mirror of
https://github.com/FFmpeg/FFmpeg.git
synced 2025-01-24 13:56:33 +02:00
d75c4693fe
These are the formats we want/need to use when dealing with the Intel VAAPI decoder for 12bit 4:2:0, 12bit 4:2:2, 10bit 4:4:4 and 12bit 4:4:4 respectively. As with the already supported Y210 and YUVX (XVUY) formats, they are based on formats Microsoft picked as their preferred 4:2:2 and 4:4:4 video formats, and Intel ran with it. P12 and Y212 are simply an extension of 10 bit formats to say 12 bits will be used, with 4 unused bits instead of 6. XV30, and XV36, as exotic as they sound, are variants of Y410 and Y412 where the alpha channel is left formally undefined. We prefer these over the alpha versions because the hardware cannot actually do anything with the alpha channel and respecting it is just overhead. Y412/XV46 is a normal looking packed 4 channel format where each channel is 16bits wide but only the 12msb are used (like P012). Y410/XV30 packs three 10bit channels in 32bits with 2bits of alpha, like A/X2RGB10 style formats. This annoying layout forced me to define the BE version as a bitstream format. It seems like our pixdesc infrastructure can handle the LE version being byte-defined, but not when it's reversed. If there's a better way to handle this, please let me know. Our existing X2 formats all have the 2 bits at the MSB end, but this format places them at the LSB end and that seems to be the root of the problem.
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.