Dave Hinz wrote:
The actual reading of the disc
is a totally analogue process. The reflected optical signal from the
pits on the CD is not a strict "one" or "zero". The signal varies within
a lower range which we call a "zero", and a higher range which we call a
"one". There is a "guard" band between these two signal levels.


Yes. And if the bit is above the upper limit, it's a one. If it's below
the lower limit, it's a zero. If it's in the middle, it's an _error_,
and the error correction bits tell your reader how to correct it.

The misconception mentioned earlier being that the change from
"one" to "zero" is instantaneous; it takes time to make that transition,
and that's an analogue thing.

Like people have pointed out; loss of data is not a problem, but since
in SP/DIF (the protocol behind the CD) the clock, which governs the
data rate, is embedded into the data itself, the rate at which those
transitions occur is extremely important, and any ambivalence as
to where a transition takes place potentially forces the system to
second-guess itself.

This is called jitter, is usually measured in nanoseconds, and it sounds
like, well, an old cheap CD player.

I suppose that getting those pesky little holes in the CD surface to
have better defined edges might make CDs sound better. However,
I seriously doubt that freezing them will do that ( although I'm open
to scientific explanation)


Hans





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