| Extended Adaptive Multi-Rate – Wideband (AMR-WB+) | |
|---|---|
| Internet media type | audio/amr-wb+, audio/3gpp |
| Type of format | Audio |
| Contained by | 3GP |
| Extended from | AMR-WB |
Extended Adaptive Multi-Rate – Wideband (AMR-WB+) is an audiocodec that extendsAMR-WB. It adds support for stereo signals and higher sampling rates. Another main improvement is the use of transform coding (transform coded excitation – TCX) additionally toACELP. This greatly improves the generic audio coding. Automatic switching between transform coding and ACELP provides both good speech and audio quality with moderate bit rates.
As AMR-WB operates at internal sampling rate 12.8 kHz, AMR-WB+ also supports various internal sampling frequencies ranges from 12.8 kHz to 38.4 kHz. AMR-WB uses 16 kHz sampling frequency with a resolution of 14 bits left justified in a 16-bit word. AMR-WB+ uses 16/24/32/48 kHz sampling frequencies with a resolution of 16 bits in a 16-bit word.[1]
3GPP originally developed the AMR-WB+ audio codec for streaming and messaging services in Global System for Mobile communications (GSM) and Third Generation (3G) cellular systems.Its primary target applications are Packet-Switched Streaming service (PSS),Multimedia Messaging Service (MMS) and Multimedia Broadcast and Multicast Service (MBMS).
File storage of AMR-WB+ encoded audio is specified within the3GPcontainer format, 3GPP-definedISO-based multimedia file format defined in 3GPP TS 26.244.[2]
The AMR-WB+ codec has a wide bit-rate range, from 5.2 to 48 kbit/s. Mono rates are scalable from 5.2 to 36 kbit/s, and stereo rates are scalable from 6.2 to 48 kbit/s, reproducing bandwidth up to 20 kHz (approaching CD quality). Moreover, it provides backward compatibility with AMR wideband.
In September 2005, VoiceAge Corporation announced availability of AMR-WB+ decoder inHelix DNA Client.[3][4]
AMR-WB+ compression incorporate severalpatents ofNokia Corporation,Telefonaktiebolaget L. M. Ericsson and VoiceAge Corporation.[5]VoiceAge Corporation is theLicense Administrator for the AMR and AMR-WB+patent pools. VoiceAge also accepts submission of patents for determination of their possible essentiality to these standards.[6]
The initial fee for applications using "real-time channels" with AMR-WB+ is $6,500. Minimum annual royalty shall be $10,000, excluding the initial fee in year 1 of the license agreement.[5]
AMR-WB+ monaural decoder in a category of personal computer products is licensed for free. Stereo AMR-WB+ decoder for personal computer products is licensed for $0.30.[5]
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