wrote:
> Regarding the difference between MD and DAT. Well. Yes, I think MD lose =
> some quality. But the real question is if its good enough for most=20
> cases. And I think it is, especially if you consider cost. An=20
> interesting question regarding ATRAC and other lossy-compression=20
> formats is what happens next. If your lossy algo has removed 70% of the =
> information while recording and then the consumer encode with MP3,=20
> DAB/MP2, MD, AAC, AC3 etc. and remove 70-90% of those remaining 30%=20
> .... well, I dont have an answer to that - its just an interesting=20
> question ;=3D)
It's really a gross simplification that it removes 80 percent. It does
reduce the disk space required by that amount, but that's not the same
as removing 80 percent of the sound or the sound samples. It gets to
that disk space by analyzing the sound and writing instructions as to
how it's decoder can synthesize a reproduction of the sound. It comes
very close to preserving 100% of the sound, some would say it actually
succeeds at that.
Yes, if you copy and recopy to MD from MD, you do reach a point where
clear degradation occurs. But, that's not the process that the nature
recordists I know use. They use MD to record, but then transfer from the
original into computer sound files, and then on to CD. One has to
exercise a bit of common sense in using MD. As far as I'm concerned it's
a non-argument that you can recopy enough times to degrade the
recording. Just how many times did it take with cassette? Yet that has
the clear recommendation of Cornell, even today.
There are clear advantages of a optical disk over magnetic tape. That's
the big reason why I went to MD. As you noted, the sound was good enough
by a wide margin. And with my newer MD equipment it's even better. I do
think that serious bioacoustic analysis won't be done on it because they
are so locked into specific models of equipment and calibration methods.
Even most of that could be done with MD. Also higher frequencies should
be done with a higher sampling rate, which precludes MD, but not because
of it's compression, if there was a MD that used a 96khz sampling rate
but did compression that would extend it's usable accurate reproduction
to much higher frequencies.
The truth is that many scientists are still doing their field recordings
on cassette tape. And don't use computers for sound processing very much
if any. Digital recording has been very slow to penetrate due to it's
cost. I know of recent papers that have come out that used analysis of
sounds that had sat for a number of years on cassette tape before
analysis. Sometimes even doing it off copies of copies.
Walt
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