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6dfaba896f
export_film_grain() copied cb_mult, cb_luma_mult and cb_offset (and the
Cr equivalents) straight from the bitstream, where they are coded with
a bias of 128, 128 and 256. AVFilmGrainAOMParams holds them unbiased:
the uv_offset documentation gives a range of [-256, 255], the AFGS1
parser in aom_film_grain.c subtracts the bias, the film grain
synthesizer uses the values as signed multipliers and offsets, and
libdav1d exports them unbiased. The AR coefficients a few lines above
are already unbiased the same way.
With -export_side_data film_grain and a hwaccel, the native decoder
therefore exported values 128 or 256 higher than libdav1d for the
same stream, and any consumer applying the exported grain scaled
chroma noise wrong.
Signed-off-by: lusoris <lusoris@proton.me>
(cherry picked from commit 2a8c6d30b9)
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.