Why can't you extract all the data on a factory-pressed CD when it Options

[guest0190]

In the past when I have burned a CD with EAC (with read and write offset correction values consistent with Andre Wiethoff's reference), I have been able to rip files from it identical to the source files.

Based on what I could gather from this forum, I used to be of the conviction that with a drive capable of overreading and overwriting, the exact same files that were burned to a CD can be extracted from it again, and that the only disadvantage of using a drive not capable of overreading was that a few samples at the beginning or end of the first or last audio file would be replaced with silence, regardless of what the samples originally contained.

Recently, however, it has come to my understanding that it is very hard (or even impossible) to extract the original files that were burned to it from a mass-produced CD.

My question is simple: How is it that I can rip files identical to the source files from a CD I have burned myself, but not from one that is factory-pressed? And, perhaps more importantly, how is it that I managed to achieve this using 'incorrect' offset values?

I apologise in advance for any difficulty I might have understanding any mathematical arguments you put forth. I fear I am slightly dyscalculic.

(I have decided, henceforth, to rip using the 'ideal scenario' reference which is 30 samples before that established by Mr Wiethoff, but I am not sure if it is relevant.)

[Rollin]

If your drive has positive offset correction value and quantity of "zero" samples in end of CD is less than offset value, then you need overread in lead-out to exactly rip CD and overwrite in lead-out to exactly write it to CD-R.
If your drive has negative offset correction value and quantity of "zero" samples in beginning of CD is less than offset value, than you need overread in lead-in to exactly rip CD and overwrite in lead-in to exactly write it to CD-R.
If quantity of "zero" samples in beginning/end of CD is more than drive offset value, then audio data will not be affected.

Also read http://blowfish.be/eac/Setup/setup5.html#no5c

This post has been edited by Rollin: Sep 6 2012, 14:15