Peer-to-Peer WebRTC

Overview

Ant Media Server supports peer-to-peer (P2P) WebRTC communication, enabling direct connections between clients with the server acting as a signaling coordinator. This mode is ideal for video conferencing, multi-party calls, and interactive applications.

P2P Modes

Ant Media Server offers two primary P2P modes:

1. Mesh P2P (Peer-to-Peer)

Direct connections between all participants. Each peer sends and receives streams from every other peer. Pros:

Ultra-low latency
No server bandwidth consumption for media
Direct peer communication

Cons:

Limited scalability (recommended max 4-6 participants)
High client bandwidth requirement (N-1 uploads per peer)

2. Conference Mode (MCU/SFU)

Server-side mixing or forwarding of streams. The server handles stream distribution. Pros:

Scalable to many participants (100+ participants)
Lower client bandwidth (single upload)
Consistent quality for all participants

Cons:

Slightly higher latency than mesh
Server bandwidth consumption

Quick Start: P2P Room

Basic P2P Example

// Initialize WebRTC Adaptor for P2P
var webRTCAdaptor = new WebRTCAdaptor({
    websocket_url: "wss://your-server.com:5443/WebRTCAppEE/websocket",
    mediaConstraints: {
        video: true,
        audio: true
    },
    peerconnection_config: {
        iceServers: [{urls: "stun:stun1.l.google.com:19302"}]
    },
    sdp_constraints: {
        OfferToReceiveAudio: true,
        OfferToReceiveVideo: true
    },
    localVideoId: "localVideo",
    callback: function(info, obj) {
        if (info == "initialized") {
            // Join P2P room
            webRTCAdaptor.join(roomId);
        }
        else if (info == "joined") {
            // Successfully joined room
            console.log("Joined room: " + roomId);
        }
        else if (info == "newStreamAvailable") {
            // New peer joined
            console.log("New peer stream: " + obj.streamId);
            playPeerStream(obj.stream, obj.streamId);
        }
        else if (info == "peer_connection_closed") {
            // Peer left the room
            console.log("Peer left: " + obj.streamId);
            removePeerVideo(obj.streamId);
        }
    },
    callbackError: function(error, message) {
        console.log("Error: " + error);
    }
});

// Room ID
var roomId = "room123";

// Helper function to display peer streams
function playPeerStream(stream, streamId) {
    var video = document.createElement("video");
    video.id = "peer_" + streamId;
    video.autoplay = true;
    video.srcObject = stream;
    document.getElementById("peers").appendChild(video);
}

function removePeerVideo(streamId) {
    var video = document.getElementById("peer_" + streamId);
    if (video) {
        video.remove();
    }
}

HTML Setup for P2P

<!DOCTYPE html>
<html>
<head>
    <title>WebRTC P2P Room</title>
    <style>
        #localVideo {
            width: 300px;
            height: 200px;
        }
        #peers video {
            width: 300px;
            height: 200px;
            margin: 10px;
        }
    </style>
</head>
<body>
    <h1>P2P Video Room</h1>
    
    <div>
        <h2>Your Video</h2>
        <video id="localVideo" autoplay muted playsinline></video>
    </div>
    
    <div>
        <h2>Participants</h2>
        <div id="peers"></div>
    </div>
    
    <button onclick="webRTCAdaptor.join('room123')">Join Room</button>
    <button onclick="webRTCAdaptor.leave('room123')">Leave Room</button>
    
    <script src="https://your-server.com:5443/WebRTCAppEE/js/webrtc_adaptor.js"></script>
    <script>
        // Initialize adaptor (see code above)
    </script>
</body>
</html>

Conference Mode

Joining a Conference Room

var webRTCAdaptor = new WebRTCAdaptor({
    websocket_url: "wss://your-server.com:5443/WebRTCAppEE/websocket",
    mediaConstraints: {
        video: true,
        audio: true
    },
    peerconnection_config: {
        iceServers: [{urls: "stun:stun1.l.google.com:19302"}]
    },
    sdp_constraints: {
        OfferToReceiveAudio: true,
        OfferToReceiveVideo: true
    },
    localVideoId: "localVideo",
    callback: function(info, obj) {
        if (info == "initialized") {
            // Join conference room
            webRTCAdaptor.joinRoom(roomId, streamId);
        }
        else if (info == "joinedTheRoom") {
            // Successfully joined conference
            console.log("Joined conference: " + obj.roomId);
            console.log("Your stream ID: " + obj.streamId);
            
            // Play other streams in the room
            obj.streams.forEach(function(stream) {
                webRTCAdaptor.play(stream);
            });
        }
        else if (info == "streamJoined") {
            // New participant joined
            console.log("New participant: " + obj.streamId);
            webRTCAdaptor.play(obj.streamId);
        }
        else if (info == "streamLeaved") {
            // Participant left
            console.log("Participant left: " + obj.streamId);
            removePeerVideo(obj.streamId);
        }
        else if (info == "play_started") {
            // Started receiving peer stream
            console.log("Playing peer: " + obj.streamId);
        }
    },
    callbackError: function(error, message) {
        console.log("Error: " + error);
    }
});

var roomId = "conference123";
var streamId = "myStream_" + Math.random().toString(36).substring(7);

Conference Room Events

callback: function(info, obj) {
    switch(info) {
        case "joinedTheRoom":
            // obj.roomId - Room identifier
            // obj.streamId - Your stream ID in the room
            // obj.streams - Array of existing stream IDs
            console.log("Room info:", obj);
            break;
            
        case "streamJoined":
            // obj.streamId - New participant's stream ID
            console.log("New participant joined");
            break;
            
        case "streamLeaved":
            // obj.streamId - Participant who left
            console.log("Participant left");
            break;
            
        case "leavedFromRoom":
            // You left the room
            console.log("Left the room: " + obj.roomId);
            break;
            
        case "roomInformation":
            // Updated room information
            // obj.streams - Current streams in room
            console.log("Active streams:", obj.streams);
            break;
    }
}

Advanced P2P Features

Multi-Track Conference

Publish and receive multiple tracks (e.g., camera + screen share):

// Publish camera stream
var cameraStreamId = "camera_" + userId;
webRTCAdaptor.publish(cameraStreamId);

// Publish screen share as additional track
var screenStreamId = "screen_" + userId;
webRTCAdaptor.publish(screenStreamId, null, null, null, {
    video: { displaySurface: "monitor" },
    audio: false
});

// Join room with multiple streams
webRTCAdaptor.joinRoom(roomId, cameraStreamId);

Data Channel in P2P

Send text messages or data between peers:

var webRTCAdaptor = new WebRTCAdaptor({
    // ... other config
    dataChannelEnabled: true,
    callback: function(info, obj) {
        if (info == "data_channel_opened") {
            console.log("Data channel ready with peer: " + obj.streamId);
        }
        else if (info == "data_received") {
            console.log("Message from " + obj.streamId + ": " + obj.data);
            displayChatMessage(obj.streamId, obj.data);
        }
    }
});

// Send message to specific peer
function sendMessage(message, streamId) {
    webRTCAdaptor.sendData(streamId, message);
}

// Send message to all peers in room
function broadcastMessage(message) {
    webRTCAdaptor.sendData(roomId, message);
}

Audio/Video Control

Mute/unmute audio and video during conference:

// Mute/unmute microphone
function toggleMute() {
    webRTCAdaptor.muteLocalMic();
}

// Turn camera on/off
function toggleCamera() {
    webRTCAdaptor.turnOffLocalCamera();
    // Or turn back on
    webRTCAdaptor.turnOnLocalCamera();
}

// Switch between front/rear camera (mobile)
function switchCamera() {
    webRTCAdaptor.switchVideoCameraCapture(streamId);
}

// Get available devices
navigator.mediaDevices.enumerateDevices()
    .then(function(devices) {
        devices.forEach(function(device) {
            if (device.kind === 'audioinput') {
                console.log("Microphone: " + device.label);
            }
            else if (device.kind === 'videoinput') {
                console.log("Camera: " + device.label);
            }
        });
    });

Room Management

Get room information and participant list:

// Get room information
webRTCAdaptor.getRoomInfo(roomId);

// Callback receives room info
callback: function(info, obj) {
    if (info == "roomInformation") {
        console.log("Room: " + obj.roomId);
        console.log("Participants: " + obj.streams.length);
        obj.streams.forEach(function(streamId) {
            console.log("Participant: " + streamId);
        });
    }
}

// Leave room
function leaveRoom() {
    webRTCAdaptor.leaveFromRoom(roomId);
}

Signaling Protocol

P2P Signaling Flow

The P2P signaling involves WebSocket messages between peers and server:

// Client A joins room
-> {command: "joinRoom", room: "room123", streamId: "streamA"}
<- {command: "joinedTheRoom", streamId: "streamA", streams: ["streamB"]}

// Client A creates offer for Client B
-> {command: "takeConfiguration", streamId: "streamB", type: "offer", sdp: "..."}

// Server forwards to Client B
<- {command: "takeConfiguration", streamId: "streamA", type: "offer", sdp: "..."}

// Client B creates answer
-> {command: "takeConfiguration", streamId: "streamA", type: "answer", sdp: "..."}

// ICE candidates exchanged
-> {command: "takeCandidate", streamId: "streamB", candidate: {...}}
<- {command: "takeCandidate", streamId: "streamA", candidate: {...}}

Conference Signaling Flow

// Join conference room
-> {command: "joinRoom", room: "conference123", streamId: "mystream"}
<- {command: "joinedTheRoom", streamId: "mystream", streams: [...]}

// Publish your stream
-> {command: "publish", streamId: "mystream"}
<- {command: "start", streamId: "mystream"}

// Play other participant's stream
-> {command: "play", streamId: "otherstream"}
<- {command: "takeConfiguration", streamId: "otherstream", type: "answer"}

// New participant notification
<- {command: "streamJoined", streamId: "newstream"}

Best Practices

1. Limit Mesh P2P Participants

var MAX_PEERS = 4;

callback: function(info, obj) {
    if (info == "roomInformation") {
        if (obj.streams.length >= MAX_PEERS) {
            alert("Room is full. Please try another room.");
            webRTCAdaptor.leaveFromRoom(roomId);
        }
    }
}

2. Handle Network Quality

callback: function(info, obj) {
    if (info == "updated_stats") {
        // Monitor quality for each peer
        if (obj.videoPacketsLost > 100) {
            console.warn("Poor connection with peer: " + obj.streamId);
            // Notify user or adjust quality
        }
    }
}

3. Graceful Disconnection

// Leave room properly
function disconnect() {
    // Leave room
    webRTCAdaptor.leaveFromRoom(roomId);
    
    // Stop publishing
    webRTCAdaptor.stop(streamId);
    
    // Close WebSocket
    webRTCAdaptor.closeWebSocket();
}

// Handle page unload
window.addEventListener('beforeunload', function() {
    disconnect();
});

4. Audio Echo Cancellation

mediaConstraints: {
    video: true,
    audio: {
        echoCancellation: true,
        noiseSuppression: true,
        autoGainControl: true
    }
}

Complete Conference Example

var roomId = "conference123";
var streamId = "user_" + Math.random().toString(36).substring(7);
var remotePeers = {};

var webRTCAdaptor = new WebRTCAdaptor({
    websocket_url: "wss://server.com:5443/WebRTCAppEE/websocket",
    mediaConstraints: {
        video: { width: 640, height: 480 },
        audio: {
            echoCancellation: true,
            noiseSuppression: true
        }
    },
    peerconnection_config: {
        iceServers: [{urls: "stun:stun1.l.google.com:19302"}]
    },
    sdp_constraints: {
        OfferToReceiveAudio: true,
        OfferToReceiveVideo: true
    },
    localVideoId: "localVideo",
    dataChannelEnabled: true,
    callback: function(info, obj) {
        if (info == "initialized") {
            joinConference();
        }
        else if (info == "joinedTheRoom") {
            console.log("Joined conference: " + obj.roomId);
            // Play existing streams
            obj.streams.forEach(function(stream) {
                playPeer(stream);
            });
        }
        else if (info == "streamJoined") {
            console.log("New participant: " + obj.streamId);
            playPeer(obj.streamId);
        }
        else if (info == "streamLeaved") {
            console.log("Participant left: " + obj.streamId);
            removePeer(obj.streamId);
        }
        else if (info == "play_started") {
            console.log("Playing: " + obj.streamId);
        }
        else if (info == "data_received") {
            handleChatMessage(obj.streamId, obj.data);
        }
    },
    callbackError: function(error, message) {
        console.error("Error: " + error + " - " + message);
    }
});

function joinConference() {
    webRTCAdaptor.joinRoom(roomId, streamId);
}

function playPeer(peerStreamId) {
    webRTCAdaptor.play(peerStreamId);
    
    // Create video element
    var video = document.createElement("video");
    video.id = "peer_" + peerStreamId;
    video.autoplay = true;
    video.playsinline = true;
    document.getElementById("peers").appendChild(video);
    
    remotePeers[peerStreamId] = video;
}

function removePeer(peerStreamId) {
    if (remotePeers[peerStreamId]) {
        remotePeers[peerStreamId].remove();
        delete remotePeers[peerStreamId];
    }
}

function sendChatMessage(message) {
    webRTCAdaptor.sendData(roomId, JSON.stringify({
        type: "chat",
        message: message,
        sender: streamId,
        timestamp: Date.now()
    }));
}

function handleChatMessage(senderId, data) {
    var msg = JSON.parse(data);
    if (msg.type == "chat") {
        console.log(msg.sender + ": " + msg.message);
        // Display in UI
    }
}

Troubleshooting

Common Issues

Issue: Peers cannot connect

Verify both peers have proper ICE configuration
Check if TURN server is needed for restrictive networks
Ensure WebSocket connection is stable

Issue: Audio echo in conference

Enable echo cancellation in media constraints
Mute local audio element (use muted attribute)
Use headphones to prevent feedback

Issue: High CPU usage with many peers

Use conference mode instead of mesh for >4 participants
Reduce video resolution
Limit frame rate in constraints

Next Steps

WebRTC Overview

Learn about WebRTC architecture and signaling

Publishing Streams

Learn how to publish WebRTC streams

REST API

WebRTC API

Data Models

Overview

P2P Modes

1. Mesh P2P (Peer-to-Peer)

2. Conference Mode (MCU/SFU)

Quick Start: P2P Room

Basic P2P Example

HTML Setup for P2P

Conference Mode

Joining a Conference Room

Conference Room Events

Advanced P2P Features

Multi-Track Conference

Data Channel in P2P

Audio/Video Control

Room Management

Signaling Protocol

P2P Signaling Flow

Conference Signaling Flow

Best Practices

1. Limit Mesh P2P Participants

2. Handle Network Quality

3. Graceful Disconnection

4. Audio Echo Cancellation

Complete Conference Example

Troubleshooting

Common Issues

Next Steps

WebRTC Overview

Publishing Streams

Build docs developers (and LLMs) love

REST API

WebRTC API

Data Models

​Overview

​P2P Modes

​1. Mesh P2P (Peer-to-Peer)

​2. Conference Mode (MCU/SFU)

​Quick Start: P2P Room

​Basic P2P Example

​HTML Setup for P2P

​Conference Mode

​Joining a Conference Room

​Conference Room Events

​Advanced P2P Features

​Multi-Track Conference

​Data Channel in P2P

​Audio/Video Control

​Room Management

​Signaling Protocol

​P2P Signaling Flow

​Conference Signaling Flow

​Best Practices

​1. Limit Mesh P2P Participants

​2. Handle Network Quality

​3. Graceful Disconnection

​4. Audio Echo Cancellation

​Complete Conference Example

​Troubleshooting

​Common Issues

​Next Steps

WebRTC Overview

Publishing Streams

Build docs developers (and LLMs) love

Overview

P2P Modes

1. Mesh P2P (Peer-to-Peer)

2. Conference Mode (MCU/SFU)

Quick Start: P2P Room

Basic P2P Example

HTML Setup for P2P

Conference Mode

Joining a Conference Room

Conference Room Events

Advanced P2P Features

Multi-Track Conference

Data Channel in P2P

Audio/Video Control

Room Management

Signaling Protocol

P2P Signaling Flow

Conference Signaling Flow

Best Practices

1. Limit Mesh P2P Participants

2. Handle Network Quality

3. Graceful Disconnection

4. Audio Echo Cancellation

Complete Conference Example

Troubleshooting

Common Issues

Next Steps