2a3640de84
AVIF specification allows for alpha channel as an auxiliary item (in case of still images) or as an auxiliary track (in case of animated images). Add support for both of these. The AVIF muxer will take exactly two streams (when alpha is present) as input (first one being the YUV planes and the second one being the alpha plane). The input has to come from two different images (one of it color and the other one being alpha), or it can come from a single file source with the alpha channel extracted using the "alphaextract" filter. Example using alphaextract: ffmpeg -i rgba.png -filter_complex "[0:v]alphaextract[a]" -map 0 -map "[a]" -still-picture 1 avif_with_alpha.avif Example using two sources (first source can be in any pixel format and the second source has to be in monochrome grey pixel format): ffmpeg -i color.avif -i grey.avif -map 0 -map 1 -c copy avif_with_alpha.avif The generated files pass the compliance checks in Compliance Warden: https://github.com/gpac/ComplianceWarden libavif (the reference avif library) is able to decode the files generated using this patch. They also play back properly (with transparent background) in: 1) Chrome 2) Firefox (only still AVIF, no animation support) Reviewed-by: James Zern <jzern@google.com> Signed-off-by: Vignesh Venkatasubramanian <vigneshv@google.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.