Editing G.722.1

{{short description|ITU-T Recommendation}}
{{Infobox technology standard
| title             = G.722.1
| long_name         = Low-complexity coding at 24 and 32&nbsp;kbit/s for hands-free operation in systems with low frame loss   
| image             = Pcm.svg 
| caption           = 
| status            = In force
| year_started      = 1999
| version           = (05/05)
| version_date      = May 2005
| preview           = 
| preview_date      = 
| organization      = [[ITU-T]]
| committee         = 
| base_standards    = [[G.711]], [[G.722]]
| related_standards = [[G.722.2]], [[G.726]]
| abbreviation      = 
| domain            = [[audio compression (data)|audio compression]]
| license           = Freely available 
| website           = https://www.itu.int/rec/T-REC-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&nbsp;kbit/s) [[wideband audio|wideband]] (50&nbsp;Hz – 7&nbsp;kHz audio bandwidth, 16 ksps (kilo-[[sampling rate|samples]] per second) audio coding.<ref>{{Cite web|url=https://www.itu.int/rec/T-REC-G.722.1|title=G.722.1 : Low-complexity coding at 24 and 32 kbit/s for hands-free operation in systems with low frame loss|website=www.itu.int|url-status=live|archive-url=https://web.archive.org/web/20160424175248/https://www.itu.int/rec/T-REC-G.722.1|archive-date=2016-04-24|access-date=2019-11-15}}</ref> It is a partial implementation of [[Siren Codec|Siren]] 7 [[audio coding format]] (which offers bit rates 16, 24, 32&nbsp;kbit/s) developed by PictureTel Corp. (now [[Polycom]], Inc.).<ref name="picturetel">{{cite web |author=Business Wire |publisher=thefreelibrary.com |url=http://www.thefreelibrary.com/PictureTel+Announces+New+Siren+Wideband+Audio+Technology+Licensing...-a072261882 |title=PictureTel Announces New Siren Wideband Audio Technology Licensing Program |date=2001-03-26 |access-date=2009-09-10 |archive-date=2012-10-13 |archive-url=https://web.archive.org/web/20121013184749/http://www.thefreelibrary.com/PictureTel+Announces+New+Siren+Wideband+Audio+Technology+Licensing...-a072261882 |url-status=dead }}</ref><ref name="g7221-faq">{{cite web|publisher=Polycom, Inc.|url=http://www.polycom.com/company/about-us/technology/siren/siren-faq.html|title=Polycom Siren/Codecs FAQs|access-date=2014-07-16|url-status=dead|archive-url=https://web.archive.org/web/20140709022721/http://www.polycom.com/company/about-us/technology/siren/siren-faq.html|archive-date=2014-07-09}}</ref> Its official name is ''Low-complexity coding at 24 and 32&nbsp;kbit/s for hands-free operation in systems with low frame loss''. It uses a [[modified discrete cosine transform]] (MDCT) [[audio data compression]] algorithm.<ref>{{cite conference |last1=Lutzky |first1=Manfred |last2=Schuller |first2=Gerald |last3=Gayer |first3=Marc |last4=Krämer |first4=Ulrich |last5=Wabnik |first5=Stefan |title=A guideline to audio codec delay |url=https://www.iis.fraunhofer.de/content/dam/iis/de/doc/ame/conference/AES-116-Convention_guideline-to-audio-codec-delay_AES116.pdf |website=[[Fraunhofer IIS]] |conference=116th AES Convention |publisher=[[Audio Engineering Society]] |date=May 2004 |access-date=24 October 2019}}</ref>

'''G.722.1 Annex C''' (or G.722.1C) is a low-complexity extension mode to G.722.1, which doubles the algorithm to permit 14&nbsp;kHz audio bandwidth using a 32&nbsp;kHz audio sample rate, at 24, 32, and 48&nbsp;kbit/s. It is included in the official ITU-T Recommendation G.722.1. The name of this annex is ''Annex C – 14&nbsp;kHz mode at 24, 32, and 48&nbsp;kbit/s''.<ref name="itu-t-g7221-2005">{{cite journal |author=ITU-T |title=ITU-T G.722.1, 05/2005 |page=i |publisher=ITU-T |date=May 2005 |url=http://www.itu.int/rec/dologin_pub.asp?lang=e&id=T-REC-G.722.1-200505-I!!SOFT-ZST-E&type=items |format=ZIP, PDF |access-date=2009-09-10}}</ref> It is an implementation of the [[monaural|mono]] version of [[Polycom]]'s [[Siren 14]] audio coding format.<ref name="findarticles-siren14">{{cite web |publisher=businesswire.com |url=http://www.businesswire.com/news/home/20050412005325/en/ITU-Approves-Polycom-Siren14-International-Standard--- |title=ITU Approves Polycom Siren14 as New International Standard |date=2005-04-12 |access-date=2014-07-16}}</ref><ref name="g7221-faq" />

G.722.1 is the successor to PT716plus developed by PictureTel Corp. (now Polycom, Inc.),<ref name="g7221-faq" /> which has been used in videoconferencing systems for many years. As ITU-T Recommendation G.722.1, it was approved on September 30, 1999 after a four-year selection process involving extensive testing.<ref name="picturetel-intel">{{cite web |author=Business Wire |publisher=thefreelibrary.com |url=http://www.thefreelibrary.com/PictureTel+Licenses+Audio+Technology+Suite+to+Intel.-a063558475 |title=PictureTel Licenses Audio Technology Suite to Intel |date=2000-07-19 |access-date=2009-09-10 |archive-date=2012-10-13 |archive-url=https://web.archive.org/web/20121013184755/http://www.thefreelibrary.com/PictureTel+Licenses+Audio+Technology+Suite+to+Intel.-a063558475 |url-status=dead }}</ref> G.722.1/Annex C was approved by ITU-T on May 14, 2005.<ref name="itu-t-g7221-2005" />

G.722.1 is a transform-based compressor that is optimized for both speech and music. The G.722.1 algorithm is based on [[lapped transform]] technology, using a [[Modulated Lapped Transform]] (MLT), a type of MDCT. 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&nbsp;ms.

The numbering of the [[Wideband audio|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&nbsp;kHz codec, using [[ADPCM]] and operating at 48–64&nbsp;kbit/s. G.722.1, another 7&nbsp;kHz codec, operates at half the data rate while delivering comparable or better quality than 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, 14&nbsp;kHz. And [[G.722.2]], which operates on [[Wideband audio|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.<ref name="siren-terms">{{cite web |publisher=Polycom, Inc. |url=http://www.polycom.com/company/about-us/technology/siren/siren-faq.html#faq40 |title=Polycom Siren/Codecs FAQs – What are the terms on the free license? |access-date=2014-07-16 |url-status=dead |archive-url=https://web.archive.org/web/20140709022721/http://www.polycom.com/company/about-us/technology/siren/siren-faq.html#faq40 |archive-date=2014-07-09 }}</ref><ref name="libg7221">{{cite web |publisher=FreeSWITCH |url=https://stash.freeswitch.org/projects/FS/repos/freeswitch/browse/libs/libg722_1/COPYING |title=libg722_1 – COPYING |access-date=2014-07-16}}</ref><ref name="licensing">{{cite web |publisher=Polycom, Inc. |url=http://www.polycom.com/company/about-us/technology/siren/siren-license-agreement.html |title=Siren7/Siren14/G.719 License Agreement |access-date=2014-07-16 |url-status=dead |archive-url=https://web.archive.org/web/20140709021430/http://www.polycom.com/company/about-us/technology/siren/siren-license-agreement.html |archive-date=2014-07-09 }}</ref><ref name="celt-comparison">{{cite web |author=Xiph.Org Foundation |publisher=Xiph.Org Foundation |url=http://www.celt-codec.org/comparison/ |title=CELT – Codec Feature Comparison |year=2009 |access-date=2009-09-07 |archive-date=2009-09-12 |archive-url=https://web.archive.org/web/20090912184544/http://www.celt-codec.org/comparison/ |url-status=dead }}</ref><ref name="speex-comparison">{{cite web |author=Xiph.Org Foundation |publisher=Xiph.Org Foundation |url=http://www.speex.org/comparison/ |title=Speex – Codec Quality Comparison |year=2006 |access-date=2009-09-07}}</ref> Licensees also receive the right to use Polycom's 16&nbsp;kbit/s decoder extension of G.722.1, as well as G.722.1 Annex C, and Polycom's IP within the new 20&nbsp;kHz ITU fullband codec, G.719.

== See also ==
* [[List of codecs]]
* [[Comparison of audio coding formats]]
* [[Wideband audio]]

== References ==
{{Reflist}}

== External links ==
* {{official website}} – technical specification
* {{IETF RFC|5577|link=no}} – RTP Payload Format for ITU-T Recommendation G.722.1

{{Compression formats}}

[[Category:Audio codecs]]
[[Category:Speech codecs]]
[[Category:Wideband codecs]]
[[Category:ITU-T recommendations]]
[[Category:ITU-T G Series Recommendations]]