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2-33] Who really made this CD-R blank?




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This article is from the CD-Recordable FAQ, by Andy McFadden (fadden@fadden.com) with numerous contributions by others.

2-33] Who really made this CD-R blank?

(2000/09/03)

Many of the "big name" media manufacturers don't actually make their
own media. Instead, they buy from other manufacturers and stamp their
logo on the discs. Generally speaking, this isn't a bad thing, because
the discs were certified good enough that the Big Brand was willing to
put the company name behind the product.

If you have a picky recorder or player, though, it helps to be able to
try several different pieces of media. If you buy several different
brands, and they're all coming from the same manufacturer, chances are
they'll all behave the same way, and your time and money will be wasted.

So... how do you tell who really made a piece of media? The short answer
is: you don't.

It's tempting to believe that CD-R media identifier applications (e.g.
section (6-2-9)) will give you the answer you need. Unfortunately, the
data you get is unreliable at best. Charles Palmer, from cd-recordable.com,
had this to say about the manufacturer identification:

"Two components that many users of these programs always take as gospel
are Media Manufacturer and Dye Data. These two readings are next to
worthless.

The reason for this is that many CD-R manufacturers (like CD-
Recordable.com) purchase their stampers (the nickel die that all CD-R
substrates are molded from) from 3rd party sources. These 3rd party
sources (either other disc manufacturers, or mastering houses) encode
the data that these 'Identification' programs read, at the time that
the original glass master is encoded. The 'Manufacturer' information
that is encoded is usually the name of the company that made the
master. Since stampers made from that master will be sold to disc
manufacturers the world over, all of discs that those manufacturers
produce from those stampers will contain the same 'Manufacturer'
information. Information which is obviously quite erroneous and
irrelevant. Very seldom will the 'manufacturer' information encoded on
a CD-R actually tell you anything other than who made the original
master. [...]

The second piece of data (the dye type) is also dubious. Because most
master/stamper configurations are designed to be matched to specific
dye types (Phthalocyanine, Cyanine, Azo, Etc), the 'Dye' information
that is encoded when the master is produced indicates the type of dye
that the master was designed for. This of course, does not assure that
the manufacturer that buys and uses this stamper will be using it with
the dye that it has been designed for. It is quite possible that a
stamper/dye combination is used by a CD-R manufacturer that contradicts
the 'dye' information encoded on the master. Therefore that
information becomes as potentially misleading as the 'Manufacturer'
data discussed earlier."

The only reliable piece of information in the "ATIP" region is the disc
length. See section (2-38) for further remarks.


 

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