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Compared to the MMX version, this version benefits from wider registers and pmaddubsw. It also has fewer unnecessary loads and stores: On x64, the MMX version has 12 unnecessary GPR loads and 6 stores in each line when width is eight; for width 16, there are 17 unnecessary GPR loads and six stores per line. Even the 32bit SSSE3 version only has six loads and zero stores per line more than the x64 version. Furthermore, in contrast to the MMX version, the SSSE3 version also does not clobber the array of block pointers given to it. Benchmarks: inner_add_yblock_2_c: 29.2 ( 1.00x) inner_add_yblock_2_mmx: 32.5 ( 0.90x) inner_add_yblock_2_ssse3: 28.6 ( 1.02x) inner_add_yblock_4_c: 85.2 ( 1.00x) inner_add_yblock_4_mmx: 89.2 ( 0.96x) inner_add_yblock_4_ssse3: 84.5 ( 1.01x) inner_add_yblock_8_c: 302.0 ( 1.00x) inner_add_yblock_8_mmx: 77.0 ( 3.92x) inner_add_yblock_8_ssse3: 30.6 ( 9.85x) inner_add_yblock_16_c: 1164.7 ( 1.00x) inner_add_yblock_16_mmx: 260.4 ( 4.47x) inner_add_yblock_16_ssse3: 82.3 (14.15x) Both the MMX and SSSE3 versions leave the size 2 and 4 cases to ff_snow_inner_add_yblock_c() (but the MMX version has a prologue at the beginning that it needs to undo before the call, leading to the higher overhead for these sizes). I don't know why the SSSE3 version is marginally faster than the C version in these cases. Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.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.