cd longevity

From: John Lawson <jpl15_at_panix.com>
Date: Fri May 7 12:17:18 2004

On Fri, 7 May 2004, Jay West wrote:

> This has been discussed on this list a few times before... but I just came
> across a rather detailed article about the topic of longevity of CD, DVD,
> and CDRW media.
>
> I'm thinking the best long term storage solution is... paper printouts. How
> retro :)

  Actually, if ya wanna go techno-retro - we found (MGM Studios / Library
of Congress / Filmbond Archival Institute) that the most long-lived medium
for this kind of work is optically encoded data on well-processed Mylar
linear film of some kind. With proper encoding techniques, one can get
bit densities of more than a megabyte per inch - of standard 35MM
sprocketed stock - of course an order of magnitude more using 70MM - and
even more if wider stock is used.

  Carfully processed Mylar, with proper attention to washing and drying,
will survive more than 150 years before degradation, if packed and sealed
against the environment - and stored in a 'normal' temperature range.

  And of course the devices to read the data are just a light source and
array of photo-sensors, with perhaps some simple optics for focussing and
image expansion. I've seen a prototype film-sound reproducing device
using IR LEDs and a video scanner chip - with the image being decoded back
into sound on a cheap laptop - and this was 5 years ago....

  But plastic mono-layer photographic stock film has the longest life and
a very high BPI density as well.


  Cheers

John
Received on Fri May 07 2004 - 12:17:18 BST