Commercial CDs (if they are not CD-Rs :)) are usually high quality - how do they achieve it ? Do they have super burners that write at 52x and still provide high quality CD-ROMs or do they use lower speeds like 1x to do that ?
Professional discs, both CD and DVD, are pressed (using glass masters), not burned.
This is an exemplary CD / DVD pressing / replication company: http://www.europadisk.com/Tour.htm
Yes but you must make (with a laser?) spirals on the disk so it can be read by optical units. The spirals are make at a speed --> is that comparable with burner-like 1x, 2x etc ?
And finally what’s a glass master ? Is it the machine that presses the aluminum foil on the plastic disk ?
I could write an essay now, but thankfully there is a little helper called google that makes life so much easier…
After you have read that, you’ll see what the glass master is for, and that it is the key to answering your first question as well.
DVD’s arenot burned onto DVD-R, most (if not all) are mastered onto DLT (Digital Linar Tape) thus they never reach the burner.
CDs they can master from a CD-R but they don’t have to.
CD-R & DVD-R are different than CD-ROM and DVD-ROM.
CDs are normally ‘glass mastered’ at 1x to 4x.
If the CD is audio, some factories/customers insist on 1x only so that the ‘golden ears’ will approve the final result.
DVDs are normally ‘glass mastered’ at 1x to 2x.
Some mastering encoders can now do up to 4x DVD and up to 16x CD (or more). But, it is hard to rotate a piece of glass at those speeds in an LBR and maintain good results. The glass can be 8 inches in diameter and 1/4 inch thick.
If you are really curious about the exact details of how it all works, send me an email or PM me and I will tell you what I know.
thanks i found both those sites very helpful
No problem, glad that they caught your interest.
this may be a really stupid question…but with dvd’s that are over 4.7gb in size, how are they made??
they have two recordable layers instead of one (aka: “dual-layered” if you want to google this for yourself).