Opus is a totally open, royalty-free, highly versatile audio codec. Opus is unmatched for interactive
speech and music transmission over the Internet, but is also intended for storage and streaming
applications. It is standardized by the Internet Engineering Task Force (IETF) as RFC 6716
which incorporated technology from Skype’s SILK codec and Xiph.Org’s CELT codec.
Technology
Opus can handle a wide range of audio applications, including Voice over IP, videoconferencing,
in-game chat, and even remote live music performances. It can scale from low bitrate narrowband
speech to very high quality stereo music. Supported features are:
Bitrates from 6 kb/s to 510 kb/s
Sampling rates from 8 kHz (narrowband) to 48 kHz (fullband)
Frame sizes from 2.5 ms to 60 ms
Support for both constant bitrate (CBR) and variable bitrate (VBR)
Audio bandwidth from narrowband to fullband
Support for speech and music
Support for mono and stereo
Support for up to 255 channels (multistream frames)
Dynamically adjustable bitrate, audio bandwidth, and frame size
Good loss robustness and packet loss concealment (PLC)
Floating point and fixed-point implementation
You can read the full specification, including the reference implementation, in RFC 6716.
An up-to-date implementation of the Opus standard is also available from the downloads page.
Opus 1.5.2 fixes several build issues that were discovered since
the 1.5 release. It also fixes a misalignment issue in the AVX2 code
that could cause crashes under Windows.
Opus 1.5 is the first release to make extended use of ML in the encoder and
decoder. You can read all the details in this release demo page.
In summary, major changes since 1.4 include:
Significant improvement to packet loss robustness using Deep Redundancy (DRED)
Improved packet loss concealment through Deep PLC
Low-bitrate speech quality enhancement down to 6 kb/s wideband
Improved x86 (AVX2) and Arm (Neon) optimizations
Support for 4th and 5th order ambisonics
In addition to the improvements above, this release includes many minor bug fixes.
Opus 1.5.1 fixes the meson build that was broken in 1.5.
Opus 1.5
is the first release to make extended use of ML in the encoder and
decoder. You can read all the details in this release demo page.
In summary, major changes since 1.4 include:
Significant improvement to packet loss robustness using Deep Redundancy (DRED)
Improved packet loss concealment through Deep PLC
Low-bitrate speech quality enhancement down to 6 kb/s wideband
Improved x86 (AVX2) and Arm (Neon) optimizations
Support for 4th and 5th order ambisonics
In addition to the improvements above, this release includes many minor bug fixes.