This document defines the Opus interactive speech and audio codec. Opus is designed to handle a wide range of interactive audio applications@ including Voice over IP@ videoconferencing@ in-game chat@ and even live@ distributed music performances. It scales from low bitrate narrowband speech at 6 kbit/s to very high quality stereo music at 510 kbit/s. Opus uses both Linear Prediction (LP) and the Modified Discrete Cosine Transform (MDCT) to achieve good compression of both speech and music.
RFC 6716-2012 history
2012RFC 6716-2012 Definition of the Opus Audio Codec