G.722.1

G.722.1 is a licensed royalty-free ITU-T standard audio codec providing high quality, moderate bit rate (24 and 32 kbit/s) wideband (50 Hz - 7 kHz audio bandwidth, 16 ksps) audio coding. It is an implementation of Polycom's SIREN7 codec.

G.722.1 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 (5.5 floating-point MIPS) for an efficient high-quality compressor, and the algorithmic delay end-to-end is 40 ms. A 14 kHz (32 ksps) extension, G.722.1/Annex C, was approved by ITU-T on May 14, 2005. Also known as Siren14, this extension is also available from Polycom as a royalty-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 kbit/s. G.722.1, another 7 kHz codec, operates at half the data rate while delivering comparable or better quality as G.722, but is a transform-based codec. G.722.1 Annex C is very similar to G.722.1, but provides twice the audio bandwidth, 14kHz. And G.722.2, which operates on wideband speech and delivers very low bitrates, is an ACELP-based algorithm.

Licensing

G.722.1 is available under a royalty-free license by Polycom Corporation, who owns all rights. Licensees also receive the right to use Polycom's 16 kbit/s decoder extension of G.722.1, as well as G.722.1 Annex C, and Polycom's IP within the new 20kHz ITU fullband codec, G.719.

See also

* G.711 (a-law and mu-law/u-law)
* G.718
* G.719
* G.722
* G.722.1
* G.722.2
* G.723
* G.723.1
* G.726
* G.728
* G.729
* G.729a
* List of codecs

External links

* [http://www.polycom.com/usa/en/company/about_us/technology/siren_g7221/siren_g7221.html Polycom Siren/G 722.1 Page]
* [http://www.polycom.com/usa/en/company/about_us/technology/siren14_g7221c/siren14_g7221c.html Polycom Siren14 G.722.1C Page]
* [http://www.itu.int/rec/T-REC-G.722.1/en Official ITU-T G.722.1 standard]
* [http://hdvoice.tmcnet.com]