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Andreas Rheinhardt
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Using XMM registers in this SSSE3 function leads to fewer shuffles when transposing the input; it also allows to combine calculating a1 and a2. Because of this, codesize is the same as before (on Unix64) although MMX instructions are shorter. Old benchmarks: vc1dsp.vc1_h_loop_filter4_bestcase_c: 3.0 vc1dsp.vc1_h_loop_filter4_bestcase_ssse3: 32.0 ( 0.09x) vc1dsp.vc1_h_loop_filter4_worstcase_c: 42.9 vc1dsp.vc1_h_loop_filter4_worstcase_ssse3: 31.9 ( 1.35x) New benchmarks: vc1dsp.vc1_h_loop_filter4_bestcase_c: 3.0 vc1dsp.vc1_h_loop_filter4_bestcase_ssse3: 29.9 ( 0.10x) vc1dsp.vc1_h_loop_filter4_worstcase_c: 43.7 vc1dsp.vc1_h_loop_filter4_worstcase_ssse3: 29.9 ( 1.46x) Hint: checkasm's benchmark always uses the same buffer that is partially updated by the horizontal loop filter function (the middle two of eight columns are updated using word-sized stores). They therefore lead to store-to-load-forwarding failure. If checkasm_alternate were used to alternate between two buffers, the benchmarks would be as follows: Old benchmarks: vc1dsp.vc1_h_loop_filter4_bestcase_c: 3.0 vc1dsp.vc1_h_loop_filter4_bestcase_ssse3: 16.4 ( 0.18x) vc1dsp.vc1_h_loop_filter4_worstcase_c: 23.9 vc1dsp.vc1_h_loop_filter4_worstcase_ssse3: 16.3 ( 1.47x) New benchmarks: vc1dsp.vc1_h_loop_filter4_bestcase_c: 3.0 vc1dsp.vc1_h_loop_filter4_bestcase_ssse3: 15.1 ( 0.20x) vc1dsp.vc1_h_loop_filter4_worstcase_c: 23.6 vc1dsp.vc1_h_loop_filter4_worstcase_ssse3: 15.2 ( 1.55x) Notice that at some callsites, the partially modified buffer is immediately reloaded again*, so that both scenarios can happen. *: See the TT_4X4 and TT_4X8 cases at the end of vc1_p_h_loop_filter() or vc1_b_h_intfi_loop_filter() or the luma field blocks in vc1_p_h_intfr_loop_filter(). 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.