The partial CAV writing method was selected
during the development of current Yamaha recorders as in principle
a CD should not display any links. If the Zone CLV writing method
is used, each CD will have links. Plus the buffer underrun protection
function is used to stop the burning process, increase the speed
and then continue with the writing.
As opposed to other manufacturers, Yamaha uses the Partial-CAV
(Constant Angular Velocity) write process. With this process
the CD-R/RW medium does not rotate at a constant speed throughout
the entire burning process. The recording process is started
at moderate speeds while keeping disc rotation controllable.
Afterwards the speed of the outer edge of the medium is successively
increased, as the tracks on the outside of the medium are longer
and therefore more data can be written on these tracks. Once
the recorder reaches maximum recording speeds rotation remains
constant. |
The
write quality of the inner section of the CD is improved by
the P-CAV process: moderate disc speed reduces the vibrations
which diminish the quality.
In
addition to improving the quality, the P-CAV process also
offers the advantage of producing "on the Fly" disc-copies.
Through this process the gradual acceleration of the write
speed better matches the read speed acceleration of the source
CD-ROM (CAV).
Furthermore
the working life of the laser diode is also extended, as the
moderate speed reduces both the loading on the mechanism and
the excessive heat.
Here is a comparison of the Zone-CLV write process and the
Yamaha Partial-CAV process:
|
|
YAMAHA
Partial-CAV
|
Zone
CLV
|
|
The
Partial-CAV process used by Yamaha can reach the maximum
speed through symmetrical acceleration and without
links.This is ideal for audio CDs and for pre-mastering, as
CDs with links are not ideal press.
|
Links |
The
zone-CLV (Constant Linear Velocity) process used by other
manufactures cannot reach the maximum speed without making
links. This is unacceptable to the user, who requires the
highest attainable quality.This is especially valid with
regard to audio CDs and for
pre-mastering.
|
Kept
moderate at about 5500 rpm while writing speed accelerates,
ensuring a stable, high-quality write.
|
Rotational
speed
|
Goes
high up to about 8000 rpm at the beginning of each zone,
making quality writing difficult and resulting in a
reduction in the write quality.
|
Use of
sequential writing speed allows stability while writing
maintained.
|
Writing quality |
Quality
can be impaired, especially at the link points, because
conditions such as laser power and writing strategy are
completely different before and after the
link.
| |
