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Re: Digital Distortion

Subject: Re: Digital Distortion
From: Walter Knapp <>
Date: Mon, 23 Jun 2003 14:15:19 -0400
Klas Strandberg wrote:
> It makes sense. Thank you.
> It is not only that analog changes might be "musical" (which I think is
> true, many times) but also that I can predict the errors of the analog
> changes I make. I can understand both what I am doing and - perhaps - how to
> avoid it.
> With the digital processing I don't understand anything. 

This is true for many of us, we have many more years experience with 
analog, understand it well. We are still beginners in digital.

> Of course one must use ones ears, I agree to 100%. But sometimes it is
> difficult with digital equipment.

It is still the best way. Though part of this is that different sound 
reproduction systems sound different. Ideally you listen on the same 
speakers or headphones as your intended audience, a near impossible task 
to sort out.

And we constantly have to be aware that our own brains are not being 
helpful. They process the sound our ears pick up according to our built 
in notions of how it "should" sound. Our attitude about the sound may 
change it far more than the particular equipment did. All of which means 
we have no real clue how someone else will hear it.

> An example: I had a 5 minute long wav-file. I wanted to test which MP3
> conversion that worked best. But to convert a 5 minute wav file into a good
> MP3 may take 15 minutes!
> So I took 20 sec of the 5 minute file, saved it as a wav and then made 3
> different possible conversions into MP3. Then I listened to them all. After
> listening, I could descide to use "X" conversion.
> Then I used "X" MP3 converion on the 5 minute original file, listened to the
> first 20 sec to check that everything was fine, and saved it. And - of
> course - deleted the original wav file, as I had it on tape anyway, and
> didn't want to waist harddisc memory.
> The day after, by accident more or less, - I happened to listen to the
> entire MP3 file. The bird itseld was good, just as I hade checked, but some
> bypassing thrushes some -20 db below, sounded just terrible!
> Which means that if you do something digital, you must check the entire
> file, as some part of it may be very good, while another part may sound bad,
> totally unexpected!

MP3 seems particularly prone to this sort of problem. Unfortunately, 
unlike ATRAC it's not standardized. Each piece of software seems to have 
it's own quirks with mp3, even ones who say they are using the exact 
same codex. It's so hard to learn what it will do. Always seems to be 
trial and error.

Compression is a separate sub issue in digital sound. Most discussion is 
about mp3 or ATRAC, the two "lossy" compression types commonly used. 
But, compression is very common in computers, generally considered 
perfectly reversible, it's still a source of some changes. If 
compression of the digital data bothers you then you really can't use 

Note in my preferred mp3 coder 5 minutes will take less than 15 seconds 
to encode in high quality. I assume you are using a much slower computer 
or something.



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