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Add brown noise generator, fixes #16

This commit is contained in:
Neale Pickett 2020-05-30 15:00:05 -06:00
parent d7de183d4c
commit 5b26d92b20
1 changed files with 29 additions and 1 deletions
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30
static/vail.js
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@ -132,7 +132,7 @@ class Buzzer {
// in order to avoid "pops" (square wave overtones)
// that happen with instant changes in gain.
constructor(txGain=0.3) {
constructor(txGain=0.6) {
this.txGain = txGain
this.ac = new AudioContext()
@ -140,6 +140,7 @@ class Buzzer {
this.lowGain = this.create(lowFreq)
this.highGain = this.create(highFreq)
this.errorGain = this.create(errorFreq, "square")
this.noiseGain = this.whiteNoise()
this.ac.resume()
.then(() => {
@ -160,6 +161,33 @@ class Buzzer {
return gain
}
whiteNoise() {
let bufferSize = 17 * this.ac.sampleRate
let noiseBuffer = this.ac.createBuffer(1, bufferSize, this.ac.sampleRate)
let output = noiseBuffer.getChannelData(0)
for (let i = 0; i < bufferSize; i++) {
output[i] = Math.random() * 2 - 1;
}
let whiteNoise = this.ac.createBufferSource();
whiteNoise.buffer = noiseBuffer;
whiteNoise.loop = true;
whiteNoise.start(0);
let filter = this.ac.createBiquadFilter()
filter.type = "lowpass"
filter.frequency.value = 100
let gain = this.ac.createGain()
gain.gain.value = 0.1
whiteNoise.connect(filter)
filter.connect(gain)
gain.connect(this.ac.destination)
return gain
}
gain(high) {
if (high) {
return this.highGain.gain