When CDs skip...

Factual Questions
1

What’s going on when a CD starts skipping? I’m talking about when it starts playing the same split second of a song over and over again.

We usually call it a “scratch” on the CD but is that really what’s happening? I’m trying to figure out how a scratch would cause that to happen, and I’m not picturing it.

I can’t picture any circumstance that would cause it, however. Why can’t the player simply take note of the fact that it is playing the same bit of CD over and over and skip ahead a tiny little bit?

-Kris

PS I just had a thought though! What if it’s doing that because the music is arranged on the CD in concentric circles rather than a spiral like an old LP, and the machine is somehow missing the signal to move out (or in?) to the next circle? But still, wouldn’t it be pretty simple to program a CD player to notice when its laser has been pointing at the same bit of CD for too long?

2

Can be a few things from what ppl told me, cd is dirty (laser can see dirt that you cannot),
laser is dirty, laser needs alignment, cd was written at too high a speed, these can do it
esp with games.

3

A slight scratch in the surface of the disc will cause the laser to reflect away from the stream it is following. Dirt will do the job as well.

Working with images on a CD-ROM, I discovered that a disc could be scratched all sorts of ways with no discernable change in the images. ( I could open and read them all). I made a two inch long mark on the disc with a Sharpie pen, and the disc was useless.