Sony Handycam DCR-DVD100 Technology Handbook page 7

DVD-ROM for Playback Only
DVD-ROM discs are for commercial prerecorded movies,
computer software programs, etc. Data is stored in the
form of microscopic "pits" in the record layer of the disc.
These pits are scanned by a laser and then "read" as
minute reflections. These minute changes in reflection
Record Layer of DVD-ROM
DVD-R for Recording Once
DVD-R discs are for recording only once. Since data
recorded to disc cannot be erased, DVD-R is a good
choice for data that requires long-term storage. Unlike
commercially recorded DVD-ROM discs, DVD-R discs
are recorded by a process of chemical change within the
surface of the disc. After a DVD-R disc is recorded, data
Record Layer of DVD-R
Track pitch
0.74µm
Track pitch
0.74µm
are converted to signals for further processing. There are
four different DVD configurations: single-sided discs with
one or two recordable layers, and double-sided discs
with one or two recordable layers.
Pit
is read by the optical pickup in a manner similar to the
process of reading a DVD-ROM disc; this similarity
makes DVD-R recordings compatible with DVD playback
units. Recorded (or "written") areas of a disc are called
"grooves"; unrecorded (or "unwritten") area is called
"land."
Groove
Land
D V D H a n d y c a m T E C H N O L O G Y H A N D B O O K
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