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For a frame comes from AV_HWDEVICE_TYPE_VIDEOTOOLBOX, it's CVPixelBufferRef is maintained by a pool. CVPixelBufferRef returned to the pool when frame buffer reference reached to zero. However, VTCompressionSessionEncodeFrame also hold a reference to the CVPixelBufferRef. So a new frame get from av_hwframe_get_buffer may access a CVPixelBufferRef which still used by the encoder. It's only after vtenc_output_callback that we can make sure CVPixelBufferRef has been released by the encoder. The issue can be tested with sample from trac #10884. ffmpeg -hwaccel videotoolbox \ -hwaccel_output_format videotoolbox_vld \ -i input.mp4 \ -c:v hevc_videotoolbox \ -profile:v main \ -b:v 3M \ -vf scale_vt=w=iw/2:h=ih/2:color_matrix=bt709:color_primaries=bt709:color_transfer=bt709 \ -c:a copy \ -tag:v hvc1 \ output.mp4 Withtout the patch, there are some out of order images in output.mp4. Signed-off-by: Zhao Zhili <zhilizhao@tencent.com> |
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| compat | ||
| 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.