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Michael Niedermayer
d67a6d27c2
When extending the edges of the reconstructed reference frame, the chroma plane width and height were passed to draw_edges() as w >> chroma_h_shift (floor) instead of AV_CEIL_RSHIFT(). For an odd width with subsampled chroma (e.g. 4:2:0) the chroma plane is one column wider than the floor, and draw_edges() replicates the edge columns, so it overwrote the last real chroma column with the previous one. The decoder does not draw_edges() its reference, so its copy kept the correct value: the encoder and decoder references diverged and every following inter frame was reconstructed differently by the two, breaking bit-exact (lossless) round-tripping and drifting lossy inter coding, for any odd-width 4:2:0 snow stream. Use AV_CEIL_RSHIFT(), matching the input_picture edge extension just above. Found-by: Claude Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
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.