MPEG Advanced Audio Coding (AAC), otherwise known as MPEG-2 NBC (Non-Backward Compatible) is an audio standard allowing for more channels than MP2 or MP3 ( a full 48 channels compared to 5 for MP3).
It can also handle higher frequencies than MP3, 96kHz compared to 48kHz.
It has been tested at 96kbps to be of better quality then MP3 at 128kbps.
