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feross
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Description

📡 Simple WebRTC video, voice, and data channels

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Simple WebRTC video, voice, and data channels

features

  • concise, node.js style API for WebRTC
  • works in node and the browser!
  • supports video/voice streams
  • supports data channel
  • supports advanced options like:

This package is used by WebTorrent and many others.

install

npm install simple-peer

This package works in the browser with browserify. If you do not use a bundler, you can use the

simplepeer.min.js
standalone script directly in a
 tag. This exports a 
SimplePeer
constructor on
window
. Wherever you see
Peer
in the examples below, substitute that with
SimplePeer
.

usage

Let's create an html page that lets you manually connect two peers:

<style>
  #outgoing {
    width: 600px;
    word-wrap: break-word;
    white-space: normal;
  }
</style>
</pre><form>
  <textarea id="incoming"></textarea>
  <button type="submit">submit</button>
</form>
<pre id="outgoing"></pre>
<script src="simplepeer.min.js"></script>
<script>
  const p = new SimplePeer({
    initiator: location.hash === '#1',
    trickle: false
  })

  p.on('error', err => console.log('error', err))

  p.on('signal', data => {
    console.log('SIGNAL', JSON.stringify(data))
    document.querySelector('#outgoing').textContent = JSON.stringify(data)
  })

  document.querySelector('form').addEventListener('submit', ev => {
    ev.preventDefault()
    p.signal(JSON.parse(document.querySelector('#incoming').value))
  })

  p.on('connect', () => {
    console.log('CONNECT')
    p.send('whatever' + Math.random())
  })

  p.on('data', data => {
    console.log('data: ' + data)
  })
</script>

Visit

index.html#1
from one browser (the initiator) and
index.html
from another browser (the receiver).

An "offer" will be generated by the initiator. Paste this into the receiver's form and hit submit. The receiver generates an "answer". Paste this into the initiator's form and hit submit.

Now you have a direct P2P connection between two browsers!

A simpler example

This example create two peers in the same web page.

In a real-world application, you would never do this. The sender and receiver

Peer
instances would exist in separate browsers. A "signaling server" (usually implemented with websockets) would be used to exchange signaling data between the two browsers until a peer-to-peer connection is established.

data channels

var Peer = require('simple-peer')

var peer1 = new Peer({ initiator: true }) var peer2 = new Peer()

peer1.on('signal', data => { // when peer1 has signaling data, give it to peer2 somehow peer2.signal(data) })

peer2.on('signal', data => { // when peer2 has signaling data, give it to peer1 somehow peer1.signal(data) })

peer1.on('connect', () => { // wait for 'connect' event before using the data channel peer1.send('hey peer2, how is it going?') })

peer2.on('data', data => { // got a data channel message console.log('got a message from peer1: ' + data) })

video/voice

Video/voice is also super simple! In this example, peer1 sends video to peer2.

var Peer = require('simple-peer')

// get video/voice stream navigator.mediaDevices.getUserMedia({ video: true, audio: true }).then(gotMedia).catch(() => {})

function gotMedia (stream) { var peer1 = new Peer({ initiator: true, stream: stream }) var peer2 = new Peer()

peer1.on('signal', data => { peer2.signal(data) })

peer2.on('signal', data => { peer1.signal(data) })

peer2.on('stream', stream => { // got remote video stream, now let's show it in a video tag var video = document.querySelector('video')

if ('srcObject' in video) {
  video.srcObject = stream
} else {
  video.src = window.URL.createObjectURL(stream) // for older browsers
}

video.play()

}) }

For two-way video, simply pass a

stream
option into both
Peer
constructors. Simple!

Please notice that

getUserMedia
only works in pages loaded via https.

dynamic video/voice

It is also possible to establish a data-only connection at first, and later add a video/voice stream, if desired.

var Peer = require('simple-peer') // create peer without waiting for media

var peer1 = new Peer({ initiator: true }) // you don't need streams here var peer2 = new Peer()

peer1.on('signal', data => { peer2.signal(data) })

peer2.on('signal', data => { peer1.signal(data) })

peer2.on('stream', stream => { // got remote video stream, now let's show it in a video tag var video = document.querySelector('video')

if ('srcObject' in video) { video.srcObject = stream } else { video.src = window.URL.createObjectURL(stream) // for older browsers }

video.play() })

function addMedia (stream) { peer1.addStream(stream) // {})

in node

To use this library in node, pass in

opts.wrtc
as a parameter (see the constructor options):
var Peer = require('simple-peer')
var wrtc = require('wrtc')

var peer1 = new Peer({ initiator: true, wrtc: wrtc }) var peer2 = new Peer({ wrtc: wrtc })

api

peer = new Peer([opts])

Create a new WebRTC peer connection.

A "data channel" for text/binary communication is always established, because it's cheap and often useful. For video/voice communication, pass the

stream
option.

If

opts
is specified, then the default options (shown below) will be overridden.
{
  initiator: false,
  channelConfig: {},
  channelName: '',
  config: { iceServers: [{ urls: 'stun:stun.l.google.com:19302' }, { urls: 'stun:global.stun.twilio.com:3478?transport=udp' }] },
  offerOptions: {},
  answerOptions: {},
  sdpTransform: function (sdp) { return sdp },
  stream: false,
  streams: [],
  trickle: true,
  allowHalfTrickle: false,
  wrtc: {}, // RTCPeerConnection/RTCSessionDescription/RTCIceCandidate
  objectMode: false
}

The options do the following:

  • initiator
    - set to
    true
    if this is the initiating peer
  • channelConfig
    - custom webrtc data channel configuration (used by
    createDataChannel
    )
  • channelName
    - custom webrtc data channel name
  • config
    - custom webrtc configuration (used by
    RTCPeerConnection
    constructor)
  • offerOptions
    - custom offer options (used by
    createOffer
    method)
  • answerOptions
    - custom answer options (used by
    createAnswer
    method)
  • sdpTransform
    - function to transform the generated SDP signaling data (for advanced users)
  • stream
    - if video/voice is desired, pass stream returned from
    getUserMedia
  • streams
    - an array of MediaStreams returned from
    getUserMedia
  • trickle
    - set to
    false
    to disable trickle ICE and get a single 'signal' event (slower)
  • wrtc
    - custom webrtc implementation, mainly useful in node to specify in the wrtc package. Contains an object with the properties:
  • objectMode
    - set to
    true
    to create the stream in Object Mode. In this mode, incoming string data is not automatically converted to
    Buffer
    objects.

peer.signal(data)

Call this method whenever the remote peer emits a

peer.on('signal')
event.

The

data
will encapsulate a webrtc offer, answer, or ice candidate. These messages help the peers to eventually establish a direct connection to each other. The contents of these strings are an implementation detail that can be ignored by the user of this module; simply pass the data from 'signal' events to the remote peer and call
peer.signal(data)
to get connected.

peer.send(data)

Send text/binary data to the remote peer.

data
can be any of several types:
String
,
Buffer
(see buffer),
ArrayBufferView
(
Uint8Array
, etc.),
ArrayBuffer
, or
Blob
(in browsers that support it).

Note: If this method is called before the

peer.on('connect')
event has fired, then an exception will be thrown. Use
peer.write(data)
(which is inherited from the node.js duplex stream interface) if you want this data to be buffered instead.

peer.addStream(stream)

Add a

MediaStream
to the connection.

peer.removeStream(stream)

Remove a

MediaStream
from the connection.

peer.addTrack(track, stream)

Add a

MediaStreamTrack
to the connection. Must also pass the
MediaStream
you want to attach it to.

peer.removeTrack(track, stream)

Remove a

MediaStreamTrack
from the connection. Must also pass the
MediaStream
that it was attached to.

peer.replaceTrack(oldTrack, newTrack, stream)

Replace a

MediaStreamTrack
with another track. Must also pass the
MediaStream
that the old track was attached to.

peer.addTransceiver(kind, init)

Add a

RTCRtpTransceiver
to the connection. Can be used to add transceivers before adding tracks. Automatically called as neccesary by
addTrack
.

peer.destroy([err])

Destroy and cleanup this peer connection.

If the optional

err
parameter is passed, then it will be emitted as an
'error'
event on the stream.

Peer.WEBRTC_SUPPORT

Detect native WebRTC support in the javascript environment.

var Peer = require('simple-peer')

if (Peer.WEBRTC_SUPPORT) { // webrtc support! } else { // fallback }

duplex stream

Peer
objects are instances of
stream.Duplex
. They behave very similarly to a
net.Socket
from the node core
net
module. The duplex stream reads/writes to the data channel.
var peer = new Peer(opts)
// ... signaling ...
peer.write(new Buffer('hey'))
peer.on('data', function (chunk) {
  console.log('got a chunk', chunk)
})

events

Peer
objects are instance of
EventEmitter
. Take a look at the nodejs events documentation for more information.

Example of removing all registered close-event listeners:

js
peer.removeAllListeners('close')

peer.on('signal', data => {})

Fired when the peer wants to send signaling data to the remote peer.

It is the responsibility of the application developer (that's you!) to get this data to the other peer. This usually entails using a websocket signaling server. This data is an

Object
, so remember to call
JSON.stringify(data)
to serialize it first. Then, simply call
peer.signal(data)
on the remote peer.

(Be sure to listen to this event immediately to avoid missing it. For

initiator: true
peers, it fires right away. For
initatior: false
peers, it fires when the remote offer is received.)

peer.on('connect', () => {})

Fired when the peer connection and data channel are ready to use.

peer.on('data', data => {})

Received a message from the remote peer (via the data channel).

data
will be either a
String
or a
Buffer/Uint8Array
(see buffer).

peer.on('stream', stream => {})

Received a remote video stream, which can be displayed in a video tag:

peer.on('stream', stream => {
  var video = document.querySelector('video')
  if ('srcObject' in video) {
    video.srcObject = stream
  } else {
    video.src = window.URL.createObjectURL(stream)
  }
  video.play()
})

peer.on('track', (track, stream) => {})

Received a remote audio/video track. Streams may contain multiple tracks.

peer.on('close', () => {})

Called when the peer connection has closed.

peer.on('error', (err) => {})

Fired when a fatal error occurs. Usually, this means bad signaling data was received from the remote peer.

err
is an
Error
object.

error codes

Errors returned by the

error
event have an
err.code
property that will indicate the origin of the failure.

Possible error codes: -

ERR_WEBRTC_SUPPORT
-
ERR_CREATE_OFFER
-
ERR_CREATE_ANSWER
-
ERR_SET_LOCAL_DESCRIPTION
-
ERR_SET_REMOTE_DESCRIPTION
-
ERR_ADD_ICE_CANDIDATE
-
ERR_ICE_CONNECTION_FAILURE
-
ERR_SIGNALING
-
ERR_DATA_CHANNEL
-
ERR_CONNECTION_FAILURE

connecting more than 2 peers?

The simplest way to do that is to create a full-mesh topology. That means that every peer opens a connection to every other peer. To illustrate:

full mesh topology

To broadcast a message, just iterate over all the peers and call

peer.send
.

So, say you have 3 peers. Then, when a peer wants to send some data it must send it 2 times, once to each of the other peers. So you're going to want to be a bit careful about the size of the data you send.

Full mesh topologies don't scale well when the number of peers is very large. The total number of edges in the network will be full mesh formula where

n
is the number of peers.

For clarity, here is the code to connect 3 peers together:

Peer 1

// These are peer1's connections to peer2 and peer3
var peer2 = new Peer({ initiator: true })
var peer3 = new Peer({ initiator: true })

peer2.on('signal', data => { // send this signaling data to peer2 somehow })

peer2.on('connect', () => { peer2.send('hi peer2, this is peer1') })

peer2.on('data', data => { console.log('got a message from peer2: ' + data) })

peer3.on('signal', data => { // send this signaling data to peer3 somehow })

peer3.on('connect', () => { peer3.send('hi peer3, this is peer1') })

peer3.on('data', data => { console.log('got a message from peer3: ' + data) })

Peer 2

// These are peer2's connections to peer1 and peer3
var peer1 = new Peer()
var peer3 = new Peer({ initiator: true })

peer1.on('signal', data => { // send this signaling data to peer1 somehow })

peer1.on('connect', () => { peer1.send('hi peer1, this is peer2') })

peer1.on('data', data => { console.log('got a message from peer1: ' + data) })

peer3.on('signal', data => { // send this signaling data to peer3 somehow })

peer3.on('connect', () => { peer3.send('hi peer3, this is peer2') })

peer3.on('data', data => { console.log('got a message from peer3: ' + data) })

Peer 3

// These are peer3's connections to peer1 and peer2
var peer1 = new Peer()
var peer2 = new Peer()

peer1.on('signal', data => { // send this signaling data to peer1 somehow })

peer1.on('connect', () => { peer1.send('hi peer1, this is peer3') })

peer1.on('data', data => { console.log('got a message from peer1: ' + data) })

peer2.on('signal', data => { // send this signaling data to peer2 somehow })

peer2.on('connect', () => { peer2.send('hi peer2, this is peer3') })

peer2.on('data', data => { console.log('got a message from peer2: ' + data) })

memory usage

If you call

peer.send(buf)
,
simple-peer
is not keeping a reference to
buf
and sending the buffer at some later point in time. We immediately call
channel.send()
on the data channel. So it should be fine to mutate the buffer right afterward.

However, beware that

peer.write(buf)
(a writable stream method) does not have the same contract. It will potentially buffer the data and call
channel.send()
at a future point in time, so definitely don't assume it's safe to mutate the buffer.

connection does not work on some networks?

If a direct connection fails, in particular, because of NAT traversal and/or firewalls, WebRTC ICE uses an intermediary (relay) TURN server. In other words, ICE will first use STUN with UDP to directly connect peers and, if that fails, will fall back to a TURN relay server.

In order to use a TURN server, you must specify the

config
option to the
Peer
constructor. See the API docs above.

js-standard-style

Who is using
simple-peer
?

  • WebTorrent - Streaming torrent client in the browser
  • Virus Cafe - Make a friend in 2 minutes
  • Instant.io - Secure, anonymous, streaming file transfer
  • Zencastr - Easily record your remote podcast interviews in studio quality.
  • Friends - Peer-to-peer chat powered by the web
  • Socket.io-p2p - Official Socket.io P2P communication library
  • ScreenCat - Screen sharing + remote collaboration app
  • WebCat - P2P pipe across the web using Github private/public key for auth
  • RTCCat - WebRTC netcat
  • PeerNet - Peer-to-peer gossip network using randomized algorithms
  • PusherTC - Video chat with using Pusher. See guide.
  • lxjs-chat - Omegle-like video chat site
  • Whiteboard - P2P Whiteboard powered by WebRTC and WebTorrent
  • Peer Calls - WebRTC group video calling. Create a room. Share the link.
  • Netsix - Send videos to your friends using WebRTC so that they can watch them right away.
  • Stealthy - Stealthy is a decentralized, end-to-end encrypted, p2p chat application.
  • oorja.io - Effortless video-voice chat with realtime collaborative features. Extensible using react components 🙌
  • TalktoMe - Skype alternative for audio/video conferencing based on WebRTC, but without the loss of packets.
  • CDNBye - CDNBye implements WebRTC datachannel to scale live/vod video streaming by peer-to-peer network using bittorrent-like protocol
  • Detox - Overlay network for distributed anonymous P2P communications entirely in the browser
  • Metastream - Watch streaming media with friends.
  • firepeer - secure signalling and authentication using firebase realtime database
  • Genet - Fat-tree overlay to scale the number of concurrent WebRTC connections to a single source (paper).
  • WebRTC Connection Testing - Quickly test direct connectivity between all pairs of participants (demo).
  • Firstdate.co - Online video dating for actually meeting people and not just messaging them
  • TensorChat - It's simple - Create. Share. Chat.
  • On/Office - View your desktop in a WebVR-powered environment
  • Cyph - Cryptographically secure messaging and social networking service, providing an extreme level of privacy combined with best-in-class ease of use
  • Ciphora - A peer-to-peer end-to-end encrypted messaging chat app.
  • Whisthub - Online card game Color Whist with the possibility to start a video chat while playing.
  • Brie.fi/ng - Secure anonymous video chat
  • Peer.School - Simple virtual classroom starting from the 1st class including video chat and real time whiteboard
  • FileFire - Transfer large files and folders at high speed without size limits.
  • safeShare - Transfer files easily with text and voice communication.
  • CubeChat - Party in 3D ğŸŽ‰
  • Homely School - A virtual schooling system
  • AnyDrop - Cross-platform AirDrop alternative with an Android app available at Google Play
  • Share-Anywhere - Cross-platform file transfer
  • QuaranTime.io - The Activity board-game in video!
  • Trango - Cross-platform calling and file sharing solution.
  • P2PT - Use WebTorrent trackers as signalling servers for making WebRTC connections
  • Dots - Online multiplayer Dots & Boxes game. Play Here!
  • simple-peer-files - A simple library to easily transfer files over WebRTC. Has a feature to resume file transfer after uploader interruption.
  • WebDrop.Space - Share files and messages across devices. Cross-platform, no installation alternative to AirDrop, Xender. Source Code
  • Speakrandom - Voice-chat social network using simple-peer to create audio conferences!

  • Your app here! - send a PR!

license

MIT. Copyright (c) Feross Aboukhadijeh.

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