Compact disc digital audio is the music format on an ordinary audio disc. Sound is sampled thousands of times a second, stored as uncompressed stereo samples, and read from the spiral in playing order.
The disc itself is a Compact Disc (CD). This format is the one used for a music album. A later data format on the same physical disc stores computer files instead of a single audio program.
How the Sound Is Stored
- Stereo samples. Each moment of the recording is stored as a left sample and a right sample, with no further compression.
- A fixed rate. The samples are taken at the same rate from the start of the program to the end.
- Tracks in order. The album is a sequence of tracks the player can start at a chosen point.
Music Program and Computer Files
| Compared | Music Program | Computer Files |
| What is on the disc | Uncompressed stereo sound, arranged as tracks | Files and folders a computer can copy |
| How a player reads it | Plays the samples in order | Mounts the file system and opens a file |
| A track skip | The player jumps to the next track in the program | There is no track list unless a file provides one |