What is the Red Book?
Red Book is the set of specifications created by Philips and Sony to define
the essential parameters for Compact Disc-Digital Audio (CD-DA). First released
1980, Red Book has been adopted an international standard (IEC 60908:1999,
Audio Recording — compact disc digital audio system) and forms the foundation
for all other compact disc standards.
What types of audio CDs can CD-R and CD-R/RW recorders write?
CDs were originally designed for audio so it’s only natural that CD-R
and CD-R/RW recorders write discs in the official Compact Disc-Digital Audio
Red Book format for use in any CD audio compatible player. Just like their
mass produced prerecorded (pressed) cousins, CD-R and CD-RW discs can hold
up to 80
minutes of CD quality audio (44.1 Khz, 16 bit) using as many as 99 separate
tracks. In addition to Red Book discs, recorders also write compressed digital
CDs which, instead of holding conventional tracks, contain MP3, WMA or other
compressed audio files. Depending upon the scheme used, one compressed CD-R
or CD-RW disc holds as much as ten to twenty ordinary audio CDs and can be
back in devices enhanced for compressed digital audio listening such as compatible
computers, personal, home and car CD players as well as many DVD-Video players.
What types of material can be used as sources for audio CD recording?
Depending upon the capabilities of the recorders and software used, CD-R and
CD-RW audio discs can be written from either digital or analog sources. Digital
material such as existing MP3 files or CDs are conveniently read directly from
the hard drive, recorder or from a separate CD or DVD-ROM drive. To record
analog sources such as LP records, cassette tapes, microphone or radio tuner
connected to a home stereo, signals are first digitized through the computer’s
Digital audio material comes in many forms including compressed and uncompressed
computer files such as MP3s, WMAs and WAVs, Compact Discs (CD), MiniDiscs (MD),
Digital Audio Tapes (DAT), Digital Compact Cassettes (DCC) and Alesis ADAT. How
they are handled by the computer for writing to CD varies depending upon the
capabilities the individual recording system.
A popular way to create audio discs is to use uncompressed (WAV, PCM, etc.)
and compressed (MP3, WMA, etc.) computer files as the recording sources. When
a compressed digital audio CD these files are written to disc just as they
come and, depending upon the recording software used, may be accompanied by
or other navigational information. In the case of a Red Book audio CD, compressed
files must first be uncompressed and translated into the correct format before
recording. Historically, this had to be accomplished manually but most recording
software now performs the conversion process automatically during the writing
process. As with any audio recording it’s important to remember that
the sound quality of a written disc will be no better than the source material
Higher resolution digital audio files obviously will produce better results.
Recording CD to CD is much simpler than recording from analog sources since
most CD and DVD-ROM drives are capable of transferring audio directly (Digital
Extraction) without the necessity of converting from analog to digital. As
a result, CDs can often be recorded disc to disc using a CD or DVD-ROM drive
the audio source. Where a suitable drive is not available the recorder itself
can be used as the audio source. In this case, the audio is read using the
recorder and stored temporarily on the computer’s hard drive until written
DAT, MD, DCC, ADAT
Although the contents of DATs, MDs, DCCs and ADATs are already in digital
form, most computers lack the proper connections for directly importing digital
As a result the analog outputs from the source must be connected to the computer’s
sound card and the audio re-digitized. Since there is always a loss of quality
in the conversion process, some manufacturers offer special sound cards that
connect to the digital outputs of the source deck to transfer the audio to
the computer while keeping it in quality digital form.
Analog audio equipment such as LP record players, cassette tape recorders,
microphones and radio tuners use continuous electrical signals of varying
voltages to record
and play sound. Computers, on the other hand operate, in the digital world
where everything is represented in binary form. Thus, before the computer
or record analog audio sources to a hard drive or a CD-R/RW disc, the sounds
must be converted into digital form through the computer’s sound card.
Higher quality sound cards will produce better results but most cards are
capable of recording at the 44.1 kHz frequency, 16 bit resolution used by
Some recording software automates the conversion and writing processes into
a few simple steps by performing time saving tasks such as detecting the
silences between songs to automatically split the music into separate tracks.
What is MultiAudio?
The MultiAudio specification was created by OSTA in 2001 to provide a standardized
structure for compressed digital audio files (MP3, WMA, etc.) written onto
removable optical media, such as CD-R and CD-RW discs. This uniformity allows
to be played back in the same way on any compatible device including MultiAudio-compliant
computer software media players and consumer electronics devices such as
CD and DVD audio and video players. To accomplish this goal MultiAudio requires
in addition to compressed digital audio files, an appropriately formatted
also must contain a defined table of contents which the playing device will
use for file navigation. In addition, the specification allows playlists
to be created
to organize material so it can be accessed by categories such as genre, album,
artist or even in custom groupings created by the user. MultiAudio formatted
discs are created by standard recording software packages and CD-R/RW recording-enabled
audio jukebox applications which support the MultiAudio specification. Written
discs can then be played back in MultiAudio compliant devices and even in
compressed digital audio units not supporting the specification, albeit in
a more limited
fashion. Since MultiAudio is simply an organizing system it’s important
to remember that the types of discs and specific compressed digital audio
file formats supported depend upon the individual capabilities of the particular
devices or software employed.
Can consumer compact disc audio recorders write to any CD-R or CD-RW media or
are special discs required?
Even though general purpose CD-R and CD-RW discs and their consumer audio
versions appear for all practical purposes identical, only blank media
bearing the “Compact
Disc Digital Audio Recordable” (CD-DA Recordable) and “Compact Disc
Digital Audio Rewritable” (CD-DA Rewritable) logos can be written in consumer
audio recorders. The reason for this restriction is to comply with international
copyright agreements. A special Disc Application Code present in the ATIP information
of a CD-DA Recordable/Rewritable disc’s pregroove wobble identifies
it specifically for audio use. Consumer audio recorders are programmed
discs not containing the correct code. By adopting this safeguard various
countries and other authorizing jurisdictions may selectively apply copyright
to the price of blank discs intended for consumer audio use while exempting
destined for computer or professional applications.
Does using lower CD-R recording speeds and lower capacity media produce better
High speed CD-R writing often creates discs with low I3 and I11 signal amplitudes
(optical signals generated from the smallest and largest marks) and 80 minute
discs achieve their capacity by packing marks and lands more tightly together.
These result in reduced recording and playing margins and sometimes lead to perceptible
sound degradation, especially in older CD audio players which may not employ
equalization (signal boosting). Consequently, many high speed recorder manufacturers
recommend creating audio discs at reduced writing speeds while some recorders
even limit their maximum speed to 24x when writing audio discs. In addition to
slower recording speeds, some manufacturers also suggest using 74 minute instead
of 80 minute discs. Several of the latest recorders even offer special writing
modes which record audio discs with longer marks and lands than would normally
be the case, albeit at the expense of some capacity. For example, an 80 minute
disc written with longer marks and lands might only hold 74 minutes of audio
and a 74 minute disc just 68 minutes of material.