Playing with WebAudio and WebRTC

webrtc.js

// Browser compat
window.AudioContext = window.AudioContext || window.webkitAudioContext;
window.RTCPeerConnection = window.RTCPeerConnection || window.webkitRTCPeerConnection || window.mozRTCPeerConnection;
navigator.getUserMedia = navigator.getUserMedia || navigator.webkitGetUserMedia;

var key = window.location.hash.substring(1);

var audio_context = new AudioContext();
var local_output = audio_context.createMediaStreamDestination();

function gen_sinusoid(freq) {
	var samples = 1024; // TODO: Pick a number so theres no discontinuity on loop
	var buffer = audio_context.createBuffer(1, samples, audio_context.sampleRate);
	var data = buffer.getChannelData(0);
	for (var i=0; i<data.length; ++i) {
		data[i] = Math.sin(i*2*Math.PI*freq/audio_context.sampleRate);
	}
	return buffer;
}

var tone = null;
function play_tone() {
	var n = audio_context.createBufferSource();
	n.buffer = tone;
	n.connect(local_output);
	n.loop = true;
	n.start(0);
	n.stop(2);
}

function use_mic() {
	// Request local microphone access
	navigator.getUserMedia({
		audio:true
	}, function(stream) {
		var devices = stream.getAudioTracks();
		console.log("Opened audio sources: " + devices.map(function(v){return v.label;}).join());

		audio_context.createMediaStreamSource(stream).connect(local_output);
	}, function(err) {
		console.error(err);
	});
}

// Create peer object
var rtc_config = null;
var pc = new RTCPeerConnection(rtc_config);

var ice_list = [];
pc.onsignalingstatechange = function(event) {
	console.log("onsignalingstatechange", event);
};
// onicecandidate is called once for each element in list of ice candidates; followed by null
pc.onicecandidate = function(event) {
	if (event.candidate !== null) {
		ice_list.push(event.candidate);
	} else {
		// console.log("ICE:"+JSON.stringify(ice_list));
		localStorage[key] = JSON.stringify({
			type: "ice",
			data: ice_list
		});
		localStorage.removeItem(key);
		ice_list = [];
	}
};

pc.ondatachannel = function(event) {
	console.log("ondatachannel", event);
	event.channel.onmessage = function(event) {
		console.log("DATA", event);
	};
};
//pc.createDataChannel("mydata", {});

pc.onaddstream = function(event) {
	console.log("onaddstream", event);
	// Connect remote source to local speakers

	/* Chrome doesn't support remote audio streams in audio contexts....
	var remote_source = audio_context.createMediaStreamSource(event.stream);
	remote_source.connect(audio_context.destination);

	// Use an audio element instead
	*/
	var audio_elem = document.createElement("audio");
	// var audio_elem = document.getElementById("audio");
	audio_elem.src = URL.createObjectURL(event.stream);
	audio_elem.play();
};
pc.onremovestream = function(event) {
	console.log("onremovestream", event);
};

var on_description = function(desc) {
	console.log("on_description", desc);
	pc.setLocalDescription(desc);
	localStorage[key] = JSON.stringify({
		type: desc.type,
		data: desc
	});
	localStorage.removeItem(key);
};
pc.onnegotiationneeded = function(event) {
	console.log("onnegotiationneeded", event);
	pc.createOffer(on_description);
};
var initiate_call = function() {
	pc.createOffer(on_description);
};

var on_incoming_sdp_offer = function(desc) {
	pc.setRemoteDescription(new RTCSessionDescription(desc), function() {
		pc.createAnswer(on_description);
	});
};
var on_incoming_sdp_answer = function(desc) {
	pc.setRemoteDescription(new RTCSessionDescription(desc));
};
var on_incoming_ice = function(candidate_list) {
	for (var i in candidate_list) {
		var candidate = candidate_list[i];
		pc.addIceCandidate(new RTCIceCandidate(candidate));
	}
	console.log("Added ICE Candidates",candidate_list);
};

// Use localStorage to communicate between tabs
function listen_to(who) {
	window.addEventListener("storage", function(e){
		if (e.newValue === null) return;
		if (e.key !== who) return;
		var val = JSON.parse(e.newValue);
		switch (val.type) {
			case "offer":
				on_incoming_sdp_offer(val.data);
				break;
			case "answer":
				on_incoming_sdp_answer(val.data);
				break;
			case "ice":
				on_incoming_ice(val.data);
				break;
		}
	}, false);
}


if (key == "local") {
	local_output.connect(audio_context.destination);
} else if (key == "asd") {
	listen_to("qwe");
	initiate_call();
	tone = gen_sinusoid(300);
	play_tone()
	pc.addStream(local_output.stream);
} else if (key == "qwe") {
	listen_to("asd");
	tone = gen_sinusoid(600);
	play_tone()
	// pc.addStream(local_output.stream);
}