Add ring buffer to p5.SoundFile AudioWorklet processor

Author: oshoham

src/audioWorklet/soundFileProcessor.js

@@ -1,13 +1,29 @@
-// import processor name via preval.require so that it's available as a value at compile time
+// import dependencies via preval.require so that they're available as values at compile time
 const processorNames = preval.require('./processorNames');
+const RingBuffer = preval.require('./ringBuffer').default;
 
 class SoundFileProcessor extends AudioWorkletProcessor {
+  constructor(options) {
+    super();
+
+    const processorOptions = options.processorOptions || {};
+    this.bufferSize = processorOptions.bufferSize || 256;
+    this.inputRingBuffer = new RingBuffer(this.bufferSize, 1);
+    this.inputRingBufferArraySequence = [new Float32Array(this.bufferSize)];
+  }
+
   process(inputs) {
     const input = inputs[0];
-    const inputChannel = input[0];
-    const position = inputChannel[inputChannel.length - 1] || 0;
+    // we only care about the first input channel, because that contains the position data
+    this.inputRingBuffer.push([input[0]]);
+
+    if (this.inputRingBuffer.framesAvailable >= this.bufferSize) {
+      this.inputRingBuffer.pull(this.inputRingBufferArraySequence);
+      const inputChannel = this.inputRingBufferArraySequence[0];
+      const position = inputChannel[inputChannel.length - 1] || 0;
 
-    this.port.postMessage({ name: 'position', position: position });
+      this.port.postMessage({ name: 'position', position: position });
+    }
 
     return true;
   }

src/customAudioNode.js

@@ -1243,7 +1243,9 @@ define(function (require) {
       self._workletNode.disconnect();
       delete self._workletNode;
     }
-    self._workletNode = new AudioWorkletNode(ac, processorNames.soundFileProcessor);
+    self._workletNode = new AudioWorkletNode(ac, processorNames.soundFileProcessor, {
+      processorOptions: { bufferSize: 256 }
+    });
     self._workletNode.port.onmessage = event => {
       if (event.data.name === 'position') {
         // event.data.position should only be 0 when paused