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mirror of https://github.com/FFmpeg/FFmpeg.git synced 2025-03-23 04:24:35 +02:00
Ganesh Ajjanagadde 07a11ebcab lavc/cbrt_tablegen: speed up tablegen
This exploits an approach based on the sieve of Eratosthenes, a popular
method for generating prime numbers.

Tables are identical to previous ones.

Tested with FATE with/without --enable-hardcoded-tables.

Sample benchmark (Haswell, GNU/Linux+gcc):
prev:
7860100 decicycles in cbrt_tableinit,       1 runs,      0 skips
7777490 decicycles in cbrt_tableinit,       2 runs,      0 skips
[...]
7582339 decicycles in cbrt_tableinit,     256 runs,      0 skips
7563556 decicycles in cbrt_tableinit,     512 runs,      0 skips

new:
2099480 decicycles in cbrt_tableinit,       1 runs,      0 skips
2044470 decicycles in cbrt_tableinit,       2 runs,      0 skips
[...]
1796544 decicycles in cbrt_tableinit,     256 runs,      0 skips
1791631 decicycles in cbrt_tableinit,     512 runs,      0 skips

Both small and large run count given as this is called once so small run
count may give a better picture, small numbers are fairly consistent,
and there is a consistent downward trend from small to large runs,
at which point it stabilizes to a new value.

Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
2016-01-11 17:20:38 -05:00
2015-11-12 22:31:46 +01:00
2016-01-10 16:31:30 +01:00
2016-01-06 16:43:06 +00:00
2015-12-04 02:35:42 +01:00
2016-01-06 16:43:06 +00:00
2015-12-07 10:43:43 -08:00
2016-01-07 16:57:37 -08:00
2016-01-06 16:43:06 +00:00
2015-12-04 02:35:42 +01:00

FFmpeg README

FFmpeg is a collection of libraries and tools to process multimedia content such as audio, video, subtitles and related metadata.

Libraries

  • libavcodec provides implementation of a wider range of codecs.
  • libavformat implements streaming protocols, container formats and basic I/O access.
  • libavutil includes hashers, decompressors and miscellaneous utility functions.
  • libavfilter provides a mean to alter decoded Audio and Video through chain of filters.
  • libavdevice provides an abstraction to access capture and playback devices.
  • libswresample implements audio mixing and resampling routines.
  • libswscale implements 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, ismindex and qt-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.

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