What Is the File Format of a Music CD?

compact disc image by Nini from Fotolia.com

Music CD tracks are displayed on computers in the Compact Disc Audio (CDA) file format. CDA is a shortened form of CD-DA, which stands for Compact Disc Digital Audio. When you place a music CD in your computer’s disk drive, the Windows operating system reads the disc and creates a set of CDA files that can be viewed in the drive’s folder. CDA files are denoted by ".cda" at the end of the file name.

Music CD Data Storage

Data stored on a music CD is in the form of a continuous stream of raw digital data. This means it is not in a format that is recognized by your computer. Instead, the Windows CD driver is forced to create CDA files, which the operating system can read each time you place a music CD in your disc drive.


CDA files are 44 bytes in size. Each contains the indexing information that allows software programs to tell when each track on your music CD begins and ends. The files do not contain the pulse code modulation (PCM) wave data, and therefore are much smaller than digital audio files stored in formats such as MP3. If the CDA files did contain the wave data, they would take up roughly 10MB for each minute of audio.


Because CDA files only contain indexing information, they must be played from the music CD itself and cannot be stored on your computer’s hard drive for playback. Most music playback software will play CDA files, so long as it can access the CD in your disc drive.


To enable storage for playback on your computer, CDA files must be digitally encoded and converted into a format such as MP3, WAV or FLAC. This task can also be completed by most music playback software.

Burning a CD

When you burn music files from your computer onto a recordable CD, your computer converts the file format into compact disc audio. When placed in your computer’s disk drive, the burned files will again appear in the .CDA file format.