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75960ac270
This happens on systems where get_pixels really needs
to be properly aligned, like ARMV7 or RISC-V. For these
systems, 0401ca714a caused
a bus error for the vsynth3-asv[12] tests, because
the stride in these tests is unaligned. See e.g.
https://fate.ffmpeg.org/report.cgi?slot=armv7-linux-gcc-13&time=20250527020548
https://fate.ffmpeg.org/report.cgi?slot=rv64gcvb-linux-gnu-gcc&time=20250527001827
It can also happen (even before said commit) if the pointers
itself are unaligned, e.g. by using the crop filter:
ffmpeg -filter_complex nullsrc=s=740x576:r=25,format=yuv420p,crop=w=720:x=2 \
-c:v asv2 -f null -
The alignment requirements for the frames passed to encoders are
mostly undocumented; the only thing I could find is the documentation
of AVFrame.linesize: "For video the linesizes should be multiples
of the CPUs alignment preference". This means that the FFmpeg cli
violates our API.
Yet as the above command line shows, it can also happen with
unaligned pointers and there does not seem to be a prohibition
of this, so we need to handle this case. This commit does so
by using get_pixels_unaligned when needed.
Reviewed-by: Martin Storsjö <martin@martin.st>
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.