Re: [LAD] Mixing audio: Noiseless volume changes

From: Harry van Haaren <harryhaaren@email-addr-hidden>
Date: Tue Mar 19 2013 - 04:09:11 EET

On Mon, Mar 18, 2013 at 11:45 PM, Fons Adriaensen <fons@email-addr-hiddenwrote:

> A critically damped
> second order lowpass with a rise time of 30 ms or so will eliminate all
> audible artefacts. It's very low on CPU and you only need to run it while
> the gain is changing.
>

Although I understand the words & their meaning, I have no idea how to
start implementing such a filter.
I've found a 1st order algorithm on musicdsp:
http://www.musicdsp.org/showone.php?id=257
Since its second order I understand it needs the previous 2 outputs.
Critically dampened implies that the "factor" of influence of the previous
samples is very close to 1 ( 'a' in the algorithm linked )

How is the "rise time" determined here?
Noobie questions :) -Harry

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Received on Tue Mar 19 04:15:05 2013

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