Red Book is the
standard for audio
CDs (
Compact Disc Digital Audio system, or
CDDA). It is named after one of a set of
color-bound books 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. The standard is not freely available and must be licensed from Philips. As of 2004, the cost per the relevant Philips order form is
US$5,000. As of 2009, the IEC 60908 document is also available as a PDF download for US$260.
Red Book Audio Specifications
The basic specifications state that
- Maximum playing time is 79.8 minutes
[Clifford, Martin (1987). "The Complete Compact Disc Player." Prentice Hall. p. 57. ISBN 0-13-159294-7.]
- Minimum duration for a track is 4 seconds (including 2-second pause)
- Maximum number of tracks is 99
- Maximum number of index points (subdivisions of a track) is 99 with no maximum time limit
Technical details
The pits in a CD are 500
nm wide, between 830 nm and 3,000 nm long and 150 nm deep.
Individual pits are visible on the micrometre scale.
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 PCM sampled at 44,100
Hz. This
sample rate is adapted from that attained when recording digital audio on
PAL 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
bit rate is 1411.2
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 are stored in sectors of 2352 bytes each, read at 75 sectors per second. Onto this the overhead of EFM, CIRC,
L2 ECC, and so on, is added, but these are not typically exposed to the application reading the disc.
By comparison, the bit rate of a "1x"
data CD is defined as 2048 bytes per sector × 75 sectors per second = 150
KiB/s, or approximately 9.2 million
bytes per minute.
Copy prevention
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.
See also
