Implement a basic video call

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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 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 ZEGO Real-Time Audio and Video Cloud.

• Stream playing: The process of the client app receiving and playing audio and video streams from the ZEGO 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:

• Create a project in ZEGOCLOUD Console, and get the AppID of your project.
• The ZEGO Express SDK has been integrated into the project. For details, see Integration.

Implementation process

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

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

Optional: Create the UI

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

Create a ZegoExpressEngine instance

To create a singleton instance of the ZegoExpressEngine class, call the createEngine method with the AppID of your project.

To receive callbacks, implement an event handler object that conforms to the IZegoEventHandler protocol, and then pass the implemented event handler object to the createEngine method as the eventHandler parameter. Alternatively, you can pass null to the createEngine method as the eventHandler parameter for now, and then call the method setEventHandler to set up the event handler after creating the engine.

/** Define a ZegoExpressEngine object */
ZegoExpressEngine engine;

ZegoEngineProfile profile = new ZegoEngineProfile();
/** AppID format: 123456789L */
profile.appID = appID;
/** General scenario */
profile.scenario = ZegoScenario.GENERAL;
/** Set application object of App */
profile.application = getApplication();
/** Create a ZegoExpressEngine instance */
engine = ZegoExpressEngine.createEngine(profile, null);

Log in to a room

To log in to a room, call the loginRoom method.

/** create a user */
ZegoUser user = new ZegoUser("user1");


ZegoRoomConfig roomConfig = new ZegoRoomConfig();
/** Token is generated by the user's own server. For an easier and convenient debugging, you can get a temporary token from the ZEGOCLOUD Admin Console */
roomConfig.token = "xxxx";
/** onRoomUserUpdate callback can be received only by passing in a ZegoRoomConfig whose "isUserStatusNotify" parameter value is "true".*/
roomConfig.isUserStatusNotify = true;

/** log in to a room */
engine.loginRoom("room1", user, roomConfig, (int error, JSONObject extendedData)->{
    // (Optional callback) The result of logging in to the room. If you only pay attention to the login result, you can use this callback.
});  

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.

engine.setEventHandler(new IZegoEventHandler() {

    /** Common event callbacks related to room users and streams. */

    /** Callback for updates on the current user's room connection status. */
    @Override
    public void onRoomStateUpdate(String roomID, ZegoRoomState state, int errorCode, JSONObject extendedData) {
        /** Implement the callback handling logic as needed. */
    }

    /** Callback for updates on the status of other users in the room. */
    @Override
    public void onRoomUserUpdate(String roomID, ZegoUpdateType updateType, ArrayList<ZegoUser> userList) {
        /** Implement the callback handling logic as needed. */
    }

    /** Callback for updates on the status of the streams in the room. */
    @Override
    public void onRoomStreamUpdate(String roomID, ZegoUpdateType updateType, ArrayList<ZegoStream> streamList, JSONObject extendedData){
        /** Implement the callback handling logic as needed. */
     }

});

Start the local video preview

To start the local video preview, call the startPreview method with the view for rendering the local video passed to the canvas parameter.

You can use a SurfaceView, TextureView, or SurfaceTexture to render the video.

/**
 *  Set up a view for the local video preview and start the preview with SDK's default view mode (AspectFill).
 *  The following play_view is a SurfaceView, TextureView, or SurfaceTexture object on the UI.
 */
engine.startPreview(new ZegoCanvas(preview_view));

Publish streams

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 */
engine.startPublishingStream("stream1");

Then, 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.

engine.setEventHandler(new IZegoEventHandler() {
    /** Common event callbacks related to stream publishing. */

    /** Callback for updates on stream publishing status.   */
    @Override
    public void onPublisherStateUpdate(String streamID, ZegoPublisherState state, int errorCode, JSONObject extendedData){
        /** Implement the callback handling logic as needed. */
    }
});

Play streams

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.

You can obtain the stream IDs of the streams published by other users in the room from the callback onRoomStreamUpdate.

You can use a SurfaceView, TextureView, or SurfaceTexture to render the video.

/**
 *  Start playing a remote stream with the SDK's default view mode (AspectFill).
 *  The play_view below is a SurfaceView/TextureView/SurfaceTexture object on UI.
 */
engine.startPlayingStream("stream1", new ZegoCanvas(play_view));

Then, 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.

engine.setEventHandler(new IZegoEventHandler() {
    /** Common event callbacks related to stream playing. */

    /** Callback for updates on stream playing status.  */
    @Override
    public void onPlayerStateUpdate(String streamID, ZegoPlayerState state, int errorCode, JSONObject extendedData){
        /** 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

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

/** Stop publishing a stream */
engine.stopPublishingStream();

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

/** Stop local video preview */
engine.stopPreview();

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*/
engine.stopPlayingStream(streamID);

Log out of a room

To log out of a room, call the logoutRoom method with the corresponding room ID passed to the roomID parameter.

/** Log out of a room */
engine.logoutRoom("room1");

Destroy the ZegoExpressEngine instance

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

• If you want to receive a callback to make sure the hardware resources are released, pass in the value callback when destroying the ZegoExpressEngine instance. This callback can only be used to send out a notification when the destruction of the engine is completed. You can't use this callback method to release engine-related resources.
• If you don't want to receive any callbacks, pass null to destroyEngine instead.

/** Destroy the ZegoExpressEngine instance */
ZegoExpressEngine.destroyEngine(null);

API call sequence diagram

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

Related documents

• How can I obtain the SDK logs and stack traces?
• Does ZEGO SDK support a fast reconnection for temporary disconnection?
• How can I listen for the event callbacks related to room users' login/logout in live streaming?？