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51 responses total.

  The best practical option seems to be high-quality paper.  The jury is
  still out on current digital media -- most of what we use currently
  hasn't been around long enough to form a really good idea of its longevity.

  Still, I'd think that mini-disc would be a comparatively poor choice.
  Even if the data persists, I think you'd have a really hard time finding
  a mini-disc player twenty years from now.  The relative ubiquity of the
  CD standard makes me think that CD-R is probably a better choice, although
  there is disagreement over how long the data on a CD-R is likely to last.

I agree with mcnally.  Acid-free paper is your best bet.  I wouldn't use 
Minidisc because it seems doomed to become the 8-track-tape of digital 
media.

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There are two issues in archiving digital audio.
1) How long will the media last?
2) Will any players be around for it?
 
It's too early to tell the real answers for question #1, and 
for question #2, you're making guesses about future market trends.
Probably the best choice, if price were no object, would be a 
manufactured CD.  :) 

Let's not forget the most important question:
1.  How much portability will you need?

MiniDisc is great for remote recording; while it's not quite as good a sound
quality as CD it's a lot smaller & lighter than carrying your PC with the CD
burner around.

Finally, you can easily enough transfer the audio to CD later for longer term
storage.

Magnetic media have a proven track record of durability if properly handled,
and as far as the digital content, i'd think that the best way to store it
would be completely umcompressed, raw digital data.  This is because the
encoding algorthms are devloping and changing so quickly that there is a
virtual guarantee that any algorithm you use now would be obsolete and
virtually impossible to decode in 20-30 years.

This leads me to to conclude that DAT would be good, especially since the
medium is in common use by professionals in the audio industry.

Well, if you want it to last "forever"...

I don't think we have any real data on how long magnetic media is
actually good for.  The best claim I've heard is that 9 track tape might
be good for a hundred years.  The plastic medium isn't the issue - mylar
tape is probably good for thousands of years.  The issue is the magnetic
domains, and the glue that secures the magnetic stuff to the mylar.
Probably the most durable magnetic media made was digital's DECtape;
which recorded fixed sized blocks on really big tape at a very low data
rate.  Of course, finding a working DECtape drive these days may be a
bit of a challenge.

Paper has a good track record for storing data over historical periods
of time.  Unfortunately, paper has its own problems, which are equally
well understood.  These include vulnerability to water, fire, termites,
wasps, ants, &etc.  The paper records we have today are basically of two
forms: stuff dating back to the middle ages that was mostly stored on
purpose, and didn't get recycled, faded, burned, rotted, or otherwise
destroyed.  Most of that is pure luck, and some of what we have is
fragmented or singed.  Experimentally, the reliability of paper records
over periods > 400 years is considerably less than 50%, even under the
most conscientious conditions.  The remaining stuff we have is basically
from archeology - stuff people *did* trash, bury, left in a hole, or
otherwise forgot about, and by some accidental coincidence, it didn't
rot away or get destroyed.  We have a lot of stuff from Egypt because
(a) they wrote a lot, (b) they liked to bury stuff with their friend's
rotting corpses, and (c) they lived in the middle of a desert, so the
cheap burial ground was basically anywhere except right next to the
river.

An even better recording technique than either magnetic tape or ink on
paper is probably punched mylar tape.  Mylar is considerably more
chemically stable than tape and might persist for geologic time.  Holes
in mylar won't fade, are durable and easy to read.  So punched mylar
tape is probably the most practical long-term solution.  Creating a
mylar tape does present some practical problems; probably the simplest
solution is to acquire an ASR-33 or 35.

Storing digital data does require some consideration.  Compression could
be dangerous in that it destroys redundancy in the input data, which
makes it harder to understand.  As long as the data isn't compressed, it
can probably be understood without too much work; after all, computers
in the future will be *much* faster so it may almost be child's play to
decipher audio from a given digital data format.  If you're really
worried, however, you could include an ASCII preamble that describes in
English the format of the audio data that follows.  You definitely don't
need to worry about documenting either ASCII or English; any future data
archeologists worth their salt will know these by heart.  (Unless
they're aliens, in which case they won't care.)

If you want something that lasts *longer* than mylar, well, there
certainly are things...  The big catch is finding something that's
chemically inert, rugged, yet without value.  Gold does well for both
inertness and ruggedness.  Thin plates of stamped gold would be a
perfectly viable way to store data for geological amounts of time.  The
problem is gold is also scarce & valuable - so if any human finds it,
they're much more likely to melt your gold down first, and not ask any
questions later about why anyone would bother stamping little
meaningless marks into gold.  Glass is just as inert, relatively cheap,
but not very rugged.

Engraved rock is a possibility.  Indeed many of our more ancient records
were first recorded in rock.  The major problem was later ages had an
unfortunate tendency to dismantle monuments to use them as a cheap
source of prefabricated stone of *almost* the right size (ie, fine after
some trimming and polishing...) Small hard stones of ugly rock might
work fine.  It turns out that the surface of Venus might be a much
better source of such rock - it's essentially been baked under several
thousand atmospheres worth of acid, which makes it a much harder & more
durable rock than almost everything here on Earth.

(hehehheheheheheheheh... that response amused me immensely)

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You can also use a PC with a CD burner.  The output from a MD is quite
compatible with a sound card line-in.

Sounds like jp2 has made up his mind to use minidiscs no matter what 
anyone says.

Bits on a rock?  Presumably little tiny pits.  Obviously, the finer
grained the rock, the higher the bit density.  Or you could for the
opposite extreme, go for large flat crystals and engrave multiple pits
per crystal.  Flat crystals may also pack better but would likely be
more expensive.  Amorphorous material has possibilities as well, but
then you're back to the glass problem.  One of the issues you'll have to
worry about is how close to the edge you store material - edges tend to
receive the most wear so that's where you'll lose information first.

There's an analogous problem with paper records - we have countless old
books and other records which are missing the first dozen pages, the
last dozen pages, the left margin of every page, or are just generally
moth-eaten.  Modern CD's write data from the inside edge to the outside
- - this is the opposite order from what's used for rotating magnetic
media and presumably designed to combat the "edge" problem.

Instead of digital audio, you could record analog sound directly, as a
wavey line.  This should be obvious technology to any archeologists
coming from a sufficiently advanced technological civilization.  You'll
have to choose between a flat disk and a cylinder, and of course, like
any record, you'll have to worry about scratches.  If cost were no
object, diamond disks might be the ultimate solution.  It's true diamond
can burn, but not easily and not likely by accident.  Of course, diamond
is expensive (and subject to the same problems as gold) but only if pure
and pretty.  You might want to use "industrial quality" black diamond
instead, and hope no future scavenger has a sudden need to drill oil
wells.  Since we don't yet know how to make very large industrial
quality diamonds, quartz is probably a more practical material.  It will
be tough enough to machine high precision wavey lines in it.

You don't think jp2 is considering lithic media?

Recording digital audio onto rock seems to me to be a bit much.. imagine how
large the rock would have to be in order to record an hour of audio - and how
much time it would take to record the audio.

(MiniDiscs have *really* come down in price over the past couple of 
years, and have begun challenging DAT tapes as a recording standard
[at least among U.P. radio stations] because of price, ease of use,
and ability to use with a DSB port.)

(FWIW, at both WUPX-FM and WNMU-FM, we use DAT tapes for "long" recordings
[of an hour or more].  WUPX will have MiniDisc technology by the end of
next month, and we're planning to use it for field recordings, reserving
DAT tape for in-studio recordings.  durability of jp2's desired standard
hasn't been a consideration, although I should note that WUPX is in the
process of putting some of those recordings onto CD-R, mostly for ease
of use for our DJs, who *detest* using DAT tapes for 3-5 minute
on-air snippets.)

I use minidisc for recording interviews when I think they'll be longer than
my hand can last. :-) It's small, handy, and I can reuse it if I don't want
to save the recording.

        I was surpised to see professional MiniDisc recorder/players in
a radio station I visted recently.  I quickly made sense.  The old
technology for short recordings (commericials, announcements) was 
cartridge tape.   Considering that a MD now costs near $2.50, it 
does not matter if it can hold more material than the near $5.00 to 
$8 tape cartridge it replaces.  On top of that, tape cartridge 
machines for radio stations require regular maintenance, some daily
(clean heads), some weekly or monthly (align heads).

The really cool thing about MiniDisc is that it's basically a little magneto
optical floppy disk, and so you can do basic audio editing (split a track into
two, move tracks around , delete tracks in the middle of the disk) without
losing capacity.  With tape you'd have to fast-forward past spots you didn't
want.  Plus the discs themselvels are immune to magnets, since there has to
be heat as well as a magnetic field to write data.

Re #10: I would strongly advise using a digital connection
  between the Minidisc recorder and CD-Recorder (whether
  that's a PC or a stand-alone piece of kit).  Where's the
  sense in recording digitally and then converting back to
  analog, and back to digital?

(The MiniDisc uses a lossy compression scheme, so you'd still lose something
even with a digital connection.  And for voice interviews, it's probably not
a big deal anyway.  I've done a couple CDs from live music recordings on MD
without noticing a big problem.)

I'd be leery of using anything magnetic, personally.  My personal 
experience has been that floppy disks fail after around 10 to 15 years, 
much less if they're read frequently.  I've also found that 3/4" 
videotape seems to have a useful life of somewhat less than 25 years.  
The adhesive binder seems to fail and let the oxide shed off the tape, 
which both degrades the tape and clogs the heads.  Some types of 
magnetic tape are known to get physically sticky over time, as well, 
with unhappy results when you try to draw it past the heads and 
capstans.

Your best bet may be something no one's brought up yet: Use digital 
media, in an uncompressed format.  Every decade or so, make a new copy 
onto whatever digital media seems best at the time.  This eliminates 
worries about obsolescence *and* degradation.

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I like the idea of mylar.  I would like it better if you could type on it with
some kind of heat element and thus make a permenent mark on the sheet.  Copper
disk etchings, or better yet, gols etching (isn't that what they used on
Voyager)?

Platinum....

(Jamie, apparently Grexians don't seem to realize that you're interested in
a "practical" solution)

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Jamie seems to have two questions: one about archiving digitial media,
and one about a digital recording system for practical interviewing.

I'd probably use CD-R, I guess, though no one's really sure if the dye 
will fade with time.  Minidisc suffers the same problem, and has the 
additional disadvantage that there aren't many players around for it, 
and the ones that are available are expensive.  The resulting lack of 
market penetration means there's less chance of working players being 
around for a long time.  It's a proprietary format, I think, which 
further limits the likelihood of them being available in the 
future.  Also, it uses lossy compression, so if the material needs to be 
copied to another format in the future there'll be quality loss.

What I found fascinating about jp2's question was his insistance that
the data last "forever".  Now "forever" is one of those elastic terms
that means different things in different contexts.  For instance, in the
computer field, "forever" means 2 years.  In 2 years, everything made
becomes obsolete, and there's a better, faster, cheaper, and more
reliable solution for which you should have waited and you will kick
yourself about how obvious it was when it comes out.  Someone's
suggestion above to "copy onto newer media" is an obvious attempt to
capitalize on this phenomena, although there would seem to be obvious
problems with "who really cares anyways?" and "why don't I just fix up
this small obvious mistake and translate that old English that nobody
understands to 29th century Volkspeak."

Conversely, in worldly terms, 4 billion years is probably a safe
estimate on "forever".  That's when (roughly) the sun runs out of
hydrogen, and various bad things happen.  It won't (exactly) fry the
earth to a crisp, but it's unlikely anyone or anything will care about
whatever is left here after that.  There have been various debates about
the ultimate age of the universe, and whether even the proton is a
stable particle, but the jury is still out on some of these issues.
However, in astronomical terms, the most stable way to preserve data
might be to shoot it off with a really high-powered maser in some less
popular radio wavelength, in as many different directions of the sky as
possible.  Unfortunately, unless we ever discover FTL flight, this won't
help anyone on earth.  I took it as kind of a given that in order to be
successfully preserved, there had to be someone at the other end who (a)
cared, and (b) was capable of understanding the data being transmitted.
Requirement (a) means the data needs to stay somewhere in the vicinity
of earth, because anyone interested in what are probably not the most
interesting of interviews is not likely to care unless they also
happened to be either born here, or for some reason travelled here.

Speaking of "the vicinity" however -- when it comes right down to it,
the earth is not a friendly place for data *in the long run*.  It's got
vile chemistry, radiation problems, geologic activity, and far too many
intelligent grubby little apes digging everything up and generally
making a mess of things.  It would clearly be attractive to store data
elsewhere in the solar system.  Where, exactly, is another question.

Most of the inner planets have the same radiation problems as earth, and
worse chemistry.  Venusian surface conditions, for instance, are
incredibly hostile, and mercury isn't much better.  Of the inner
planets, Mars might be the best bet - it at least has a stable outer
crust and a thin atmosphere.  Assuming those grubby apes stay away,
burying records in some sort of multiple redundant fashion under the
surface (and trying to mitigate the chances of having them clobbered by
a fast rock from the cometary halo) may be safe enough.  The main
problem with the outer planets is the difficulty of getting to the
surface, or indeed even of establishing if there *is* a distinct
surface.  A moon rotating one of the outer planets may be a better bet,
although there is again the risk of getting clobbered by a fast moving
rock.  There is also the question of *which* moon to pick, and hoping
that future visitors will happen to get curious about the same
moon--curious enough to find the large markers one has hopefully left on
the surface.

The ultimate location to pick is obviously Pluto, and perhaps in the
future there will be a trade as people ship their most precious secrets
out to Pluto, to be buried in huge underground vaults safe for future
generations to cherish.  No doubt this data trade will eventually be
complemented by a trade in archeologists who travel out there in the
hopes of discovering the cherished secrets of the ancient races, perhaps
starting with the secrets of that most curious and oldest of the
vanished lost races of the Earth--the "Americans".

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        Or a marker like tha face of Elvis on Mars?

Cuneiform on baked clay?  That has been shown to last 5000 years already.
Why record audio for posterity rather than an ASCII transcription?  Vinyl LP
records last at least 50 years and longer if they do not break - can you stamp
a metal recording in something like stainless steel?

Nickel has been the medium of choice for a similar project.

Stainless steel or nickel would be attractive to recycle, even in small
quantities.  Gold plating might make as much sense; it's not prone to
oxidation, and can be made *very* thin - the major issue would be making
it thick enough to survive the decay of the vinyl or whatever it's
plated on.  Vinyl acetate definitely doesn't last forever, although it
clearly does last longer than cellolose acetate, which gets pretty
brittle after 20 years.

Now linked to cyberpunk conference, just because. :-)

See new item 181, inspired by this item.

Professional audio archivists are still using analogue audio tape as a stable
long term storage medium.  I reccommend Quantagy 406 it's formula is 50+ years
old and tapes recorded 50+ years ago are still playable.

What kind of plastic is it?

Mylar if my source is correct. 1.5 mil thick.

- Backtalk version 1.3.30 - Copyright 1996-2006, Jan Wolter and Steve Weiss