f281cb4ea9
This is ~2x faster for y not an integer on Haswell+GCC, and should generally be faster due to the fact that anyway powf essentially does this under the hood. Made an inline function in lavu/internal.h for this purpose. Note that there are some accuracy differences, that should generally be negligible. In particular, FATE still passes on this platform. Results in ~ 7% speedup in aac encoding with -march=native, Haswell+GCC. before: ffmpeg -i sin.flac -acodec aac -y sin_new.aac 6.05s user 0.06s system 104% cpu 5.821 total after: ffmpeg -i sin.flac -acodec aac -y sin_new.aac 5.67s user 0.03s system 105% cpu 5.416 total This is also faster than an alternative approach that pulls in powf, gets rid of the crufty NaN checks and other special cases, exploits knowledge about the intervals, etc. This of course does not exclude smarter approaches; just suggests that there would need to be significant work on this front of lower utility than searches for hotspots elsewhere. Reviewed-by: Reimar Döffinger <Reimar.Doeffinger@gmx.de> Reviewed-by: Ronald S. Bultje <rsbultje@gmail.com> Signed-off-by: Ganesh Ajjanagadde <gajjanag@gmail.com> (cherry picked from commit bccc81dfa08e6561df6ed37860e3a08f7d983825)
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 a mean to alter decoded Audio and Video through chain of 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.
- ffserver is a multimedia streaming server for live broadcasts.
- 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. Few developers
follow pull requests so they will likely be ignored.