Adaptive Multi-Rate Wideband (AMR-WB) is a patented wideband speech coding standard developed based on Adaptive Multi-Rate encoding, using similar methodology as 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 speech coders which in general are optimized for POTS wireline quality of 300–3400 Hz. AMR-WB was developed by Nokia and VoiceAge and it was first specified by 3GPP.
AMR-WB is codified as G.722.2, an ITU-T 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.
AMR-WB codec has the following parameter:
- Delay frame size: 20 ms
- Look ahead: 5ms
- Complexity: 38 WMOPS, RAM 5.3KWords
- Voice activity detection, Discontinuous Transmission, Comfort Noise Generator
- Fixed point: Bit-exact C
- Floating point: under work.
A common file extension for 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 ISO base media file format. 3GP also allows use of AMR-WB bit streams for stereo sound.
Read more about Adaptive Multi-Rate Wideband: AMR Modes, Configurations For 3GPP, Deployment, Licensing, Tools
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