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C11 provides static assertions via _Static_assert and provides static_assert as a convenience define for this in assert.h. Our codebase uses the latter, as _Static_assert has actually already been deprecated in C23. Not all toolchains that declare support for C11 actually support it; e.g. MSVC 19.27 does not support _Static_assert, but somehow supports static_assert. MSVC 19.27 admits to be a "preview implementation of the ISO C11 standard", so this is not surprising (MSVC 19.28 does not come with this caveat). Furthermore some FATE boxes [1] use old GCC toolchains (with only experimental support for C11) where _Static_assert is supported, but assert.h does not provide the fallback define. They are broken since the first usage of static_assert. This commit therefore checks whether static_assert and _Static_assert work with assert.h included; if not, configure errors out. This intentionally drops support for MSVC 19.27. Users like the old FATE boxes above can still add -Dstatic_assert=_Static_assert to cflags as a workaround if desired. [1]: https://fate.ffmpeg.org/report.cgi?time=20240321123620&slot=sh4-debian-qemu-gcc-4.7 Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.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 means to alter decoded audio and video through a directed graph of connected 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.