Because of its exceptional performance and quality, Advanced Audio Coding (AAC) is at the core of the MPEG-4, 3GPP and 3GPP2 specifications and is the audio codec of choice for Internet, wireless and digital broadcast arenas. AAC provides audio encoding that compresses much more efficiently than older formats, such as MP3, yet delivers quality rivaling that of uncompressed CD audio.

AAC was developed by the MPEG group that includes Dolby, Fraunhofer (FhG), AT&T, Sony and Nokia—companies that have also been involved in the development of audio codecs such as MP3 and AC3 (also known as Dolby Digital). The AAC codec in QuickTime builds upon new, state-of-the art signal processing technology from Dolby Laboratories and brings true variable bit rate (VBR) audio encoding to QuickTime.

Because of its incredible quality at a wide range of data rates and ratification as an industry standard, AAC audio is gaining wide adoption in the marketplace. For example, all of the music sold in the iTunes Music Store uses AAC, for playback on desktop or iPod. AAC has also been adopted by the major standards organizations including the ISO MPEG (MPEG-4), 3GPP and 3GPP2, DVB, as well as XM satellite radio. As a result of its support for this technology, the audio you create with QuickTime is interoperable with a wide range of devices and media players.

When compared side-by-side, AAC proves itself worthy of replacing MP3 as the new Internet audio standard. Take a look at these AAC advantages over MP3:

• Improved compression provides higher-quality results with smaller file sizes
• Support for multichannel audio, providing up to 48 full frequency channels
• Higher resolution audio, yielding sampling rates up to 96 kHz
• Improved decoding efficiency, requiring less processing power for decode