Remy Davison, Insanely Great Mac writes:

Apple’s AAC audio, a subset of the QuickTime format, has been formally adopted by the DVD Forum as the DVD-Audio (DVD-A) standard, The Register notes.

Apple employs the AAC codec in iTunes for Mac and Windows, and it also supplies the encoding for songs downloaded from Apple’s iTunes Music Store (iTMS), and is used on the iPod.

AAC beat out rival formats from Microsoft (Windows Media 9) and Sony due to sound quality. However, Windows Media Video (wmv) recently scored a win with the format accepted by the Forum as the high-definition DVD video standard.

The article notes that AAC is designed for the implementation of Digital Rights Management (DRM), although DRM is not an inherent part of AAC.

DVD Audio discs deliver Dolby 5.1 and 24-bit sound at 192khz.