It's not really about preventing a corrupt TOC, but making sure there is a
TOC if you have a power failure or something else catastrophic happens to
the machine. We write to the TOC during recording, every 2 seconds, whilst
consumer MD's only write the TOC at the end of recording. If anything
happens to the machine before this TOC write, you lose all the material.
By the way, I've never heard of a corrupt TOC write using the PMD650.
Best Wishes
Matt
Matt Jarvis
Product Marketing Manager
Marantz Professional Europe
Kingsbridge House, Padbury Oaks, 575-583 Bath Road, Longford, Middx, UB7
0EH, United Kingdom
+447796610410 - Mobile
+441753686080 - UK Office
+441753686020 - Fax
Walter Knapp <>
2002-07-29 19:46
Please respond to naturerecordists
To:
cc: (bcc: Matt Jarvis/LGD/CE/PHILIPS)
Subject: Re: [Nature Recordists] Marantz PMD650
Classification:
Dan Dugan wrote:
>
> Matt Jarvis, you wrote,
>
> >You could also consider our Professional MiniDisc recorder, the PMD650,
> >which has several unique features, including a 2 second TOC update
whilst
> >recording, giving an additional layer of security for your recordings.
>
> Could you explain that a little more?
I have a HHb Portadisc, not the Marantz, but I understand what this is.
Note first, in 5 years of using MD, I've never had a TOC problem. It
probably helps that I'm careful about keeping the machine and disks
clean. And that I always do my field recording on new freshly unwrapped
disks. Those that have reported TOC problems seem to always be using
well used disks that they have done a lot of editing one (read
fragmentation), or they appear not to care for their disks or machines
well.
A MD is organized as one long continuous length of ATRAC encoded data.
And there's a Table of Contents space that contains the mapping
information to map that into tracks. It contains a whole set of pointers
to locations on the main data space. Most MD write the TOC info at the
end, often keeping it in memory and only writing it when the disk is
ejected or the machine is turned off. By the sound of it the Marantz is
periodically writing to the TOC during the recording to keep it updated.
I'm not sure if this is a good idea or not. Those frequent updates give
more chances to write a corrupt TOC. Of course in theory it's insuring
if something happens the current recording is less likely to be lost.
With my HHb Portadisc, the TOC information is being updated into a
memory buffer that will survive things like loss of battery power, so
it's pretty safe even before writing.
The real way to handle the possible damaged TOC is for a machine to have
a method of forcing a rewrite of the TOC to list the disk as one long
continuous track. Current recovery methods involve fooling certain
models of MD recorders into doing this using a disk switching technique
that's not sanctioned by the manufacturers. But, particularly in
professional machines this should be a menu choice. That way you could
always get the recording back, even though you would have to then
manually break out the tracks again, and they could be fragments if you
have been editing. Currently I know of no machine that has this bailout
built in.
Walt
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