Amazon Kinesis Video Streams WebRTC SDK for JavaScript

This SDK is intended to be used along side the AWS SDK for JS (version 2.585.0+) to interface with the Amazon Kinesis Video Streams Signaling Service for WebRTC streaming.

Installing

In the Browser

To use the SDK in the browser, simply add the following script tag to your HTML pages:

<script src="https://unpkg.com/amazon-kinesis-video-streams-webrtc/dist/kvs-webrtc.min.js"></script>

The SDK classes are made available in the global window under the KVSWebRTC namespace. For example, window.KVSWebRTC.SignalingClient.

The SDK is also compatible with bundlers like Webpack. Follow the instructions in the next section to install the NodeJS module version for use with your bundler.

In NodeJS

The preferred way to install the SDK for NodeJS is to use the npm package manager. Simply type the following into a terminal window:

npm install amazon-kinesis-video-streams-webrtc

The SDK classes can then be imported like typical NodeJS modules:

// JavaScript
const SignalingClient = require('amazon-kinesis-video-streams-webrtc').SignalingClient;

// TypeScript / ES6 supported
import { SignalingClient } from 'amazon-kinesis-video-streams-webrtc';

Getting Started

You can start by trying out the SDK with a webcam on the example WebRTC test page.

It is also recommended to develop familiarity with the WebRTC protocols and KVS Signaling Channel APIs. See the following resources:

• KVS WebRTC Developer Guide
• KVS API Reference Guide

The first step in using the SDK in your own application is to follow the Installing instructions above to install the SDK.

From there, see the Usage section below for guidance on using the SDK to build a WebRTC application. Also refer to the examples directory for examples on how to write an end-to-end WebRTC application that uses the SDK.

Usage

This section demonstrates how to use this SDK along with the AWS SDK for JS (version 2.585.0+) to build a web-based viewer application. Refer to the examples directory for an example of a complete application including both a master and viewer role.

Viewer Example With Audio/Video From Local Webcam

These code snippets demonstrate how to build a viewer application that receives audio and video and also sends audio and video from a webcam back to the master.

Set Up Variables

// DescribeSignalingChannel API can also be used to get the ARN from a channel name.
const channelARN = 'arn:aws:kinesisvideo:us-west-2:123456789012:channel/test-channel/1234567890';

// AWS Credentials
const accessKeyId = 'ACCESS_KEY_ID_GOES_HERE';
const secretAccessKey = 'SECRET_ACCESS_KEY_GOES_HERE';

// <video> HTML elements to use to display the local webcam stream and remote stream from the master
const localView = document.getElementsByTagName('video')[0];
const remoteView = document.getElementsByTagName('video')[1];

const region = 'us-west-2';
const clientId = 'RANDOM_VALUE';

See Managing Credentials for more information about managing credentials in a web environment.

Create KVS Client

const kinesisVideoClient = new AWS.KinesisVideo({
    region,
    accessKeyId,
    secretAccessKey,
    correctClockSkew: true,
});

Get Signaling Channel Endpoints

Each signaling channel is assigned an HTTPS and WSS endpoint to connect to for data-plane operations. These can be discovered using the GetSignalingChannelEndpoint API.

const getSignalingChannelEndpointResponse = await kinesisVideoClient
    .getSignalingChannelEndpoint({
        ChannelARN: channelARN,
        SingleMasterChannelEndpointConfiguration: {
            Protocols: ['WSS', 'HTTPS'],
            Role: KVSWebRTC.Role.VIEWER,
        },
    })
    .promise();
const endpointsByProtocol = getSignalingChannelEndpointResponse.ResourceEndpointList.reduce((endpoints, endpoint) => {
    endpoints[endpoint.Protocol] = endpoint.ResourceEndpoint;
    return endpoints;
}, {});

Create KVS Signaling Client

The HTTPS endpoint from the GetSignalingChannelEndpoint response is used with this client. This client is just used for getting ICE servers, not for actual signaling.

const kinesisVideoSignalingChannelsClient = new AWS.KinesisVideoSignalingChannels({
    region,
    accessKeyId,
    secretAccessKey,
    endpoint: endpointsByProtocol.HTTPS,
    correctClockSkew: true,
});

Get ICE server configuration

For best performance, we collect STUN and TURN ICE server configurations. The KVS STUN endpoint is always stun:stun.kinesisvideo.${region}.amazonaws.com:443. To get TURN servers, the GetIceServerConfig API is used.

const getIceServerConfigResponse = await kinesisVideoSignalingChannelsClient
    .getIceServerConfig({
        ChannelARN: channelARN,
    })
    .promise();
const iceServers = [
    { urls: `stun:stun.kinesisvideo.${region}.amazonaws.com:443` }
];
getIceServerConfigResponse.IceServerList.forEach(iceServer =>
    iceServers.push({
        urls: iceServer.Uris,
        username: iceServer.Username,
        credential: iceServer.Password,
    }),
);

Create RTCPeerConnection

The RTCPeerConnection is the primary interface for WebRTC communications in the Web.

const peerConnection = new RTCPeerConnection({ iceServers });

Create WebRTC Signaling Client

This is the actual client that is used to send messages over the signaling channel.

signalingClient = new KVSWebRTC.SignalingClient({
    channelARN,
    channelEndpoint: endpointsByProtocol.WSS,
    clientId,
    role: KVSWebRTC.Role.VIEWER,
    region,
    credentials: {
        accessKeyId,
        secretAccessKey,
    },
    systemClockOffset: kinesisVideoClient.config.systemClockOffset,
});

Add Signaling Client Event Listeners

// Once the signaling channel connection is open, connect to the webcam and create an offer to send to the master
signalingClient.on('open', async () => {
    // Get a stream from the webcam, add it to the peer connection, and display it in the local view
    try {
        const localStream = await navigator.mediaDevices.getUserMedia({
            video: { width: { ideal: 1280 }, height: { ideal: 720 } },
            audio: true,
        });
        localStream.getTracks().forEach(track => peerConnection.addTrack(track, localStream));
        localView.srcObject = localStream;
    } catch (e) {
        // Could not find webcam
        return;
    }

    // Create an SDP offer and send it to the master
    const offer = await viewer.peerConnection.createOffer({
        offerToReceiveAudio: true,
        offerToReceiveVideo: true,
    });
    await peerConnection.setLocalDescription(offer);
    signalingClient.sendSdpOffer(viewer.peerConnection.localDescription);
});

// When the SDP answer is received back from the master, add it to the peer connection.
signalingClient.on('sdpAnswer', async answer => {
    await peerConnection.setRemoteDescription(answer);
});

// When an ICE candidate is received from the master, add it to the peer connection.
signalingClient.on('iceCandidate', candidate => {
    peerConnection.addIceCandidate(candidate);
});

signalingClient.on('close', () => {
    // Handle client closures
});

signalingClient.on('error', error => {
    // Handle client errors
});

Add Peer Connection Event Listeners

// Send any ICE candidates generated by the peer connection to the other peer
peerConnection.addEventListener('icecandidate', ({ candidate }) => {
    if (candidate) {
        signalingClient.sendIceCandidate(candidate);
    } else {
        // No more ICE candidates will be generated
    }
});

// As remote tracks are received, add them to the remote view
peerConnection.addEventListener('track', event => {
    if (remoteView.srcObject) {
        return;
    }
    remoteView.srcObject = event.streams[0];
});

Open Signaling Connection

signalingClient.open();

Documentation

This section outlines all of the classes, events, methods, and configuration options for the SDK.

Class: SignalingClient

This class is the main class for interfacing with the KVS signaling service. It extends EventEmitter.

Constructor: new SignalingClient(config)

• config {object}
  • role {Role} "MASTER" or "VIEWER".
  • channelARN {string} ARN of a channel that exists in the AWS account.
  • channelEndpoint {string} KVS Signaling Service endpoint. Should be the "WSS" endpoint from calling the GetSignalingChannel API.
  • region {string} AWS region that the channel exists in.
  • clientId {string} Identifier to uniquely identify this client when connecting to the KVS Signaling Service. Required if the role is "VIEWER". A value should not be provided if the role is "MASTER".
  • credentials {object} Must be provided unless a requestSigner is provided. See Managing Credentials.
    • accessKeyId {string} AWS access key id.
    • secretAccessKey {string} AWS secret access key.
    • sessionToken {string} Optional. AWS session token.
  • requestSigner {RequestSigner} Optional. A custom method for overriding the default SigV4 request signing.
  • systemClockOffset {number} Optional. Applies the given offset when setting the date in the SigV4 signature. See systemClockOffset and correctClockSkew properties of the AWS SDK.

Event: 'open'

Emitted when the connection to the signaling service is open.

Event: 'sdpOffer'

• sdpOffer {RTCSessionDescription} The SDP offer received from the signaling service.
• senderClientId {string} The client id of the source of the SDP offer. The value will be null if the SDP offer is from the master.

Emitted when a new SDP offer is received over the channel. Typically only a master should receive SDP offers.

Event: 'sdpAnswer'

• sdpAnswer {RTCSessionDescription} The SDP answer received from the signaling service.
• senderClientId {string} The client id of the source of the SDP answer. The value will be null if the SDP answer is from the master.

Emitted when a new SDP answer is received over the channel. Typically only a viewer should receive SDP answers.

Event: 'iceCandidate'

• iceCandidate {RTCIceCandidate} The ICE candidate received from the signaling service.
• senderClientId {string} The client id of the source of the ICE candidate. The value will be null if the ICE candidate is from the master.

Emitted when a new ICE candidate is received over the channel.

Event: 'close'

Emitted when the connection to the signaling service is closed. Even if there is an error, as long as the connection is closed, this event will be emitted.

Event: 'error'

• error {Error}

Emitted when there is an error in the client or there is an error received from the signaling service. The connection will be closed automatically.

Method: on(event, callback)

• event {string} Event name.
• callback {function} Event handler.

Binds an event handler.

Method: open()

Opens a connection to the signaling service. An error will be thrown if there is already another connection open or opening.

Method: close()

Closes the active connection to the signaling service. Nothing will happen if there is no open connection.

Method: sendSdpOffer(sdpOffer, [recipientClientId])

• sdpOffer {RTCSessionDescription} SDP offer to send to the recipient client.
• recipientClientId {string} The id of the client to send the SDP offer to. If no id is provided, it will be sent to the master.

Method: sendSdpAnswer(sdpAnswer, [recipientClientId])

• sdpAnswer {RTCSessionDescription} SDP answer to send to the recipient client.
• recipientClientId {string} The id of the client to send the SDP answer to. If no id is provided, it will be sent to the master.

Method: sendIceCandidate(iceCandidate, [recipientClientId])

• iceCandidate {RTCIceCandidate} ICE candidate to send to the recipient client.
• recipientClientId {string} The id of the client to send the ICE candidate to. If no id is provided, it will be sent to the master.

Interface: RequestSigner

Interface for signing HTTP and WebSocket requests.

Method: getSignedURL(endpoint, queryParams, [date]) => Promise<string>

• endpoint {string} The endpoint of the URL (including protocol, host, and path).
• queryParams {object} The query parameters to include in the signed URL.
• date {Date} The date that the signature is valid (+/- 5 minutes). Default: now.
• return {Promise} The signed URL.

Class: SigV4RequestSigner

This class is used to SigV4 sign requests to the signaling service. It implements RequestSigner.

This signer is unique from the signers included in the AWS SDK for JS because it supports signing WebSocket requests.

This is a useful class to use in a NodeJS backend to sign requests and send them back to a client so that the client does not need to have AWS credentials.

Constructor: new SigV4RequestSigner(region, credentials, [service])

• region {string} The region used for signing.
• credentials {Credentials} The credentials to used for signing.
• service {string} The service name used for signing. Default: kinesisvideo.

Method: getSignedURL(endpoint, queryParams, [date]) => Promise<string>

Implementation of interface method.

• Uses the SigV4 signing mechanism.
• Supports credentials with and without a session token.
• Only supports the wss:// protocol.
• Does not support specifying an expiration.

If the signer's credentials support refreshing, they will be be refreshed if necessary before signing.

Enum: Role

An enum with the following values:

• MASTER
• VIEWER

Compatibility

The SDK is supported in the following browsers / environments:

| Chrome | Edge | Firefox | IE | Safari | Android Webview | Android Chrome | iOS Safari | NodeJS | | ------ | ---- | ------- | --- | ------ | --------------- | -------------- | ---------- | ------ | | 52 | 12 | 36 | No | 11 | 53 | 52 | 11 | 8 |

To increase WebRTC API compatibility between different browsers, it's highly recommended to use adapter.js.

Following is a quote from adapter.js docs:

adapter.js is a shim to insulate apps from spec changes and prefix differences in WebRTC. The prefix differences are mostly gone these days but differences in behaviour between browsers remain.

Managing Credentials

The SignalingClient requires a SigV4 signed URL in order to make requests to the KVS signaling service backend. The client can either be provided with AWS credentials (and then it will use those to sign requests) or it can be provided with a custom RequestSigner that can perform the request signing.

There are several mechanisms that are recommended for managing AWS credentials in a web client, such as using Cognito or Federated Identities, that are explained in the AWS SDK for JS documentation.

Alternatively, if you do not want any AWS credentials in the web client, you can provide a request signer that makes a call to your own backend that uses AWS credentials to create a signed request for the KVS WebRTC Signaling Service. With a NodeJS based backend, you can create signed requests using the SigV4RequestSigner class. Note that you will also have to get other data, such as the ICE server config, on the backend and send that to the client.

IAM Permissions

Regardless of the mechanism used to manage the credentials, the credentials will need to have permissions to perform KVS operations. The following is an example policy for a viewer of a particular channel:

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "kvsViewerPolicy",
      "Action": [
        "kinesisvideo:ConnectAsViewer", // Use "kinesisvideo:ConnectAsMaster" for master policy instead.
        "kinesisvideo:DescribeSignalingChannel",
        "kinesisvideo:GetIceServerConfig",
        "kinesisvideo:GetSignalingChannelEndpoint"
      ],
      "Effect": "Allow",
      "Resource": "arn:aws:kinesisvideo:<region>:<account_ID>:channel/<channelName>/<creationTime>"
    }
  ]
}

See KVS WebRTC Access Control Documentation for more information.

Development

Running WebRTC Test Page Locally

The SDK and test page can be edited and run locally by following these instructions:

NodeJS version 8+ is required.

1. Run npm install to download dependencies.
2. Run npm run develop to run the webserver.
3. Open the WebRTC test page at http://localhost:3001

You will need to provide an AWS region, AWS credentials, and a Channel Name.

The source code for the test page is in the examples directory.

License

This project is licensed under the Apache-2.0 License. See LICENSE.txt and NOTICE.txt for more information.