What's Here
This document contains basic practical information for users of CD media, especially CD-recordable, or CD-R. Serious users of CD-R will naturally have several important questions about the medium, including:
* What kind should I buy?
* How long will they last?
* Does recording speed matter?
This document provides answers (with varying degrees of authority) for each of these questions.
Besides the basic information, I felt it necessary or worthwhile to include some detailed background information about the structure and organization of the discs. How many bits are stored on CD? Lots more than most people realize. This was the type of information that I thought would be easy to find on the internet in the year 2000. But it wasn't. I had to check and compare a number of different sources in order to pull it all together.
Disclaimer: I am not now, nor ever have been, an expert on CD media. These were my own questions. In researching the answers for myself I wrote this document. -- Chip
Why This Document?
In December 2000 I completed a project transferring about 5 hours of audio interviews with elder family members to audio CDs using CD-Rs. My intent was that the discs would last for at least one family generation (25 years or more).
But the very day that I sent out copies to various family members I began to worry about how long these CD-Rs would last. I vaguely recalled hearing something about the instability of the dye layer. I didn't know what the "dye layer" was -- perhaps it would fade or run? Kodak offers CD-Rs that are supposed to last 12 times longer (than what?). Should I redo all the copies using these special archival (i.e. "more expensive") media?
I also began to worry that I had erred in recording my discs at high speed (8x). One of my friends had heard that CD-R creation is somehow better when done at low speed (1x or 2x). I know that low speed duplication is superior for analog tape, but it had never occurred to me that it could make any difference to a digital medium.
Anyway, having no real idea of how long CD-Rs would last, or of the real differences between "gold" and "silver" discs, etc., I decided to research the questions. My results are summarized here, along with many links that I found helpful along the way.
