AAC

(Advanced Audio Coding) Audio codec developed by the MPEG group, including Dolby, Fraunhofer, AT&T, Sony and Nokia. Codec uses VBR (variable bit rate) encoding for efficiency, has high quality at small file sizes, includes support for multi-channel audio, sample rates up to 96 kHz. Popularized as the audio standard used by the iTunes Music Store, mobile devices and XM satellite radio.