Merge pull request #26 from tidalcycles/webaudio

webaudio package

.gitignore

@@ -26,4 +26,5 @@ node_modules/
 .DS_Store
 repl-parcel
 mytunes.ts
-doc
+doc
+.parcel-cache

packages/webaudio/README.md

@@ -0,0 +1,29 @@
+# @strudel.cycles/webaudio
+
+This package contains a scheduler + a clockworker and synths based on the Web Audio API.
+It's an alternative to `@strudel.cycles/tone`, with better performance, but less features.
+
+## Install
+
+```sh
+npm i @strudel.cycles/webaudio --save
+```
+
+## Example
+
+```js
+import { Scheduler, getAudioContext } from '@strudel.cycles/webaudio';
+
+const scheduler = new Scheduler({
+    audioContext: getAudioContext(),
+    interval: 0.1,
+    onEvent: (e) => e.context?.createAudioNode?.(e),
+  });
+const pattern = sequence([55, 99], 110).osc('sawtooth').out()
+scheduler.setPattern(pattern);
+scheduler.start()
+//scheduler.stop()
+```
+
+A more sophisticated example can be found in [examples/repl.html](./examples/repl.html).
+You can run it inside this directory with `npm run example`.

packages/webaudio/clockworker.mjs

@@ -0,0 +1,69 @@
+// helpers to create a worker dynamically without needing a server / extra file
+const stringifyFunction = (func) => '(' + func + ')();';
+const urlifyFunction = (func) => URL.createObjectURL(new Blob([stringifyFunction(func)], { type: 'text/javascript' }));
+const createWorker = (func) => new Worker(urlifyFunction(func));
+
+// this class is basically the tale of two clocks
+class ClockWorker {
+  worker;
+  audioContext;
+  interval = 0.2; // query span
+  lastEnd = 0;
+  constructor(audioContext, callback, interval = this.interval) {
+    this.audioContext = audioContext;
+    this.interval = interval;
+    this.worker = createWorker(() => {
+      // we cannot use closures here!
+      let interval;
+      let timerID = null; // this is clock #1 (the sloppy js clock)
+      const clear = () => {
+        if (timerID) {
+          clearInterval(timerID);
+          timerID = null;
+        }
+      };
+      const start = () => {
+        clear();
+        if (!interval) {
+          throw new Error('no interval set! call worker.postMessage({interval}) before starting.');
+        }
+        timerID = setInterval(() => postMessage('tick'), interval * 1000);
+      };
+      self.onmessage = function (e) {
+        if (e.data == 'start') {
+          start();
+        } else if (e.data.interval) {
+          interval = e.data.interval;
+          if (timerID) {
+            start();
+          }
+        } else if (e.data == 'stop') {
+          clear();
+        }
+      };
+    });
+    this.worker.postMessage({ interval });
+    // const round = (n, d) => Math.round(n * d) / d;
+    const precision = 100;
+    this.worker.onmessage = (e) => {
+      if (e.data === 'tick') {
+        const begin = this.lastEnd || this.audioContext.currentTime;
+        const end = this.audioContext.currentTime + this.interval; // DONT reference begin here!
+        this.lastEnd = end;
+        // callback with query span, using clock #2 (the audio clock)
+        callback(begin, end);
+      }
+    };
+  }
+  start() {
+    console.log('start...');
+    this.audioContext.resume();
+    this.worker.postMessage('start');
+  }
+  stop() {
+    console.log('stop...');
+    this.worker.postMessage('stop');
+  }
+}
+
+export default ClockWorker;

packages/webaudio/examples/repl.html

@@ -0,0 +1,61 @@
+<div style="position: absolute; top: 0; right: 0; padding: 4px">
+  <button id="start" style="margin-bottom: 4px; font-size: 2em">start</button><br />
+  <button id="stop" style="font-size: 2em">stop</button>
+</div>
+<textarea
+  style="font-size: 2em; background: #e8d565; color: #323230; height: 100%; width: 100%; outline: none; border: 0"
+  id="text"
+  spellcheck="false"
+>
+Loading...</textarea
+>
+<script type="module">
+  document.body.style = 'margin: 0';
+  import * as strudel from '@strudel.cycles/core';
+  import '@strudel.cycles/core/euclid.mjs';
+  import { Scheduler, getAudioContext } from '@strudel.cycles/webaudio';
+
+  const { cat, State, TimeSpan } = strudel;
+  Object.assign(window, strudel); // add strudel to eval scope
+
+  const scheduler = new Scheduler({
+    audioContext: getAudioContext(),
+    interval: 0.1,
+    onEvent: (e) => {
+      e.context?.createAudioNode?.(e);
+    },
+  });
+
+  let initialCode = `sequence(1,2).mul(55/2) // frequencies
+.mul(slowcat(1,2))
+.mul(slowcat(1,3/2,4/3,5/3).slow(8))
+.fast(3)
+.velocity(.5)
+.osc(cat('sawtooth','square').fast(2))
+.adsr(0.01,.02,.5,0.1)
+.filter('lowshelf',800,25)
+.out()`;
+
+  try {
+    const base64 = decodeURIComponent(window.location.href.split('#')[1]);
+    initialCode = atob(base64);
+  } catch (err) {
+    console.warn('failed to decode', err);
+  }
+  const input = document.getElementById('text');
+  input.value = initialCode;
+  const evaluate = () => {
+    try {
+      const pattern = eval(input.value);
+      scheduler.setPattern(pattern);
+      window.location.hash = '#' + encodeURIComponent(btoa(input.value)); // update url hash
+    } catch (err) {
+      console.warn(err);
+    }
+  };
+  evaluate();
+  input.addEventListener('input', () => evaluate());
+
+  document.getElementById('start').addEventListener('click', () => scheduler.start());
+  document.getElementById('stop').addEventListener('click', () => scheduler.stop());
+</script>

packages/webaudio/index.mjs

@@ -0,0 +1,3 @@
+export { default as ClockWorker } from './clockworker.mjs';
+export { default as Scheduler } from './scheduler.mjs';
+export * from './webaudio.mjs';

packages/webaudio/package.json

@@ -0,0 +1,32 @@
+{
+  "name": "@strudel.cycles/webaudio",
+  "version": "0.0.1",
+  "description": "Web Audio helpers for Strudel",
+  "main": "index.mjs",
+  "directories": {
+    "example": "examples"
+  },
+  "scripts": {
+    "example": "parcel examples/repl.html"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/tidalcycles/strudel.git"
+  },
+  "keywords": [
+    "tidalcycles",
+    "strudel",
+    "pattern",
+    "livecoding",
+    "algorave"
+  ],
+  "author": "Felix Roos <flix91@gmail.com>",
+  "license": "GPL-3.0-or-later",
+  "bugs": {
+    "url": "https://github.com/tidalcycles/strudel/issues"
+  },
+  "homepage": "https://github.com/tidalcycles/strudel#readme",
+  "devDependencies": {
+    "parcel": "^2.4.1"
+  }
+}

packages/webaudio/scheduler.mjs

@@ -0,0 +1,38 @@
+import ClockWorker from './clockworker.mjs';
+
+class Scheduler {
+  worker;
+  pattern;
+  constructor({ audioContext, interval = 0.2, onEvent }) {
+    this.worker = new ClockWorker(
+      audioContext,
+      (begin, end) => {
+        this.pattern.query(new State(new TimeSpan(begin, end))).forEach((e) => {
+          if (!e.part.begin.equals(e.whole.begin)) {
+            return;
+          }
+          if (onEvent) {
+            onEvent?.(e);
+          } else {
+            console.warn('unplayable event: no audio node nor onEvent callback', e);
+          }
+        });
+      },
+      interval,
+    );
+  }
+  start() {
+    if (!this.pattern) {
+      throw new Error('Scheduler: no pattern set! call .setPattern first.');
+    }
+    this.worker.start();
+  }
+  stop() {
+    this.worker.stop();
+  }
+  setPattern(pat) {
+    this.pattern = pat;
+  }
+}
+
+export default Scheduler;

packages/webaudio/webaudio.mjs

@@ -0,0 +1,74 @@
+import { Pattern } from '@strudel.cycles/core';
+
+let audioContext;
+export const getAudioContext = () => {
+  if (!audioContext) {
+    audioContext = new AudioContext();
+  }
+  return audioContext;
+};
+
+const lookahead = 0.2;
+
+const adsr = (attack, decay, sustain, release, velocity, begin, end) => {
+  const gainNode = getAudioContext().createGain();
+  gainNode.gain.setValueAtTime(0, begin);
+  gainNode.gain.linearRampToValueAtTime(velocity, begin + attack); // attack
+  gainNode.gain.linearRampToValueAtTime(sustain * velocity, begin + attack + decay); // sustain start
+  gainNode.gain.setValueAtTime(sustain * velocity, end); // sustain end
+  gainNode.gain.linearRampToValueAtTime(0, end + release); // release
+  // for some reason, using exponential ramping creates little cracklings
+  return gainNode;
+};
+
+Pattern.prototype.withAudioNode = function (createAudioNode) {
+  return this._withEvent((event) => {
+    return event.setContext({
+      ...event.context,
+      createAudioNode: (e) => createAudioNode(e, event.context.createAudioNode?.(event)),
+    });
+  });
+};
+
+Pattern.prototype._osc = function (type) {
+  return this.withAudioNode((e) => {
+    const osc = getAudioContext().createOscillator();
+    osc.type = type;
+    osc.frequency.value = e.value; // expects frequency..
+    osc.start(e.whole.begin.valueOf() + lookahead);
+    osc.stop(e.whole.end.valueOf() + lookahead); // release?
+    return osc;
+  });
+};
+Pattern.prototype.adsr = function (a = 0.01, d = 0.05, s = 1, r = 0.01) {
+  return this.withAudioNode((e, node) => {
+    const velocity = e.context?.velocity || 1;
+    const envelope = adsr(a, d, s, r, velocity, e.whole.begin.valueOf() + lookahead, e.whole.end.valueOf() + lookahead);
+    node?.connect(envelope);
+    return envelope;
+  });
+};
+Pattern.prototype.filter = function (type = 'lowshelf', frequency = 1000, gain = 25) {
+  return this.withAudioNode((e, node) => {
+    const filter = getAudioContext().createBiquadFilter();
+    filter.type = type;
+    filter.frequency.value = frequency;
+    filter.gain.value = gain;
+    node?.connect(filter);
+    return filter;
+  });
+};
+
+Pattern.prototype.out = function () {
+  const master = getAudioContext().createGain();
+  master.gain.value = 0.1;
+  master.connect(getAudioContext().destination);
+  return this.withAudioNode((e, node) => {
+    if (!node) {
+      console.warn('out: no source! call .osc() first');
+    }
+    node?.connect(master);
+  });
+};
+
+Pattern.prototype.define('osc', (type, pat) => pat.osc(type), { patternified: true });