Extended Adaptive Multi-Rate – Wideband

Extended Adaptive Multi-Rate – Wideband (AMR-WB+) is an audio codec that extends AMR-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 to ACELP. 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.

Extended Adaptive Multi-Rate – Wideband (AMR-WB+)
Internet media type
audio/amr-wb+, audio/3gpp
Type of formatAudio
Contained by3GP
Extended fromAMR-WB

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 the 3GP container format, 3GPP-defined ISO-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.

Software support

In September 2005, VoiceAge Corporation announced availability of AMR-WB+ decoder in Helix DNA Client.[3][4]

Licensing and patent issues

AMR-WB+ compression incorporate several patents of Nokia Corporation, Telefonaktiebolaget L. M. Ericsson and VoiceAge Corporation. [5] VoiceAge Corporation is the License 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]

See also

References
  1. 3GPP TS 26.290; Audio codec processing functions; Extended Adaptive Multi-Rate – Wideband (AMR-WB+) codec; Transcoding functions, Page 10, Retrieved on 2009-07-08
  2. "Media Type Registration". 7.1. RTP Payload Format for the Extended Adaptive Multi-Rate Wideband (AMR-WB+) Audio Codec. p. 31. sec. 7.1. doi:10.17487/RFC4352. RFC 4352.
  3. "State-of-the-art AMR-WB+ Hi-fi Audio Compression is Now Available for Helix". sys-con. 2005-09-28. Retrieved 2009-09-11.
  4. "AMR-WB+ audio codec being integrated into Helix". Helix Community mailinglist. 2005-09-28. Retrieved 2009-09-11.
  5. VoiceAge Corporation (2007-10-14). "AMR-WB+ Licensing Terms". VoiceAge Corporation. Archived from the original on 2007-10-14. Retrieved 2009-09-12.
  6. VoiceAge Corporation. "Licensing – Patent Calls". VoiceAge Corporation. Archived from the original on 2007-10-14. Retrieved 2009-09-12.
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