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8777fa60e6
Manually unrolling loops increases code size, which can sometimes
improve performance, but more often than not, it degrades performance.
Keep the C version simple, and add assembly optimizations when needed.
x86-clang x86-gcc-arch-native x86-msvc m1-clang rpi5-clang pi5-gcc-14
-------------------------------------------------------------------------------------------------------------
bswap_buf_c 57.3 ( 1.00x) 19.4 ( 1.00x) 55.4 ( 1.00x) 0.5 ( 1.00x) 143.5 ( 1.00x) 59.8 ( 1.00x)
bswap_buf_this* 49.0 ( 1.17x) 12.5 ( 1.56x) 17.7 ( 3.13x) 0.3 ( 2.04x) 57.9 ( 2.48x) 73.5 ( 0.81x)
bswap_buf_sse2 28.4 ( 2.02x) 24.3 ( 0.80x) 25.5 ( 2.18x) - - -
bswap_buf_ssse3 24.6 ( 2.32x) 16.0 ( 1.22x) 19.0 ( 2.92x) - - -
bswap_buf_avx2 21.2 ( 2.70x) 11.1 ( 1.74x) 11.2 ( 4.95x) - - -
bswap_buf_c: C implementation before this patch
bswap_buf_this: C implementation after this patch
Signed-off-by: Zhao Zhili <zhilizhao@tencent.com>
FFmpeg README
FFmpeg is a collection of libraries and tools to process multimedia content such as audio, video, subtitles and related metadata.
Libraries
libavcodecprovides implementation of a wider range of codecs.libavformatimplements streaming protocols, container formats and basic I/O access.libavutilincludes hashers, decompressors and miscellaneous utility functions.libavfilterprovides means to alter decoded audio and video through a directed graph of connected filters.libavdeviceprovides an abstraction to access capture and playback devices.libswresampleimplements audio mixing and resampling routines.libswscaleimplements color conversion and scaling routines.
Tools
- ffmpeg is a command line toolbox to manipulate, convert and stream multimedia content.
- ffplay is a minimalistic multimedia player.
- ffprobe is a simple analysis tool to inspect multimedia content.
- Additional small tools such as
aviocat,ismindexandqt-faststart.
Documentation
The offline documentation is available in the doc/ directory.
The online documentation is available in the main website and in the wiki.
Examples
Coding examples are available in the doc/examples directory.
License
FFmpeg codebase is mainly LGPL-licensed with optional components licensed under GPL. Please refer to the LICENSE file for detailed information.
Contributing
Patches should be submitted to the ffmpeg-devel mailing list using
git format-patch or git send-email. Github pull requests should be
avoided because they are not part of our review process and will be ignored.