Opus Interactive Audio Codec

Overview

Opus is a totally open, royalty-free, highly versatile audio codec. Opus is unmatched for interactivespeech and music transmission over the Internet, but is also intended for storage and streamingapplications. It is standardized by the Internet Engineering Task Force (IETF) asRFC 6716which 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 narrowbandspeech 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, inRFC 6716.An up-to-date implementation of the Opus standard is also available from thedownloads page.

News

• libopus 1.5.2

  Apr 12, 2024

  Opus 1.5.2 fixes several build issues that were discovered sincethe 1.5 release. It also fixes a misalignment issue in the AVX2 codethat could cause crashes under Windows.

  Source code:opus-1.5.2.tar.gz
  SHA256: 65c1d2f78b9f2fb20082c38cbe47c951ad5839345876e46941612ee87f9a7ce1

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• libopus 1.5.1

  Mar 4, 2024

  Opus 1.5 is the first release to make extended use of ML in the encoder anddecoder. You can read all the details in thisrelease 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.

  Source code:opus-1.5.1.tar.gz
  SHA256: b84610959b8d417b611aa12a22565e0a3732097c6389d19098d844543e340f85

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• libopus 1.5

  Mar 4, 2024

  Opus 1.5 is the first release to make extended use of ML in the encoder anddecoder. You can read all the details in thisrelease 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.

  Source code:opus-1.5.tar.gz
  SHA256: d8230bbeb99e6d558645aaad25d79de8f4f28fdcc55f8af230050586d62c4f2c

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• libopus 1.4

  Apr 20, 2023

  ThisOpus 1.4 major release brings the following improvements and fixes:

  • Improved tuning of the Opus in-band FEC (LBRR). See theissue for details
  • Added a OPUS_SET_INBAND_FEC(2) option that turns on FEC, but does not force SILK mode (FEC will be disabled in CELT mode)
  • Improved tuning and various fixes to DTX
  • Added Meson support, improved CMake supportIn addition to the improvements above, this release includes many minor bug fixes.

  Additionally, we have begun experiments on upcomingneural packet loss concealment anddeep redundancy (DRED) features.Although not included in this release, you can see two IETF drafts describing the proposedextensionandredundancy mechanisms.The code is also available on thisdevelopment branch.

  Source code:opus-1.4.tar.gz

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