Adaptive Multi-Rate Wideband (AMR-WB) is a

patent A patent is a type of intellectual property that gives its owner the legal right to exclude others from making, using, or selling an invention for a limited period of time in exchange for publishing an sufficiency of disclosure, enabling discl ...

wideband In communications, a system is wideband when the message bandwidth significantly exceeds the coherence bandwidth of the channel. Some communication links have such a high data rate that they are forced to use a wide bandwidth; other links ma ...

speech Speech is the use of the human voice as a medium for language. Spoken language combines vowel and consonant sounds to form units of meaning like words, which belong to a language's lexicon. There are many different intentional speech acts, suc ...

audio coding standard An audio coding format (or sometimes audio compression format) is a content representation format for storage or transmission of digital audio (such as in digital television, digital radio and in audio and video files). Examples of audio coding f ...

developed based on 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 Hz compared to

narrowband Narrowband signals are signals that occupy a narrow range of frequencies or that have a small fractional bandwidth. In the audio spectrum, ''narrowband sounds'' are sounds that occupy a narrow range of frequencies. In telephony, narrowband is ...

speech coders which in general are optimized for POTS wireline quality of 300–3400 Hz. AMR-WB was developed by

Nokia Nokia Corporation is a Finnish multinational corporation, multinational telecommunications industry, telecommunications, technology company, information technology, and consumer electronics corporation, originally established as a pulp mill in 1 ...

and VoiceAge and it was first specified by 3GPP. AMR-WB is codified as G.722.2, an

ITU-T The International Telecommunication Union Telecommunication Standardization Sector (ITU-T) is one of the three Sectors (branches) of the International Telecommunication Union (ITU). It is responsible for coordinating Standardization, standards fo ...

standard speech codec, formally known as ''Wideband coding of speech at around 16 kbit/s using Adaptive Multi-Rate Wideband (AMR-WB)''. G.722.2 AMR-WB is the same codec as the

3GPP The 3rd Generation Partnership Project (3GPP) is an umbrella term for a number of standards organizations which develop protocols for mobile telecommunications. Its best known work is the development and maintenance of: * GSM and related 2G and ...

AMR-WB. The corresponding 3GPP specifications are TS 26.190 for the speech codec and TS 26.194 for the Voice Activity Detector. The AMR-WB format has the following parameters: * Frequency bands processed: 50–6400 Hz (all modes) plus 6400–7000 Hz (23.85 kbit/s mode only) * Delay frame size: 20 ms * Look ahead: 5 ms * AMR-WB codec employs a bandsplitting filter; the one-way delay of this filter is 0.9375 ms * Complexity: 38 WMOPS, RAM 5.3 kilowords * Voice activity detection, discontinuous transmission, comfort noise generator * Fixed point: bit-exact C code * Floating point: under work A common

file extension File or filing may refer to: Mechanical tools and processes * File (tool), a tool used to remove fine amounts of material from a workpiece. ** Filing (metalworking), a material removal process in manufacturing ** Nail file, a tool used to gen ...

for the AMR-WB file format is .awb. 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 A container format (informally, sometimes called a wrapper) or metafile is a file format that allows multiple data streams to be embedded into a single file, usually along with metadata for identifying and further detailing those streams. Nota ...

, based on the ISO base media file format. 3GP also allows use of AMR-WB bit streams for stereo sound.

AMR modes

AMR-WB operates, like AMR, with nine different bit rates. The lowest bit rate providing excellent speech quality in a clean environment is 12.65 kbit/s. Higher bit rates are useful in background noise conditions and for music. Also, lower bit rates of 6.60 and 8.85 kbit/s provide reasonable quality, especially when compared to narrow-band codecs. The frequencies from 6.4 kHz to 7 kHz are only transmitted in the highest bitrate mode (23.85 kbit/s), while in the rest of the modes the decoder generates sounds by using the lower frequency data (75–6400 Hz) along with random noise (in order to simulate the high frequency band). All modes are sampled at 16 kHz (using 14-bit resolution) and processed at 12.8 kHz. The bit rates are the following: * Mandatory multi-rate configuration ** 6.60 kbit/s (used for circuit switched

GSM The Global System for Mobile Communications (GSM) is a family of standards to describe the protocols for second-generation (2G) digital cellular networks, as used by mobile devices such as mobile phones and Mobile broadband modem, mobile broadba ...

and

UMTS The Universal Mobile Telecommunications System (UMTS) is a 3G mobile cellular system for networks based on the GSM standard. UMTS uses Wideband Code Division Multiple Access, wideband code-division multiple access (W-CDMA) radio access technolog ...

connections; should only be used temporarily during bad radio connections and is not considered

speech) ** 8.85 kbit/s (used for circuit switched GSM and UMTS connections; should only be used temporarily during bad radio connections and is not considered

speech; provides quality equal to G.722 at 48 kbit/s for clean speech) ** 12.65 kbit/s (main anchor bitrate; used for circuit switched GSM and UMTS connections; offers superior audio quality to AMR at and above this bit rate; provides quality equal to or better than G722 at 56 kbit/s for clean speech) * Higher bitrates for speech in adverse background noise environments, combined speech and music, and multi-party conferencing. ** 14.25 kbit/s ** 15.85 kbit/s ** 18.25 kbit/s ** 19.85 kbit/s ** 23.05 kbit/s (not targeted for full-rate GSM channels) ** 23.85 kbit/s (provides quality equal to G.722 at 64 kbit/s for clean speech; not targeted for full-rate GSM channels) Notes: "The codec mode can be changed every 20 ms in 3G WCDMA channels and every 40 ms in GSM/GERAN channels. (For Tandem Free Operation interoperability with GSM/GERAN, mode change rate is restricted in 3G to 40 ms in AMR-WB encoders.)"

Configurations for 3GPP

When used in mobile phone networks, there are three different configurations (combinations of bitrates) that may be used for voice channels: * Configuration A (Config-WB-Code 0): 6.6, 8.85, and 12.65 kbit/s (Mandatory multi-rate configuration) * Configuration B (Config-WB-Code 2): 6.6, 8.85, 12.65, and 15.85 kbit/s * Configuration C (Config-WB-Code 4): 6.6, 8.85, 12.65, and 23.85 kbit/s This limitation was designed to simplify the negotiation of bitrate between the handset and the base station, thus vastly simplifying the implementation and testing. All other bitrates can still be used for other purposes in mobile phone networks, including multimedia messaging, streaming audio, etc.

Deployment

AMR-WB has been standardized by a mobile phone manufacturer consortium for future usage in networks such as

. Its speech quality is high, but older networks will have to be upgraded to support a wideband codec. In October 2006, the first AMR-WB tests were conducted in a deployed network by T-Mobile in Germany, in cooperation with Ericsson. In 2007 an end-to-end AMR-WB TrFO capable 3G & VoIP product line was commercially released by NSN (M13.6 MSS, U3C MGW). AMR-WB TFO support was commercially released in 2008 (M14.2, U4.0). End-to-end TFO/TrFO negotiation and mid-call optimization (e.g. on

handover In cellular telecommunications, handover, or handoff, is the process of transferring an ongoing call or data session from one channel connected to the core network to another channel. In satellite communications it is the process of transf ...

, CF or CT events) was released in 2009 (M14.3, U4.1). In late 2009,

Orange UK Orange UK was a mobile network operator and internet service provider in the United Kingdom, launched in 1994. It was once a constituent of the FTSE 100 Index but was purchased by France Télécom (now Orange S.A.) in 2000, which then adopted ...

announced that it would be introducing AMR-WB on its network in 2010. In France

Orange S.A. Orange S.A. (; formerly , stylised as france telecom) is a French multinational telecommunications corporation founded in 1988 and headquartered in Issy-les-Moulineaux, near Paris. ''Orange'' has been the corporation's main brand for mobile, ...

and SFR are using AMR-WB format on their 3G+ networks since the end of summer 2010. WIND Mobile in Canada launched HD Voice (AMR-WB) on its 3G+ network in February, 2011. WIND Mobile also announced that several handsets will support HD Voice (AMR-WB) in the first half of 2011, with the first one being Alcatel Tribe. In January 2013, T-Mobile became the first GSM/UMTS based network in the US to enable AMR-WB. In Feb 2013, Chunghwa Telecom became the first GSM/UMTS based network in Taiwan to enable AMR-WB. In August 2013 the AMR-WB standard was introduced in Ukraine by Kyivstar.

developed the VMR-WB format for

CDMA2000 CDMA2000 (also known as C2K or IMT Multi‑Carrier (IMT‑MC)) is a family of 3G mobile technology standards for sending voice, data, and signaling data between mobile phones and cell sites. It is developed by 3GPP2 as a backwards-compatib ...

networks, which is fully interoperable with 3GPP AMR-WB. AMR-WB is also a widely adapted format in mobile handsets for ringtones. The AMR wideband speech format shall be supported in 3G multimedia services when

speech working at 16 kHz sampling frequency is supported. This requirement is defined in 3GPP technical specifications for

IP Multimedia Subsystem The IP Multimedia Subsystem or IP Multimedia Core Network Subsystem (IMS) is a standardised architectural framework for delivering IP multimedia services. Historically, mobile phones have provided voice call services over a circuit-switched-sty ...

(IMS),

Multimedia Messaging Service Multimedia Messaging Service (MMS) is a standard way to send messages that include multimedia content to and from a mobile phone over a cellular network. Users and providers may refer to such a message as a PXT, a picture message, or a multimedia ...

(MMS) and Transparent end-to-end Packet-switched Streaming Service ( PSS). In 3GPP specifications is AMR-WB format also used in 3GP container format.

Licensing

The patent for AMR expired in 2024. Previously G.722.2 was licensed by VoiceAge Corporation.

Tools

For encoding and decoding AMR-WB, an open-source library named OpenCORE exists. The OpenCORE codec can be used in

ffmpeg FFmpeg is a free and open-source software project consisting of a suite of libraries and programs for handling video, audio, and other multimedia files and streams. At its core is the command-line ffmpeg tool itself, designed for processing vide ...

. For encoding, another open-source library exists as well, provided by

VisualOn __NOTOC__ Nero AAC Codec is a set of software tools for codec, encoding and decoding Advanced Audio Coding (AAC) format audio, and editing MPEG-4 metadata. It was developed and distributed by Nero AG, and is available at no cost for Windows and ...

. It is included in the Android mobile operating system.

References

External links

ITU-T Recommendation G.722.2 (AMR-WB) – technical specification

* ttp://www.3gpp.org/ftp/Specs/html-info/26194.htm Adaptive Multi-Rate – Wideband (AMR-WB) speech codec; Voice Activity Detector (VAD); 3GPP TS 26.194 – 3GPP technical specification
Adaptive Multi-Rate – Wideband (AMR-WB) speech codec; General description; 3GPP TS 26.171 – 3GPP technical specification

* – RTP Payload Format and File Storage Format for the Adaptive Multi-Rate (AMR) and Adaptive Multi-Rate Wideband (AMR-WB) Audio Codecs * – The Codecs Parameter for "Bucket" Media Types

* ttps://web.archive.org/web/20071013214817/http://www.voiceage.com/media/WidebandSpeech.pdf Wideband Speech Coding Standards and Applications
3GPP – Technical Specification Group Services and System Aspects

ITU-T Implementors' Guide for G.722.2

Report on Mobile HD Voice using AMR Wideband, as of 20th of Feb 2012
{{Compression formats Audio codecs Speech codecs Wideband codecs ITU-T recommendations ITU-T G Series Recommendations