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This implements the limited DM metadata compression scheme described in chapter 9 of the dolby vision bitstream specification. The spec is a bit unclear about how to handle the presence of static metadata inside compressed frames; in that it doesn't explicitly forbid an encoder from repeating redundant metadata. In theory, we would need to detect this case and then strip the corresponding duplicate metadata from the existing set of static metadata. However, this is difficult to implement - esspecially for the case of metadata blocks which may be internally repeated (e.g. level 10). That said, the spec states outright that static metadata should be constant throughout the entire sequence, so a sane bitstream should not have any static metadata values changing from one frame to the next (at least up to a keyframe boundary), and therefore they should never be present in compressed frames. As a consequence, it makes sense to treat this as an error state regardless. (Ignoring them by default, or erroring if either AV_EF_EXPLODE or AV_EF_AGGRESSIVE are set) I was not able to find such samples in the wild (outside of artificially produced test cases for this exact scenario), so I don't think we need to worry about it until somebody produces one. |
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| doc | ||
| ffbuild | ||
| fftools | ||
| libavcodec | ||
| libavdevice | ||
| libavfilter | ||
| libavformat | ||
| libavutil | ||
| libpostproc | ||
| libswresample | ||
| libswscale | ||
| presets | ||
| tests | ||
| tools | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| Changelog | ||
| configure | ||
| CONTRIBUTING.md | ||
| COPYING.GPLv2 | ||
| COPYING.GPLv3 | ||
| COPYING.LGPLv2.1 | ||
| COPYING.LGPLv3 | ||
| CREDITS | ||
| INSTALL.md | ||
| LICENSE.md | ||
| MAINTAINERS | ||
| Makefile | ||
| README.md | ||
| RELEASE | ||
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.