26
FREECOM Traveller II Series
GB
6
Physical Image
Before writing a CD, an identical 1:1 copy of the new CD is created on the hard
disk. The file will be the size of the record (i.e. up to 650 MB). Creating a physical
image requires a certain amount of processing which is not necessary for writing.
For the writing procedure, only the file to be written is transferred. The CPU
load (
C
entral
P
rocessing
U
nit) remains small and cannot cause disruption.
When creating several identical CDs, the physical image is less time-consuming
because the processing mentioned above only has to be carried out once.
"Raw" Files
A "raw" file contains data which is already in CD format. It can be directly
written without further modification. One "raw" file corresponds to one track.
For example, a "raw" audio file can be used as the contents of one CD-DA
track. Image files are "raw" files.
Red Book
Specification for audio CDs.
Session
A session is one sitting with the recorder. Audio CDs are always single sessions.
Data CDs can be recorded over several sittings and the CDs can be used right
from the start (multisession). However, the CDs can only be recognized by
reading devices once they have been fully recorded and fixed.
Single session
The CD is recorded in one sitting (session). Audio CDs are always single session
CDs.
Thermal Calibration
Procedure for adapting hard disks to the effects of thermal expansion. The hard
disk cannot be accessed while it is calibrating. This can be a sufficient amount of
time to empty the driver's buffer space. This leads to a 'buffer underrun' which
will interrupt the writing procedure and will render the blank disc unusable. It
is not possible to control the moment at which calibration takes place. If no
calibration occurred beforehand but happens during writing, even a test-run of
the drive can occur. This type of hard disk is unsuitable as a source drive (or for
physical and virtual images).
