DVD-Rs What do different colours mean?

22nd Apr 2003 21:11 #1

Member

Some blank DVD-Rs have a light purple underside (Eg Princo 2x) and others have a much deeper purple underside (Eg Ritek 4x). Any clues?
Is there such a thing as Japanese Dye, Taiwanese Dye and Chinese Dye?

TIA

Quote

25th Apr 2003 03:16 #2

garryheather

Member

The colour difference comes down to the dye used and the characteristics of the reflective layer. You don't see so much devience on DVD-R's as you do CD's but the principle is similar - just not so profound.

There are several different dyes out there used by the manufacturers, and they obviously have different qualities. The DVD player is more concerned with reflectivity tuned towards the laser diode used whereas your eyes see across a wider spectrum, so as a rule, so long as the combination of dye and reflective layer meets the standards, the DVD player won't care what colour the disc is.

In the CD-R domain, there are a lot more dye / reflective layer combinations, which is why you get red, black, gold, silver, blue... but in a CD player, the laser is in the infra-red spectrum and therefore doesn't give a pair of dingo's kidneys (RIP, Mr Adams !) what colour the disc is because it simply can't see it.

Since the focal length of a DVD is so much more critical than on a CD, the quality of the dye is paramount to ensure consistent burns, with well defined pits and lands. If the dye burns too fast, you get streaks in the (supposedly) unburnt areas on the disc, and if it doesn't burn correctly or the reflective part... isn't... then the disc will be unreadable or difficult to read and unreliable.

Some cheap media is fantastic - I've had great results with the likes of the 69p e-Proformance discs but this is rare. The dyes and the like may be fine, but on the cheap discs they don't seem to worry so much about the problems like dust getting in with the dyes and so on. Don't forget the dyes are predominantly organic, so even with the best manufacturers, there may be the odd batch which isn't as good as it could be - but the difference between batches is negligable on the quality brands.

Don't forget there aren't THAT many manufacturers of DVD media at the moment, so a lot of them will be using common consituent "parts" from the same manufacturers, so a lot of discs will appear similar. With the problem of copied disc manufacturer ID's (read Princo / TDK), not even your recorder might be able to tell the difference. But when push comes to shove, chances are your DVD player will. It depends on a number of factors as to how good your DVD player is at handling recordable media, but the physical colour of the disc is not likely to be one of them.

HTH.