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Re: [AV Media Matters] Digital audio file formats

Thanks for the responses folks. Here's a couple questions thrown at me that
I'll answer in a batch:

>I don't quite understand the part about back up migration and access copies.
>These are mutually exclusive I would think.

I think of migration as making a new copy of a "primary source",
which can be thought of as the new PS, keeping the old original
around (in case of future magic inventions). As we don't use PS
carriers to respond to access requests, there needs to be a
high-quality copy available. With a digital audio file, if it's
sitting on a server and being backed up with all the other giant
piles of data, there's one level of coverage right there. If we then
have another off-line data backup somewhere archivally pleasant
(cool and dry, natch), then anyone with priveleges can search,
access, and even make a copy of a file to their local recording
medium if they desire.  We imagine the recordings being made direct
to digital and put on the server immediately, available to anyone
who formerly would have waited for a transcript to be pulled and
then ordered a cassette copy. As soon as a committee hearing was
done, the file could be available to anyone with access priveleges.
Protocol would ensure the proper duplicates get made (simultaneously
on different servers?) so the redundancy would be immediate. Flaws?

>Just to get a better understanding of your content, this is all audio
>content or is it a mix of audio and video?

There is video in the mix, but it is a tiny amount compared to the audio,
and video digitization is an extremely loaded issue, so we are discussing
only audio digitization now.

>A hard disc based archive will be useful if you need permanent and
>instant access to the stuff stored on it. But actually you still have to
>pay a high price for the luxury of having instant access to hours and
>hours of PCM audio (rule of thumb in IT: The faster the access, the more
>expensive the media).

Right. How about near-line? A request could come in, and the requester
might be notified when the file would be available (10 minutes? one hour?).
That would still beat ordering a tape copy, having it handled, and shipped.
This part is obviously all speculative.. Since these records are largely
accessed within 1-2 years of their creation, those years could be "hot" and
the others stored near- or off-line, the material only available "by

But obviously, when you're talking about giant pots of audio, you're also
talking giant pots of money. We're into millions of $US, anyway you look at
it, a large part of that being person-hours, slaving over hot computer
set-ups. This collection consists of approximately 50,000 hours of
(largely) mono audio, mostly recorded at 3.75 ips, so fidelity is not the
paramount issue here. I expect we'll need a second scenario for any
high-resolution audio mixed in with the lower-Q parts of the collection.

Bob Curtis-Johnson

Alaska Moving Image Preservation Association
phone 907-279-8433
fax   907-276-0450

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