[v0.5.31] adds bpf and hpf, updates lpf. all use new BiQuadFilter mid…

…dleware with configurable cutoff and q
nnirror · Mar 22, 2023 · f51dedd · f51dedd
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diff --git a/README.md b/README.md
@@ -324,6 +324,11 @@ You might need to activate a MIDI driver on your machine in order to send MIDI f
 		- `$('example').turing(16).at(0,1); // the 1st value of the 16-step Turing sequence (i.e. 0% position) is always 1`
 		- `$('example').turing(16).at(0.5,2); // the 9th value of the 16-step Turing sequence (i.e. 50% position) is always 2`
 ---
+- **bpf** ( _cutoff_ = 1000, _q_ = 2.5 )
+	- applies a bandpass filter with configurable `cutoff` and `q` to the FacetPattern.
+	- example:
+		- `$('example').noise(n1).bpf(1000,6).gain(0.1).play(); // band-passed noise`
+---
 - **changed** ( )
 	- returns a 1 or 0 for each value in the FacetPattern. If the value is different than the previous value, returns a 1. Otherwise returns a 0. (The first value is compared against the last value in the FacetPattern.)
 	- example:
@@ -415,6 +420,11 @@ You might need to activate a MIDI driver on your machine in order to send MIDI f
 	- example:
 		- `$('example').from([0.1,0.3,0.5,0.7]).gte(0.5); // 0 0 1 1`
 ---
+- **hpf** ( _cutoff_ = 100, _q_ = 2.5 )
+	- applies a high pass filter with configurable `cutoff` and `q` to the FacetPattern.
+	- example:
+		- `$('example').noise(n1).hpf(2000,6).gain(0.1).play(); // high-passed noise`
+---
 - **ifft** ( )
 	- computes the IFFT of the FacetPattern. Typically it would be used to reconstruct a FacetPattern after it had been translated into "phase data". But you can run an IFFT on any data.
 	- example:
@@ -459,9 +469,9 @@ You might need to activate a MIDI driver on your machine in order to send MIDI f
 		- `$('example').ramp(1,0,1000).log(100); // a logarithmic curve from 1 to 0`
 ---
 - **lpf** ( _cutoff_ )
-	- applies a simple low pass filter to the FacetPattern.
+	- applies a low pass filter with configurable `cutoff` and `q` to the FacetPattern.
 	- example:
-		- `$('example').noise(n1).lpf(random(1,1000)); // low-passed noise`
+		- `$('example').noise(n1).lpf(1000,6).gain(0.1).play(); // low-passed noise`
 ---
 - **modulo** ( _amt_ )
 	- returns the modulo i.e. `% amt` calculation for each value in the FacetPattern.

diff --git a/js/FacetPattern.js b/js/FacetPattern.js
@@ -5,6 +5,7 @@ const WaveFile = require('wavefile').WaveFile;
 const FacetConfig = require('./config.js');
 const FACET_SAMPLE_RATE = FacetConfig.settings.SAMPLE_RATE;
 const curve_calc = require('./lib/curve_calc.js');
+const BiQuadFilter = require('./lib/BiQuadFilter.js').BiQuadFilter;
 const FFT = require('./lib/fft.js');
 const { Midi, Scale } = require("tonal");
 const http = require('http');
@@ -1163,25 +1164,43 @@ class FacetPattern {
     return this;
   }
 
-  lpf (cutoff) {
-    // copy-modded from: https://github.com/rochars/low-pass-filter/blob/master/index.js
-    let numChannels = 1;
-    let rc = 1.0 / (cutoff * 2 * Math.PI);
-    let dt = 1.0 / FACET_SAMPLE_RATE;
-    let alpha = dt / (rc + dt);
-    let last_val = [];
-    let offset;
-    for (let i=0; i<numChannels; i++) {
-        last_val[i] = this.data[i];
+
+  lpf (cutoff = 2000 , q = 2.5) {
+    // first argument is 0 for type = lpf. last arg is the filter gain (1)
+    BiQuadFilter.create(0,cutoff,FACET_SAMPLE_RATE,q,1);
+    let out = [];
+    for ( var i = 1; i < 6; i++ ) {
+      var v = BiQuadFilter.constants()[i-1];
+      v = BiQuadFilter.formatNumber(v,8);
+      out.push(v);
     }
-    for (let i=0; i<this.data.length; i++) {
-      for (let j=0; j< numChannels; j++) {
-          offset = (i * numChannels) + j;
-          last_val[j] =
-              last_val[j] + (alpha * (this.data[offset] - last_val[j]));
-          this.data[offset] = last_val[j];
-      }
+    this.biquad(out[2],out[3],out[4],out[0],out[1]);
+    return this;
+  }
+
+  hpf (cutoff = 100, q = 2.5) {
+    // first argument is 1 for type = hpf. last arg is the filter gain (1)
+    BiQuadFilter.create(1,cutoff,FACET_SAMPLE_RATE,q,1);
+    let out = [];
+    for ( var i = 1; i < 6; i++ ) {
+      var v = BiQuadFilter.constants()[i-1];
+      v = BiQuadFilter.formatNumber(v,8);
+      out.push(v);
+    }
+    this.biquad(out[2],out[3],out[4],out[0],out[1]);
+    return this;
+  }
+
+  bpf (cutoff = 1000, q = 2.5) {
+    // first argument is 2 for type = bpf. last arg is the filter gain (1)
+    BiQuadFilter.create(2,cutoff,FACET_SAMPLE_RATE,q,1);
+    let out = [];
+    for ( var i = 1; i < 6; i++ ) {
+      var v = BiQuadFilter.constants()[i-1];
+      v = BiQuadFilter.formatNumber(v,8);
+      out.push(v);
     }
+    this.biquad(out[2],out[3],out[4],out[0],out[1]);
     return this;
   }
 

diff --git a/js/lib/BiQuadFilter.js b/js/lib/BiQuadFilter.js
@@ -0,0 +1,228 @@
+// copy-modded from: https://arachnoid.com/BiQuadDesigner/index.html
+/***************************************************************************
+ *   Copyright (C) 2017, Paul Lutus                                        *
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ *   This program is distributed in the hope that it will be useful,       *
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+ *   GNU General Public License for more details.                          *
+ *                                                                         *
+ *   You should have received a copy of the GNU General Public License     *
+ *   along with this program; if not, write to the                         *
+ *   Free Software Foundation, Inc.,                                       *
+ *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
+ ***************************************************************************/
+
+var BiQuadFilter = BiQuadFilter || {}
+
+
+BiQuadFilter.LOWPASS = 0;
+BiQuadFilter.HIGHPASS = 1;
+BiQuadFilter.BANDPASS = 2;
+BiQuadFilter.PEAK = 3;
+BiQuadFilter.NOTCH = 4;
+BiQuadFilter.LOWSHELF = 5;
+BiQuadFilter.HIGHSHELF = 6;
+
+BiQuadFilter.a0 = 0;
+BiQuadFilter.a1 = 0;
+BiQuadFilter.a2 = 0;
+BiQuadFilter.b0 = 0;
+BiQuadFilter.b1 = 0;
+BiQuadFilter.b2 = 0;
+BiQuadFilter.x1 = 0;
+BiQuadFilter.x2 = 0;
+BiQuadFilter.y1 = 0;
+BiQuadFilter.y2 = 0;
+BiQuadFilter.type = 0;
+BiQuadFilter.center_freq = 0;
+BiQuadFilter.sample_rate = 0;
+BiQuadFilter.Q = 0;
+BiQuadFilter.gainDB = 0;
+
+BiQuadFilter.create = function(type, center_freq, sample_rate, Q, gainDB = 0) {
+  BiQuadFilter.configure(type, center_freq, sample_rate, Q, gainDB);
+}
+
+BiQuadFilter.reset = function() {
+  BiQuadFilter.x1 = BiQuadFilter.x2 = BiQuadFilter.y1 = BiQuadFilter.y2 = 0;
+}
+
+BiQuadFilter.frequency = function() {
+  return BiQuadFilter.center_freq;
+}
+
+BiQuadFilter.configure = function(type,center_freq,sample_rate, Q, gainDB) {
+  BiQuadFilter.functions = [
+  BiQuadFilter.f_lowpass,
+  BiQuadFilter.f_highpass,
+  BiQuadFilter.f_bandpass,
+  BiQuadFilter.f_peak,
+  BiQuadFilter.f_notch,
+  BiQuadFilter.f_lowshelf,
+  BiQuadFilter.f_highshelf
+  ];
+  BiQuadFilter.reset();
+  BiQuadFilter.Q = (Q == 0) ? 1e-9 : Q;
+  BiQuadFilter.type = type;
+  BiQuadFilter.sample_rate = sample_rate;
+  BiQuadFilter.gainDB = gainDB;
+  BiQuadFilter.reconfigure(center_freq);
+}
+
+// allow parameter change while running
+BiQuadFilter.reconfigure = function(cf) {
+  BiQuadFilter.center_freq = cf;
+  // only used for peaking and shelving filters
+  var gain_abs = Math.pow(10, BiQuadFilter.gainDB / 40);
+  var omega = 2 * Math.PI * cf / BiQuadFilter.sample_rate;
+  var sn = Math.sin(omega);
+  var cs = Math.cos(omega);
+  var alpha = sn / (2 * BiQuadFilter.Q);
+  var beta = Math.sqrt(gain_abs + gain_abs);
+
+  // call the corresponding setup function
+  BiQuadFilter.functions[BiQuadFilter.type](gain_abs,omega,sn,cs,alpha,beta);
+
+  // by prescaling filter constants, eliminate one variable
+  BiQuadFilter.b0 /= BiQuadFilter.a0;
+  BiQuadFilter.b1 /= BiQuadFilter.a0;
+  BiQuadFilter.b2 /= BiQuadFilter.a0;
+  BiQuadFilter.a1 /= BiQuadFilter.a0;
+  BiQuadFilter.a2 /= BiQuadFilter.a0;
+}
+
+BiQuadFilter.f_bandpass = function(gain_abs,omega,sn,cs,alpha,beta) {
+  BiQuadFilter.b0 = alpha;
+  BiQuadFilter.b1 = 0;
+  BiQuadFilter.b2 = -alpha;
+  BiQuadFilter.a0 = 1 + alpha;
+  BiQuadFilter.a1 = -2 * cs;
+  BiQuadFilter.a2 = 1 - alpha;
+}
+
+BiQuadFilter.f_lowpass = function(gain_abs,omega,sn,cs,alpha,beta) {
+  BiQuadFilter.b0 = (1 - cs) / 2;
+  BiQuadFilter.b1 = 1 - cs;
+  BiQuadFilter.b2 = (1 - cs) / 2;
+  BiQuadFilter.a0 = 1 + alpha;
+  BiQuadFilter.a1 = -2 * cs;
+  BiQuadFilter.a2 = 1 - alpha;
+}
+
+BiQuadFilter.f_highpass = function(gain_abs,omega,sn,cs,alpha,beta) {
+  BiQuadFilter.b0 = (1 + cs) / 2;
+  BiQuadFilter.b1 = -(1 + cs);
+  BiQuadFilter.b2 = (1 + cs) / 2;
+  BiQuadFilter.a0 = 1 + alpha;
+  BiQuadFilter.a1 = -2 * cs;
+  BiQuadFilter.a2 = 1 - alpha;
+}
+
+BiQuadFilter.f_notch = function(gain_abs,omega,sn,cs,alpha,beta) {
+  BiQuadFilter.b0 = 1;
+  BiQuadFilter.b1 = -2 * cs;
+  BiQuadFilter.b2 = 1;
+  BiQuadFilter.a0 = 1 + alpha;
+  BiQuadFilter.a1 = -2 * cs;
+  BiQuadFilter.a2 = 1 - alpha;
+}
+
+BiQuadFilter.f_peak = function(gain_abs,omega,sn,cs,alpha,beta) {
+  BiQuadFilter.b0 = 1 + (alpha * gain_abs);
+  BiQuadFilter.b1 = -2 * cs;
+  BiQuadFilter.b2 = 1 - (alpha * gain_abs);
+  BiQuadFilter.a0 = 1 + (alpha / gain_abs);
+  BiQuadFilter.a1 = -2 * cs;
+  BiQuadFilter.a2 = 1 - (alpha / gain_abs);
+}
+
+BiQuadFilter.f_lowshelf = function(gain_abs,omega,sn,cs,alpha,beta) {
+  BiQuadFilter.b0 = gain_abs * ((gain_abs + 1) - (gain_abs - 1) * cs + beta * sn);
+  BiQuadFilter.b1 = 2 * gain_abs * ((gain_abs - 1) - (gain_abs + 1) * cs);
+  BiQuadFilter.b2 = gain_abs * ((gain_abs + 1) - (gain_abs - 1) * cs - beta * sn);
+  BiQuadFilter.a0 = (gain_abs + 1) + (gain_abs - 1) * cs + beta * sn;
+  BiQuadFilter.a1 = -2 * ((gain_abs - 1) + (gain_abs + 1) * cs);
+  BiQuadFilter.a2 = (gain_abs + 1) + (gain_abs - 1) * cs - beta * sn;
+}
+
+BiQuadFilter.f_highshelf = function(gain_abs,omega,sn,cs,alpha,beta) {
+  BiQuadFilter.b0 = gain_abs * ((gain_abs + 1) + (gain_abs - 1) * cs + beta * sn);
+  BiQuadFilter.b1 = -2 * gain_abs * ((gain_abs - 1) + (gain_abs + 1) * cs);
+  BiQuadFilter.b2 = gain_abs * ((gain_abs + 1) + (gain_abs - 1) * cs - beta * sn);
+  BiQuadFilter.a0 = (gain_abs + 1) - (gain_abs - 1) * cs + beta * sn;
+  BiQuadFilter.a1 = 2 * ((gain_abs - 1) - (gain_abs + 1) * cs);
+  BiQuadFilter.a2 = (gain_abs + 1) - (gain_abs - 1) * cs - beta * sn;
+}
+
+// provide a static amplitude result for testing
+BiQuadFilter.result = function(f) {
+  var phi = Math.pow((Math.sin(2.0 * Math.PI * f / (2.0 * BiQuadFilter.sample_rate))), 2.0);
+  var r = (Math.pow(BiQuadFilter.b0 + BiQuadFilter.b1 + BiQuadFilter.b2, 2.0) - 4.0 * (BiQuadFilter.b0 * BiQuadFilter.b1 + 4.0 * BiQuadFilter.b0 * BiQuadFilter.b2 + BiQuadFilter.b1 * BiQuadFilter.b2) * phi + 16.0 * BiQuadFilter.b0 * BiQuadFilter.b2 * phi * phi) / (Math.pow(1.0 + BiQuadFilter.a1 + BiQuadFilter.a2, 2.0) - 4.0 * (BiQuadFilter.a1 + 4.0 * BiQuadFilter.a2 + BiQuadFilter.a1 * BiQuadFilter.a2) * phi + 16.0 * BiQuadFilter.a2 * phi * phi);
+  r = (r < 0)?0:r;
+  return Math.sqrt(r);
+}
+
+// provide a static decibel result for testing
+BiQuadFilter.log_result = function(f) {
+  var r;
+  try {
+    r = 20 * Math.log10(BiQuadFilter.result(f));
+  }
+  catch (e) {
+    //console.log(e);
+    r = -100;
+  }
+  if(!isFinite(r) || isNaN(r)) {
+    r = -100;
+  }
+  return r;
+}
+
+// return the constant set for this filter
+BiQuadFilter.constants = function() {
+  return [BiQuadFilter.a1, BiQuadFilter.a2,BiQuadFilter.b0, BiQuadFilter.b1, BiQuadFilter.b2];
+}
+
+// perform one filtering step
+BiQuadFilter.filter = function(x) {
+  var y = BiQuadFilter.b0 * x + BiQuadFilter.b1 * BiQuadFilter.x1 + BiQuadFilter.b2 * BiQuadFilter.x2 - BiQuadFilter.a1 * BiQuadFilter.y1 - BiQuadFilter.a2 * BiQuadFilter.y2;
+  BiQuadFilter.x2 = BiQuadFilter.x1;
+  BiQuadFilter.x1 = BiQuadFilter.x;
+  BiQuadFilter.y2 = BiQuadFilter.y1;
+  BiQuadFilter.y1 = y;
+  return (y);
+}
+
+BiQuadFilter.formatNumber = function(n,p) {
+  return n.toFixed(p);
+}
+
+module.exports = {
+  BiQuadFilter: BiQuadFilter
+};
+
+// filter type, cutoff, sr, q, gain
+// BiQuadFilter.create(0,100,44100,2.5,1);
+//   let lemma = [];
+//   let out = [];
+//   for(var i = 1; i < 6;i++) {
+//     var v = BiQuadFilter.constants()[i-1]; // contains [a1,a2,b0,b1,b2]
+//     v = BiQuadFilter.formatNumber(v,8);
+//     lemma.push(v);
+//   }
+//   out[0] = lemma[2];
+//   out[1] = lemma[3];
+//   out[2] = lemma[4];
+//   out[3] = lemma[0];
+//   out[4] = lemma[1];
+//   console.log(out);
+//   // the numbers in out can go directly into biquad.
+//   // all you need to do is create different functions that are for filter type: bandpass = 2, lowpass = 0, highpass = 1  to start
+//   // then you send the sample rate constant and the gain as 1
+//   // and it's only cutoff and q that are the arguments.
diff --git a/package-lock.json b/package-lock.json
diff --git a/package.json b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "facet",
-  "version": "0.5.30",
+  "version": "0.5.31",
   "description": "Facet is a live coding system for algorithmic music",
   "main": "index.js",
   "directories": {