wavesurfer.js
Version:
Interactive navigable audio visualization using Web Audio and Canvas
658 lines (584 loc) • 21.3 kB
JavaScript
/**
* Calculate FFT - Based on https://github.com/corbanbrook/dsp.js
*/
/* eslint-disable complexity, no-redeclare, no-var, one-var */
const FFT = function(bufferSize, sampleRate, windowFunc, alpha) {
this.bufferSize = bufferSize;
this.sampleRate = sampleRate;
this.bandwidth = 2 / bufferSize * sampleRate / 2;
this.sinTable = new Float32Array(bufferSize);
this.cosTable = new Float32Array(bufferSize);
this.windowValues = new Float32Array(bufferSize);
this.reverseTable = new Uint32Array(bufferSize);
this.peakBand = 0;
this.peak = 0;
switch (windowFunc) {
case 'bartlett':
for (var i = 0; i < bufferSize; i++) {
this.windowValues[i] =
2 /
(bufferSize - 1) *
((bufferSize - 1) / 2 - Math.abs(i - (bufferSize - 1) / 2));
}
break;
case 'bartlettHann':
for (var i = 0; i < bufferSize; i++) {
this.windowValues[i] =
0.62 -
0.48 * Math.abs(i / (bufferSize - 1) - 0.5) -
0.38 * Math.cos(Math.PI * 2 * i / (bufferSize - 1));
}
break;
case 'blackman':
alpha = alpha || 0.16;
for (var i = 0; i < bufferSize; i++) {
this.windowValues[i] =
(1 - alpha) / 2 -
0.5 * Math.cos(Math.PI * 2 * i / (bufferSize - 1)) +
alpha / 2 * Math.cos(4 * Math.PI * i / (bufferSize - 1));
}
break;
case 'cosine':
for (var i = 0; i < bufferSize; i++) {
this.windowValues[i] = Math.cos(
Math.PI * i / (bufferSize - 1) - Math.PI / 2
);
}
break;
case 'gauss':
alpha = alpha || 0.25;
for (var i = 0; i < bufferSize; i++) {
this.windowValues[i] = Math.pow(
Math.E,
-0.5 *
Math.pow(
(i - (bufferSize - 1) / 2) /
(alpha * (bufferSize - 1) / 2),
2
)
);
}
break;
case 'hamming':
for (var i = 0; i < bufferSize; i++) {
this.windowValues[i] =
0.54 - 0.46 * Math.cos(Math.PI * 2 * i / (bufferSize - 1));
}
break;
case 'hann':
case undefined:
for (var i = 0; i < bufferSize; i++) {
this.windowValues[i] =
0.5 * (1 - Math.cos(Math.PI * 2 * i / (bufferSize - 1)));
}
break;
case 'lanczoz':
for (var i = 0; i < bufferSize; i++) {
this.windowValues[i] =
Math.sin(Math.PI * (2 * i / (bufferSize - 1) - 1)) /
(Math.PI * (2 * i / (bufferSize - 1) - 1));
}
break;
case 'rectangular':
for (var i = 0; i < bufferSize; i++) {
this.windowValues[i] = 1;
}
break;
case 'triangular':
for (var i = 0; i < bufferSize; i++) {
this.windowValues[i] =
2 /
bufferSize *
(bufferSize / 2 - Math.abs(i - (bufferSize - 1) / 2));
}
break;
default:
throw Error("No such window function '" + windowFunc + "'");
}
var limit = 1;
var bit = bufferSize >> 1;
var i;
while (limit < bufferSize) {
for (i = 0; i < limit; i++) {
this.reverseTable[i + limit] = this.reverseTable[i] + bit;
}
limit = limit << 1;
bit = bit >> 1;
}
for (i = 0; i < bufferSize; i++) {
this.sinTable[i] = Math.sin(-Math.PI / i);
this.cosTable[i] = Math.cos(-Math.PI / i);
}
this.calculateSpectrum = function(buffer) {
// Locally scope variables for speed up
var bufferSize = this.bufferSize,
cosTable = this.cosTable,
sinTable = this.sinTable,
reverseTable = this.reverseTable,
real = new Float32Array(bufferSize),
imag = new Float32Array(bufferSize),
bSi = 2 / this.bufferSize,
sqrt = Math.sqrt,
rval,
ival,
mag,
spectrum = new Float32Array(bufferSize / 2);
var k = Math.floor(Math.log(bufferSize) / Math.LN2);
if (Math.pow(2, k) !== bufferSize) {
throw 'Invalid buffer size, must be a power of 2.';
}
if (bufferSize !== buffer.length) {
throw 'Supplied buffer is not the same size as defined FFT. FFT Size: ' +
bufferSize +
' Buffer Size: ' +
buffer.length;
}
var halfSize = 1,
phaseShiftStepReal,
phaseShiftStepImag,
currentPhaseShiftReal,
currentPhaseShiftImag,
off,
tr,
ti,
tmpReal;
for (var i = 0; i < bufferSize; i++) {
real[i] =
buffer[reverseTable[i]] * this.windowValues[reverseTable[i]];
imag[i] = 0;
}
while (halfSize < bufferSize) {
phaseShiftStepReal = cosTable[halfSize];
phaseShiftStepImag = sinTable[halfSize];
currentPhaseShiftReal = 1;
currentPhaseShiftImag = 0;
for (var fftStep = 0; fftStep < halfSize; fftStep++) {
var i = fftStep;
while (i < bufferSize) {
off = i + halfSize;
tr =
currentPhaseShiftReal * real[off] -
currentPhaseShiftImag * imag[off];
ti =
currentPhaseShiftReal * imag[off] +
currentPhaseShiftImag * real[off];
real[off] = real[i] - tr;
imag[off] = imag[i] - ti;
real[i] += tr;
imag[i] += ti;
i += halfSize << 1;
}
tmpReal = currentPhaseShiftReal;
currentPhaseShiftReal =
tmpReal * phaseShiftStepReal -
currentPhaseShiftImag * phaseShiftStepImag;
currentPhaseShiftImag =
tmpReal * phaseShiftStepImag +
currentPhaseShiftImag * phaseShiftStepReal;
}
halfSize = halfSize << 1;
}
for (var i = 0, N = bufferSize / 2; i < N; i++) {
rval = real[i];
ival = imag[i];
mag = bSi * sqrt(rval * rval + ival * ival);
if (mag > this.peak) {
this.peakBand = i;
this.peak = mag;
}
spectrum[i] = mag;
}
return spectrum;
};
};
/* eslint-enable complexity, no-redeclare, no-var, one-var */
/**
* @typedef {Object} SpectrogramPluginParams
* @property {string|HTMLElement} container Selector of element or element in
* which to render
* @property {number} fftSamples=512 number of samples to fetch to FFT. Must be
* a pwer of 2.
* @property {number} noverlap Size of the overlapping window. Must be <
* fftSamples. Auto deduced from canvas size by default.
* @property {string} windowFunc='hann' The window function to be used. One of
* these: `'bartlett'`, `'bartlettHann'`, `'blackman'`, `'cosine'`, `'gauss'`,
* `'hamming'`, `'hann'`, `'lanczoz'`, `'rectangular'`, `'triangular'`
* @property {?number} alpha Some window functions have this extra value.
* (Between 0 and 1)
* @property {number} pixelRatio=wavesurfer.params.pixelRatio to control the
* size of the spectrogram in relation with its canvas. 1 = Draw on the whole
* canvas. 2 = Draw on a quarter (1/2 the length and 1/2 the width)
* @property {?boolean} deferInit Set to true to manually call
* `initPlugin('spectrogram')`
*/
/**
* Render a spectrogram visualisation of the audio.
*
* @implements {PluginClass}
* @extends {Observer}
* @example
* // es6
* import SpectrogramPlugin from 'wavesurfer.spectrogram.js';
*
* // commonjs
* var SpectrogramPlugin = require('wavesurfer.spectrogram.js');
*
* // if you are using <script> tags
* var SpectrogramPlugin = window.WaveSurfer.spectrogram;
*
* // ... initialising wavesurfer with the plugin
* var wavesurfer = WaveSurfer.create({
* // wavesurfer options ...
* plugins: [
* SpectrogramPlugin.create({
* // plugin options ...
* })
* ]
* });
*/
export default class SpectrogramPlugin {
/**
* Spectrogram plugin definition factory
*
* This function must be used to create a plugin definition which can be
* used by wavesurfer to correctly instantiate the plugin.
*
* @param {SpectrogramPluginParams} params parameters use to initialise the plugin
* @return {PluginDefinition} an object representing the plugin
*/
static create(params) {
return {
name: 'spectrogram',
deferInit: params && params.deferInit ? params.deferInit : false,
params: params,
staticProps: {
FFT: FFT
},
instance: SpectrogramPlugin
};
}
constructor(params, ws) {
this.params = params;
this.wavesurfer = ws;
this.util = ws.util;
this.frequenciesDataUrl = params.frequenciesDataUrl;
this._onScroll = e => {
this.updateScroll(e);
};
this._onReady = () => {
const drawer = (this.drawer = ws.drawer);
this.container =
'string' == typeof params.container
? document.querySelector(params.container)
: params.container;
if (!this.container) {
throw Error('No container for WaveSurfer spectrogram');
}
this.width = drawer.width;
this.pixelRatio = this.params.pixelRatio || ws.params.pixelRatio;
this.fftSamples =
this.params.fftSamples || ws.params.fftSamples || 512;
this.height = this.fftSamples / 2;
this.noverlap = params.noverlap;
this.windowFunc = params.windowFunc;
this.alpha = params.alpha;
this.createWrapper();
this.createCanvas();
this.render();
drawer.wrapper.addEventListener('scroll', this._onScroll);
ws.on('redraw', () => this.render());
};
}
init() {
// Check if ws is ready
if (this.wavesurfer.isReady) {
this._onReady();
}
this.wavesurfer.on('ready', this._onReady);
}
destroy() {
this.unAll();
this.wavesurfer.un('ready', this._onReady);
this.drawer.wrapper.removeEventListener('scroll', this._onScroll);
this.wavesurfer = null;
this.util = null;
this.params = null;
if (this.wrapper) {
this.wrapper.parentNode.removeChild(this.wrapper);
this.wrapper = null;
}
}
createWrapper() {
const prevSpectrogram = this.container.querySelector('spectrogram');
if (prevSpectrogram) {
this.container.removeChild(prevSpectrogram);
}
const wsParams = this.wavesurfer.params;
this.wrapper = document.createElement('spectrogram');
// if labels are active
if (this.params.labels) {
const labelsEl = (this.labelsEl = document.createElement('canvas'));
labelsEl.classList.add('spec-labels');
this.drawer.style(labelsEl, {
left: 0,
position: 'absolute',
zIndex: 9,
height: `${this.height / this.pixelRatio}px`,
width: `${55 / this.pixelRatio}px`
});
this.wrapper.appendChild(labelsEl);
// can be customized in next version
this.loadLabels(
'rgba(68,68,68,0.5)',
'12px',
'10px',
'',
'#fff',
'#f7f7f7',
'center',
'#specLabels'
);
}
this.drawer.style(this.wrapper, {
display: 'block',
position: 'relative',
userSelect: 'none',
webkitUserSelect: 'none',
height: `${this.height / this.pixelRatio}px`
});
if (wsParams.fillParent || wsParams.scrollParent) {
this.drawer.style(this.wrapper, {
width: '100%',
overflowX: 'hidden',
overflowY: 'hidden'
});
}
this.container.appendChild(this.wrapper);
this.wrapper.addEventListener('click', e => {
e.preventDefault();
const relX = 'offsetX' in e ? e.offsetX : e.layerX;
this.fireEvent('click', relX / this.scrollWidth || 0);
});
}
createCanvas() {
const canvas = (this.canvas = this.wrapper.appendChild(
document.createElement('canvas')
));
this.spectrCc = canvas.getContext('2d');
this.util.style(canvas, {
position: 'absolute',
zIndex: 4
});
}
render() {
this.updateCanvasStyle();
if (this.frequenciesDataUrl) {
this.loadFrequenciesData(this.frequenciesDataUrl);
} else {
this.getFrequencies(this.drawSpectrogram);
}
}
updateCanvasStyle() {
const width = Math.round(this.width / this.pixelRatio) + 'px';
this.canvas.width = this.width;
this.canvas.height = this.height;
this.canvas.style.width = width;
}
drawSpectrogram(frequenciesData, my) {
const spectrCc = my.spectrCc;
const length = my.wavesurfer.backend.getDuration();
const height = my.height;
const pixels = my.resample(frequenciesData);
const heightFactor = my.buffer ? 2 / my.buffer.numberOfChannels : 1;
let i;
let j;
for (i = 0; i < pixels.length; i++) {
for (j = 0; j < pixels[i].length; j++) {
const colorValue = 255 - pixels[i][j];
my.spectrCc.fillStyle =
'rgb(' +
colorValue +
', ' +
colorValue +
', ' +
colorValue +
')';
my.spectrCc.fillRect(
i,
height - j * heightFactor,
1,
heightFactor
);
}
}
}
getFrequencies(callback) {
const fftSamples = this.fftSamples;
const buffer = (this.buffer = this.wavesurfer.backend.buffer);
const channelOne = buffer.getChannelData(0);
const bufferLength = buffer.length;
const sampleRate = buffer.sampleRate;
const frequencies = [];
if (!buffer) {
this.fireEvent('error', 'Web Audio buffer is not available');
return;
}
let noverlap = this.noverlap;
if (!noverlap) {
const uniqueSamplesPerPx = buffer.length / this.canvas.width;
noverlap = Math.max(0, Math.round(fftSamples - uniqueSamplesPerPx));
}
const fft = new FFT(
fftSamples,
sampleRate,
this.windowFunc,
this.alpha
);
const maxSlicesCount = Math.floor(
bufferLength / (fftSamples - noverlap)
);
let currentOffset = 0;
while (currentOffset + fftSamples < channelOne.length) {
const segment = channelOne.slice(
currentOffset,
currentOffset + fftSamples
);
const spectrum = fft.calculateSpectrum(segment);
const array = new Uint8Array(fftSamples / 2);
let j;
for (j = 0; j < fftSamples / 2; j++) {
array[j] = Math.max(-255, Math.log10(spectrum[j]) * 45);
}
frequencies.push(array);
currentOffset += fftSamples - noverlap;
}
callback(frequencies, this);
}
loadFrequenciesData(url) {
const ajax = this.util.ajax({ url: url });
ajax.on('success', data =>
this.drawSpectrogram(JSON.parse(data), this)
);
ajax.on('error', e =>
this.fireEvent('error', 'XHR error: ' + e.target.statusText)
);
return ajax;
}
freqType(freq) {
return freq >= 1000 ? (freq / 1000).toFixed(1) : Math.round(freq);
}
unitType(freq) {
return freq >= 1000 ? 'KHz' : 'Hz';
}
loadLabels(
bgFill,
fontSizeFreq,
fontSizeUnit,
fontType,
textColorFreq,
textColorUnit,
textAlign,
container
) {
const frequenciesHeight = this.height;
bgFill = bgFill || 'rgba(68,68,68,0)';
fontSizeFreq = fontSizeFreq || '12px';
fontSizeUnit = fontSizeUnit || '10px';
fontType = fontType || 'Helvetica';
textColorFreq = textColorFreq || '#fff';
textColorUnit = textColorUnit || '#fff';
textAlign = textAlign || 'center';
container = container || '#specLabels';
const getMaxY = frequenciesHeight || 512;
const labelIndex = 5 * (getMaxY / 256);
const freqStart = 0;
const step =
(this.wavesurfer.backend.ac.sampleRate / 2 - freqStart) /
labelIndex;
const ctx = this.labelsEl.getContext('2d');
this.labelsEl.height = this.height;
this.labelsEl.width = 55;
ctx.fillStyle = bgFill;
ctx.fillRect(0, 0, 55, getMaxY);
ctx.fill();
let i;
for (i = 0; i <= labelIndex; i++) {
ctx.textAlign = textAlign;
ctx.textBaseline = 'middle';
const freq = freqStart + step * i;
const index = Math.round(
freq / (this.sampleRate / 2) * this.fftSamples
);
const label = this.freqType(freq);
const units = this.unitType(freq);
const x = 16;
const yLabelOffset = 2;
if (i == 0) {
ctx.fillStyle = textColorUnit;
ctx.font = fontSizeUnit + ' ' + fontType;
ctx.fillText(units, x + 24, getMaxY + i - 10);
ctx.fillStyle = textColorFreq;
ctx.font = fontSizeFreq + ' ' + fontType;
ctx.fillText(label, x, getMaxY + i - 10);
} else {
ctx.fillStyle = textColorUnit;
ctx.font = fontSizeUnit + ' ' + fontType;
ctx.fillText(units, x + 24, getMaxY - i * 50 + yLabelOffset);
ctx.fillStyle = textColorFreq;
ctx.font = fontSizeFreq + ' ' + fontType;
ctx.fillText(label, x, getMaxY - i * 50 + yLabelOffset);
}
}
}
updateScroll(e) {
if (this.wrapper) {
this.wrapper.scrollLeft = e.target.scrollLeft;
}
}
resample(oldMatrix) {
const columnsNumber = this.width;
const newMatrix = [];
const oldPiece = 1 / oldMatrix.length;
const newPiece = 1 / columnsNumber;
let i;
for (i = 0; i < columnsNumber; i++) {
const column = new Array(oldMatrix[0].length);
let j;
for (j = 0; j < oldMatrix.length; j++) {
const oldStart = j * oldPiece;
const oldEnd = oldStart + oldPiece;
const newStart = i * newPiece;
const newEnd = newStart + newPiece;
const overlap =
oldEnd <= newStart || newEnd <= oldStart
? 0
: Math.min(
Math.max(oldEnd, newStart),
Math.max(newEnd, oldStart)
) -
Math.max(
Math.min(oldEnd, newStart),
Math.min(newEnd, oldStart)
);
let k;
/* eslint-disable max-depth */
if (overlap > 0) {
for (k = 0; k < oldMatrix[0].length; k++) {
if (column[k] == null) {
column[k] = 0;
}
column[k] += overlap / newPiece * oldMatrix[j][k];
}
}
/* eslint-enable max-depth */
}
const intColumn = new Uint8Array(oldMatrix[0].length);
let m;
for (m = 0; m < oldMatrix[0].length; m++) {
intColumn[m] = column[m];
}
newMatrix.push(intColumn);
}
return newMatrix;
}
}