[Ham-Computers] RE: CD-ROM "signatures"?

[Hsu, Aaron (NBC Universal)]

I was going to mention CD-R's in the last e-mail, but decided not to.  But, since the question came up...

CD-R's store the same info in what's known as the "ATIP" (sorry, don't remember what ATIP stands for).  Originally, the ATIP contained the media manufacturer, media type, dye type, and media size (in blocks).  Later they added the max burn speed so drives would not exceed the "coaster" value (a "coaster" is term used to describe a bad CD burn).

Luckily, there are only a small handful of burn strategies for CD's as they're all based on dye type.  So long as a CD-R's formulation is similiar to a known dye type, then that dye type is recorded in the ATIP.  From what I remember, the number of dye types is limited (4-bit number?), so most all CD-R's are signed with a known type.  Some drive tables are further optimized for specific vendor's media and will use additional ATIP info to optimize the burn (BTW, this is also true of DVD media).

Unfortunately, not all media works well with all burners.  Burning 52x media in a drive rated at 48x is usually not a problem.  The problem is that a lot of 52x media is pretty crappy even at 16x!  Media is designed to work at all burn speeds upto the max rating and that's a pretty wide range.  What you'll find is that any particular batch of media may have a "sweet spot" with any one particular drive.  Other times, another particular batch of media may constantly produce coasters with that same drive.  It's a matter of finding out what media works best with *your* particular drive.

Another problem is that most vendors are not manufacturer's of media.  Here's a list of actual *manufacturers* that I know of (in no particular order) - see how many you recognize as a brand:

Taiyo-Yuden
Mitsui-Toatsu
Verbatim (aka Mitsubishi Chemicals Corporation or MCC)
RiTek
CMC Magnetics
ProDisc
Hitachi-Maxell
Sony

But wait, you're thinking, "where's TDK, Imation, Memorex, Fujifilm" and all the other names you see on storeshelves.  Well, all these companies contract out to an actual manufacturer and then put their own names on it.  And, when it comes to the consumer market (what we by at the local Best Buy, Circuit City, Staples, Target, etc), these companies just buy whatever is currently the cheapest on the market as most "consumers" can't tell the difference.  The "cheapest" disks are often manufactured with lax quality control and if you actually run a test of how well a disc burned at 52x, you'll see many errors - most correctable (C1), some not (C2).

What makes this more difficult is that even manufacturer's (like Verbatim, Sony, Maxell, etc.) outsource some of their products (the low-cost products).  So just buying a manufacturer's branded product doesn't guarantee that they've manufactured them.  For Verbatim, just about anything you find on store shelves is outsourced - as of 2006, their in-house manufactured products are only available via media houses such as Meritline.  If a Verbatim product uses the AZO dye, it's most likely produced in-house.  For other "manufacturers", it's hit or miss...you really can't tell from the packaging if it was produced in-house or outsourced.

I've mentioned in the past which manufacturers I've found that have excellent quality control.  This is where the quality of the disc is consistant throughout manufacturing "batches" (the three companies listed on the top).  But, you won't find these on storeshelves.  What you typically find on store shelves is manufactured by Ritek, CMC, or ProDisc.  There are free utilities out there that will read the ATIP and give you the manufacturer's info.  However, realize that the ATIP is easily forged, so it can't be used as an accurate identifier unless you know your source.

If you want to find out more about your CD-R's, here's an app that is widely used by reviewers.

http://www.cdspeed2000.com/

If you have a drive that supports "diagnostic level" commands, it will be able to do low-level testing of your media to see how well your drive works with that particular media.

Anyways, back to the original question.  Yes, it's usually OK to use 52x media in a 48x drive.  However, the bigger question is how well your drive works with that particular batch of media.  I usually burn CD's at 16x, 24x, or 32x even though my drives all support 48x or 52x.  Reason?  Because the resulting burned disks are higher in final burn quality than if they were burned at the higher speed(s).  Best thing to do is to "burn" (pardon the pun) one CD (or more) from each box/spindle/batch of CD's you buy and test it with diagnostic software (such as CDSPEED).  See how well matched it is with your drive.  If it doesn't burn well at one particular speed (such as high error rates at the "end" of the CD), then try a different burn speed (usually lower).  Once you've found the "sweet spot", burn the rest of the CD's in that box/spindle/batch at that speed.  Repeat for the next box/spindle/batch of CD's you buy.

As for sources for "manufacturer" makes of CD's, try http://www.meritline.com.  T-Y and Mitsui are harder to come by, buy Meritline carries the bulk Verbatim products which are very good.

73,

  - Aaron Hsu, NN6O


p.s.  For reference, I use Plextor drives which include "PlexTools" - software that include the low-level C1 and C2 diagnostic tests.  The CDSPEED software mentioned above also has similar capability if your drive supports it.


-----Original Message-----
Sent: Wednesday, January 03, 2007 6:15 AM
Subject: [Ham-Computers] CD-ROM "signatures"?

In his response on 01/02/2007 to a post from John on the same date, Aaron gave us some very useful information related to  DVD "signatures" that help the burner understand what's in the oven and at which temperature to cook for best results.

Does the same apply to CD-ROM...if your burner is 48x and you can't buy 48x because only 52x are available, should you expect trouble?

John W0IKT