Implement a basic video call

Introduction

This guide describes how to implement basic audio and video functions with the ZEGO Express SDK.

Basic concepts:

• ZEGO Express SDK: The real-time audio and video SDK developed by ZEGOCLOUD 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 Real-Time Audio and Video Cloud.

• Stream playing: The process of the client app receiving and playing audio and video streams from the ZEGOCLOUD Real-Time Audio and Video Cloud.

• Room: The service for organizing groups of users, allowing users in the same room to send and receive real-time audio, video, and messages to each other.

  1. Logging in to a room is required to perform stream publishing and playing.
  2. Users can only receive notifications about changes in the room they are in (such as new users joining the room, existing users leaving the room, new audio and video streams being published, etc.).

For more basic concepts, refer to the Glossary.

Prerequisites

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

1. Create a project in ZEGOCLOUD Admin Console, and get the AppID of your project.
2. Integrate the ZEGO Express SDK into your project. For more details, see Quick starts-Integration.

Implementation steps

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:

The following sections explain each step of this process in more detail.

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. Initialize the ZegoExpressEngine instance

To initialize the ZegoExpressEngine, call the createEngine method with the AppID of your project.

// Import the ZegoExpressEngine
const zgEngine = window.require('zego-express-engine-electron/ZegoExpressEngine');
const zgDefines = window.require('zego-express-engine-electron/ZegoExpressDefines');

// Use the AppID assigned by ZEGO when you create your project in the ZEGOCLOUD Admin Console. 
// Use the settings for the General scenario.
const profile = {
appID : xxx,
scenario : zgDefines.ZegoScenario.General
};

zgEngine.createEngine(profile)
.then(() => {
    console.log("init succeed")
}).catch((e) => {
    console.log("init failed", e)
});

Log in to a room

To log in to a room, call the loginRoom method. If the roomID does not exist, a new room will be created and you will log in automatically when you call the loginRoom method.

zgEngine.loginRoom("TheRoomID",  { userID: "TheUserID", userName: "TheUserName"}, {token:'xxxxxx' });

Then, 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:

• onRoomStateUpdate: 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.

• onRoomUserUpdate: 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.

• onRoomStreamUpdate: 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.

// Common event callbacks related to room users and streams.
// Callback for updates on the current user's room connection status.
zgEngine.on("onRoomStateUpdate", (param)=>{
    // Implement the callback handling logic as needed. 
});

// Callback for updates on the status of other users in the room.
zgEngine.on("onRoomUserUpdate", (param)=>{
    // Implement the callback handling logic as needed. 
});

// Callback for updates on the status of the streams in the room.
zgEngine.on("onRoomStreamUpdate", (param)=>{
    // Implement the callback handling logic as needed. 
});

Publish streams

1. Start publishing a stream

To start publishing a local audio or video stream to remote users, call the startPublishingStream method with the corresponding Stream ID passed to the streamID parameter.

// Start publishing a stream
zgEngine.startPublishingStream("streamID");

2. Optional: Start the local video preview

// Obtain a canvas element
let localCanvas = document.getElementById("localCanvas");

// Start the local video preview
zgEngine.startPreview({
    canvas: localCanvas,
});

3. Listen for and handle the event callbacks related to stream publishing

To listen for and handle various events that may happen after stream publishing starts, you can implement the corresponding event callback methods of the event handler as needed. The following is a common event callback related to stream publishing:

• onPublisherStateUpdate: Callback for updates on stream publishing status. After stream publishing starts, if the status changes, (for example, when the stream publishing is interrupted due to network issues and the SDK retries to start publishing the stream again), the SDK sends out the event notification through this callback.

// Common event callbacks related to stream publishing.
// Callback for updates on stream publishing status.  
zgEngine.on("onPublisherStateUpdate", (param)=>{
    // Implement the callback handling logic as needed. 
});

Play streams

1. Start playing a stream

To start playing a remote audio or video stream, call the startPlayingStream method with the corresponding Stream ID passed to the streamID parameter and the view for rendering the video passed to the canvas parameter.

// Obtain a canvas element
let remoteCanvas = document.getElementById("remoteCanvas");
// Start playing a stream
zgEngine.startPlayingStream("streamID", {
    canvas: remoteCanvas,
});

2. Listen for and handle the event callbacks related to stream playing

To listen for and handle various events that may happen after stream playing starts, you can implement the corresponding event callback methods of the event handler as needed. The following is a common event callback related to stream playing:

• onPlayerStateUpdate: Callback for updates on stream playing status. After stream playing starts, if the status changes (for example, when the stream playing is interrupted due to network issues and the SDK retries to start playing the stream again), the SDK sends out the event notification through this callback.

// Common event callbacks related to stream playing.
// Callback for updates on stream playing status. 
zgEngine.on("onPlayerStateUpdate", (param)=>{
    // Implement the callback handling logic as needed. 
});

Test out the video call

We recommend you run your project on a real device. If your app runs successfully, you should hear the sound and see the video captured locally from your device.

To test out the real-time audio and video features, visit the ZEGO Express Web Demo, and enter the same AppID, Server and RoomID to join the same room. If it runs successfully, you should be able to view the video from both the local side and the remote side, and hear the sound from both sides as well.

Stop publishing and playing streams

1. Stop publishing a stream

To stop publishing a local audio or video stream to remote users, call the stopPublishingStream method.

// Stop publishing a stream
zgEngine.stopPublishingStream();

2. Stop the local video preview

If local video preview is started, call the stopPreview method to stop it as needed.

// Stop local video preview
zgEngine.stopPreview();

3. Stop playing a stream

To stop playing a remote audio or video stream, call the stopPlayingStream method with the corresponding stream ID passed to the streamID parameter.

// Stop playing a stream
zgEngine.stopPlayingStream("streamID");

Log out of a room

To log out from a room, call the logoutRoom method.

// Log out of a room  
zgEngine.logoutRoom("TheRoomID");   

Uninitialize the ZegoExpressEngine instance

To uninitialize the ZegoExpressEngine instance and release the resources it occupies, call the destroyEngine method.

// Uninitialize the ZegoExpressEngine
zgEngine.destroyEngine();

FAQ

1. The latest version of Google's core graphics card rendering acceleration integrated by Electron makes it impossible to see the local preview and streaming screen, but the cdn streaming screen is normal. How to solve it?

Currently there are two main solutions to this problem:

• Disable graphics card acceleration: By disabling the graphics card acceleration and not using the Google kernel graphics card rendering acceleration function, you can watch the local preview and streaming screen normally.
• Replace the old version of Electron: Upgrade the version of Electron to adapt to the latest version of Google's kernel graphics card rendering acceleration function.