0bd1be65e8
The framework will allocate a buffer and copy the data to it, that takes time. But it avoids constently creating and destroyng the shared memory segment, and that saves more time. On my setup, from ~200 to ~300 FPS at full screen (1920×1200), from ~1400 to ~3300 at smaller size (640×480), similar to legacy x11grab and confirmed by others. Plus, shared memory segments are a scarce resource, allocating potentially many is a bad idea. Note: if the application were to drop all references to the buffer before the next call to av_read_frame(), then passing the shared memory segment as a refcounted buffer would be even more efficient, but it is hard to guarantee, and it does not happen with the ffmpeg command-line tool. Using a small number of preallocated buffers and resorting to a copy when the pool is exhausted would be a solution to get the better of both worlds.
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 a mean to alter decoded Audio and Video through chain of 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.
- ffserver is a multimedia streaming server for live broadcasts.
- 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.