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Re: Digital Distortion

Subject: Re: Digital Distortion
From: Klas Strandberg <>
Date: Mon, 23 Jun 2003 21:52:24 +0200
Hi Walt!

What you write sounds reasonable, too. Psycho-acoustics is a factor causing
great difficulties in judging "quality".

Yes, I use a 5 year old Pentium. But it is also WaveLab which seems to be
slow. If I choose the "normal" MP3 process it takes about 2 minutes, "low
quality" about 30 sec.

But I'm not so worried about .wav to MP3 conversion, here we all know how
approximative and risky it is. It's just a way to save file-size. It is much
worse when I don't know - for example - in which order a digital editing
should be made, to get lowest distortion. 
I long for some real digitfreak to give me a list, like 1/ First do
filtering, 2/ then dynamic work, 3/ then noise gates, 4/ finally
normalizing. Just very practical and straightforward rules! And teaching me
the errors with doing in another way.

I know people who normalize between each step, say, all 10 steps. It appears
to me to be a dangerous way, but they claim it's okay.

Anyway, I think too little attention is payed to such "basic" knowledge in
editing! I mean, most of us need it. 

Btw, have you any idea of which MP3 compression that works best with
birdsong in general? WaveLab gives me 2 options "Lame" and "Fraunhofer". 


At 14:15 2003-06-23 -0400, you wrote:
>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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