Version 1.6 of libopus as the library for the open-source Opus audio codec is now available. Opus 1.6 brings new machine learning “ML” based features in building atop the machine learning features initially added to Opus 1.5.
Opus 1.6 changes 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
The Speech Bandwidth Extension “BWE” is an experimental feature in Opus 1.6 that is based on a neural network trained for generating high frequency speech content for wideband speech. The demo page further explains:
“Opus 1.6 introduces an experimental wideband-to-fullband speech enhancer that was presented at WASPAA 2025. It is an addition to the family of Opus speech coding enhancement algorithms which are covered by the related IETF draft. The new Bandwidth Extension (BWE) model is based on a neural network that was trained to generate high frequency speech content (8-20 kHz) from wideband speech (0-8 kHz) without any side information. It can therefore be used to enhance speech from any previous Opus version and there is no risk of breaking compatibility as the model gets improved in the future. Generating highband content from wideband speech is possible since all phonetic information is already contained in the lower frequency range. This is unlike the problem of narrowband (telephone) to wideband extension, which is hard to achieve and tends to be unreliable (which is why we are not attempting it here).
The model can be used to optionally decode wideband speech into fullband speech sampled at 48 kHz as shown below. It can furthermore be used in combination with the wideband enhancement methods introduced in Opus 1.5. It is, however, not intended to replace highband content encoded in hybrid mode and it will never activate for super-wideband or fullband audio.”
The 96Hz audio for experimental “Opus HD” support is also interesting and worth highlighting.
Downloads and more details on the Opus 1.6 release via Opus-Codec.org.
