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== External links ==
== External links ==
* [http://webrtc.googlecode.com/svn/trunk/src/modules/audio_coding/codecs/ WebRTC codecs - SVN - source code for iSAC and other codecs]
* [https://code.google.com/p/webrtc/source/browse/#svn%2Ftrunk%2Fwebrtc%2Fmodules%2Faudio_coding%2Fcodecs%2Fisac WebRTC codecs - SVN - source code for iSAC and other codecs]
* [http://www.gipscorp.com/files/english/datasheets/Codecs.pdf Global IP Solutions VoIP codecs] (dead link)
* [http://www.gipscorp.com/files/english/datasheets/Codecs.pdf Global IP Solutions VoIP codecs] (dead link)



Revision as of 21:55, 21 March 2013

internet Speech Audio Codec (iSAC)
Internet media type
audio/isac[1]
Developed byGlobal IP Solutions, now Google Inc
Type of formatAudio compression format
iSAC Codec
Developer(s)Global IP Solutions, now Google Inc
Written inC
Operating systemCross-platform
TypeAudio codec, reference implementation
Licenseformerly proprietary, now 3-clause BSD
Website[1]

internet Speech Audio Codec (iSAC) is a wideband speech codec, developed by Global IP Solutions (GIPS) (acquired by Google Inc in 2011[2][3]). 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 16 kHz[1] (or 32 kHz according to WebRTC[6][7])
  • Adaptive and variable bit rate (10 kbit/s to 32 kbit/s) (or 10 kbit/s to 52 kbit/s according to WebRTC[6][7])
  • Adaptive packet size 30 to 60ms
  • Complexity comparable to G.722.2 at comparable bit-rates
  • Algorithmic delay of frame size plus 3ms

See also

References

  1. ^ a b "RTP Payload Format for the iSAC Codec - Internet Draft - draft-legrand-rtp-isac-02.txt". 2009. Retrieved 2011-06-23.
  2. ^ Dana Blankenhorn (2010-05-18). "Why Google bought Global IP Solutions". Retrieved 2011-06-23.
  3. ^ "iLBC Freeware". Retrieved 2011-06-23.
  4. ^ http://sites.google.com/site/webrtc/faq#TOC-What-is-the-iSAC-audio-codec-
  5. ^ http://sites.google.com/site/webrtc/license-rights/additional-ip-grant
  6. ^ a b "WebRTC FAQ - What are the parameters of iSAC?". Retrieved 2011-06-23.
  7. ^ a b "WebRTC components". Retrieved 2011-06-23.

External links