Interesting 100 gen CD copy test.

BWX · Feb 16, 2004, 12:43 PM

As I was exploring around the web today I came across an interesting article of a test done to see if after making 100 copies of copies of CD's if there would be any errors.

QUOTE:
"The premise of this article is simple: To burn 100 generations of a CD and then compare the 100th generation copy with the original CD to see if the data is the same or if there are any differences. Now, I don't mean making 100 copies of the same CD; that would be pointless. I'm talking about making a copy of a copy of a copy, 100 times. In other words, take a CD (original) then copy it making "gen 1". Then copy "gen 1" which gives you "gen 2". Then copy "gen 2" which gives you "gen 3". Do this until you get to "gen 100". So you see, "gen 100" is a copy of "gen 99" which is a copy of "gen 98"...... all the way back to the original CD. You get the point. "

The Article

~~craig588~~ · Feb 16, 2004, 12:50 PM

hmm, not bad. I figured they would pick up 1 or 2 insignifigant errors.

Matth · Feb 17, 2004, 01:22 PM

A truly daft test!

Data CD's have a second layer of correction, so the data is either good, or is bad - unless you got a "bad burn", there will be no deterioration. For an error to go through C1, C2 and ECC is very unlikely, unless the drive/media combination results in substandard burns, or unless you get a damaged/defected media - and the odds aren't swayed by doing 100 in line - other than that the first failure will result in all subsequent cycles being bad.

100 generations of an audio CD, or a VCD, would have been a tougher test - when you have no data ECC, you are more likely to pick up errors.

The notes with an old copy program did mention that SOME drives were actually used to copy "RAW", and that could result in progressive deterioration, as errors introduced int yje data, though still ECC corractable, would be copied, rather than repaired.

Copying the data in RAW mode would have made it a realistic test, as that would have left the possibility of uncorrected errors growing to unmanageable proportions.

BWX · Feb 18, 2004, 07:25 AM

Quote:

Originally posted by Matth
A truly daft test!

Data CD's have a second layer of correction, so the data is either good, or is bad - unless you got a "bad burn", there will be no deterioration. For an error to go through C1, C2 and ECC is very unlikely, unless the drive/media combination results in substandard burns, or unless you get a damaged/defected media - and the odds aren't swayed by doing 100 in line - other than that the first failure will result in all subsequent cycles being bad.

100 generations of an audio CD, or a VCD, would have been a tougher test - when you have no data ECC, you are more likely to pick up errors.

The notes with an old copy program did mention that SOME drives were actually used to copy "RAW", and that could result in progressive deterioration, as errors introduced int yje data, though still ECC corractable, would be copied, rather than repaired.

Copying the data in RAW mode would have made it a realistic test, as that would have left the possibility of uncorrected errors growing to unmanageable proportions.

You should right that dude an email saying that- he'll probably go buy another 100 CDs' and do it all over again.