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Before Use
5
About CD-ROMs
A CD-ROM disc is a compact disc containing high-density read-only data. It
has many applications, including the playback of music and video, the archiving
of data, as well as on-line documentation. The following are descriptions of each
CD-ROM format:
CD-DA: Up to 79 minutes of stereo audio is written in 16-bit resolution at a
sampling rate of 44.1kHz for a 79 minute disc.
Data CD: Up to 700 megabytes of computer data is stored in standard ISO9660
format for a 700MB disc.
Video CD: These hold movies in which the video and audio data has been
compressed using MPEG-1 technology.
About Partial CAV (Constant Angular Velocity)
Writing to a CD-R disc is normally done using the CLV (Constant Linear
Velocity) method. In this method, the disc rotation speed will be so adjusted as
to keep a constant data transfer rate at any portion of the disc. In other words,
the disc rotation speed will vary in CLV writing.
In contrast, the CAV (Constant Angular Velocity) method uses a constant disc
rotation speed for all portions of the disc so that the data transfer rate will vary.
Because the CAV method has the advantage of largely increasing the data
transfer rate with a minimum load to the drive’s mechanism (compared to CLV’s
rotation speed adjustment), many current CD-ROM drives use the CAV method.
CD formats define the constant linear density of written data (data should be
written onto the disc track in the constant pitch) so that the amount of recorded
data per disc rotation will increase as the writing point moves from the inner to
the outer. In other words, in CAV writing the outer portion has an increased data
transfer rate.
The CRW2200E drive uses the CAV method in the inner portions as well as the
CLV method in the outer portions (Partial CAV) in order to enable up to 20X-
speed writing. The drive will control the disc rotation speed to start writing at
12X speed in the inner portions, gradually accelerating up to 20X speed and
maintaining 20X speed in the outer portions.