nealey/starship-engine-noise.html

## starship-engine-noise.html
<!DOCTYPE html>
<html>
  <head>
    <title>Starship Engine Noise</title>
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <script>
      function whiteNoise(audioCtx) {
        var bufferSize = 17 * audioCtx.sampleRate,
        noiseBuffer = audioCtx.createBuffer(1, bufferSize, audioCtx.sampleRate),
        output = noiseBuffer.getChannelData(0);
        for (var i = 0; i < bufferSize; i++) {
          output[i] = Math.random() * 2 - 1;
        }
        var whiteNoise = audioCtx.createBufferSource();
        whiteNoise.buffer = noiseBuffer;
        whiteNoise.loop = true;
        whiteNoise.start(0);
        return whiteNoise;
      }

      function bandpassFilter(audioCtx, freq, gain) {
        var filt = audioCtx.createBiquadFilter();
        filt.type = "bandpass";
        filt.frequency.value = freq;
        filt.gain.value = gain;
        return filt;
      }

      function boop() {
        var audioCtx = new window.AudioContext();
        var synth = whiteNoise(audioCtx);
        var filterA = bandpassFilter(audioCtx, 100, 20);
        var filterB = bandpassFilter(audioCtx, 50, 20);
        var gainA = audioCtx.createGain();

        whiteNoise(audioCtx).connect(filterA);
        filterA.connect(filterB);
        filterB.connect(gainA);
        gainA.connect(audioCtx.destination);

        function setFade() {
          var faderPos = document.querySelector("#fader").value;

          gainA.gain.value = faderPos;
        }
        setFade();
        document.querySelector("#fader").addEventListener("input", setFade);
      }


      window.addEventListener("load", boop);
    </script>
    <style>
      body {
        max-width: 40em;
      }
    </style>
  </head>
  <body>
    <h1>Sharship Engine Noise</h1>
    <div>
      <input id="fader" type="range" min="0" max="10" step="0.01"> Gain
    </div>

    <p>
      I work in a building with no HVAC,
      which means we can hear <i>everything</i> people are saying,
      anywhere in the building.
    </p>

    <p>
      This page is a low-CPU noise generator that runs entirely in JavaScript.
      Once it starts you don't need an Internet connection to keep it going.
      You can leave it running forever if you like.
    </p>

    <p>
      For those interested,
      it uses the new (in 2017)
      <a href="https://developer.mozilla.org/en-US/docs/Web/API/Web_Audio_API">Web Audio API</a>.
    </p>
  </body>
</html>
	<!DOCTYPE html>
	<html>
	<head>
	<title>Starship Engine Noise</title>
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<script>
	function whiteNoise(audioCtx) {
	var bufferSize = 17 * audioCtx.sampleRate,
	noiseBuffer = audioCtx.createBuffer(1, bufferSize, audioCtx.sampleRate),
	output = noiseBuffer.getChannelData(0);
	for (var i = 0; i < bufferSize; i++) {
	output[i] = Math.random() * 2 - 1;
	}
	var whiteNoise = audioCtx.createBufferSource();
	whiteNoise.buffer = noiseBuffer;
	whiteNoise.loop = true;
	whiteNoise.start(0);
	return whiteNoise;
	}

	function bandpassFilter(audioCtx, freq, gain) {
	var filt = audioCtx.createBiquadFilter();
	filt.type = "bandpass";
	filt.frequency.value = freq;
	filt.gain.value = gain;
	return filt;
	}

	function boop() {
	var audioCtx = new window.AudioContext();
	var synth = whiteNoise(audioCtx);
	var filterA = bandpassFilter(audioCtx, 100, 20);
	var filterB = bandpassFilter(audioCtx, 50, 20);
	var gainA = audioCtx.createGain();

	whiteNoise(audioCtx).connect(filterA);
	filterA.connect(filterB);
	filterB.connect(gainA);
	gainA.connect(audioCtx.destination);

	function setFade() {
	var faderPos = document.querySelector("#fader").value;

	gainA.gain.value = faderPos;
	}
	setFade();
	document.querySelector("#fader").addEventListener("input", setFade);
	}


	window.addEventListener("load", boop);
	</script>
	<style>
	body {
	max-width: 40em;
	}
	</style>
	</head>
	<body>
	<h1>Sharship Engine Noise</h1>
	<div>
	<input id="fader" type="range" min="0" max="10" step="0.01"> Gain
	</div>

	<p>
	I work in a building with no HVAC,
	which means we can hear <i>everything</i> people are saying,
	anywhere in the building.
	</p>

	<p>
	This page is a low-CPU noise generator that runs entirely in JavaScript.
	Once it starts you don't need an Internet connection to keep it going.
	You can leave it running forever if you like.
	</p>

	<p>
	For those interested,
	it uses the new (in 2017)
	<a href="https://developer.mozilla.org/en-US/docs/Web/API/Web_Audio_API">Web Audio API</a>.
	</p>
	</body>
	</html>