AAC @ 128kbps listening test discussion Reply #50 – 2004-02-08 16:42:20 QuoteThis may seem a stupid question but does the Quick Time Professional AAC Codec differ from the I-Tunes one or are they one and the same? I thought I read somewhere that there were slight differences but I cannot remember where I read this!They are the same encoder. The difference is that in QuickTime you have the option to encode in three quality modes: Good, Better and Best. iTunes is hard-coded at Better. Best supposedly is the same as Better in 16bit streams, and only shows any improvement in 24bit streams.