Xefir/audio-mixer
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average mixing

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alfred 2014-01-01 00:27:03 +00:00
parent 362a00c967
commit 08c3a63dc1
1 changed files with 37 additions and 3 deletions
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40
lib/mixer.js
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@ -9,11 +9,27 @@ function Mixer(args) {
if (typeof args === 'undefined') args = {};
if (args.channels != 1 && args.channels != 2) args.channels = 2;
if (args.bitDepth != 8 && args.bitDepth != 16 && args.bitDepth != 32) args.bitDepth = 16;
if (typeof args.sampleRate === 'number' || args.sampleRate < 1) args.sampleRate = 44100;
this.channels = args.channels;
this.bitDepth = args.bitDepth;
if (args.bitDepth == 8) {
this.readSample = Buffer.readInt8;
this.writeSample = Buffer.writeInt8;
this.sampleByteLength = 1;
}
else if (args.bitDepth == 32) {
this.readSample = Buffer.readInt32LE;
this.writeSample = Buffer.writeInt32LE;
this.sampleByteLength = 4;
}
else {
args.bitDepth = 16;
this.readSample = Buffer.readInt16LE;
this.writeSample = Buffer.writeInt16LE;
this.sampleByteLength = 2;
}
this.channels = args.channels;
this.sampleRate = args.sampleRate;
this.inputs = [];
@ -22,7 +38,25 @@ function Mixer(args) {
util.inherits(Mixer, Readable);
Mixer.prototype._read = function() {
this.push(0);
var samples = 9007199254740992;
this.inputs.forEach(function (input) {
var as = input.availSamples();
if (as < samples) samples = as;
});
if (samples > 0) {
var mixedBuffer = new Buffer(samples * this.sampleByteLength);
for (var i = 0; i < samples; i++) {
var mixedSample = 0;
for (var j = 0; j < this.inputs.length; j++) {
mixedSample += this.inputs[j].readSample.call(this.inputs[j], i * this.inputs[j].sampleByteLength);
}
this.writeSample.call(mixedBuffer, Math.round(mixedSample / this.inputs.length), i * this.sampleByteLength);
}
this.push(mixedBuffer);
}
}
Mixer.prototype.input = function (args) {