Red Book is the standard for audio CDs (Compact Disc Digital Audio system, CDDA or CD-DA). It is named after one of the Rainbow Books, a series of books (bound in different colors) that contain the technical specifications for all CD and CD-ROM formats.
The first edition of the Red Book was released in 1980 by Philips and Sony; it was adopted by the Digital Audio Disc Committee and ratified as IEC 60908, published in 1987. The second edition of IEC 60908 was published in 1999 and it cancels and replaces the first edition. The standard is not freely available and must be licensed from Philips.
The Red Book specifies the physical parameters and properties of the CD, the optical "stylus" parameters, deviations and error rate, modulation system (eight-to-fourteen modulation, EFM) and error correction (cross-interleaved Reed-Solomon coding, CIRC), and subcode channels and graphics.
It also specifies the form of digital audio encoding: 2-channel signed 16-bit Linear PCM sampled at 44,100 Hz. This sample rate is adapted from that attained when recording digital audio on a PAL (or NTSC) videotape with a PCM adaptor, an earlier way of storing digital audio. An audio CD can represent frequencies up to 22.05 kHz, the Nyquist frequency of the 44.1 kHz sample rate.
The audio bit rate is 1,411.2 kbit/s: 2 channels x 44,100 samples per second per channel × 16 bits per sample = 1,411,200 bit/s = 1,411.2 kbit/s. As each sample is a signed 16-bit two's complement integer, sample values range from −32768 to +32767.
On the disc, the data is stored in sectors of 2352 bytes each, read at 75 sectors per second. Onto this the overhead of EFM, CIRC, L2 ECC, eight subcode data channels, and so on, is added, but these are not typically exposed to the application reading the disc. Because of this overhead, the raw bitrate (at the optical pickup) is considerably higher than the audio bitrate.
By comparison, the bit rate of a "1x" data CD is defined as 2048 bytes per sector × 75 sectors per second = 150 KiB/s (1228.8 kbit/s), or approximately 9.2 million bytes per minute
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