime: simply stick in an abort call in
asym_quant to check if c < 0 and run FATE. I don't know ac3 so I can't
confirm if negative coefficients are intentional, but at the moment they
clearly are according to FATE.
This resolves the undefined behavior. Tested with FATE.
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
* commit '00cc10aee380f882507bac994ac469d8358d12e8':
asfdec: do not skip padding if offset is above packet size - padding
Merged-by: Hendrik Leppkes <h.leppkes@gmail.com>
* commit '8b830ee9a26d47b138f12a82085cdb372f407f1e':
avconv: Do not try to configure filter outputs without streams
Merged-by: Hendrik Leppkes <h.leppkes@gmail.com>
* commit 'd7a5a178c252b625537adc046392624ad543dea7':
configure: When disabling a library disable all the related components
Merged-by: Hendrik Leppkes <h.leppkes@gmail.com>
the pps offset is used to locate pps in the spspps_buf; however, the
current calc method is wrong because it is the offset of the original
avctx->extradata;
when there is only one sps in the avcc; the value is correct by
coincidence, however, it will fail in avcc with multi sps
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This fixes a warning observed on Clang 3.7:
"warning: attribute 'deprecated' is ignored, place it after "struct" to apply attribute to type declaration [-Wignored-attributes]"
and thus enables deprecation warning for the relevant struct.
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>
This should fix the first undefined behavior reported in:
https://trac.ffmpeg.org/ticket/4727.
I can't reproduce the runtime behavior reported in the ticket, hence I
can't confirm that this actually fixes the exact issue reported in the
ticket.
Regardless, I can confirm that this is a genuine issue, and that
negative shifts can (and do) occur, fixed by this.
Tested with FATE.
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
Currently only 2 profiles are evaluated because they are the only 2
with distributed test sequences.
- CID 1260: YUV 4:2:2 10 bits with block-adaptive interlace coding,
from ticket 4876;
- CID 1270: YUV 4:4:4 10 bits (HR), 1920x839, from ticket 4581.
They were generated from the ticket sequences by running the
following kind of command-line;
ffmpeg -i $INPUT -an -sn -vcodec copy -vframes 1 -y $OUTPUT.mov
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
On lines 1633,1634 FFABS(pts) is performed. However, if av_stream_get_end_pts
returns AV_NOPTS_VALUE always, pts remains stuck at INT64_MIN, leading
to undefined behavior on FFABS.
One could conceive of a solution using FFNABS. However, such a solution
has to deal with the implementation defined rounding of integer division
with at least one negative operand in ANSI C89. C99 forces truncation to
zero, but I am not sure that all of our platforms compile with full C99
support, and in particular whether we can safely assume a fixed
rounding behavior across all platforms.
This solution is simple, and I doubt changing INT64_MIN to INT64_MIN + 1
has any practical loss - if it is stuck at its initial value, the stream
is messed up anyway.
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
When trying to build the binary dct-test under MSYS2/Win64, the
makefile rule does not have the SUBDIR in the target for its
object file.
Consequently, modifications to various include files (e.g. C ones)
do not trigger a recompilation.
When tracing the dependency generating, the dependency generation
has this strange content (linebreak inserted):
sed -e "/^#.*/d" -e "s,^[[:space:]]*dct\\.o,libavcodec/dct.o," \
> libavcodec/dct-test.d
For some reason, the $(*F) has weird content. It looks simpler to
use $(@F) instead of $(*F)\\.o, although this was tested on one
single version of make.
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
Change to https for FFmpeg websites.
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
There is not much reason to generate such a small table at runtime.
Signed-off-by: Derek Buitenhuis <derekb@vimeo.com>
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
