Opus Interactive Audio Codec

Overview

Opus is a totally open, royalty-free, highly versatile audio codec. Opus is unmatched for interactive speech and music transmission over the Internet, but also intended for storage and streaming applications. It is standardized by the Internet Engineering Task Force (IETF) as RFC 6716 which incorporated technology from Skype’s SILK codec and Xiph.Org’s CELT codec.

Technology

Opus can handle a wide range of audio applications, including Voice over IP, videoconferencing, in-game chat, and even remote live music performances. It can scale from low bit-rate narrowband speech to very high quality stereo music. Supported features are:

  • Bit-rates from 6 kb/s to 510 kb/s
  • Sampling rates from 8 kHz (narrowband) to 48 kHz (fullband)
  • Frame sizes from 2.5 ms to 60 ms
  • Support for both constant bit-rate (CBR) and variable bit-rate (VBR)
  • Audio bandwidth from narrowband to full-band
  • Support for speech and music
  • Support for mono and stereo
  • Support for up to 255 channels (multistream frames)
  • Dynamically adjustable bitrate, audio bandwidth, and frame size
  • Good loss robustness and packet loss concealment (PLC)
  • Floating point and fixed-point implementation

You can read the full specification, including the reference implementation, in RFC 6716. An up-to-date implementation of the Opus standard is also available from the downloads page.

 

Listen from the cloud.

Our app was developed using HTML5, a language mobile devices love. You can listen to audio books across all devices and browsers and you’ll never have to download another plug in again. We’ve also incorporated a cloud-based technology which allows you to access your audio books from anywhere in the world and eliminates the frustration that comes with slow downloads and storage constraints.

Basically, our new app allows you to:

  • Listen to unlimited audio books on-demand
  • Easily switch between listening devices—pause your audio book on your iPhone at the gym and find your place instantly when you continue listening from your laptop at the office
  • Instantly access more than 10,000 best sellers, top new releases and classic favourites
  • Never have to worry about storage restraints because the content lives on a cloud

That’s the way you do it.