Audio CD (CD-DA) Physical Parameters

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∟Audio CD (Compact Disc Digital Audio or CD-DA) Format

∟Audio CD (CD-DA) Physical Parameters

This section describes the physical parameters of an audio CD (Compact Disc Digital Audio or CD-DA).

According the Compact Disc Digital Audio or CD-DA specification, the "Red Book", an audio CD should have the following physical parameters as mentioned on wikipedia.org:

Scanning velocity: 1.2-1.4 m/s (constant linear velocity) - equivalent to approximately 500 rpm at the inside of the disc, and approximately 200 rpm at the outside edge. (A disc played from beginning to end slows down during playback.)
Track pitch: 1.6 micrometer
Disc diameter 120 mm
Disc thickness: 1.2 mm
Inner radius program area: 25 mm
Outer radius program area: 58 mm
Center spindle hole diameter: 15 mm
The program area is 86.05 cm**2 and the length of the recordable spiral is 86.05 cm**2 / 1.6 micrometer = 5.38 km.

An audio CD with data packed slightly more densely is tolerated by most players (though some old ones fail). Using a linear velocity of 1.2 m/s and a track pitch of 1.5 micrometer leads to a playing time of 80 minutes, or a capacity of 700 MB. Even higher capacities on non-standard discs (up to 99 minutes) are available at least as recordables, but generally the tighter the tracks are squeezed the worse the compatibility.