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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.

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.

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.

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.

Licensing and patent issues

AMR-WB+ compression incorporate several patents of Nokia Corporation, Telefonaktiebolaget L. M. Ericsson and VoiceAge Corporation. 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.

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.

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.

See also

• Adaptive Multi-Rate (AMR)
• Adaptive Multi-Rate Wideband (AMR-WB)
• 3GP
• Comparison of audio coding formats
• RTP audio video profile

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.

External links

• 3GPP codecs specifications; 3G and beyond / GSM, 26 series
• 3GPP TS 26.290; Audio codec processing functions; Extended Adaptive Multi-Rate – Wideband (AMR-WB+) codec; Transcoding functions
• RFC 4352 – RTP Payload Format for the Extended Adaptive Multi-Rate Wideband (AMR-WB+) Audio Codec
• RFC 4281 – The Codecs Parameter for "Bucket" Media Types

• Audio codecs
• Speech codecs