This new version of Quicktime features an MPEG-4 video codec and Advanced Audio Coding (AAC) support. MPEG-4 AAC is a technology co-developed by Dolby, Fraunhofer (FhG), AT&T, Sony, and Nokia (as members of the MPEG group) that provides true variable bit rate (VBR) audio encoding. According to the AAC website, the new technology when compared to MPEG-1 Layer 3 (MP3) audio brings higher quality audio reproduction and requires approximately 50% less data. Download Quicktime 6.