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Avi Halachmi (:avih) 45499e557c configure: speed up check_deps()
x4 - x25 faster.

check_deps() recursively enables/disables components, and its loop is
iterated nearly 6000 times. It's particularly slow in bash - currently
consuming more than 50% of configure runtime, and about 20% with other
shells.

This commit applies few local optimizations, most effective first:
- Use $1 $2 ... instead of pushvar/popvar, and same at enable_deep*
- Abort early in one notable case - empty deps, to avoid costly no-op.
- Smaller changes which do add up:
  - Handle ${cfg}_checking locally instead of via enable[d]/disable
  - ${cfg}_checking: test done before inprogress - x2 faster in 50%+
  - one eval instead of several at the empty-deps early abort path.

- The "actual work" part is unmodified - just its surroundings.

Biggest speedups (relative and absolute) are observed with bash.

Tested-by: Michael Niedermayer <michael@niedermayer.cc>
Tested-by: Helmut K. C. Tessarek <tessarek@evermeet.cx>
Tested-by: Dave Yeo <daveryeo@telus.net>
Tested-by: Reino Wijnsma <rwijnsma@xs4all.nl>
Signed-off-by: James Almer <jamrial@gmail.com>
2018-08-27 11:34:10 -03:00
2017-01-27 17:06:42 +01:00
2018-01-06 18:31:37 +00:00
2018-08-27 11:34:10 -03:00
2016-09-18 10:02:13 +01:00
2014-05-28 22:38:38 +02:00
2018-01-06 18:31:37 +00:00

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.
  • 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 and will be ignored.

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