Better convolution reverb by generating impulse responses

.eslintignore

@@ -18,4 +18,5 @@ vite.config.js
 **/*.json
 **/dev-dist
 **/dist
-/src-tauri/target/**/*
+/src-tauri/target/**/*
+reverbGen.mjs

packages/core/controls.mjs

@@ -979,20 +979,64 @@ const generic_params = [
    *
    */
   [['room', 'size']],
+  /**
+   * Reverb lowpass starting frequency (in hertz).
+   * When this property is changed, the reverb will be recaculated, so only change this sparsely..
+   *
+   * @name roomlp
+   * @synonyms rlp
+   * @param {number} frequency between 0 and 20000hz
+   * @example
+   * s("bd sd").room(0.5).rlp(10000)
+   * @example
+   * s("bd sd").room(0.5).rlp(5000)
+   */
+  ['roomlp', 'rlp'],
+  /**
+   * Reverb lowpass frequency at -60dB (in hertz).
+   * When this property is changed, the reverb will be recaculated, so only change this sparsely..
+   *
+   * @name roomdim
+   * @synonyms rdim
+   * @param {number} frequency between 0 and 20000hz
+   * @example
+   * s("bd sd").room(0.5).rlp(10000).rdim(8000)
+   * @example
+   * s("bd sd").room(0.5).rlp(5000).rdim(400)
+   *
+   */
+  ['roomdim', 'rdim'],
+  /**
+   * Reverb fade time (in seconds).
+   * When this property is changed, the reverb will be recaculated, so only change this sparsely..
+   *
+   * @name roomfade
+   * @synonyms rfade
+   * @param {number} seconds for the reverb to fade
+   * @example
+   * s("bd sd").room(0.5).rlp(10000).rfade(0.5)
+   * @example
+   * s("bd sd").room(0.5).rlp(5000).rfade(4)
+   *
+   */
+  ['roomfade', 'rfade'],
   /**
    * Sets the room size of the reverb, see {@link room}.
+   * When this property is changed, the reverb will be recaculated, so only change this sparsely..
    *
    * @name roomsize
    * @param {number | Pattern} size between 0 and 10
-   * @synonyms size, sz
+   * @synonyms rsize, sz, size
+   * @example
+   * s("bd sd").room(.8).rsize(1)
    * @example
-   * s("bd sd").room(.8).roomsize("<0 1 2 4 8>")
+   * s("bd sd").room(.8).rsize(4)
    *
    */
   // TODO: find out why :
   // s("bd sd").room(.8).roomsize("<0 .2 .4 .6 .8 [1,0]>").osc()
   // .. does not work. Is it because room is only one effect?
-  ['size', 'sz', 'roomsize'],
+  ['roomsize', 'size', 'sz', 'rsize'],
   // ['sagogo'],
   // ['sclap'],
   // ['sclaves'],

packages/superdough/reverb.mjs

@@ -1,23 +1,30 @@
-if (typeof AudioContext !== 'undefined') {
-  AudioContext.prototype.impulseResponse = function (duration, channels = 1) {
-    const length = this.sampleRate * duration;
-    const impulse = this.createBuffer(channels, length, this.sampleRate);
-    const IR = impulse.getChannelData(0);
-    for (let i = 0; i < length; i++) IR[i] = (2 * Math.random() - 1) * Math.pow(1 - i / length, duration);
-    return impulse;
-  };
+import reverbGen from './reverbGen.mjs';
 
-  AudioContext.prototype.createReverb = function (duration) {
+if (typeof AudioContext !== 'undefined') {
+  AudioContext.prototype.generateReverb = reverbGen.generateReverb;
+  AudioContext.prototype.createReverb = function (duration, fade, lp, dim) {
     const convolver = this.createConvolver();
-    convolver.setDuration = (d) => {
-      convolver.buffer = this.impulseResponse(d);
-      convolver.duration = duration;
-      return convolver;
+    convolver.generate = (d, fade, lp, dim) => {
+      this.generateReverb(
+        {
+          audioContext: this,
+          sampleRate: 44100,
+          numChannels: 2,
+          decayTime: d,
+          fadeInTime: fade,
+          lpFreqStart: lp,
+          lpFreqEnd: dim,
+        },
+        (buffer) => {
+          convolver.buffer = buffer;
+        },
+      );
+      convolver.duration = d;
+      convolver.fade = fade;
+      convolver.lp = lp;
+      convolver.dim = dim;
     };
-    convolver.setDuration(duration);
+    convolver.generate(duration, fade, lp, dim);
     return convolver;
   };
 }
-
-// TODO: make the reverb more exciting
-// check out https://blog.gskinner.com/archives/2019/02/reverb-web-audio-api.html

packages/superdough/reverbGen.mjs

@@ -0,0 +1,129 @@
+// Copyright 2014 Alan deLespinasse
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+var reverbGen = {};
+
+/** Generates a reverb impulse response.
+
+    @param {!Object} params TODO: Document the properties.
+    @param {!function(!AudioBuffer)} callback Function to call when
+      the impulse response has been generated. The impulse response
+      is passed to this function as its parameter. May be called
+      immediately within the current execution context, or later. */
+reverbGen.generateReverb = function (params, callback) {
+  var audioContext = params.audioContext || new AudioContext();
+  var sampleRate = params.sampleRate || 44100;
+  var numChannels = params.numChannels || 2;
+  // params.decayTime is the -60dB fade time. We let it go 50% longer to get to -90dB.
+  var totalTime = params.decayTime * 1.5;
+  var decaySampleFrames = Math.round(params.decayTime * sampleRate);
+  var numSampleFrames = Math.round(totalTime * sampleRate);
+  var fadeInSampleFrames = Math.round((params.fadeInTime || 0) * sampleRate);
+  // 60dB is a factor of 1 million in power, or 1000 in amplitude.
+  var decayBase = Math.pow(1 / 1000, 1 / decaySampleFrames);
+  var reverbIR = audioContext.createBuffer(numChannels, numSampleFrames, sampleRate);
+  for (var i = 0; i < numChannels; i++) {
+    var chan = reverbIR.getChannelData(i);
+    for (var j = 0; j < numSampleFrames; j++) {
+      chan[j] = randomSample() * Math.pow(decayBase, j);
+    }
+    for (var j = 0; j < fadeInSampleFrames; j++) {
+      chan[j] *= j / fadeInSampleFrames;
+    }
+  }
+
+  applyGradualLowpass(reverbIR, params.lpFreqStart || 0, params.lpFreqEnd || 0, params.decayTime, callback);
+};
+
+/** Creates a canvas element showing a graph of the given data.
+
+    @param {!Float32Array} data An array of numbers, or a Float32Array.
+    @param {number} width Width in pixels of the canvas.
+    @param {number} height Height in pixels of the canvas.
+    @param {number} min Minimum value of data for the graph (lower edge).
+    @param {number} max Maximum value of data in the graph (upper edge).
+    @return {!CanvasElement} The generated canvas element. */
+reverbGen.generateGraph = function (data, width, height, min, max) {
+  var canvas = document.createElement('canvas');
+  canvas.width = width;
+  canvas.height = height;
+  var gc = canvas.getContext('2d');
+  gc.fillStyle = '#000';
+  gc.fillRect(0, 0, canvas.width, canvas.height);
+  gc.fillStyle = '#fff';
+  var xscale = width / data.length;
+  var yscale = height / (max - min);
+  for (var i = 0; i < data.length; i++) {
+    gc.fillRect(i * xscale, height - (data[i] - min) * yscale, 1, 1);
+  }
+  return canvas;
+};
+
+/** Applies a constantly changing lowpass filter to the given sound.
+
+    @private
+    @param {!AudioBuffer} input
+    @param {number} lpFreqStart
+    @param {number} lpFreqEnd
+    @param {number} lpFreqEndAt
+    @param {!function(!AudioBuffer)} callback May be called
+    immediately within the current execution context, or later.*/
+var applyGradualLowpass = function (input, lpFreqStart, lpFreqEnd, lpFreqEndAt, callback) {
+  if (lpFreqStart == 0) {
+    callback(input);
+    return;
+  }
+  var channelData = getAllChannelData(input);
+  var context = new OfflineAudioContext(input.numberOfChannels, channelData[0].length, input.sampleRate);
+  var player = context.createBufferSource();
+  player.buffer = input;
+  var filter = context.createBiquadFilter();
+
+  lpFreqStart = Math.min(lpFreqStart, input.sampleRate / 2);
+  lpFreqEnd = Math.min(lpFreqEnd, input.sampleRate / 2);
+
+  filter.type = 'lowpass';
+  filter.Q.value = 0.0001;
+  filter.frequency.setValueAtTime(lpFreqStart, 0);
+  filter.frequency.linearRampToValueAtTime(lpFreqEnd, lpFreqEndAt);
+
+  player.connect(filter);
+  filter.connect(context.destination);
+  player.start();
+  context.oncomplete = function (event) {
+    callback(event.renderedBuffer);
+  };
+  context.startRendering();
+
+  window.filterNode = filter;
+};
+
+/** @private
+    @param {!AudioBuffer} buffer
+    @return {!Array.<!Float32Array>} An array containing the Float32Array of each channel's samples. */
+var getAllChannelData = function (buffer) {
+  var channels = [];
+  for (var i = 0; i < buffer.numberOfChannels; i++) {
+    channels[i] = buffer.getChannelData(i);
+  }
+  return channels;
+};
+
+/** @private
+    @return {number} A random number from -1 to 1. */
+var randomSample = function () {
+  return Math.random() * 2 - 1;
+};
+
+export default reverbGen;

packages/superdough/superdough.mjs

@@ -107,17 +107,25 @@ function getDelay(orbit, delaytime, delayfeedback, t) {
 }
 
 let reverbs = {};
-function getReverb(orbit, duration = 2) {
+
+function getReverb(orbit, duration = 2, fade, lp, dim) {
+  // If no reverb has been created for a given orbit, create one
   if (!reverbs[orbit]) {
     const ac = getAudioContext();
-    const reverb = ac.createReverb(duration);
+    const reverb = ac.createReverb(duration, fade, lp, dim);
     reverb.connect(getDestination());
     reverbs[orbit] = reverb;
   }
-  if (reverbs[orbit].duration !== duration) {
-    reverbs[orbit] = reverbs[orbit].setDuration(duration);
-    reverbs[orbit].duration = duration;
+
+  if (
+    reverbs[orbit].duration !== duration ||
+    reverbs[orbit].fade !== fade ||
+    reverbs[orbit].lp !== lp ||
+    reverbs[orbit].dim !== dim
+  ) {
+    reverbs[orbit].generate(duration, fade, lp, dim);
   }
+
   return reverbs[orbit];
 }
 
@@ -215,7 +223,10 @@ export const superdough = async (value, deadline, hapDuration) => {
     delaytime = 0.25,
     orbit = 1,
     room,
-    size = 2,
+    roomfade = 0.1,
+    roomlp = 15000,
+    roomdim = 1000,
+    roomsize = 2,
     velocity = 1,
     analyze, // analyser wet
     fft = 8, // fftSize 0 - 10
@@ -353,8 +364,8 @@ export const superdough = async (value, deadline, hapDuration) => {
   }
   // reverb
   let reverbSend;
-  if (room > 0 && size > 0) {
-    const reverbNode = getReverb(orbit, size);
+  if (room > 0 && roomsize > 0) {
+    const reverbNode = getReverb(orbit, roomsize, roomfade, roomlp, roomdim);
     reverbSend = effectSend(post, reverbNode, room);
   }