The U on iTunes - Terms
AAC (Advanced Audio Coding)
AAC or Advanced Audio Coding is a standardized
compression and encoding scheme for digital audio. Especially
for bitrates below about 100 kbit/s AAC achieves better
quality sound than the more popular MP3 format when compared
at the same bitrate. iTunes U supports AAC file formats
and it is recommend over MP3 encoding/compression.
Often AAC incorrectly gets associated with Apple's DRM
(Digital Rights Management) called FairPlay that is used
to protect commercial media purchased from the iTunes Store.
But, using AAC doesn't require using DRM like FairPlay
and iTunes U doesn't support DRM anyway, so it can't be
used.
Also, AAC is incorrectly thought as an Apple proprietary
format, and only used by Apple. This is incorrect!!! It’s
not even controlled or invented by Apple, or any other
single company. It is an ISO standard that was invented
by engineers at Dolby,
working with companies like Fraunhofer, Sony, AT&T,
and Nokia and licensing is controlled by Via.
In terms of licensing costs, patents, and openness, AAC
is very much comparable to MP3.
- Microsoft Zune
- Sandisk Sansa e200R
- Sony PlayStation Portable
- Sony Walkman S-Series players
- Sony Ericsson phones
- Nokia phones
- Palm OS PDAs
- Microsoft Xbox 360
- Sony PlayStation 3
So, AAC is NOT a proprietary format only used by Apple. It is used by nearly every serious competitor to the iPod, & iPhone.
AAC is a lossy compression, meaning that the compressed version is diifferent from the original, and provides smaller compressed files than loseless compression. AAC uses the file extensions .m4a, .mp4, .aac, and .3gp.