- Company: Xiph, IETF
- Extension: .opus
- Specification (codec): https://tools.ietf.org/html/rfc6716
- Specification (Ogg encapsulation): https://tools.ietf.org/html/draft-terriberry-oggopus-01
- Reference implementation: http://www.opus-codec.org/downloads/
Open standard for low-latency, scalable lossy audio coding based on the speech-oriented SILK codec and the low-latency CELT codec. Opus can transition between a linear prediction codec at low bitrates and a transform codec at high bitrates and supports a hybrid mode for a small bitrate range. Opus defaults to a latency that's 1/10th that of earlier music codecs (20ms vs. 200ms), making it possible for use in VoIP, and yet performs better in listening tests.