|
 |
 Glossary |
|
| Caddy |
|
| A plastic case in which the CD can be placed before being
put into a reader or CD-Recorder. |
| Capacity |
|
| A CD usually has 650Mb organized into 335250 sectors
of 2 kb each. This is equivalent to 74 minutes of high-quality sound.
A CD can hold a minimum of 650 Mb but capacity depends on several
factors such as rotation velocity or the pitch of the track. It is
sometimes possible to record or copy more data that the nominal capacity
(over writing) but some readers will have problems reading it. |
| CAV (Constant Linear Velocity) |
|
| This depends on the reading speed of the data track.
Many magnetic storage media such as floppy-disks and hard-discs revolve
at a constant angular velocity (a constant number of revolutions per
minute) so the data on the outer edge is more widely distributed than
in the center. |
| CD-DA (Compact Disc - Digital Audio) |
|
| Commonly known as a CD, this is an audio disc containing
up to 74 minutes of high-fidelity stereo sound. Unlike a vinyl disc
where the needle follows a groove with a variable depth and transmits
vibrations, the laser beam detects the presence of hollows on the
surface and transmits binary information (0 or 1). The sound is converted
to a digital signal 44,1000 times a second, and its value is encoded
into 16 bits (for example 1001 0101 1011 1101). Encoding one second
of hi-fi sound takes 1.5 million bits. Other CD types exist: the CD-ROM,
CD-ROM/XA, and the CD-I. Introduced in the US in 1983, CD sales overtook
vinyl in 1986. The Red Book gives specifications for CD-DA. |
| CD-ROM (Compact Disc - Read Only Memory) |
|
| A CD format used to save computerized text, pictures
or sound. CD-ROMs are similar to CD-DAs but use several tracks for
data. A CD-DA reader cannot read a CD-ROM but a CD-ROM reader can
read a CD-DA. A CD-ROM can hold the equivalent of 250.000 pages of
text or 20.000 pictures at average resolution. |
| CD-ROM mode 1 |
|
| Has three error detection and correction levels for computerized
data. |
| CD-ROM mode 2 |
|
| Has two error detection and correction levels for sound
and videos. |
| CD-ROM/XA |
|
| (Compact Disc Read Only Memory eXtended Architecture) |
|
| A CD-ROM using mode 1 and mode 2 and enabling simultaneous
reading of low-quality sound and data. |
| CD-Bridge Disc |
|
| A version of CD-ROM/XA readable by a CD-I or CD-ROM/XA
reader. |
| CD-I (Compact Disc Interactive) |
|
| CD which can store data, sound, video, etc. The Green
Book gives the specifications of the CD-I. It can only be read by
one specific reader. |
| CDV (Compact Disc Video) |
|
| A version of the CD storing only video and sound. |
| CD-WO (Compact Disc – Write Once) |
|
| A CD writable only once (also known as a CD-R). A CD-WO
complies with ISO standard 9660 and can be read by a CD-ROM reader. |
| CIRC (Cross Interleaved Reed-Solomon
Code) |
|
| Error-correction method specially developed for use with
CDs meeting Red Book standards. |
| Close Session |
|
| Closing a recordable CD session consists of writing the
TOC onto the disc and preparing a lead-in area for the next operation. |
| Close disc |
|
| Closing a CD prevents other write operations regardless
of remaining free space. When the disc is closed, the lead-in area
for the final session will not include the address for the next recording
area. |
| CLV (Constant Linear Velocity) |
|
| Data speed in front of the pick-up head is constant.
Disc rotation speed varies according to the position of the reading
head. |
| CRC (Cyclic Redundancy Check) |
|
| Returns the number of blocks per second where CRC errors
have been detected. This parameter varies between 0 and 75 blocks
per second. |
| Cross Talk |
|
| DAT (Digital Audio Tape) |
|
| System for recording onto special magnetic tape. Used
for saving computerized information. |
| Data Area |
|
| An area of data beginning with reference number 00:00:00
(ISO 9660). |
| Data transfer rate |
|
| A CD-DA reader can transfer data at a rate of 150 kb
per second. A CD-ROM 12x reader transfers at 1.8 Mb per second. |
| Digital audio |
|
| Each sample is coded using 16 bits. |
| Digital data |
|
| All computer data is digitalized. |
| Digitalize |
|
| To convert an analogue signal (a sound, a picture, etc.)
to digital. |
| Disc Description Protocol |
|
| Protocol for describing CD sectors. |
| Disc at Once |
|
| Method for writing in a single session and by making
only one pass. The TOC and the lead-in area are written in succession
and must be compiled beforehand by the recording software. |
| DRAW (Direct Read After Write) |
|
| DVI (Digital Video Interactive) |
|
| A data compression/decompression algorithm for video
files. |
| DVD-R |
|
| Recordable DIGITAL VERSATILE DISC |
|
|
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