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Dear Brian, <br>
My name is Peter Copeland, and I am the "Conservation Manager"
at <br>
the British Library National Sound Archive. I'm slightly puzzled why
<br>
no-one has jumped in before me; but you have of course opened a very
<br>
big issue! <br>
In principle, I support the strategy that analogue media should be <br>
converted to a digital medium with error-correction, so that as errors
<br>
build up over time, it is possible to monitor the state of the <br>
degradation and invoke a "cloning" operation before the
failures become <br>
catastrophic. My policy is also to digitise analogue audio *in <br>
duplicate*, using two different types of carrier and storing them at
<br>
opposite ends of the country, to spread the burdens of self-destroying
<br>
media and World War III. I also make my staff and contractors use media
<br>
with greater "power-bandwidth product" so we do not lose
anything, and <br>
to use their ears (in the case of sound, of course!) to check the <br>
digitised version sounds exactly the same as the original. This is <br>
besides objective measurements of frequency-respose, speeds, noise,
<br>
etc. <br>
However, there are two "lateral" issues against which I must
warn <br>
you. <br>
One is the problem of "software." As I'm sure you know, the
<br>
computer industry is bedevilled with software incompatibilities, and
<br>
no matter how well the digital data is stored, if you cannot get the
<br>
recording into a state which human beings can appreciate, you have <br>
failed as an archive. Unfortunately, computer software can be <br>
copyrighted, and (in Britain) it lasts 70 years after the death of the
<br>
person who wrote it. Therefore you cannot copy the software to enable
<br>
an archival recovery programme to be monitored (let alone used). For
<br>
this reason, we currently honour patent law (which covers *hard*ware)
<br>
and lasts only eighteen years, and use formats covered by patents <br>
rather than software. <br>
My employer, the British Library, is currently planning to <br>
circumvent this difficulty by storing the digitised artefacts <br>
indefinitely. This involves a really massive digital store. The plan
<br>
is to store all our books, photographs, manuscripts, etc. in the <br>
digital domain, using an IBM computer system with enough intelligence
<br>
capable of monitoring itself, doing its own cloning as required, and
<br>
storing the results in two separate locations. I don't think this is
<br>
feasible for an archive such as yours. Either prices will have to come
<br>
down or co-operative agreements will have to be invoked to make <br>
everything work. Then, a century from now (when software copyright has
<br>
expired), one can get a representation back without breaking the law.
<br>
The other issue is getting analogue originals digitised in a way which
<br>
conserves all their properties. For audio this is comparatively <br>
simple, we are only digitising a representation of two analogue <br>
sound-pressures. (Anyone who thinks I'm oversimplifying, please shut
<br>
up for the moment). But for moving pictures, the problem is much more
<br>
complex. Different individuals have different tolerances to different
<br>
defects. I had to leave the television industry because my eyes were
<br>
predicted to fail, so I know I'm not normal; but I can see many <br>
defects on DVD, for example, which other people evidently cannot. So
<br>
the digitisation of moving pictures is currently at a very primitive
<br>
state compared with audio. <br>
On basic "information theory" arguments, I consider the format
known as <br>
DVC (with its extensions DVC-Pro or DVC-50, and DVC-HD or DVC-100, all of
<br>
which use the same chipsets - hardware) offers a route to the future. It
is <br>
not specific to a particular frame-rate (like film or video), and the (by
<br>
now) conventional metal-particle tape has been proven to last a decade at
<br>
least (unlike metal-evaporated, used by Super8). However, I do not think
<br>
there is yet enough hardware in the world for this format to be easily
<br>
readable in decades from now. But it is the nearest thing to an archival
<br>
format for video which has yet appeared. <br>
Returning to audio: I am playing "devil's advocate" now. I
respect the <br>
strategy of the Library of Congress that analogue is more likely to be
<br>
playable in future. The trouble is that the power-bandwidth product of
<br>
analogue media always degrades with time, and this affects engineering
<br>
test tapes just as much as tapes of audio subject-matter. So you can
never <br>
know where you are as the sound degrades (at least, if you don't have
<br>
access to new and properly-made test tapes)! It is at least sensible to
<br>
consider digital alternatives, even if they may affect the analogue sound
<br>
(or image), on the principle "don't put all your eggs into one
basket". <br>
For audio, we use CD-Rs ourselves. Besides anything else, I support
<br>
the idea that the more CD players there are in the World Out There, the
<br>
more likely it is that we shall be able to play CDs in future years.
<br>
(There are now more than a billion, which is unprecedented). <br>
You can see I am a very conservative philosopher, so I will end with
<br>
a very practical suggestion. Whilst I approve of Philips Red-Book <br>
Standard CD-R media for storing most analogue audio (only high-end audio
<br>
and long running-times defeat it), I must urge you not to use
"silver" <br>
CD-Rs. Assuming you mean CD-Rs with the *metal* silver, these have been
<br>
tested to give longevity in a laboratory "standard atmosphere."
But this <br>
ignores the fact there is sulphur in the atmosphere of most areas of the
<br>
world, which can leach into the disc and form silver sulphate, so the
<br>
disc goes brown. The very earliest CDs made by Philips Dupont Optical
<br>
here in Britain suffered this fault, and we've been living with it ever
<br>
since. (I must, in all fairness, say that Philips have replaced all their
<br>
affected CDs honourably). But we conservative nutters do not use CD-Rs
<br>
which are silver *in colour*, to be certain! We only use ones with a gold
<br>
(metal, not colour) reflective layer. <br>
I will stop now, I must give the rest of the world a chance to <br>
comment. <br>
Peter Copeland <br>
<peter.copeland@bl.uk> <br>
<br>
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<font face="Century Gothic, Avant Garde">------------------------------------------<br>
Brian Levy<br>
Cultural Activist<br>
Kiwat Hasinay Foundation:<br>
Preserving Caddo Heritage<br>
211 W. Colorado Ave.<br>
Anadarko, OK 73005 USA<br>
(1) 405-247-5840<br>
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