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 enabling disclosure of the invention."A ...

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 audio coding standard developed based on

Adaptive Multi-Rate The Adaptive Multi-Rate (AMR, AMR-NB or GSM-AMR) audio codec is an audio compression format optimized for speech coding. AMR speech codec consists of a multi-rate narrowband speech codec that encodes narrowband (200–3400 Hz) signals at var ...

encoding, using a similar methodology to

algebraic code-excited linear prediction Algebraic code-excited linear prediction (ACELP) is a speech coding algorithm in which a limited set of pulses is distributed as excitation to a linear prediction filter. It is a linear predictive coding (LPC) algorithm that is based on the cod ...

(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 usua ...

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

Nokia Nokia Corporation (natively Nokia Oyj, referred to as Nokia) is a Finnish multinational telecommunications, information technology, and consumer electronics corporation, established in 1865. Nokia's main headquarters are in Espoo, Finland, i ...

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

ITU-T The ITU Telecommunication Standardization Sector (ITU-T) is one of the three sectors (divisions or units) of the International Telecommunication Union (ITU). It is responsible for coordinating standards for telecommunications and Information Comm ...

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 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 Voice activity detection (VAD), also known as speech activity detection or speech detection, is the detection of the presence or absence of human speech, used in speech processing. The main uses of VAD are in speech coding and speech recognition. I ...

discontinuous transmission Discontinuous transmission (DTX) is a means by which a mobile telephone is temporarily shut off or muted while the phone lacks a voice input. Misconception A common misconception is that DTX improves capacity by freeing up TDMA time slots for us ...

, comfort noise generator * Fixed point: bit-exact C code * Floating point: under work A common

file extension A filename extension, file name extension or file extension is a suffix to the name of a computer file (e.g., .txt, .docx, .md). The extension indicates a characteristic of the file contents or its intended use. A filename extension is typically d ...

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, based on the

ISO base media file format The ISO base media file format (ISOBMFF) is a container file format that defines a general structure for files that contain time-based multimedia data such as video and audio. It is standardized in ISO/IEC 14496-12, a.k.a. MPEG-4 Part 12, and wa ...

. 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 standard developed by the European Telecommunications Standards Institute (ETSI) to describe the protocols for second-generation ( 2G) digital cellular networks used by mobile devices such ...

and

UMTS The Universal Mobile Telecommunications System (UMTS) is a third generation mobile cellular system for networks based on the GSM standard. Developed and maintained by the 3GPP (3rd Generation Partnership Project), UMTS is a component of the In ...

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 transfe ...

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

Orange UK Orange mobile 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 ...

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

Orange S.A. Orange S.A. (), formerly France Télécom S.A. (stylized as france telecom) is a French multinational telecommunications corporation. It has 266 million customers worldwide and employs 89,000 people in France, and 59,000 elsewhere. In 2015, ...

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 Variable-Rate Multimode Wideband (VMR-WB) is a source-controlled variable-rate multimode codec designed for robust encoding/decoding of wideband/narrowband speech. The operation of VMR-WB is controlled by speech signal characteristics (i.e., source ...

format for CDMA2000 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 (IMS), Multimedia Messaging Service (MMS) and Transparent end-to-end Packet-switched Streaming Service ( PSS).ETSI (2009-01
ETSI TS 126 141 V8.0.0 (2009-01); 3GPP TS 26.141; IP Multimedia System (IMS) Messaging and Presence; Media formats and codecs
Page 10. Retrieved on 2009-06-02. In 3GPP specifications is AMR-WB format also used in 3GP container format.

Licensing

G.722.2 is 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 of vid ...

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