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f440c422b7
In this case the current code tries to warn once; to do so, it uses ordinary static ints to store whether the warning has already been emitted. This is both a data race (and therefore undefined behaviour) as well as a race condition, because it is really possible for multiple threads to be the one thread to emit the warning. This is actually common since the introduction of the new multithreaded scaling API. This commit fixes this by using atomic integers for the state; furthermore, these are not static anymore, but rather contained in the user-facing SwsContext (i.e. the parent SwsContext in case of slice-threading). Given that these atomic variables are not intended for synchronization at all (but only for atomicity, i.e. only to output the warning once), the atomic operations use memory_order_relaxed. This affected the nv12, nv21, yuv420, yuv420p10, yuv422, yuv422p10 and yuv444 filter-overlay FATE-tests. Reviewed-by: Michael Niedermayer <michael@niedermayer.cc> 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 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.