[Slight OT] - CD Lables

[Benjamin Scott]

On Apr 24 at 7:38pm, Dan Jenkins wrote:
> ATIP apparently stands for Absolute Time in Pre-Groove. (Perhaps someone 
> else knows what that has to do with the media manufacturer. :-)

    CD-Rs have a "pre-recorded groove" or "pre-groove" which guides the laser 
during the recording process.  The groove is not a straight line but rather 
"wobbles" at a particular frequency.  The drive matches that frequency to 
achieve the proper rotation speed.  It is also useful to know how far from the 
start of the disc you are -- the "absolute time".  This is encoded in the 
pre-grove by modulating the wobble.  Thus, "absolute time in pre-grove".

    What I've never been able to figure out is how the hell this gives us the 
disc manufacturer info.  :-)

    I get the general feeling that, at some area on the disc, the wobble 
modulation encodes this info rather then the absolute time.  However, that's 
pure guesswork on my part.

> The -atip option will also print out the DVD ADIP information as well.

    It should be pointed out that the "ATIP" information only indicates the 
company that manufactured the *glass master* used to manufacturer the CD-R 
blanks themselves.  It says nothing about who actually manufactures the CD-R 
blank itself.  Kind of like how the fact that a mechanic has a particular 
brand of tools says little to nothing about how good the mechanic himself is.

    Cheers,

-- 
Ben <dragonhawk at iname.com>