Opus


 * Not to be confused with the Opus-CBCS BBS software.

Opus is a lossy audio compression format designed by the Internet Engineering Task Force (IETF) for applications requiring high-quality, low-delay audio transmission (e.g. telephony or network music performance). It incorporates technology from Skype's SILK codec and Xiph.org's CELT codec.

Opus-coded audio is usually found inside an Ogg container (where it carries the extension ) or in a WebM container.

Information

 * RFC 6716 - Definition of the Opus Audio Codec
 * Ogg Encapsulation for the Opus Audio Codec (draft-ietf-codec-oggopus-00)
 * RTP Payload Format for Opus Speech and Audio Codec (draft-spittka-payload-rtp-opus-03)
 * Opus, the Swiss Army Knife of Audio Codecs (Presentation at linux.conf.au 2012]

Software
The Opus Codec downloads page contains opus-tools (encode / inspect / decode) .opus files and opusfile, an API for developers.
 * foobar2000 can play back and encode Opus files (with the Free Encoder Pack
 * SoX
 * FFmpeg

Sample files

 * https://telparia.com/fileFormatSamples/audio/opus/
 * https://github.com/xiph/opus-website/tree/master/static/examples

Links

 * Bitstream conformance set
 * The .opus test set (including intentionally malformed files)
 * How Opus Came To Be