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Re: Re: again about compression

Subject: Re: Re: again about compression
From: Walter Knapp <>
Date: Thu, 04 Apr 2002 15:14:00 -0500
Dan Dugan wrote:
> Walter Knapp asked,
> >Is there any trace of the original wanted sound in your difference file?
> Yes, it bursts louder when the audio is louder.

As noise or identifiable sounds?

> >Sounds like using a analog transfer to get the sound back to the mac
> >caused most of the signal transfer in the stuff I did.
> For differencing to null the levels have to be very precisely
> matched. Hard to do with Analog.

Yes, ideally you need it matched exactly sample for sample. It falls
apart very quickly if you are not that precisely synced.

I used a set of single sample pulses I would hand draw into the waveform
at the beginning of the sample. Those did make it through my analog
setup well enough for a exact match. But, you are right it's not easy. 

The difference files were always very much lower in level than the
originals in my analog try. 

I burned a audio CD of the samples with the sync marks for my master and
then used the ability of my MXD-D3 Sony deck to clone a CD onto MD to
make the copy. The analog step was returning the samples to the mac.
Both the CD and the MD were run through the same analog link, which at
that time was the built in audio in of the G4. That way everything went
through as close to the same path as I could get it. I expect I only got
it to work because the copy from the built in CD is so direct within
that deck. It's all one unit, probably running off the same clock. It
is, of course, entirely digital that direction. The MXD-D3 does not have
a digital out, only digital in. I primarily use the deck to make MD's
from our CD collection for use in our car and boat stereo's, all of
which are MD.



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