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e29db08cf7
exp10 is a function available in GNU libm. Looks like no other common libm has it. This adds support for it to FFmpeg. There are essentially 2 ways of handling the fallback: 1. Using pow(10, x) 2. Using exp2(M_LOG2_10 * x). First one represents a Pareto improvement, with no speed or accuracy regression anywhere, but speed improvement limited to GNU libm. Second one represents a slight accuracy loss (relative error ~ 1e-13) for non GNU libm. Speedup of > 2x is obtained on non GNU libm platforms, ~30% on GNU libm. These are "average case numbers", another benefit is the lack of triggering of the well-known terrible worst case paths through pow. Based on reviews, second one chosen. Comment added accordingly. Reviewed-by: Hendrik Leppkes <h.leppkes@gmail.com> Reviewed-by: Michael Niedermayer <michael@niedermayer.cc> Reviewed-by: Ronald S. Bultje <rsbultje@gmail.com> Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.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 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.