Article · Wikipedia archive · Last revised Jun 16, 2026

Internet Speech Audio Codec

internet Speech Audio Codec (iSAC) is a wideband speech codec, developed by Global IP Solutions (GIPS). It is suitable for VoIP applications and streaming audio. The encoded blocks have to be encapsulated in a suitable protocol for transport, e.g. RTP.

Last revised
Jun 16, 2026
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internet Speech Audio Codec
Internet media type
audio/isac1
Developed byGlobal IP Solutions, now Google Inc
Type of formatAudio compression format
Codec
DevelopersGlobal IP Solutions, now Google Inc
Written inC
Operating systemCross-platform
TypeAudio codec, reference implementation
Licenseformerly proprietary, now 3-clause BSD
Websitewebrtc.org

internet Speech Audio Codec (iSAC) is a wideband speech codec, developed by Global IP Solutions (GIPS) (acquired by Google Inc in 2011).23 It is suitable for VoIP applications and streaming audio. The encoded blocks have to be encapsulated in a suitable protocol for transport, e.g. RTP.

It is one of the codecs used by AIM Triton, the Gizmo5, QQ, and Google Talk. It was formerly a proprietary codec licensed by Global IP Solutions. As of June 2011, it is part of open source WebRTC project,4 which includes a royalty-free license for iSAC when using the WebRTC codebase.5

Parameters and features

  • Sampling frequency of 16 kHz (wideband) or 32 kHz (superwideband)167
  • Adaptive and variable bit rate of 10 kbit/s to 32 kbit/s (wideband) or 10 kbit/s to 52 kbit/s (superwideband)167
  • Adaptive packet size 30 to 60 ms
  • Complexity comparable to G.722.2 at comparable bit-rates
  • Algorithmic delay of frame size plus 3 ms
See also

See also

References

References

  1. Grand, Tina le; Jones, Paul; Huart, Pascal; Shabestary, Turaj Zakizadeh; Alvestrand, Harald T. (2013). "RTP Payload Format for the iSAC Codec". Retrieved 2016-04-30.
  2. Dana Blankenhorn (2010-05-18). "Why Google bought Global IP Solutions". ZDNet. Archived from the original on May 21, 2010. Retrieved 2011-06-23.
  3. "iLBC Freeware". Archived from the original on 2011-07-05. Retrieved 2011-06-23.
  4. webrtc.org/faq/#what-is-the-isac-audio-codec Archived 2011-06-07 at the Wayback Machine.
  5. webrtc.org/license/additional-ip-grant/ Archived 2017-11-13 at the Wayback Machine.
  6. "WebRTC FAQ - What are the parameters of iSAC?". Archived from the original on 2016-11-17. Retrieved 2011-06-23.
  7. "WebRTC components". Archived from the original on 2011-06-28. Retrieved 2011-06-23.
External links