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Audio data compression scheme optimized for speech coding in GSM (Global System for Mobile Communications) and UMTS (Universal Mobile Telecommunications System). It is an extension of AMR-WB, adding support for stereo signals, higher sampling rates, and transform coded excitation (TCX) in addition to the Algebraic Code Excited Linear Prediction (ACELP) compression coding featured in AMR and AMR-WB. Automatic switching between TCX and ACELP provides good quality for all types of sound at moderate bit rates.  AMR-WB+ is backward compatible with AMR-WB.

The 3GPP (3d Generation Partnership Project) developed the AMR-WB+ audio codec for streaming and messaging services; its primary target applications are Packet-Switched Streaming service (PSS), Multimedia Messaging Service (MMS), and Multimedia Broadcast and Multicast Service (MBMS). (Preceding adapted from the Wikipedia AMR-WB+ entry.)

AMR-WB+ is less constrained than AMR-WB; for this reason AMR-WB is treated as a subtype of AMR-WB+ at this Web site; Comments welcome.

3GPP TS 26.290 v.6.3.0 (2005-06), 3rd Generation Partnership Project; Technical Specification Group Service and System Aspects; Audio codec processing functions; Extended Adaptive Multi-Rate - Wideband (AMR-WB+) codec; Transcoding functions, and other specifications listed in Format specifications below. Some of the other specifications carry different version numbers; it is not clear to the compiler of this Web page if AMR-WB+ in and of itself has a version number; Comments welcome.

Significant technical information about AMR-WB+ is provided in RFC 4352 from IETF (Internet Engineering Task Force).

A number of patents pertaining to AMR-WB+ are listed at the ETSI Web site. These have not been evaluated by compiler of this Web page. The 3GPP specification for AMR-WB+ states that "pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee can be given as to the existence of other IPRs not referenced [at the ETSI Webserver]."

VoiceAge claims related patents and offers licensing.

From section 4.3 of the specification:

• "Principles of the extended adaptive multi-rate wideband codec. The AMR-WB+ audio codec contains all the AMR-WB speech codec modes 1-9 and AMR-WB VAD and DTX. AMRWB+ extends the AMR-WB codec by adding TCX, bandwidth extension, and stereo. The AMR-WB+ audio codec processes input frames equal to 2048 samples at an internal sampling frequency Fs . The internal sampling frequency is limited to the range 12800-38400 Hz, see section 8 for more details. The 2048-sample frames are split into two critically sampled equal frequency bands. This results in two superframes of a 1024 samples corresponding to the low frequency (LF) and high frequency (HF) band. Each superframe is divided into four 256-samples frames. Sampling at the internal sampling rate is obtained by using a variable sampling conversion scheme, which re-samples the input signal. The LF and HF signals are then encoded using two different approaches: the LF is encoded and decoded using the "core" encoder/decoder, based on switched ACELP and transform coded excitation (TCX). In ACELP mode, the standard AMR-WB codec is used. The HF signal is encoded with relatively few bits (16 bits/frame) using a bandwidth extension (BWE) method. The basic set of rates are built based on AMR-WB rates in addition to bandwidth extension. . . .
• "ACELP encoding and decoding are similar to standard AMR-WB speech codec. The ACELP coding consists of LTP analysis and synthesis and algebraic codebook excitation. The ACELP coding mode is used in AMR-WB operation within AMR-WB+ codec. In TCX mode the perceptually weighted signal is processed in the transform domain. The Fourier transformed weighted signal is quantised using split multi-rate lattice quantisation (algebraic VQ). Transform is calculated in 1024, 512 or 256 samples windows. The excitation signal is recovered by inverse filtering the quantised weighted signal through the inverse weighting filter (same weighting filter as in AMR-WB)."
• From the VoiceAge AMR-WB+ Web page (consulted April 4, 2007): "Emerging end-to-end digital communication systems enable the use of wideband audio coding in a large and varied collection of applications for mobile environments, including mobile TV/radio, streaming services for music, news and sports and multimedia messaging for person-to-person and business-to-person communications. . . . Extended Adaptive Multi-Rate Wideband (AMR-WB+) addresses mixed speech and audio content, providing superior-quality sound across all content types, even at low and very low bit rates. . . . AMR-WB+ delivers high-quality music, speech-over-music, and speech-between-music, making it perfectly suited to low-bit-rate mixed-content audio applications . . . ."