Opus is an audio codec standard designed to handle a range of interactive audio applications, including VoIP, videoconferencing, in-game chat and live music performances. It scales from low bitrate narrowband speech at six kilobits per second to very high quality stereo music at 510 kilobits per second.
Skype has used its own SILK audio codec since January 2009, but it will now transition to the new Opus specification.
Karlheinz Wurm, audio/video product engineering director for Skype, explained in a blog that Skype initiated the idea of developing and standardizing a codec built specifically for the Internet back in March 2009. The company submitted the new codec to the IETF in September 2010. It was approved two years later.
"Opus will make a quiet but crystal clear entry into the world--most people will take for granted the high sound fidelity when it arrives in the Skype client, through browsers and gateways, and we hope on mobile phones, game consoles and conference rooms, too," explained Wurm.
Because it was designed for the Internet, Opus can adjust seamlessly to any of its operating modes, whether moving from 3G to WiFi or competing with the house next door for broadband bandwidth. Opus has "multiple mechanisms to deal with and recover from packet loss plaguing the network, making for fewer annoying gaps in conversation and lost moments in your precious calls," Wurm said.
In addition to Skype, Mozilla, Xiph.Org, Octasic, Broadcom (NASDAQ: BRCM) and Google (NASDAQ: GOOG) worked with IETF on the Opus codec, related Jean-Marc Valin and Timothy Terriberry in a Mozilla blog.
"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 Vorbis," they explained.
Opus "can adapt seamlessly within these operating points. Doing all of this with proprietary codecs would require at least six different codecs. Opus replaces all of them, with better quality," they added.
