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Most of the VLCs used by RealVideo 3 and 4 obey three simple rules: Shorter codes are on the left of the tree, for each length, the symbols are ascending from left to right and the symbols either form a permutation of 1..size or 0..(size - 1). For the latter case, one just needs to store the length of each symbol and create the codes according to the other rules; no explicit code or symbol array must be stored. The former case is also treated in much the same way by artificially assigning a length of zero to the symbol 0; when a length of zero was encountered, the element was ignored except that the symbol counter was still incremented. If the length was nonzero, the symbol would be assigned via the symbol counter and the length copied over into a new array. Yet this is unnecessary, as ff_init_vlc_sparse() follows exactly the same pattern: If a length of zero is encountered, the element is ignored and only the symbol counter incremented. So one can directly forward the length array and also need not create a symbol table oneself, because ff_init_vlc_sparse() will infer the same symbol table in this case. Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@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.
- 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 and will be ignored.