rnewman/aw.html

## aw.html
<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
    <title>Audio Worklet loopback test</title>
  </head>
  <body>
    <h1>Loopback test</h1>
    <ol>
      <li>Make sure your Bluetooth device is your default input and output device.</li>
      <li>Play music. Verify that you hear high-quality music.</li>
      <li>Hit one of the buttons below. You should hear a shift to a low-quality mode.</li>
      <li>Talk: in Chrome you should hear a choppy version of your own voice.</li>
    </ol>
    <audio id="output"></audio>
    <div>
      <button id="worklet">Start with worklet</button>
    </div>

    <div>
      <button id="noworklet">Start without worklet</button>
    </div>
    <script>
      async function loopback(worklet) {
        const context = new AudioContext({
          latencyHint: 0,
        });
        const input = await window.navigator.mediaDevices.getUserMedia({
          audio: {
            channelCount: 1,
          },
        });

        const source = context.createMediaStreamSource(input);
        const destination = context.createMediaStreamDestination();

        if (worklet) {
          const module = await context.audioWorklet.addModule('https://gistpreview.github.io/?29b7e88f0acbde78c20f32187ee652ea/loopback.js');
          console.info('Got module.', module);
          const node = new AudioWorkletNode(context, 'loopback-worklet', {
            numberOfInputs: 1,
            numberOfOutputs: 1,
            outputChannelCount: [1]
          });

          console.info('Connecting to Audio Worklet.');
          source.connect(node);
          node.connect(destination);
        } else {
          console.info('Piping straight through.');
          source.connect(destination);
        }

        const outputElement = document.getElementById('output');
        outputElement.srcObject = destination.stream;
        outputElement.play();
      }

      document.getElementById('worklet').onclick = () => loopback(true);
      document.getElementById('noworklet').onclick = () => loopback(false);
    </script>

  </body>
</html>

## loopback.js
class Loopback extends AudioWorkletProcessor {
  constructor() {
    super();
    console.info('Constructed loopback');
  }

  process(inputs, outputs, parameters) {
    if (!inputs) {
      console.warn('No inputs.');
    }

    // Mono only.
    const input = inputs[0][0];
    const output = outputs[0][0];
    if (!input) {
      console.warn('No input; waiting.');
      return true;
    }
    for (let i = 0; i < 128; ++i) {
      output[i] = input[i];
    }
    return true;
  }
}

registerProcessor('loopback-worklet', Loopback);
	<!DOCTYPE html>
	<html lang="en">
	<head>
	<meta charset="utf-8">
	<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
	<title>Audio Worklet loopback test</title>
	</head>
	<body>
	<h1>Loopback test</h1>
	<ol>
	<li>Make sure your Bluetooth device is your default input and output device.</li>
	<li>Play music. Verify that you hear high-quality music.</li>
	<li>Hit one of the buttons below. You should hear a shift to a low-quality mode.</li>
	<li>Talk: in Chrome you should hear a choppy version of your own voice.</li>
	</ol>
	<audio id="output"></audio>
	<div>
	<button id="worklet">Start with worklet</button>
	</div>

	<div>
	<button id="noworklet">Start without worklet</button>
	</div>
	<script>
	async function loopback(worklet) {
	const context = new AudioContext({
	latencyHint: 0,
	});
	const input = await window.navigator.mediaDevices.getUserMedia({
	audio: {
	channelCount: 1,
	},
	});

	const source = context.createMediaStreamSource(input);
	const destination = context.createMediaStreamDestination();

	if (worklet) {
	const module = await context.audioWorklet.addModule('https://gistpreview.github.io/?29b7e88f0acbde78c20f32187ee652ea/loopback.js');
	console.info('Got module.', module);
	const node = new AudioWorkletNode(context, 'loopback-worklet', {
	numberOfInputs: 1,
	numberOfOutputs: 1,
	outputChannelCount: [1]
	});

	console.info('Connecting to Audio Worklet.');
	source.connect(node);
	node.connect(destination);
	} else {
	console.info('Piping straight through.');
	source.connect(destination);
	}

	const outputElement = document.getElementById('output');
	outputElement.srcObject = destination.stream;
	outputElement.play();
	}

	document.getElementById('worklet').onclick = () => loopback(true);
	document.getElementById('noworklet').onclick = () => loopback(false);
	</script>

	</body>
	</html>
	class Loopback extends AudioWorkletProcessor {
	constructor() {
	super();
	console.info('Constructed loopback');
	}

	process(inputs, outputs, parameters) {
	if (!inputs) {
	console.warn('No inputs.');
	}

	// Mono only.
	const input = inputs[0][0];
	const output = outputs[0][0];
	if (!input) {
	console.warn('No input; waiting.');
	return true;
	}
	for (let i = 0; i < 128; ++i) {
	output[i] = input[i];
	}
	return true;
	}
	}

	registerProcessor('loopback-worklet', Loopback);