Glossary
TELEX SpinWise CD Duplicator
38
Compact Disc
CD stands for compact disc which is a general term for all formats of CD
media. CD formats available on the market now include CD Audio, CD-
ROM, CD-ROMXA, Video CD, CD-I and others.
Compact Disc
Formats
During the last two decades several Compact Disc formats were developed
to serve different purposes and uses. Starting with the CD-DA format in
1980, as a way to distribute high quality music in a compact and
convenient format, the first compact disc standard was formulated. Then,
the idea of storing computer data on the same media, more than 10 years
ago, lead to a new format: the CD-ROM (along with CD). In the last few
years, the desire to store a whole new generation of multimedia
contents(audio, video, games, pictures etc.) demanded new formats: CD-
I,CD-XA, Photo-CD, Video-CD, CD+ etc. were invented.
Digital Audio
Although digital audio can have a variety of sampling rates and
quantization, the Red Book specifies CD-Digital Audio as being sampled
at 44.1KHz, and quantized at 16 bits/sample, for high quality stereo sound
(65,536 values).Therefore, sound of different quality, even if it is placed in
a CD, is not Red Book Digital Audio.
Digital Audio
Extraction
(DAE)
The process of copying CD-DA audio tracks digitally from your CD-
writer or another CD-ROM drive, to a hard disk or to a recordable CD.
Not all CD-ROM drives support this.
Disc Read
Head--Disc
Write Head
Storage drives (magnetic and optical) have a head or heads that float over
the recorded area to read and write. Obviously, CD-ROM drives have only
a read head, which involves a low-intensity red laser diode (a.k.a. infrared
laser diode), lenses that focus the laser on the track, and others that
redirect the reflections to one of the photodiodes for appropriate decoding.
Some Write-Once and Rewritable optical drives involve two heads (to
write and read), while other drives, including CD-Recordable, use only
one head to do both--using a high-intensity blue argon laser for the write
function. For mass replication of CD-Audio, CD-ROM, and DVDs, the
glass master is produced by encoders that have special recording heads.
Disc-At-Once
(DAO)
A method of writing in which one or more tracks are written in a single
operation. The laser will not stop until the whole disc recording is finished
and the disc is closed - hence no clicks between audio tracks. Disc-at-
Once has only been added/available with the recent generation of CD
recorders and recent firmware upgrades.
