This is an extension to improve error resilience on AAC. In MPEG-4, it combines it with Perceptual Noise Substitution (PNS) extension. The main codec for AAC, as defined in MPEG-2, had 3 profiles: MPEG-4 AAC is used by iTunes and iPod (see also Apple webpage on AAC) and most of the portable devices. It also has much better handling of frequencies above 16 kHz.ĭepending on the AAC profile and the MP3 encoder, 96 kbit/s AAC can give nearly the same or better perceptional quality as 128 kbit/s MP3. It has some advantages over MP3 - it has a greater range of sample frequencies, up to 48 channels and higher coding efficiency. It has many options and is heavily customisable depending on the desired output AAC actually refers to two similar codecs - MPEG-2 Part 7 (Advanced Audio Coding) and MPEG-4 Part 3.
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