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Up until now, our muxer wrote FFV1 in video-for-windows compatibility mode out of concern for old demuxers that only support that (whereas the demuxer accepts V_FFV1). This commit switches to using native mode, because a) V_FFV1 is around long enough so that old demuxers should not be an issue (support in FFmpeg has been added in commit9ae762da7ein March 2017/FFmpeg 3.3), b) using native mode uses fewer bytes for the CodecPrivate, c) the VfW extradata is zero-padded to an even length if necessary, but our demuxer forgot to undo the padding until very recently (92e310eb82), so that there are many versions of our demuxer around that are buggy wrt VFW, but not V_FFV1. This affects the FFV1 extradata checksums, specifically the (experimental) version 4 files with error check version 2* as created by ffmpeg -i ../fate-suite/mpeg2/sony-ct3.bs -c:v ffv1 \ -slices 16 -frames 1 -level 4 -strict experimental ffv1.mkv VFW files like the above created by this muxer before this patch would not work with an old demuxer. *: Without error check version 2, the CRC for the whole extradata is zero, which is not changed by appending a zero byte. Reviewed-by: compn <ff@hawaiiantel.net> Reviewed-by: Dave Rice <dave@dericed.com> 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.