The Free On-line Dictionary of Computing (30 December 2018):

MPEG-4 AAC Main Profile

    A successor of
   MP3 allowing transparent coding at data rates of 70-75% of
   that of MP3.  It is very different from MP3, only used
   MDCT, no subband coding.  It is much more complex that
   MP3 and MPEG-2 AAC Low Profile.

   (2001-12-08)