Most CD & DVD burners made in the past 3 years are able to test the CD
being
burned, to determine good workable burning parameters for that particular
disc. Burning speed and other parameters are adjusted accordingly.

Yep which brings something more I have to say that is totally unrelated to
audio but nonetheless in context with the thread.

Since a CD-R is write once how is it possible to test the recording
parameters without actually recording on the disc? If the software does lay
down some form of 'reference' data to the disc how then can the disc be
'overwritten' ?

The success of these operations varies with the quality of implementation.

Do you mean the hardware and software used or more inline with the knowledge
of the user?

Steve

Since a CD-R is write once how is it possible to test the recording
parameters without actually recording on the disc? If the software does lay
down some form of 'reference' data to the disc how then can the disc be
'overwritten' ?


There's an area on the disk reserved for that purpose.

In article , Arny Krueger
wrote:
[snip]

"The PCA is a sort of testing ground for the CD burner. In order to
ensure that the write laser is set at the right level, the burner will
make a series of test marks along the PCA section of track. The burner
will then read over these marks, checking for the intensity of
reflection in marked areas as compared to unmarked areas. Based on this
information, the burner determines the optimum laser setting for writing
onto the disc.
[snip]

AFAIK, when this function is implemented, it's entirely automatic. One
sees evidence of its activities in two ways:

(1) A lot of discs that work really well, seemingly regardless of the
properties of the media. Media you thought was total crap suddenly
starts playing well, even on *picky* players.

(2) Occasional discs are rejected right at the beginning of recording.

Curiously, using an 'audio' CDR drive I occasionally see a third sign.

Sometimes when adding more tracks to a CDR that was partly recorded on a
previous occasion the result is visibly 'banded' with the newly written
areas having a distinctly different appearance to the previous areas. I
assume this is a result of the player coming to a different conclusion as
to the optimum burning settings. I guess this should not happen, but it
does seem to on occasion.

Slainte,

Jim

--
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Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html