[William Sommerwerck]

When you say digital, do you mean store the data as a number,
as is done now, and feed it to a DAC, the output of which is a
pulse width rather than a voltage? If so, that could be done with
the CDs we have right now.

When I say "digital", I mean "quantized" -- there is only a finite
number of possible pulse widths.

This is doable right now, and in fact was done 30 years ago, with the
original LaserDisks, which used a form of analog pulse-width modulation.


OK, I get it. But why would the possible number of pulse widths be
finite (apart from quantum effects of course)? You can theoretically
make a pit any arbitrary length. Of course you would instantly be at
the mercy of scratches and dirt. Error correction would be a thing of
the past.

I feel like Peewee Herman going "Aaaaaahhh!"

Yes, the pit _can_ be of any arbitrary length. But if we quantize the
length, then we have a digital system. If the width falls within a
particular range, then we know -- with almost perfect certainty -- what
_number_ it represents.

As you point out, this is not possible in an analog system.