xiph/opus

Free

Modern audio compression for the internet.

FreeFree tier

Inputs: audio

Type

Open Source

Company

Xiph.Org Foundation

Visit Website GitHub (38 stars)

About xiph/opus

Opus is a highly versatile audio codec designed for interactive speech and audio transmission over the Internet. It handles a wide range of applications from low bit-rate narrowband speech to high-quality stereo music, making it suitable for Voice over IP, videoconferencing, in-game chat, and remote live music performances. Opus is also used for non-realtime stored-file applications like music distribution and game soundtracks, offering lower latency than traditional formats like MP3, AAC, or Vorbis. The implementation provides a shared library for encoding and decoding raw Opus bitstreams and includes a deep learning-based redundancy encoder (added in Opus 1.5) to improve audio quality in lossy network environments.

Key Features

Scales from low bit-rate narrowband speech to high quality stereo music

Designed for interactive real-time communication (VoIP, videoconferencing, in-game chat)

Also suitable for stored-file applications (music distribution, game soundtracks)

Low latency compared to MP3, AAC, Vorbis

Royalty-free patent and copyright licenses

Includes deep learning based redundancy encoder for packet loss concealment (Opus 1.5)

Specified by IETF RFC 6716

Shared library for encoding and decoding raw Opus bitstreams

Pros & Cons

Pros

Handles wide range of audio quality from narrowband to stereo
Low latency ideal for real-time communication
Royalty-free open standard with permissive licensing
Deep learning based redundancy encoder improves quality on lossy networks
Well-established with IETF specification (RFC 6716)
Open source implementation with active development

Cons

Raw Opus bitstreams are not suitable for file storage as they include debugging data and cannot support seeking
Requires Ogg encapsulation for proper file distribution and seeking support
Not all platforms have native Opus support, requiring additional libraries or codec packs

Best For

Voice over IP (VoIP)VideoconferencingIn-game chatRemote live music performancesNon-realtime music distributionGame soundtracksPortable music players

FAQ

What is Opus?

Opus is a royalty-free audio codec for interactive speech and audio transmission over the Internet, specified by IETF RFC 6716.

What applications is Opus suitable for?

Opus can handle real-time applications like Voice over IP, videoconferencing, in-game chat, and remote live music performances, as well as non-realtime stored-file applications such as music distribution and game soundtracks.

Is Opus royalty-free?

Yes, the Opus format and this implementation are subject to royalty-free patent and copyright licenses specified in the COPYING file.

How does Opus handle packet loss?

Opus includes a deep learning based redundancy encoder that embeds one second of recovery data to enhance audio quality in lossy network environments (added in Opus 1.5).

How should Opus files be stored?

For proper file distribution and seeking support, Opus bitstreams should be encapsulated in the Ogg container format as described in RFC 7845.