The U on iTunes U - 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.

Here is a selection of devices that support AAC:

- 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.


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