Posted by PTravel on 01/12/01 11:52

<mmaker@my-deja.com> wrote in message
news:1152471732.786210.173400@35g2000cwc.googlegroups.com...
> Binba wrote:
>> 2. On the same note, I keep hearing that in a firewire dub there's
>> "VIRTUALLY" no generation loss. Why always this "virtually"?
>
> Because bits get lost between the tapes: either because they're
> corrupted in the Firewire transfer, or they're unreadable from the
> original tape.

Bits don't get corrupted during a firewire transfer, and drop-out, i.e.
uncorrectable data loss, is incredibly rare for digital video media. In the
200-300 hours of digital video that I've shot, I've never had a single
instance of drop-out -- not one.

There is no generation loss when copying digital video.


>
>> One post
>> mentioned that after some 18 generations it will start degrading.
>
> Doubt it. I do remember one test involving multiple generations of
> recompression of DV footage which claimed degradation after about 18
> generations, but you shouldn't see serious issues when making digital
> copies. You're likely to have the odd dropout on the tape, but
> otherwise the general quality should be fine.

You're correct that the there will be no generation loss. However, drop-out
from digital video tape is very, very rare.


>
>> When I copy a file in my computer even a hundred times, it should
>> be exactly the same.
>
> But hard disks are far less prone to bit errors than tape: for one
> thing they can detect faulty disk blocks and move the data elsewhere...
> you can't do that with tape. On the other hand, the lifespan of a hard
> disk is typically far less than that of a tape.

Both hard drives and digital tape employ error correction, which is one of
the reasons why drop-out is so rare for digital video tape.


>
> Mark
>

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