server.js

var express = require('express');
var app = express();
//var http = require('http').Server(app);


//var ffmpeg = require('fluent-ffmpeg');
//var stream = require('stream');
var spawn = require('child_process').spawn;
var fs = require('fs');
var https = require('https');
app.use(express.static('public'));

const server = require('http').createServer(//{
 //key: fs.readFileSync('abels-key.pem'),
 // cert: fs.readFileSync('abels-cert.pem')
 
	//},
	app);


var io = require('socket.io')(server);
spawn('ffmpeg',['-h']).on('error',function(m){
	console.error("FFMpeg not found in system cli; please install ffmpeg properly or make a softlink to ./!");
	process.exit(-1);
});


io.on('connection', function(socket){
	socket.emit('message','Hello from mediarecorder-to-rtmp server!');
	socket.emit('message','Please set rtmp destination before start streaming.');
	
	
	
	var ffmpeg_process, feedStream=false;
	socket.on('config_rtmpDestination',function(m){
		if(typeof m != 'string'){
			socket.emit('fatal','rtmp destination setup error.');
			return;
		}
		var regexValidator=/^rtmp:\/\/[^\s]*$/;//TODO: should read config
		if(!regexValidator.test(m)){
			socket.emit('fatal','rtmp address rejected.');
			return;
		}
		socket._rtmpDestination=m;
		socket.emit('message','rtmp destination set to:'+m);
	}); 
	//socket._vcodec='libvpx';//from firefox default encoder
	socket.on('config_vcodec',function(m){
		if(typeof m != 'string'){
			socket.emit('fatal','input codec setup error.');
			return;
		}
		if(!/^[0-9a-z]{2,}$/.test(m)){
			socket.emit('fatal','input codec contains illegal character?.');
			return;
		}//for safety
		socket._vcodec=m;
	}); 	


	socket.on('start',function(m){
		if(ffmpeg_process || feedStream){
			
			socket.emit('fatal','stream already started.');
			return;
		}
		if(!socket._rtmpDestination){
			socket.emit('fatal','no destination given.');
			return;
		}
		
		var framerate = socket.handshake.query.framespersecond;
		var audioBitrate = parseInt(socket.handshake.query.audioBitrate);
	    var audioEncoding = "64k";
		if (audioBitrate ==11025){
			audioEncoding = "11k";
		} else if (audioBitrate ==22050){
			audioEncoding = "22k";
		} else if (audioBitrate ==44100){
			audioEncoding = "44k";
		}
		console.log(audioEncoding, audioBitrate);
		console.log('framerate on node side', framerate);
		//var ops = [];
		if (framerate == 1){
			var ops = [
				'-i','-',
				 '-c:v', 'libx264', '-preset', 'ultrafast', '-tune', 'zerolatency', 
				//'-max_muxing_queue_size', '1000', 
				//'-bufsize', '5000',
			       '-r', '1', '-g', '2', '-keyint_min','2', 
					'-x264opts', 'keyint=2', '-crf', '25', '-pix_fmt', 'yuv420p',
			        '-profile:v', 'baseline', '-level', '3', 
     				'-c:a', 'aac', '-b:a', audioEncoding, '-ar', audioBitrate, 
			        '-f', 'flv', socket._rtmpDestination		
			];
			
		}else if (framerate == 15){
			var ops = [
				'-i','-',
				 '-c:v', 'libx264', '-preset', 'ultrafast', '-tune', 'zerolatency', 
				'-max_muxing_queue_size', '1000', 
				'-bufsize', '5000',
			       '-r', '15', '-g', '30', '-keyint_min','30', 
					'-x264opts', 'keyint=30', '-crf', '25', '-pix_fmt', 'yuv420p',
			        '-profile:v', 'baseline', '-level', '3', 
     				'-c:a', 'aac', '-b:a',audioEncoding, '-ar', audioBitrate, 
			        '-f', 'flv', socket._rtmpDestination		
			];
			
		}else{
		   var ops=[
			 '-i','-',
			//'-c', 'copy', 
			'-c:v', 'libx264', '-preset', 'ultrafast', '-tune', 'zerolatency',  // video codec config: low latency, adaptive bitrate
			'-c:a', 'aac', '-ar', audioBitrate, '-b:a', audioEncoding, // audio codec config: sampling frequency (11025, 22050, 44100), bitrate 64 kbits
			//'-max_muxing_queue_size', '4000', 
			//'-y', //force to overwrite
			//'-use_wallclock_as_timestamps', '1', // used for audio sync
			//'-async', '1', // used for audio sync
			//'-filter_complex', 'aresample=44100', // resample audio to 44100Hz, needed if input is not 44100
			//'-strict', 'experimental', 
			'-bufsize', '5000',
			
			'-f', 'flv', socket._rtmpDestination
			/*. original params
			'-i','-',
			'-c:v', 'libx264', '-preset', 'veryfast', '-tune', 'zerolatency',  // video codec config: low latency, adaptive bitrate
			'-c:a', 'aac', '-ar', '44100', '-b:a', '64k', // audio codec config: sampling frequency (11025, 22050, 44100), bitrate 64 kbits
			'-y', //force to overwrite
			'-use_wallclock_as_timestamps', '1', // used for audio sync
			'-async', '1', // used for audio sync
			//'-filter_complex', 'aresample=44100', // resample audio to 44100Hz, needed if input is not 44100
			//'-strict', 'experimental', 
			'-bufsize', '1000',
			'-f', 'flv', socket._rtmpDestination
			*/
			
		];
	}
	console.log("ops", ops);
		console.log(socket._rtmpDestination);
		ffmpeg_process=spawn('ffmpeg', ops);
		console.log("ffmpeg spawned");
		feedStream=function(data){
			
			ffmpeg_process.stdin.write(data);
			//write exception cannot be caught here.	
		}

		ffmpeg_process.stderr.on('data',function(d){
			socket.emit('ffmpeg_stderr',''+d);
		});
		ffmpeg_process.on('error',function(e){
			console.log('child process error'+e);
			socket.emit('fatal','ffmpeg error!'+e);
			feedStream=false;
			socket.disconnect();
		});
		ffmpeg_process.on('exit',function(e){
			console.log('child process exit'+e);
			socket.emit('fatal','ffmpeg exit!'+e);
			socket.disconnect();
		});
	});

	socket.on('binarystream',function(m){
		if(!feedStream){
			socket.emit('fatal','rtmp not set yet.');
			ffmpeg_process.stdin.end();
			ffmpeg_process.kill('SIGINT');
			return;
		}
		feedStream(m);
	});
	socket.on('disconnect', function () {
		console.log("socket disconnected!");
		feedStream=false;
		if(ffmpeg_process)
		try{
			ffmpeg_process.stdin.end();
			ffmpeg_process.kill('SIGINT');
			console.log("ffmpeg process ended!");
		}catch(e){console.warn('killing ffmoeg process attempt failed...');}
	});
	socket.on('error',function(e){
		
		console.log('socket.io error:'+e);
	});
});

io.on('error',function(e){
	console.log('socket.io error:'+e);
});


server.listen(process.env.PORT || 1437, function(){
  console.log('https and websocket listening on *:1437');
});

process.on('uncaughtException', function(err) {
    // handle the error safely
    console.log(err)
    // Note: after client disconnect, the subprocess will cause an Error EPIPE, which can only be caught this way.
})