| iTunes works with six audio file formats: MPEG-4 AAC, MP3, CD-DA, AIFF, WAV, and Apple Lossless. Using the Import feature, iTunes can encode CD-DA files from a CD to MP3, AIFF, or WAV files. It can also encode MP3, AIFF, and WAV files to CD-DA format when burning a CD. Each file format is suited for a specific purpose. | To select an encoder when importing files, see page 109. |
CD-DA (Compact Disc Digital Audio) is the file format used on all music CDs. When you burn a CD from a playlist, iTunes by default automatically encodes the files in the playlist as CD-DA formatted files so they'll play on CD players. In the iTunes preferences window you can set iTunes to burn files in the MP3 format, or as a data disc which will retain the original file format of song fileswhatever they happen to bebut the songs may not play in a CD player. MP3 (MPEG-3) is a highly efficient compression system that reduces music files up to 90 percent, but maintains a very high quality. Highly compressed, MP3s are ideal for downloading from the Internet or for storing on your computer. MPEG-4 AAC (Advanced Audio Coding) format compresses files even smaller than MP3 without a noticeable loss of quality. When iTunes imports a song from a CD to your computer, by default it encodes the CD-DA formatted song to an AAC format. MP3s and AACs are ideal for storing music on your computer, requiring 80 to 90 percent less disk space than other formats. | If you have a version of QuickTime installed that's older than version 6.2, songs are by default imported in the MP3 format instead of the AAC format. |
Apple Lossless encodes CD-DA files (CD music files) into a size that's half the size of the original file, without any loss of quality. This format creates files that are larger than the MP3 and AAC formats, but if you have a discriminating ear for music, the Apple Lossless format provides the best quality possible. AIFF (Audio Interchange File Format) is sometimes referred to as Apple Interchange File Format. It is a music format used by the Macintosh operating system. Web designers use snippets in the AIFF format for sound files that can play in web pages on a Macintosh computer. The file size of the Beatles song "I Want To Hold Your Hand" is 24.3MB as an AIFF file, compared to 2.7 MB as an MP3 file. WAV (Windows waveform format) is a music file format used by the Microsoft Windows operating system. Web designers use snippets in the WAV format for sound files that can play in web pages on a Windows computer. The file size of the Beatles song "I Want To Hold Your Hand" is 24.3 MB as a WAV file, compared to 2.7MB as an MP3 file.
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