G.722.1

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G.722.1 is an ITU-T standard audio codec meant for low bit rate (24 and 32 kbit/s) wideband (50 Hz - 7 kHz audio bandwidth, 16 ksps) audio coding. It is based on Polycom's SIREN codec.

It is the successor to PT716plus, which has been used in videoconferencing systems for many years. As ITU-T Recommendation G.722.1, it was approved on September 30, 1999.

G.722.1 is a transform-based compressor that is optimized for both speech and music. The computational complexity is quite low (2 – 9 floating-point MIPS) for an efficient high-quality compressor, and the algorithmic delay end-to-end is 40 ms.

There is also a 14 kHz (32 ksps) extension, G.722.1/Annex C, approved by ITU-T on May 14, 2005. Also known as Siren14™, this extension is available from Polycom as a free license.

The numbering of the wideband ITU audio codecs is sometimes confusing. There are three principal codecs, which are unrelated, but all carrying the G.722 label. G.722 is the original 7 kHz codec, using ADPCM and operating at 48 – 64 kbps. G.722.1 operates at half the data rate while delivering comparable or better quality as G.722, but is a transform-based codec. And G.722.2, which operates on wideband speech and delivers very low bitrates, is a CELP-based algorithm.

[edit] Licensing

At this time, G.722 patents have expired so it is freely available. G.722.1 is licensed by Polycom Corporation, who owns all rights. Licensees also receive the right to use Polycom's 16 kbps decoder extension of the standard. G.722.2, also known as AMR-WB, is licensed by VoiceAge Corporation.