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Frame size of Opus stream was previously presumed here to be 960 samples (20ms), however sizes of 120, 240, 480, 1920, and 2880 are also allowed. It can also alter on a per-packet basis and even multiple frames may be present in a single packet according to the specification, for the sake of simplicity however, let us assume that this doesn't occur. Because the mFramesPerPacket field, representing the number of samples per packet in the ffmpeg terminilogy, is the key factor in calculating packet durations and all that follows from that (index, bitrate, ...), it is crucial to get right. Therefore, if the packet size is not available ahead of time (as it is in the case of Opus), calculate an average from the stream duration once we know how many packets there are and update the filed in the header.
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.
- 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.