| Media type | Optical disc |
|---|---|
| Encoding | 2 channels of LPCM audio, each signed 16-bit values sampled at 44100 Hz |
| Capacity | up to 74–80 minutes (up to 24 minutes for mini 8 cm CD) |
| Read mechanism | 780 nm wavelength semiconductor laser |
| Standard | IEC 60908 |
| Developed by | Sony & Philips |
| Usage | Audio storage |
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|---|---|
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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;[1][2] it was adopted by the Digital Audio Disc Committee and ratified as IEC 60908 (published in 1987[3]). The second edition of IEC 60908 was published in 1999[4] and it cancels and replaces the first edition, amendment 1 (1992) and the corrigendum to amendment 1. The standard is not freely available and must be licensed from Philips.
Contents |
The basic specifications state that
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 facility (cross-interleaved Reed–Solomon coding, CIRC), and the eight subcode channels.
It also specifies the form of digital audio encoding: 2-channel signed 16-bit Linear PCM sampled at 44,100 Hz. This sampling 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.[6] 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 (as 2 channels × 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 2,352 bytes each, read at 75 sectors per second, excluding the overhead of EFM encoding, CIRC, L2 ECC, subcode channels, and so on, which are not typically exposed to the application reading the disc. As the table of contents locates track listings according to sector, tracks must be aligned on sector (588-sample) boundaries.
By comparison, the bit rate of a "1×" Data CD is defined as 2,048 bytes per sector × 75 sectors per second = 150 KiB/s (1,228.8 kbit/s).
Some major recording publishers have begun to sell 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 as DualDisc, which includes both a CD layer and a DVD layer whereby the CD layer is much thinner, 0.9 mm, than required by the Red Book, which stipulates a nominal 1.2 mm, but at least 1.1 mm. Philips and many other companies have warned them that including the Compact Disc Digital Audio logo on such non-conforming discs may constitute trademark infringement. Either in anticipation or in response, recent copy-protected CDs bear stickers and warnings that the CD is not standard and may not play in all CD players, and no longer display the long-familiar logo.
In the beginning of the 21st century, two advanced versions of the audio CD emerged: the Super Audio CD and DVD Audio. The two rival formats were designed to feature audio of higher fidelity. Both formats apply a higher sampling rate and use 650 nm lasers.
The standard is available from Philips and the IEC. As of 2004, the cost per the relevant Philips order form is US$5,000.[7] As of 2009, the IEC 60908 document is available as a PDF download for US$260.[8]
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