Opus: the free audio codec which should become the standard

The free audio compression format known as Opus Interactive Audio Codec should become the Internet standard.

Opus Interactive Audio Codec has been standardised by the Internet Engineering Task Force (IETF). This free audio compression format has been designed for the Web to allow a standard format for most audio ranging from VoIP with low bot rates to music (from 6 Kbps to 510 Kbps).

During its implementation into Firefox 15, Mozilla was looking for an open source format to provide better compression with MP3, Ogg or AAC. Opus will be used with WebRTC, the future Web standard for audio and video communication in the browser without a plugin.

Opus is the result from collaborative work between the IETF, Mozilla, Microsoft (via Skype), Xiph.Org, Octasic, Broadcom and Google.

Jean-Marc Valin from Mozilla, one of Opus’ developers states "Opus is the first state of the art, free audio codec to be standardized. We think this will help us achieve wider adoption than prior royalty-free codecs like Speex and VorbisOpus."

In a press release, the Xiph.org foundation points out the advantages of a codec which covers a wide range of uses for optimal performance. It has low latency and can be adapted to changing bandwidth without disrupting the memory buffer.

Opus in reality combines two codecs: SILK, which is an audio codec introduced by Skype in 2009 for voice, and the CELT codec by Xiph.org for music. This is therefore a hybrid which uses both codecs at the same time.