Music on an audio CD is not compressed. Compressing music from an audio CD using a "lossy" encoder may reduce the sound quality depending on your the bit rate. The MP3 and AAC formats are forms of lossy compression. Encoding music using the Apple Lossless encoder will preserve the highest-quality sound found on the CD. If you intend to use iTunes to make a custom audio CD from your audio CD collection, you should always use the Apple Lossless encoder for best results.
Follow these steps to burn the highest-quality sound to audio CD using iTunes:
- Choose Edit > Preferences (Windows) or choose iTunes > Preferences (Mac OS X).
- Click General and then click the Import Settings button.
- Choose Apple Lossless Encoder from the Import Using pop-up menu.
- Insert an audio CD.
- Make sure the checkbox next to the names of the songs (tracks) that you want to include on your disc is checked and click Import. Repeat this step until you've imported all the songs you want to save on the disc.
- Choose File > New Playlist.
- Type a name for the playlist and press Return.
- Click the Music icon under Library on the left side of the iTunes window.
- Drag the songs you want to include on the audio CD to the new playlist.
- In the playlist, drag the songs so they are ordered according to how you want to hear them when they're played back. The approximate total time of the songs in the list is displayed at the bottom of the window. (It does not include the Preference setting for the amount of silence between songs.) Most discs can hold a maximum of 74 minutes of music.
- Click Burn CD.
- In the Burn Settings window, select Audio CD. Optionally, you may also want to set the Gap Between Songs setting to 0 seconds.
- Insert a blank CD-R disc.
- Click Burn.
It takes several minutes to save, or "burn" the songs to the disc.
If you also want the songs to be available in iTunes for playback you may want to delete the Apple Lossless versions from the Library to free up hard disk space and import them again using the AAC Encoder.
You can follow the steps in technical document HT1550 "iTunes: How to convert a song to a different file format" to create MP3 files from the AIFF files.
Apple Lossless encoding requires more hard disk space than MP3 or AAC encoding because less information is compressed. You should make sure you have enough free hard disk space before importing many songs. Uncompressed audio from a CD will take up about 10 MB/min of uncompressed data (about 640 MB total for an average audio CD). Apple Lossless will encode at 5 MB/min (or about 320 MB total for an average audio CD), while AAC encoding will be around 1 MB/min.