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Extract bucket generation

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This commit is contained in:
Jordan Eldredge 2018-10-28 22:24:01 -07:00
parent 03acc5feba
commit 21425fba12
1 changed files with 22 additions and 24 deletions
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46
js/components/Visualizer.js
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@ -22,6 +22,27 @@ function sliceAverage(dataArray, sliceWidth, sliceNumber) {
return sum / sliceWidth;
}
function octaveBucketsForBufferLength(bufferLength) {
const octaveBuckets = new Array(NUM_BARS).fill(0);
const minHz = 200;
const maxHz = 22050;
const octaveStep = Math.pow(maxHz / minHz, 1 / NUM_BARS);
octaveBuckets[0] = 0;
octaveBuckets[1] = minHz;
for (let i = 2; i < NUM_BARS - 1; i++) {
octaveBuckets[i] = octaveBuckets[i - 1] * octaveStep;
}
octaveBuckets[NUM_BARS - 1] = maxHz;
for (let i = 0; i < NUM_BARS; i++) {
const octaveIdx = Math.floor((octaveBuckets[i] / maxHz) * bufferLength);
octaveBuckets[i] = octaveIdx;
}
return octaveBuckets;
}
class Visualizer extends React.Component {
componentDidMount() {
this.barPeaks = new Array(NUM_BARS).fill(0);
@ -84,29 +105,6 @@ class Visualizer extends React.Component {
return barWidth - 1;
}
_generateOctaveBuckets() {
const octaveBuckets = new Array(NUM_BARS).fill(0);
const minHz = 200;
const maxHz = 22050;
const octaveStep = Math.pow(maxHz / minHz, 1 / NUM_BARS);
octaveBuckets[0] = 0;
octaveBuckets[1] = minHz;
for (let i = 2; i < NUM_BARS - 1; i++) {
octaveBuckets[i] = octaveBuckets[i - 1] * octaveStep;
}
octaveBuckets[NUM_BARS - 1] = maxHz;
for (let i = 0; i < NUM_BARS; i++) {
const octaveIdx = Math.floor(
(octaveBuckets[i] / maxHz) * this.bufferLength
);
octaveBuckets[i] = octaveIdx;
}
return octaveBuckets;
}
setStyle() {
if (!this.props.colors) {
return;
@ -124,7 +122,7 @@ class Visualizer extends React.Component {
this.dataArray = new Uint8Array(this.bufferLength);
if (!this.octaveBuckets) {
this.octaveBuckets = this._generateOctaveBuckets();
this.octaveBuckets = octaveBucketsForBufferLength(this.bufferLength);
}
}
}