The DDS is better because of what Ted wrote better than I about not
wanting to conceal errors -- i.e. "faking" the audio in the machine.
If, when you are comparing, you see a burst of errors on the DDS tape
but not on the DAT tape, it is most likely that same area has
concealment happening on the DAT tape. But it is true, you don't know
if the spot has errors in the DAT or DDS, but if you don't hear
errors in the DDS and see a difference and can't hear errors in the
DAT either, you are pretty sure that the DAT is using error
CONCEALMENT in that area. I would suspect that most errors in the DDS
would be audible if they were substantial.
In addition, with the DDS playback, as I understand it, you get a
printout of suspect areas where the error CORRECTION might have been
stressed to the limit and might have failed, so you DO know if the
DDS is more accurate, or not.
I do not think that DDS can have any more robust error CORRECTION
when playing DAT tapes than a DAT machine can as the additional
interleaving and error correction codes are not in the DAT tape.
That is not to say that DDS tapes themselves do not have more error
CORRECTION than audio DATs. It's like CD-ROM (as I understand it) has
another layer of error CORRECTION as opposed to audio CDs -- which is
why the actual bit/byte capacity of a CD-ROM is LOWER than an audio
CD. 74 minutes of audio at 44.1/16/stereo is about 747 MiB or 783 MB,
while a "74 minute" CD holds only about 650 "MB" in CD-ROM mode. (I
don't know if the CD-ROM "650" number is really MB or MiB.)
One thing that needs to be mentioned is pre-emphasis. I don't know
the answers, but DDS extract will probably not de-emphasize unless
it's built into the software. I believe DAT carried across that flag
that was inflicted upon the CD because it was inflicted upon the F1
format in some incarnations.
I really want to know when someone has a "freelance" DDS DAT reading
"factory" set up so I can refer people to them.
At 02:37 AM 2010-01-21, Shai Drori wrote:
>My own experience with dat is that almost all tapes have some form
>of errors on them. I think the idea in dds is that errors are better
>fixed than dat machines. There were many machines that came off
>assembly lines not at spec, thus making the tape not a standard
>tape. Some machines are better at coping with these (my experience
>with Sony is better than tascam for example, but I suspect this is
>highly subjective). All in all, I think the DAT format was the word
>digital format I have ever come across.
>Also' checking two files one against the other will not necessarily
>prove one format better than the other. If you get some audio, how
>can you be sure one stream is correct and the other is corrupt?
>Either the dat or dds stream could be better, or am I missing
>something in the methodology?
Richard L. Hess email: [log in to unmask]
Aurora, Ontario, Canada (905) 713 6733 1-877-TAPE-FIX
Detailed contact information: http://www.richardhess.com/tape/contact.htm
Quality tape transfers -- even from hard-to-play tapes.