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This happens when the pixel format of the output does not have an alpha channel. It leads to FATE failures with the ffmpeg-filter_colorkey, filter-overlay-dvdsub-2397 filter-overlay, filter-overlay_{gbrp_gbrap,nv12,nv21,yuv420,yuv420_yuva420, yuv420p10,yuv422_yuva422,yuv422p10,yuv444_yuva444,yuv444p10} and sub2video tests when using Clang UBSan. Fix this by only performing the pointer arithmetic when it is going to be used. This can be checked via variables that compile-time constants due to inlining, so that the checks are free. Given that the pointer is potentially used as a function argument, the compiler could elide the calculation, but not it can. The size of .text decreased by 1632B with GCC 14 and by 1392B with Clang 19 (both -O3). Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
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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 means to alter decoded audio and video through a directed graph of connected 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
andqt-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.
Languages
C
90.1%
Assembly
7.9%
Makefile
1.3%
C++
0.2%
Objective-C
0.2%
Other
0.1%