streamy.js

var http = require('http');
var fs = require('fs');

var PassThrough = require('stream').PassThrough;
var lame = require('lame');
var spawn = require('child_process').spawn
var random = require("random-js")();


var streams = [];
var playlistDB = [{
	title: 'Detrooklyn',
	tracks: fs.readdirSync('files')	
}];
console.log(playlistDB[0].tracks.length);
function Mixer(){
	this.inStream = null;
	this.input = new PassThrough();
	this.startTime = null;
	this.bytesCommited = 0;
	this.output = new PassThrough();
	this.bps = 176400;
	var self = this;
	function a(){
		if(self.startTime == null) {
			self.startTime = Date.now();
			self.commit();
		}
		setTimeout(function(){
			self.commit();
			a();
		}, 4);
	}
	a()
}
Mixer.prototype.attach = function(stream) {
	if(this.inStream !== null) this.inStream.unpipe(this.input);
	this.inStream = stream;
	this.inStream.pipe(this.input, {end: false});
}
Mixer.prototype.commit = function() {
	//var start = Date.now();
	var processSize = Math.ceil((((Date.now()-this.startTime)/1000)*this.bps - this.bytesCommited)/8)*8;
	var out = this.input.read(processSize);	
	if(out == null || out.length != processSize) out = Buffer.alloc(processSize);
	this.output.write(out);
	this.bytesCommited += processSize;
	//console.log("took", Date.now()-start, 'did', processSize);
};

function Stream(playlistID){
	this.listeners = 0;
	this.playlist = playlistDB[playlistID];
	this.trackID = 0;
	this.mixer = new Mixer();
	this.encoder = new lame.Encoder({
		// input
		channels: 2,        // 2 channels (left and right)
		bitDepth: 16,       // 16-bit samples
		sampleRate: 44100,  // 44,100 Hz sample rate

		// output
		bitRate: 192,
		outSampleRate: 44100,
		mode: lame.STEREO // STEREO (default), JOINTSTEREO, DUALCHANNEL or MONO
	});
	this.mixer.output.pipe(this.encoder);

	this.changeTrack();
	this.play();
}
Stream.prototype.changeTrack = function(){
	this.trackID = random.integer(0, this.playlist.tracks.length-1);
	//this.trackID = Math.floor(Math.random() * this.playlist.tracks.length);
}
Stream.prototype.play = function(){
	console.log("playing", this.playlist.tracks[this.trackID]);
	var me = this;
	var vlcPs = spawn('ffmpeg', ['-i', 'files/'+this.playlist.tracks[this.trackID], '-vn', '-filter', 'volume=-12dB,equalizer=f=35:width_type=q:width=8.93:g=12', '-ar', '44100', '-ac', '2', '-acodec', 'pcm_s16le', '-f', 's16le', '-acodec', 'pcm_s16le', '-']);
	me.mixer.attach(vlcPs.stdout);

	vlcPs.addListener('close', function(){
		console.log('track finished');
		me.changeTrack();
		me.play();
	});
}

http.createServer(function(request, response) {
    response.writeHead(200, {
        //'Content-Type': 'audio/mpeg, audio/x-mpeg, audio/x-mpeg-3, audio/mpeg3'
        //'Content-Type': 'audio/pcm'
		'Content-type': 'audio/mpeg, audio/x-mpeg, audio/x-mpeg-3, audio/mpeg3'
    });

    var streamid="007";
    if(typeof streams[streamid] == 'undefined'){
    	streams[streamid] = new Stream(0);
    }

    var i = 0;
    function sendData(data){
        if(i % 40 == 0) console.log("encoded update", i, request.connection.remoteAddress);
        response.write(data);
        i++;
    }
    
    streams[streamid].encoder.on('data', sendData);

    request.on('close', function(err) {
        streams[streamid].encoder.removeListener('data', sendData);
        response.end();
    });
})
.listen(9000);