I decided to re-rip all of my CDs and I was weighing out the differences between AAC and MP3.  When you rip songs from a CD in iTunes, you can choose what file format you would like the songs to be saved in, and different file formats do have different strengths and weaknesses.  Generally speaking trading off file size for sound quality.

The two (2) most common file types in iTunes are MP3 and AAC, although iTunes also offers Apple Lossless Encoding, AIFF, and WAV.  For the sake of this post I will be focusing on AAC and MP3. AAC was created as an improved performance codec over MP3, and the advanced audio coding (AAC) was promoted as successor to MP3.  These encoded files are higher in quality, but the same could also be said of Microsoft’s Windows Media format, and OGG files, but none are supported as well as good old MP3.  AAC is the native file format for iTunes, however one may not want to use due to this format now being as widely supported.  Just about every OS (including favors of Linux) will play an MP3 file out of the box, however playing AAC files generally requires the end user to download a 3rd party piece of software (Apple’s Mac OS X excluded).

AAC’s file format does have some improvements over MP3, and I have outlined a few of them.

* More frequencies (from 8 to 96 kHz) than MP3 (16 to 48 kHz)
* Up to 48 channels
(MP3 supports up to two channels in MPEG-1 mode and up to 5.1 channels in MPEG-2 mode)
* Higher efficiency and simpler filterbank
* Higher coding efficiency for stationary signals
(AAC uses a blocksize of 1024 or 960 samples, allowing more efficient coding than MP3’s 576 sample blocks)
* Higher coding accuracy for transient signals
(AAC uses a blocksize of 128 or 120 samples, allowing more accurate coding than MP3’s 192 sample blocks)

With all of this being said, why do many people still prefer to use MP3 file formats?  I would have to answer that mainly with the how easy it is create and also from the popularity it had gained from peer-2-peer applications.  The first large peer-2-peer application was Napster which came online in 1999 – 2000.  This gave thousands (if not  millions at the time)  of music fans access to download (illegally) all of their favorite songs and albums from just about every artist.

My Recommendation:

If you have a PC or a Mac, and also have a iPhone or iPod, I would recommend using the AAC file format.  As an end user you can convert the AAC file to a MP3 file if desired, or if you wish to play a particular track on a device that does not support AAC.  In the long run you will be able to store more music, while still obtaining a high quality sound.  Please take a moment to vote on which file type you prefer.