Merge pull request #820 from daslyfe/multichannel_audio

Multichannel audio

packages/core/controls.mjs

@@ -381,6 +381,19 @@ const generic_params = [
    */
   ['coarse'],
 
+  /**
+   * Allows you to set the output channels on the interface
+   *
+   * @name channels
+   * @synonyms ch
+   *
+   * @param {number | Pattern} channels pattern the output channels
+   * @example
+   * note("e a d b g").channels("3:4")
+   *
+   */
+  ['channels', 'ch'],
+
   ['phaserrate', 'phasr'], // superdirt only
 
   /**

packages/superdough/superdough.mjs

@@ -27,28 +27,16 @@ export function getSound(s) {
 export const resetLoadedSounds = () => soundMap.set({});
 
 let audioContext;
+
 export const getAudioContext = () => {
   if (!audioContext) {
     audioContext = new AudioContext();
+    const maxChannelCount = audioContext.destination.maxChannelCount;
+    audioContext.destination.channelCount = maxChannelCount;
   }
   return audioContext;
 };
 
-let destination;
-const getDestination = () => {
-  const ctx = getAudioContext();
-  if (!destination) {
-    destination = ctx.createGain();
-    destination.connect(ctx.destination);
-  }
-  return destination;
-};
-
-export const panic = () => {
-  getDestination().gain.linearRampToValueAtTime(0, getAudioContext().currentTime + 0.01);
-  destination = null;
-};
-
 let workletsLoading;
 
 function loadWorklets() {
@@ -95,6 +83,39 @@ export async function initAudioOnFirstClick(options) {
 let delays = {};
 const maxfeedback = 0.98;
 
+let channelMerger, destinationGain;
+
+// input: AudioNode, channels: ?Array<int>
+export const connectToDestination = (input, channels = [0, 1]) => {
+  const ctx = getAudioContext();
+  if (channelMerger == null) {
+    channelMerger = new ChannelMergerNode(ctx, { numberOfInputs: ctx.destination.channelCount });
+    destinationGain = new GainNode(ctx);
+    channelMerger.connect(destinationGain);
+    destinationGain.connect(ctx.destination);
+  }
+  //This upmix can be removed if correct channel counts are set throughout the app,
+  // and then strudel could theoretically support surround sound audio files
+  const stereoMix = new StereoPannerNode(ctx);
+  input.connect(stereoMix);
+
+  const splitter = new ChannelSplitterNode(ctx, {
+    numberOfOutputs: stereoMix.channelCount,
+  });
+  stereoMix.connect(splitter);
+  channels.forEach((ch, i) => {
+    splitter.connect(channelMerger, i % stereoMix.channelCount, clamp(ch, 0, ctx.destination.channelCount - 1));
+  });
+};
+
+export const panic = () => {
+  if (destinationGain == null) {
+    return;
+  }
+  destinationGain.gain.linearRampToValueAtTime(0, getAudioContext().currentTime + 0.01);
+  destinationGain = null;
+};
+
 function getDelay(orbit, delaytime, delayfeedback, t) {
   if (delayfeedback > maxfeedback) {
     //logger(`delayfeedback was clamped to ${maxfeedback} to save your ears`);
@@ -104,7 +125,7 @@ function getDelay(orbit, delaytime, delayfeedback, t) {
     const ac = getAudioContext();
     const dly = ac.createFeedbackDelay(1, delaytime, delayfeedback);
     dly.start?.(t); // for some reason, this throws when audion extension is installed..
-    dly.connect(getDestination());
+    connectToDestination(dly, [0, 1]);
     delays[orbit] = dly;
   }
   delays[orbit].delayTime.value !== delaytime && delays[orbit].delayTime.setValueAtTime(delaytime, t);
@@ -163,7 +184,7 @@ function getReverb(orbit, duration, fade, lp, dim, ir) {
   if (!reverbs[orbit]) {
     const ac = getAudioContext();
     const reverb = ac.createReverb(duration, fade, lp, dim, ir);
-    reverb.connect(getDestination());
+    connectToDestination(reverb, [0, 1]);
     reverbs[orbit] = reverb;
   }
   if (
@@ -269,7 +290,7 @@ export const superdough = async (value, deadline, hapDuration) => {
     bpsustain = 1,
     bprelease = 0.01,
     bandq = 1,
-
+    channels = [1, 2],
     //phaser
     phaser,
     phaserdepth = 0.75,
@@ -301,6 +322,10 @@ export const superdough = async (value, deadline, hapDuration) => {
     compressorAttack,
     compressorRelease,
   } = value;
+
+  //music programs/audio gear usually increments inputs/outputs from 1, so imitate that behavior
+  channels = (Array.isArray(channels) ? channels : [channels]).map((ch) => ch - 1);
+
   gain *= velocity; // legacy fix for velocity
   let toDisconnect = []; // audio nodes that will be disconnected when the source has ended
   const onended = () => {
@@ -434,9 +459,9 @@ export const superdough = async (value, deadline, hapDuration) => {
   }
 
   // last gain
-  const post = gainNode(postgain);
+  const post = new GainNode(ac, { gain: postgain });
   chain.push(post);
-  post.connect(getDestination());
+  connectToDestination(post, channels);
 
   // delay
   let delaySend;