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Lynne
c9a6817e3d
The bitonic sort needed a 64 KiB shared buffer, more than some devices have, and for larger slices sorted in place in an unqualified buffer with a memoryBarrierBuffer() after the barrier, which under the Vulkan memory model does not make the writes visible to other invocations. It also takes log2(N)^2/2 barriers, 91 for the UHD slices, and a slice of millions of pixels times out the GPU. Replace it with an LSD radix sort, 4 bits per pass, between the pairs region of a plane and a scratch region. Each subgroup owns a block of rows of elements, one per lane, and ranks them with ballots from the digit counts of the blocks, which take up to 16 KiB of shared memory. The bitmaps of the planes now follow the pairs of all planes, as the setup shader only fills them once the sort is done, so their region serves as the scratch and the buffer keeps its size. At UHD with the default slicing on an RX 6900 XT, the sort of a frame goes from 14 ms to 3.4 ms.
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.