iTunes isn’t just a cupboard for music; it’s also a food processor. You can convert any song or sound file into almost any other format: MP3 to AIFF, AAC to WAV, MP3 to AAC, and so on.
If you’re going from a compressed format like MP3 to a full-bodied, uncompressed format like AIFF, you shouldn’t hear much difference in the resulting file. Quality could take a hit, however, if you convert a file from one compressed format to another, like MP3 to AAC. If you’re a stickler for sound but still want the space-saving benefit of the AAC format, it’s best just to set the iTunes preferences to encode in AAC format and re-rip the song from the original CD.
To get the conversion underway, choose iTunes → Preferences and click the Importing button. From the Import Using pop-up menu, pick the format you want to convert to, then click OK.
Figure 3-5. Lower right: The Get Info box for each is where you can add, correct, and customize information for each song.Upper left: Click the Summary tab for the lowdown on the song’s bit rate, file format, and other fascinating technical details.
Now, in your iTunes library, select the song file you want to convert, and then choose Advanced → Convert Selection to AAC (or MP3 or AIFF or whatever you just picked as your import preference).
If you have a whole folder or disk full of potential converts, hold down the Option key as ...