benz-recorderjs
Version:
Record audio from a node in the Web Audio API
256 lines (218 loc) • 8.24 kB
JavaScript
(function (global, factory) {
typeof exports === 'object' && typeof module !== 'undefined' ? module.exports = factory() :
typeof define === 'function' && define.amd ? define(factory) :
(global.Recorder = factory());
}(this, (function () {
var recorderWorker = function () {
var recLength = 0,
recBuffersL = [],
recBuffersR = [],
sampleRate;
self.onmessage = function (e) {
switch (e.data.command) {
case 'init':
init(e.data.config);
break;
case 'record':
record(e.data.buffer);
break;
case 'exportWAV':
exportWAV(e.data.type);
break;
case 'getBuffer':
getBuffer();
break;
case 'clear':
clear();
break;
}
};
function init(config) {
sampleRate = config.sampleRate;
}
function record(inputBuffer) {
recBuffersL.push(inputBuffer[0]);
recBuffersR.push(inputBuffer[1]);
recLength += inputBuffer[0].length;
}
function exportWAV(type) {
var bufferL = mergeBuffers(recBuffersL, recLength);
var bufferR = mergeBuffers(recBuffersR, recLength);
var interleaved = interleave(bufferL, bufferR);
var dataview = encodeWAV(interleaved);
var audioBlob = new Blob([dataview], {type: type});
self.postMessage({
type: 'blob',
data: audioBlob
});
}
function getBuffer() {
var buffers = [];
buffers.push(mergeBuffers(recBuffersL, recLength));
buffers.push(mergeBuffers(recBuffersR, recLength));
self.postMessage({
type: 'buffer',
data: buffers
});
}
function clear() {
recLength = 0;
recBuffersL = [];
recBuffersR = [];
}
function mergeBuffers(recBuffers, recLength) {
var result = new Float32Array(recLength);
var offset = 0;
for (var i = 0; i < recBuffers.length; i++) {
result.set(recBuffers[i], offset);
offset += recBuffers[i].length;
}
return result;
}
function interleave(inputL, inputR) {
var length = inputL.length + inputR.length;
var result = new Float32Array(length);
var index = 0,
inputIndex = 0;
while (index < length) {
result[index++] = inputL[inputIndex];
result[index++] = inputR[inputIndex];
inputIndex++;
}
return result;
}
function floatTo16BitPCM(output, offset, input) {
for (var i = 0; i < input.length; i++, offset += 2) {
var s = Math.max(-1, Math.min(1, input[i]));
output.setInt16(offset, s < 0 ? s * 0x8000 : s * 0x7FFF, true);
}
}
function writeString(view, offset, string) {
for (var i = 0; i < string.length; i++) {
view.setUint8(offset + i, string.charCodeAt(i));
}
}
function encodeWAV(samples) {
var buffer = new ArrayBuffer(44 + samples.length * 2);
var view = new DataView(buffer);
/* RIFF identifier */
writeString(view, 0, 'RIFF');
/* RIFF chunk length */
view.setUint32(4, 36 + samples.length * 2, true);
/* RIFF type */
writeString(view, 8, 'WAVE');
/* format chunk identifier */
writeString(view, 12, 'fmt ');
/* format chunk length */
view.setUint32(16, 16, true);
/* sample format (raw) */
view.setUint16(20, 1, true);
/* channel count */
view.setUint16(22, 2, true);
/* sample rate */
view.setUint32(24, sampleRate, true);
/* byte rate (sample rate * block align) */
view.setUint32(28, sampleRate * 4, true);
/* block align (channel count * bytes per sample) */
view.setUint16(32, 4, true);
/* bits per sample */
view.setUint16(34, 16, true);
/* data chunk identifier */
writeString(view, 36, 'data');
/* data chunk length */
view.setUint32(40, samples.length * 2, true);
floatTo16BitPCM(view, 44, samples);
return view;
}
};
var recorderWorkerStr = recorderWorker.toString()
.replace(/^\s*function.*?\(\)\s*{/, '')
.replace(/}\s*$/, '');
// var WORKER_PATH = './recorderWorker.js';
var Recorder = function(source, cfg){
var config = cfg || {};
var bufferLen = config.bufferLen || 4096;
this.context = source.context;
this.node = (this.context.createScriptProcessor ||
this.context.createJavaScriptNode).call(this.context,
bufferLen, 2, 2);
var worker = new Worker((window.URL || window.webkitURL).createObjectURL(new Blob([recorderWorkerStr], {type:"text/javascript"})));
worker.onmessage = function(e){
if (e.data.type === 'blob') {
currCallbackWithBlob(e.data.data);
} else {
currCallbackWithBuffer(e.data.data);
}
};
worker.postMessage({
command: 'init',
config: {
sampleRate: this.context.sampleRate
}
});
var recording = false,
currCallbackWithBuffer,
currCallbackWithBlob;
this.node.onaudioprocess = function(e){
if (!recording) return;
worker.postMessage({
command: 'record',
buffer: [
e.inputBuffer.getChannelData(0),
e.inputBuffer.getChannelData(1)
]
});
};
this.configure = function(cfg){
for (var prop in cfg){
if (cfg.hasOwnProperty(prop)){
config[prop] = cfg[prop];
}
}
};
this.record = function(){
recording = true;
};
this.stop = function(){
recording = false;
};
this.clear = function(){
worker.postMessage({ command: 'clear' });
};
this.getBuffer = function(cb) {
currCallbackWithBuffer = cb || config.callback;
worker.postMessage({ command: 'getBuffer' });
};
this.exportWAV = function(cb, type){
currCallbackWithBlob = cb || config.callback;
type = type || config.type || 'audio/wav';
if (!currCallbackWithBlob) throw new Error('Callback not set');
worker.postMessage({
command: 'exportWAV',
type: type
});
};
this.release = function() {
this.stop();
this.clear();
this.configure = this.record = this.stop = this.clear = this.getBuffer = this.exportWAV = function () {};
source.disconnect(this.node);
this.node.onaudioprocess = null;
this.node.disconnect();
worker.terminate();
};
source.connect(this.node);
this.node.connect(this.context.destination); //this should not be necessary
};
Recorder.forceDownload = function(blob, filename){
var url = (window.URL || window.webkitURL).createObjectURL(blob);
var link = window.document.createElement('a');
link.href = url;
link.download = filename || 'output.wav';
var click = document.createEvent("Event");
click.initEvent("click", true, true);
link.dispatchEvent(click);
};
var recorder = Recorder;
return recorder;
})));