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Adaptive Multi-Rate Wide Band (AMR-WB)
File name extension . A filename extension is a suffix to the name of a Computer file applied to indicate the encoding convention ( File format) of its contents awb
Internet media type audio/amr-wb
Type of format Audio

Adaptive Multi Rate – WideBand (AMR-WB) is a speech coding standard developed after the AMR using same technology like ACELP. An Internet media type, originally called a MIME type after MIME and sometimes a Content-type after the name of a header in several protocols whose value Speech coding is the application of Data compression of Digital audio signals containing Speech. Adaptive Multi-Rate (AMR is an Audio data compression scheme optimized for Speech coding. Algebraic code excited linear prediction (ACELP is a Speech encoding algorithm where a limited set of pulses is distributed as excitation to linear prediction filter The codec provides excellent speech quality due to wider speech bandwidth of 50–7000 Hz compared to narrowband speech codecs which in general are optimized for POTS wireline quality of 300–3400 Hz. AMR-WB is codified as G. 722. 2, an ITU-T standard speech codec. The ITU Telecommunication Standardization Sector ( ITU-T) coordinates standards for telecommunications on behalf of the International Telecommunication A common file extension for AMR-WB is . A filename extension is a suffix to the name of a Computer file applied to indicate the encoding convention ( File format) of its contents awb.

Contents

AMR modes

AMR-WB operates like AMR with 9 different bit rates. Adaptive Multi-Rate (AMR is an Audio data compression scheme optimized for Speech coding. 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 in the case of music. Also lower bit rates of 6. 60 and 8. 85 provide reasonable quality especially if compared to narrow band codecs.

All modes are sampled at 16 kHz and processed at 12. 8 kHz.

The bit rates are the following:

Configurations for 3GPP

When used in mobile phone networks, there are three different configurations (combinations of bitrates) that may be used for voice channels:

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 is already standardized for future usage in networks such as UMTS. There it provides so much higher speech quality that it seems probable that also older networks will have to gradually be transformed to support wide band.

In October 2006, first AMR-WB tests have taken place in a deployed network by T-Mobile in Germany together with Ericsson. For further details, see this link or the original T-Mobile press release (in German).

Nokia developed VMR-WB codec for CDMA2000 networks, which is fully interoperable with 3GPP AMR-WB. Nokia Corporation (pronunciation /'nɔkiɑ/),,) is a Finnish multinational Communications Corporation, headquartered Variable Multi Rate – WideBand ( VMR-WB) is a source-controlled variable-rate multimode Codec designed for robust encoding/decoding of wideband/narrowband speech CDMA2000 is a hybrid 25G / 3G technology of mobile Telecommunications standards that use CDMA, a multiple access scheme for Digital

AMR-WB is also widely adapted format in mobile handsets for tones.

See also

References

Adaptive Multi Rate – WideBand plus ( AMR-WB+) is an audio Codec that extends AMR-WB.
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