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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 TS 26.290; Audio codec processing functions; Extended Adaptive Multi-Rate - Wideband (AMR-WB+) codec; Transcoding functions ), Page 10, Retrieved on 2009-07-08〕 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.〔RFC 4352, page 30〕 The AMR-WB+ codec has a wide bit-rate range, from 5.2–48 kbit/s. Mono rates are scalable from 5.2–36 kbit/s, and stereo rates are scalable from 6.2–48 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. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Extended Adaptive Multi-Rate – Wideband」の詳細全文を読む スポンサード リンク
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