Posted by Martin Heffels on 07/11/06 21:45

On Tue, 11 Jul 2006 15:51:58 -0500, "Steve King"
<steveSPAMBLOCK@stevekingSPAMBLOCK.net> wrote:

>I hadn't read that. So, where did the difference lie between mini-DV and
>typical tape-backup hardware do you think? In the tape formulations? In
>the way the ones and zeros are put on the tape? On the tape speed? On the
>way the head scans the tape? Something else?

The difference is in the error-correction. As has been mentioned in this
thread, DV25 can borrow data from other places to repair data. This repair
is done according to what is optically accepteable (meaning that you don't
see it).
Digital video has been designed to throw away data which we won't see. Oh,
that many colours we can trhow away half of them, and juggle them around on
even and odd lines, nobody notices.
You can't throw away data in computer back-up. Here you are limited to
something like "ok, here follow 221 times the letter A", and then you can
throw away the other 220 letters to save space.
If if you start replacing data in DV25 error-correction, you would need a
huge amount of error-correction data (check-sums and repair-data) to be
able to reconstruct it back to it's original. Because you would have to
notice that a chunck of data has been replaced, and then replace it with
what it originally was. Just too complicated :-)

But that doesn;t mean that the delopment is completely stopped. Here are
some solutions:
http://www.jakeludington.com/project_studio/20050828_backup_files_to_dv_camera.html
for Mac and PC.

cheers

-martin-
--
"I'm full of dust and guitars." - Syd Barrett
11/07/06 The Crazy Diamond is now a star in heaven

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