The optophone, first presented in 1931, was an early device which used light for both recording and playback of sound signals on a transparent photograph. More than thirty years later, American inventor James T. Russellhas

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The Red Book specifies the physical parameters and properties of the CD, the optical parameters, deviations and error rate, modulation system (

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The audio contained in a CD-DA consists of two-channel signed 16-bit LPCM sampled at 44,100 Hz and written as a little-endian interleaved stream with left channel coming first.

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The creators of the CD originally aimed at a playing time of 60 minutes with a disc diameter of 100 mm (Sony) or 115 mm (Philips). Sony vice-president Norio Ohga suggested extending the capacity to 74 minutes to accommodate the recording of Wilhelm Furtwängler

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Recording publishers have created CDs that violate the Red Book standard. Some do so for the purpose of copy prevention, using systems like Copy Control. Some do so for extra features such

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There have been moves by the recording industry to make audio CDs (Compact Disc Digital Audio) unplayable on computer CD-ROMdrives,

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Data encoding
Each audio sample is a signed 16-bit two's complement integer, with sample values ranging from −32768 to

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