On Tue, Mar 19, 2013 at 04:26:21AM +0100, Tim Goetze wrote:
> A 2nd-order IIR filter is often called a "biquad"; at musicdsp, look
> for that instead.
Not really. A biquad is one way to implement a 2nd order IIR, and
in many cases related to audio DSP, not really the best way.
Anyway, using a
On Tue, Mar 19, 2013 at 1:02 PM, Fons Adriaensen wrote:
> The code below will do the trick
>
Brilliant, thanks for sharing. Will be implementing & learning from this
later, appreciated!
-Harry
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[Fons Adriaensen]
>On Tue, Mar 19, 2013 at 04:26:21AM +0100, Tim Goetze wrote:
>> A 2nd-order IIR filter is often called a "biquad"; at musicdsp, look
>> for that instead.
>
>Not really. A biquad is one way to implement a 2nd order IIR, and
>in many cases related to audio DSP, not really the best
On Tue, Mar 19, 2013 at 03:02:19PM +0100, Tim Goetze wrote:
> > for (i = 0; i < nframes; i++)
> > {
> > g1 += w * (gt - g1 - a * g2);
> > g2 += w * (b * g1 - g2);
> > out [i] = g2 * in [i];
> > }
>
> Surely you realise this version executes exactly as many additions and
> multiplicati
[Fons Adriaensen]
>On Tue, Mar 19, 2013 at 03:02:19PM +0100, Tim Goetze wrote:
>> Surely you realise this version executes exactly as many additions and
>> multiplications per sample as a biquad?
>
>Yes. In this case it's possible to remove one multiplication:
>
>a = 0.07f;
>b = 1 + a;
>
>// ...
>
On Tue, Mar 19, 2013 at 04:46:10PM +0100, Tim Goetze wrote:
> However, I still take issue with the rather exaggerated claim that
> using a biquad to smoothen gain changes would be "giant overkill". It
> may be slightly less efficient than your now optimised version, but
> certainly not enough to
Spring is nigh.
Qtractor 0.5.8 (india romeo) is out, singing a serenade...
Nothing but the change-log (see below:))
Enjoy && lots of fun.
Website:
http://qtractor.sourceforge.net
Project page:
http://sourceforge.net/projects/qtractor
Downloads:
- source tarball:
http://downloads.s
[Fons Adriaensen]
>Exactly the same with the form I proposed, w, a, b need to be computed
>just once, not for every gain change. In fact only w depends on the
>sample rate, a and b are fixed constants.
Ah yes, sorry, I see that now.
If that extra operation comes around to bite hard enough, I'l
Hi all,
Hopefully this will be useful to others. I just wrote a short note
describing my experiences when moving from a SysV init script based
OpenMixer[*] system to one that uses systemd. In short, yes, it is
possible, no, it was not easy (mostly because of my own ignorance of
systemd, of co
On Tue, Mar 19, 2013 at 08:15:41PM +0100, Tim Goetze wrote:
> [Fons Adriaensen]
> >Exactly the same with the form I proposed, w, a, b need to be computed
> >just once, not for every gain change. In fact only w depends on the
> >sample rate, a and b are fixed constants.
>
> Ah yes, sorry, I see th
On Tue, Mar 19, 2013 at 2:15 PM, Tim Goetze wrote:
> [Fons Adriaensen]
> >Exactly the same with the form I proposed, w, a, b need to be computed
> >just once, not for every gain change. In fact only w depends on the
> >sample rate, a and b are fixed constants.
>
> Ah yes, sorry, I see that now.
>
On Tue, Mar 19, 2013 at 05:26:27PM -0500, Charles Z Henry wrote:
> You guys are splitting hairs... kind of misses the forest for the trees.
> Here's my nit to pick: two identical 1st-order lowpass filters in series
> are only equivalent to a 2nd-order lowpass filter when the quality factor
> is 0.
On Tue, Mar 19, 2013 at 5:57 PM, Fons Adriaensen wrote:
> On Tue, Mar 19, 2013 at 05:26:27PM -0500, Charles Z Henry wrote:
>
> > You guys are splitting hairs... kind of misses the forest for the trees.
> > Here's my nit to pick: two identical 1st-order lowpass filters in series
> > are only equiva
On Tue, Mar 19, 2013 at 06:12:21PM -0500, Charles Z Henry wrote:
> If it was always a fixed time over which you need to fade in, I think you
> could find a good analytical function to use, or make a table that always
> has a predictable effect.
Raised cosine is a good solution, but you don't need
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