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Andreas Rheinhardt 527b853d1a avcodec/smacker: Replace implicit checks for overread by explicit ones
Using explicit checks has the advantage that one can combine several
checks into one and does not have to check every time. E.g. reading a
16bit PCM sample involves two calls to get_vlc2(), each of which may
read up to three times up to SMKTREE_BITS (= 9) bits. But given that the
padding that the input packet is supposed to have is large enough, it is
no problem to only check once for each sample.

This turned out to be beneficial for performance: For GCC 9, the time for
one call of smka_decode_frame() for the sample from ticket #2425 went down
from 2055905 to 1804751 decicycles; for Clang 9 it went down from 1510538
to 1479680 decicycles.

Reviewed-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
2020-09-18 02:03:36 +02:00
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libavcodec avcodec/smacker: Replace implicit checks for overread by explicit ones 2020-09-18 02:03:36 +02:00
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libavfilter avfilter/vf_showinfo: add const to the AVFrameSideData instance 2020-09-17 18:52:11 +08:00
libavformat avformat/3dostr: make probing more robust 2020-09-17 23:47:10 +02:00
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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.