66 lines
2.0 KiB
Markdown
66 lines
2.0 KiB
Markdown
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---
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title: Starship Noise Generator
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---
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<div>
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<input id="fader" type="range" min="0" max="10" step="0.01"> Gain
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</div>
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I work in a building with no HVAC,
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which means we can hear *everything* people are saying,
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anywhere in the building.
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This page is a low-CPU noise generator that runs entirely in JavaScript.
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Once it starts,
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you don't need an Internet connection to keep it going.
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You can leave it running forever, if you like.
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For those interested,
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it uses the new (in 2017) and seriously powerful
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[Web Audio API](https://developer.mozilla.org/en-US/docs/Web/API/Web_Audio_API).
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<script>
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function whiteNoise(audioCtx) {
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var bufferSize = 17 * audioCtx.sampleRate,
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noiseBuffer = audioCtx.createBuffer(1, bufferSize, audioCtx.sampleRate),
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output = noiseBuffer.getChannelData(0);
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for (var i = 0; i < bufferSize; i++) {
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output[i] = Math.random() * 2 - 1;
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}
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var whiteNoise = audioCtx.createBufferSource();
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whiteNoise.buffer = noiseBuffer;
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whiteNoise.loop = true;
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whiteNoise.start(0);
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return whiteNoise;
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}
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function bandpassFilter(audioCtx, freq, gain) {
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var filt = audioCtx.createBiquadFilter();
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filt.type = "bandpass";
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filt.frequency.value = freq;
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filt.gain.value = gain;
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return filt;
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}
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function boop() {
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var audioCtx = new window.AudioContext();
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var synth = whiteNoise(audioCtx);
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var filterA = bandpassFilter(audioCtx, 100, 20);
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var filterB = bandpassFilter(audioCtx, 50, 20);
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var gainA = audioCtx.createGain();
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whiteNoise(audioCtx).connect(filterA);
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filterA.connect(filterB);
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filterB.connect(gainA);
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gainA.connect(audioCtx.destination);
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function setFade() {
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var faderPos = document.querySelector("#fader").value;
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gainA.gain.value = faderPos;
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}
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setFade();
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document.querySelector("#fader").addEventListener("input", setFade);
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}
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window.addEventListener("load", boop);
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</script>
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