working example with one input to the mixer

example/example.js

@@ -0,0 +1,46 @@
+var
+	fs = require('fs'),
+	Speaker = require('speaker'),
+
+	Mixer = require('../index.js'),
+
+	lame = require('lame')
+	;
+
+/*
+ * Create the mixer and stream to speaker:
+ */
+
+var mixer = new Mixer({
+	channels: 1
+});
+
+var speaker = new Speaker({
+	channels: 1,
+	bitDepth: 16,
+	sampleRate: 44100
+});
+
+mixer.pipe(speaker);
+
+/*
+ * Decode mp3 and add the stream as mixer input:
+ */
+
+var file = fs.createReadStream('example0.mp3');
+
+var decoder = new lame.Decoder();
+var mp3stream = file.pipe(decoder);
+
+decoder.on('format', function (format) {
+	console.log(format);
+
+	mp3stream.pipe(mixer.input({
+		sampleRate: format.sampleRate,
+		channels: format.channels,
+		bitDepth: format.bitDepth
+	}));
+
+});
+
+

example/package.json

@@ -0,0 +1,6 @@
+{
+  "dependencies": {
+    "lame": "*",
+    "speaker": "*"
+  }
+}

lib/input.js

@@ -1,10 +1,10 @@
 var
 	Writable = require('stream').Writable,
-	util = require('util'),
+	util = require('util')
 	;
 
 function Input(args) {
-	this.buffer = Buffer.concat([this.buffer, chunk]);
+	Writable.call(this, args);
 
 	if (typeof args === 'undefined') args = {};
 	if (args.channels != 1 && args.channels != 2) args.channels = 2;
@@ -16,19 +16,19 @@ function Input(args) {
 	if (args.channels == 2) this.readStereo = this.read;
 
 	if (args.bitDepth == 8) {
-		this.readSample = Buffer.readInt8;
+		this.readSample = this.buffer.readInt8;
-		this.writeSample = Buffer.writeInt8;
+		this.writeSample = this.buffer.writeInt8;
 		this.sampleByteLength = 1;
 	}
 	else if (args.bitDepth == 32) {
-		this.readSample = Buffer.readInt32LE;
+		this.readSample = this.buffer.readInt32LE;
-		this.writeSample = Buffer.writeInt32LE;
+		this.writeSample = this.buffer.writeInt32LE;
 		this.sampleByteLength = 4;
 	}
 	else {
 		args.bitDepth = 16;
-		this.readSample = Buffer.readInt16LE;
+		this.readSample = this.buffer.readInt16LE;
-		this.writeSample = Buffer.writeInt16LE;
+		this.writeSample = this.buffer.writeInt16LE;
 		this.sampleByteLength = 2;
 	}
 
@@ -42,10 +42,13 @@ function Input(args) {
 util.inherits(Input, Writable);
 
 Input.prototype.read = function (samples) {
+	console.log('read()');
 	var bytes = samples * (this.bitDepth / 8) * this.channels;
 	if (this.buffer.length < bytes) bytes = this.buffer.length;
+	console.log(this.buffer.length);
 	var r = this.buffer.slice(0, bytes);
 	this.buffer = this.buffer.slice(bytes);
+	console.log(this.buffer.length);
 
 	if (this.buffer.length <= 131072 && this.getMoreData !== null) {
 		var getMoreData = this.getMoreData;
@@ -57,6 +60,7 @@ Input.prototype.read = function (samples) {
 }
 
 Input.prototype.readMono = function (samples) {
+	console.log('readMono()');
 	// This function will be overridden by this.read, if input already is mono.
 	var stereoBuffer = this.read(samples);
 	var monoBuffer = new Buffer(stereoBuffer.length / 2);
@@ -70,6 +74,7 @@ Input.prototype.readMono = function (samples) {
 }
 
 Input.prototype.readStereo = function (samples) {
+	console.log('readStereo()');
 	// This function will be overridden by this.read, if input already is stereo.
 	var monoBuffer = this.read(samples);
 	var stereoBuffer = new Buffer(monoBuffer.length * 2);
@@ -82,12 +87,15 @@ Input.prototype.readStereo = function (samples) {
 	return stereoBuffer;
 }
 
-Input.availSamples = function (length) {
+Input.prototype.availSamples = function (length) {
 	if (typeof length === 'undefined') length = this.buffer.length;
 	return Math.floor(length / ((this.bitDepth / 8) * this.channels));
 }
 
 Input.prototype._write = function (chunk, encoding, next) {
+
+	console.log('_write', arguments);
+
 	/*
 	if (!Buffer.isBuffer(chunk)) {
 		chunk = new Buffer(chunk, encoding);
@@ -103,3 +111,4 @@ Input.prototype._write = function (chunk, encoding, next) {
 	
 }
 
+module.exports = Input;

lib/mixer.js

@@ -6,26 +6,29 @@ var
 	;
 
 function Mixer(args) {
+	Readable.call(this, args);
 
 	if (typeof args === 'undefined') args = {};
 	if (args.channels != 1 && args.channels != 2) args.channels = 2;
 	if (typeof args.sampleRate === 'number' || args.sampleRate < 1) args.sampleRate = 44100; 
 
+	this.buffer = new Buffer(0);
+
 	this.bitDepth = args.bitDepth;
 	if (args.bitDepth == 8) {
-		this.readSample = Buffer.readInt8;
+		this.readSample = this.buffer.readInt8;
-		this.writeSample = Buffer.writeInt8;
+		this.writeSample = this.buffer.writeInt8;
 		this.sampleByteLength = 1;
 	}
 	else if (args.bitDepth == 32) {
-		this.readSample = Buffer.readInt32LE;
+		this.readSample = this.buffer.readInt32LE;
-		this.writeSample = Buffer.writeInt32LE;
+		this.writeSample = this.buffer.writeInt32LE;
 		this.sampleByteLength = 4;
 	}
 	else {
 		args.bitDepth = 16;
-		this.readSample = Buffer.readInt16LE;
+		this.readSample = this.buffer.readInt16LE;
-		this.writeSample = Buffer.writeInt16LE;
+		this.writeSample = this.buffer.writeInt16LE;
 		this.sampleByteLength = 2;
 	}
 
@@ -39,23 +42,33 @@ util.inherits(Mixer, Readable);
 
 Mixer.prototype._read = function() {
 
+	console.log('_read', arguments);
+
 	var samples = 9007199254740992;
 	this.inputs.forEach(function (input) {
 		var as = input.availSamples();
 		if (as < samples) samples = as;
 	});
-	if (samples > 0) {
+	if (samples > 0 && samples != 9007199254740992) {
+		console.log('read samples', samples);
 
-		var mixedBuffer = new Buffer(samples * this.sampleByteLength);
+		var mixedBuffer = new Buffer(samples * this.sampleByteLength * this.channels);
-		for (var i = 0; i < samples; i++) {
+		mixedBuffer.fill(0);
-			var mixedSample = 0;
+		this.inputs.forEach(function (input) {
-			for (var j = 0; j < this.inputs.length; j++) {
+			if (this.channels == 1) {
-				mixedSample += this.inputs[j].readSample.call(this.inputs[j], i * this.inputs[j].sampleByteLength);
+				var inputBuffer = input.readMono(samples);
+			} else {
+				var inputBuffer = input.readStereo(samples);
 			}
-			this.writeSample.call(mixedBuffer, Math.round(mixedSample / this.inputs.length), i * this.sampleByteLength);
+			for (var i = 0; i < samples * this.channels; i++) {
+				this.writeSample.call(mixedBuffer, this.readSample.call(mixedBuffer, i * this.sampleByteLength) + Math.round(this.readSample.call(inputBuffer, i * this.sampleByteLength) / this.inputs.length), i * this.sampleByteLength);
 			}
+		}.bind(this));
 
 		this.push(mixedBuffer);
+	} else {
+		console.log('Nothing to read.');
+		setImmediate(this._read.bind(this));
 	}
 }