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This marks the first time anyone has written an Opus encoder without using any libopus code. The aim of the encoder is to prove how far the format can go by writing the craziest encoder for it. Right now the encoder's basic, it only supports CBR encoding, however internally every single feature the CELT layer has is implemented (except the pitch pre-filter which needs to work well with the rest of whatever gets implemented). Psychoacoustic and rate control systems are under development. The encoder takes in frames of 120 samples and depending on the value of opus_delay the plan is to use the extra buffered frames as lookahead. Right now the encoder will pick the nearest largest legal frame size and won't use the lookahead, but that'll change once there's a psychoacoustic system. Even though its a pretty basic encoder its already outperforming any other native encoder FFmpeg has by a huge amount. The PVQ search algorithm is faster and more accurate than libopus's algorithm so the encoder's performance is close to that of libopus at zero complexity (libopus has more SIMD). The algorithm might be ported to libopus or other codecs using PVQ in the future. The encoder still has a few minor bugs, like desyncs at ultra low bitrates (below 9kbps with 20ms frames). Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com>
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.