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

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html