Implement audio and video features using Angular

Introduction

This document describes how to implement an audio and video call using Angular.

Basic concepts:

• ZEGO Express SDK: The real-time audio and video SDK developed by ZEGO to help you quickly build high-quality, low-latency, and smooth real-time audio and video communications into your apps across different platforms, with support for massive concurrency.
• Stream publishing: The process of the client app capturing and transmitting audio and video streams to the ZEGOCLOUD server.
• Stream playing: The process of the client app receiving and playing audio and video streams from the ZEGOCLOUD server.

Prerequisites

Before you begin, make sure you complete the following steps:

• A project has been created in ZEGOCLOUD Console and applied for a valid AppID and AppSign. For details, please refer to Console - How to view project information .
• ZEGO Express SDK has been integrated into the project to implement basic real-time audio and video functions. For details, please refer to Integrate the SDK and Implement a basic video call.

Implementation process

The following diagram shows the basic process of User A playing a stream published by User B:

The following diagram shows the API call sequence of the stream publishing and playing process:

Create a ZegoExpressEngine instance

1. Optional: Create the UI

Add UI elements

Before creating a ZegoExpressEngine instance, we recommend you add the following UI elements to implement basic real-time audio and video features:

• A view for local preview
• A view for remote video
• An End button

2. Create a ZegoExpressEngine instance

To create a singleton instance of the ZegoExpressEngine class, pass in your AppID as the appID parameter and the Server URL as the server parameter. You can obtain them from the ZEGOCLOUD Admin Console.

Initialize the ZegoExpressEngine instance.

// Initialize the [ZegoExpressEngine] instance.
export class AppComponent {
    zg:any = null;

    createZegoExpressEngine() {
        this.zg = new ZegoExpressEngine(appID, server);
    }
}

3. Optional: Listen for and handle the event callbacks

this.zg.on('roomStateUpdate', (roomID, state, errorCode, extendedData) => {
    if (state == 'DISCONNECTED') {
        // Disconnected from the room.
    // ...
    }

    if (state == 'CONNECTING') {
        // Connecting to the room.
    // ...
    }

    if (state == 'CONNECTED') {
        // Connected to the room.
    // ...
    }
})

Optional: Check your browser's WebRTC support

const result = await this.zg.checkSystemRequirements();
// The [result] indicates whether it is compatible. It indicates WebRTC is supported when the [webRTC] is [true]. For more results, see the API documents.
console.log(result);
// {
//   webRTC: true,
//   customCapture: true,
//   camera: true,
//   microphone: true,
//   videoCodec: { H264: true, H265: false, VP8: true, VP9: true },
//   screenSharing: true,
//   errInfo: {}
// }

Log in to a room

1. Obtain the login token

When logging in to a room, you need to pass in a login token for user authentication. For information about how to obtain the login token, see User privilege control.

2. Log in

To log in to a room, call the loginRoom with the following parameters:

• A unique room ID as the roomID parameter
• The login token you obtained in the previous step as the token parameter
• The user ID and user name as the roomID and userName parameter
• Optional: Pass the corresponding object to the config parameter based on the actual situation.

// Log in to a room. It returns `true` if the login is successful.
// The roomUserUpdate callback is disabled by default. To receive this callback, you must set the `userUpdate` property to `true` when logging in to a room. 
const result = await this.zg.loginRoom(roomID, token, {userID, userName}, {userUpdate: true});

3. Listen for and handle the event callbacks related to room users and streams

To listen for and handle various events that may happen after logging in to a room, you can implement the corresponding event callback methods of the event handler as needed. The following are some common event callbacks related to room users and streams:

• roomStateUpdate: Callback for updates on current user's room connection status. When the current user's room connection status changes (for example, when the current user is disconnected from the room or login authentication fails), the SDK sends out the event notification through this callback.

• roomUserUpdate : Callback for updates on the status of other users in the room. When other users join or leave the room, the SDK sends out the event notification through this callback.

• roomStreamUpdate: Callback for updates on the status of the streams in the room. When new streams are published to the room or existing streams in the room stop, the SDK sends out the event notification through this callback.

// Callback for updates on the current user's room connection status.
this.zg.on('roomStateUpdate', (roomID,state,errorCode,extendedData) => {
    if (state == 'DISCONNECTED') {
        // Disconnected from the room.
    }

    if (state == 'CONNECTING') {
        // Connecting to the room.
    }

    if (state == 'CONNECTED') {
        // Connected to the room.
    }
})

// Callback for updates on the status of ther users in the room.
this.zg.on('roomUserUpdate', (roomID, updateType, userList) => {
    console.warn(
        `roomUserUpdate: room ${roomID}, user ${updateType === 'ADD' ? 'added' : 'left'} `,
        JSON.stringify(userList),
    );
});

// Callback for updates on the status of the streams in the room.
this.zg.on('roomStreamUpdate', async (roomID, updateType, streamList, extendedData) => {
    if (updateType == 'ADD') {
        // New stream added, start playing the stream.
    } else if (updateType == 'DELETE') {
        // Stream deleted, stop playing the stream.
    }
});

Publish streams

1. Create a stream

a. To create a local audio and video stream, call the createZegoStream method. By default, the engine captures video data from the camera and captures audio data from the microphone.

Creating a container

<div id="local-video" style="width: 320px;height: 240px;"></div>

// After calling the createZegoStream method, you need to wait for the ZEGO server to return the local stream object before any further operation.
this.localStream = await this.zg.createZegoStream({
    camera: {
        video: {
          input: videoDeviceID
        },
        audio: {
          input: audioDeviceID
        },
    }
});

// [localStream] is the MediaStream object created by calling creatStream in the previous step.
this.zg.startPublishingStream(streamID, localStream)

this.zg.on('publisherStateUpdate', result => {
    // Callback for updates on stream publishing status.
    // ... 
})

this.zg.on('publishQualityUpdate', (streamID, stats) => {
    // Callback for reporting stream publishing quality.
    // ... 
})

<div id="remote-video" style="width: 320px;height: 240px;"></div>

this.remoteStream = await this.zg.startPlayingStream(streamID,options);

const remoteView = this.zg.createRemoteStreamView(this.remoteStream);
remoteView.play("remote-video", {enableAutoplayDialog:true});

this.zg.on('playerStateUpdate', result => {
    // Callback for updates on stream playing status.
    // ...
})

this.zg.on('playQualityUpdate', (streamID,stats) => {
    // Callback for reporting stream playing quality.
})

this.zg.stopPublishingStream(streamID)

// localStream is the MediaStream object created when calling the createZegoStream method.
this.zg.destroyStream(localStream)

this.zg.stopPlayingStream(streamID)

this.zg.logoutRoom(roomID)