electro-music.com :: View topic - Hilbert transform code

| |

| | | | |

FAQ

Calendar

Memberlist

Usergroups

Links

Profile

Chat Room

Forum index » DIY Hardware and Software » ChucK programming language

Hilbert transform code

Moderators: Kassen
Page 1 of 1 [1 Post]

View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic

Author

Message

DrDoug

Joined: Feb 14, 2011
Posts: 3
Location: Cambridge

Posted: Sun Apr 01, 2018 5:47 am Post subject: Hilbert transform code

In case it's useful to anyone, here's the "Hilbert transform" ported from Pure Data.

Code:

///////////////////////////////////////////////////
// hilbert.ck - v1.0 - Douglas Nunn, April 2018
//
// IIR "Hilbert transform" - porting [hilbert~] from Pure Data to ChucK
// ("the name is abused here according to computer music tradition")
// (I Can't Believe It's Not The Analytic Signal)
//
// This is a pair of 4th-order all-pass filters whose outputs somehow manage to be about
// 90 degrees out of phase from each other. Both have different phases from the original.
// Adapted from a 4X patch by Emmanuel Favreau, circa 1982.
//
// Note that the signs of a1 and a2 are flipped compared to the pd parameters.
// This is because ChucK's BiQuad is implemented differently to pd's [biquad~].
// References
// https://ccrma.stanford.edu/~jos/filters/Direct_Form_II.html
// https://en.wikipedia.org/wiki/Digital_biquad_filter#Direct_form_2
// https://github.com/olilarkin/OL-OWLPatches/blob/master/IIRHilbert.dsp - FAUST code

class HilbertOne extends Chubgraph
{
inlet => BiQuad out1filter1 => BiQuad out1filter2 => outlet;
// [biquad~ -0.02569 0.260502 -0.260502 0.02569 1]
0.02569 => out1filter1.a1;
-0.260502 => out1filter1.a2;
-0.260502 => out1filter1.b0;
0.02569 => out1filter1.b1;
1.0 => out1filter1.b2;
// [biquad~ 1.8685 -0.870686 0.870686 -1.8685 1]
-1.8685 => out1filter2.a1;
0.870686 => out1filter2.a2;
0.870686 => out1filter2.b0;
-1.8685 => out1filter2.b1;
1.0 => out1filter2.b2;
}

class HilbertTwo extends Chubgraph
{
inlet => BiQuad out2filter1 => BiQuad out2filter2 => outlet;
// [biquad~ 1.94632 -0.94657 0.94657 -1.94632 1]
-1.94632 => out2filter1.a1;
0.94657 => out2filter1.a2;
0.94657 => out2filter1.b0;
-1.94632 => out2filter1.b1;
1.0 => out2filter1.b2;
// [biquad~ 0.83774 -0.06338 0.06338 -0.83774 1]
-0.83774 => out2filter2.a1;
0.06338 => out2filter2.a2;
0.06338 => out2filter2.b0;
-0.83774 => out2filter2.b1;
1.0 => out2filter2.b2;
}

// testing
SinOsc ef;
Std.mtof(63) => ef.freq;
0.5 => ef.gain;

ef => HilbertOne h1 => dac.chan(0);
ef => HilbertTwo h2 => dac.chan(1);

dac => WvOut2 w => blackhole;
me.dir()+"testhilbert.wav" => w.wavFilename;
null @=> w;

1982::ms => now;
/**/

Moderators: Kassen
Page 1 of 1 [1 Post]

View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic

Forum index » DIY Hardware and Software » ChucK programming language

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum

Please support our site. If you click through and buy from
our affiliate partners, we earn a small commission.