Editing Adaptive Multi-Rate Wideband (section)

{{Short description|Wideband speech audio coding standard}}
{{Infobox technology standard
|title=G.722.2
|long_name=Wideband coding of speech at around 16&nbsp;kbit/s using Adaptive Multi-Rate Wideband (AMR-WB) 
|image=
|caption=
|status= In force
|year_started=2002
|version=(08/18)
|version_date=August 2018
|preview=
|preview_date=
|organization= [[ITU-T]]
|committee= [[ITU-T Study Group 16]]
|base_standards=
|related_standards=
|abbreviation=
|domain=[[telecommunication]]
|license=Freely available
|website=https://www.itu.int/rec/T-REC-G.722.2
}}
'''Adaptive Multi-Rate Wideband''' ('''AMR-WB''') is a [[patent]]ed [[Wideband audio|wideband]] [[speech coding|speech]] [[audio coding standard]] developed based on [[Adaptive Multi-Rate audio codec|Adaptive Multi-Rate]] encoding, using a similar methodology to [[algebraic code-excited linear prediction]] (ACELP). AMR-WB provides improved speech quality due to a wider speech bandwidth of 50–7000&nbsp;Hz compared to [[narrowband]] speech coders which in general are optimized for [[Plain old telephone service|POTS]] wireline quality of 300–3400&nbsp;Hz. AMR-WB was developed by [[Nokia]]<ref>{{cite web |title=Nokia Research Center: AMR-WB and the Nokia Voice Experience - Istanbul |url=http://research.nokia.com/news/12097 |archive-url=https://web.archive.org/web/20130210012744/http://research.nokia.com/news/12097 |archive-date=2013-02-10 |url-status=dead}}</ref> and VoiceAge and it was first specified by 3GPP.<ref>{{cite web |title=G.722.2: Wideband coding of speech at around 16 kbit/s using Adaptive Multi-Rate Wideband (AMR-WB) |url=https://www.itu.int/rec/T-REC-G.722.2/ |url-status=live |archive-url=https://web.archive.org/web/20210614081446/https://www.itu.int/rec/T-REC-G.722.2/ |archive-date=2021-06-14 |access-date=2021-12-14 |website=ITU Telecommunication Standard Sector}}</ref>

AMR-WB is codified as G.722.2, an [[ITU-T]] standard speech codec, formally known as ''Wideband coding of speech at around 16&nbsp;kbit/s using Adaptive Multi-Rate Wideband (AMR-WB)''. G.722.2 AMR-WB is the same codec as the [[3GPP]] AMR-WB. The corresponding 3GPP specifications are TS 26.190 for the speech codec<ref>{{cite web |title=Specification # 26.190: Speech codec speech processing functions; Adaptive Multi-Rate - Wideband (AMR-WB) speech codec; Transcoding functions |url=https://portal.3gpp.org/desktopmodules/Specifications/SpecificationDetails.aspx?specificationId=1424 |website=3GPP Portal |publisher=3GPP |access-date=2021-12-14}}</ref> and TS 26.194 for the Voice Activity Detector.<ref>{{cite web |title=Specification # 26.194: Speech codec speech processing functions; Adaptive Multi-Rate - Wideband (AMR-WB) speech codec; Voice Activity Detector (VAD) |url=https://portal.3gpp.org/desktopmodules/Specifications/SpecificationDetails.aspx?specificationId=1428 |website=3GPP Portal |publisher=3GPP |access-date=2021-12-14}}</ref>

The AMR-WB format has the following parameters:<ref>{{cite web |title=Wideband Speech Coding Standards and Applications |url=http://www.voiceage.com/media/WidebandSpeech.pdf |archive-url=https://web.archive.org/web/20071013214817/http://www.voiceage.com/media/WidebandSpeech.pdf |archive-date=2007-10-13 |access-date=2012-02-22 |url-status=dead}}</ref>
* Frequency bands processed: 50–6400&nbsp;Hz (all modes) plus 6400–7000&nbsp;Hz (23.85&nbsp;kbit/s mode only)
* Delay frame size: 20&nbsp;ms
* Look ahead: 5&nbsp;ms
* AMR-WB codec employs a bandsplitting filter; the one-way delay of this filter is 0.9375&nbsp;ms<ref>{{cite web |title=Specification # 26.976: Performance characterization of the Adaptive Multi-Rate Wideband (AMR-WB) speech codec; Chapter 25: Transmission Delay |url=https://portal.3gpp.org/desktopmodules/Specifications/SpecificationDetails.aspx?specificationId=1509 |website=3GPP Portal |publisher=3GPP |access-date=2021-12-14}}</ref>
* Complexity: 38 [[Weighted Million Operations Per Second|WMOPS]], RAM 5.3&nbsp;kilowords
* [[Voice activity detection]], [[discontinuous transmission]], [[comfort noise generator]]
* Fixed point: bit-exact [[C (programming language)|C code]]
* Floating point: under work

A common [[file extension]] for the AMR-WB file format is <code>.awb</code>. There also exists another storage format for AMR-WB that is suitable for applications with more advanced demands on the storage format, like random access or synchronization with video. This format is the 3GPP-specified [[3GP]] [[container format (digital)|container format]], based on the [[ISO base media file format]].<ref>{{Cite IETF |title=RTP Payload Format and File Storage Format for the Adaptive Multi-Rate (AMR) and Adaptive Multi-Rate Wideband (AMR-WB) Audio Codecs |rfc=4867 |sectionname=AMR and AMR-WB Storage Format |section=5 |page=35 }}</ref> 3GP also allows use of AMR-WB bit streams for stereo sound.