In article , chung
wrote:

The data is still bit perfect. So if you use a good digital audio
extraction program, you will still have bit-perfect data. However, when
the CD is being played in real time, jitter, which is basically noise in
the frequency of the DAC clock, can be affected if the servo circuitry
has a tougher time tracking the lands and pits.

Can theoretically be affected. I don't think I've ever seen anything
establishing a concrete link, just speculation about extra servo
"circuit" noise being coupled into something else. ("Circuit" in quotes
because the servo system here is likely to be a bit of extra DSP
software.)

If there is a real effect along those lines, jitter in the playback
clock does not seem likely -- plain old noise coupling into the DAC
output is a far more realistic scenario. Any change in the digital
portion of the system is unlikely since digital circuits are highly
resistant to noise.

Not that I think noise coupling into the analog section is a likely
scenario either. Servo corrections happen all the time even when there
aren't problems with the disc -- otherwise it wouldn't be necessary to
have servos.

By far the most likely scenario in which nominally bit identical discs
play back different is when they don't actually read back bit identical,
i.e. one or both of the "identical" discs has recording problems serious
enough to sometimes result in uncorrectable errors during playback.

--
Tim