Re: [Gwc-general] A few general questions

[Jeff W. <we...@ya...>]

Hi John,

Sorry to take so long to reply.

The feather width "tapers" in (and out) the effect, so you don't have a 
hard edge produced -- think about amplification, and if you multiplied
each sample by 2, then with no feathering, the last sample amplified 
might jump from 1000 to 2000 -- this is almost guaranteed to produce
a new "click artifact..

For the biquad filter (which I admittedly implemented, playing around 
trying to get rid of 60hz hum), I'm not sure on the lowpass and high 
pass exactly what the center frequency refers to.  I have a document 
here titled "The Equivalence of Various Methods of Computing Biquad 
Coefficients for Audio Paramentric Equalizers" by Robert Bristow-Johnson 
which may serve as a starting point for you to investigate.

I think you should equate "center frequency" with "cutoff frequency".  a 
small bandwidth would give a sharp cutoff.

As for deleting the track, and leaving the *.wav.gwc file, the only 
bullet-proofing gwc does is to check that the number of samples, the 
number of channels and the audio rate are the same
for the *.wav.gwc file as the audio file itself.  Not likely a problem 
if you are using track_rec.

jw

John Cirillo wrote:

> Hi, I have been using GWC for a long time now, but some various 
> questions come up from time to time and I forget that I can ask about 
> them here.
> Here are the recent ones:
>
> 1) What is the effect of the 'feather width' parameter on the various 
> things it applies to (amplify, what else?).  I mean, what is it 
> looking at and how does this affect the result?
>
> 2) With the new DSP filters, how to set the center and octaves? 
> Supposing I want to do my own  decrackle by killing off the high end 
> at 8,000 Hz using the highpass function. What would I put?
>
> 3) What would be the effect of deleting a track, but accidentally 
> leaving behind the .wav.gwc file for it, and then recording a new 
> track with the same name and opening it in gwc?  This is a very real 
> possibility when using track_rec to record files so I wondered what 
> would happen (without actually trying it!)
>
> Thanks for any advice on these!
>
> John Cirillo
>
>
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