Open Source

Opus open-source audio codec now available in beta

The open-source and royalty-free audio codec, Opus has reached its beta stage with the release of Opus 1.3-beta.

Opus has been designed for interactive speech and music over the Internet. The Opus library, libopus, is now up to version 1.3 beta. This Opus 1.3 update is working on incorporating the specification fixes via RFC-8251, improvements to the VAD and speeh/music classification, improvements to cthe stereo speech coding at a low bit-rate, support for ambisonics projection, and fixes to the CELT PLC.

According to a short release note over at, the project reveals what’s part of version 1.3:

  • Enabling by default the spec fixes in RFC 8251
  • Improvements to the VAD and speech/music classification using an RNN
  • Improvements to stereo speech coding at low bitrate
  • Added support for ambisonics projection using mapping 3 (disabled by default)
  • Fixes to the CELT PLC

Additionally, as a way to test the upcoming update to opus-tools, the project is also providing Windows binaries built with 1.3-beta. These binaries are based on libopusenc, which means opusenc is finally able to make use of the Opus delayed-decision feature to make better speech/music transitions.