Opus Interactive Audio Codec

Overview

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.

News

• libopus 1.6.1

  Jan 14, 2026

  Opus 1.6.1 fixes several minor issues that were discovered since the 1.6 release.

  Source code: opus-1.6.1.tar.gz
  SHA256: 6ffcb593207be92584df15b32466ed64bbec99109f007c82205f0194572411a1

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• libopusenc 0.3

  Jan 3, 2026

  This release fixes a number of issues:

  • Fix ope_encoder_drain() assertion failures
  • Fix use of uninitialized fields
  • Fix undefined behaviour in picture.c
  • Fix crash with WIN32_LEAN_AND_MEAN on 64-bit Windows
  • Fix various warnings under C23
  • Drop use of private __opus_check_* macros
  • Port update_version from bash to sh
  • Clean up documentation files

  Source code: libopusenc-0.3.tar.gz
  SHA256: f616d3aff9b2034547894ccb8ab56c36cf1a4acb0d922c5d7119f97bbe58642c

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• libopus 1.6

  Dec 15, 2025

  Opus 1.6 builds on the new ML-based features introduced in Opus 1.5. You can read all the details in this release demo page. In summary, major changes since version 1.5 include:

  • A new wideband-to-fullband bandwidth extension (BWE) module
  • Support for 96 kHz audio with Opus HD
  • Significant improvement to Deep Redundancy (DRED)
  • A new 24-bit encoder/decoder API
  • Fixed-point improvements

  In addition to the improvements above, this release includes many minor bug fixes.

  Source code: opus-1.6.tar.gz
  SHA256: b7637334527201fdfd6dd6a02e67aceffb0e5e60155bbd89175647a80301c92c

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• libopus 1.5.2

  Apr 12, 2024

  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.

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

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