Voice-only quickstart

This Flutter quickstart shows you how to create a basic Voice Calling app using the Agora RTC SDK.

Understand the tech

To start a Voice Calling session, implement the following steps in your app:

• Initialize the Agora Engine: Before calling other APIs, create and initialize an Agora Engine instance.

• Join a channel: Call methods to create and join a channel.

• Send and receive audio: All users can publish streams to the channel and subscribe to audio streams published by other users in the channel.

Prerequisites

• Flutter 2.10.5 or higher with Dart 2.14.0 or higher.

• Android Studio, IntelliJ, VS Code, or any other IDE that supports Flutter. See Set up an editor.

• Prepare your development and testing environment according to your target platform.

  Run the flutter doctor command to confirm that your development environment is set up correctly for Flutter development.

• A microphone

• A valid Agora account and project. Please refer to Agora account management for details.

Set up your project

This section shows you how to set up your Flutter project and install the Agora RTC SDK.

flutter create agora_project
cd agora_project

Install the SDK

Install the Agora RTC SDK and other dependencies.

1. Add the latest version of Agora RTC SDK to your Flutter project:

   flutter pub add agora_rtc_engine

2. Add the permission processing package:

   flutter pub add permission_handler

   The dependencies in your pubspec.yaml file should look like the following:

   dependencies:
    flutter:
     sdk: flutter
    agora_rtc_engine: ^6.5.0 # Agora Flutter SDK, please use the latest version
    permission_handler: ^11.3.1 # Package for managing runtime permissions
    cupertino_icons: ^1.0.8

3. Install the dependencies.

   Execute the following command in the project path:

   flutter pub get

Implement Voice Calling

This section guides you through the implementation of basic real-time audio interaction in your app.

The following figure illustrates the essential steps:

This guide includes complete sample code that demonstrates implementing basic real-time interaction. To understand the core API calls in the sample code, review the following implementation steps.

Import packages

Import the following packages in your dart file.

import 'dart:async';

import 'package:agora_rtc_engine/agora_rtc_engine.dart';
import 'package:flutter/material.dart';
import 'package:permission_handler/permission_handler.dart';

Initialize the engine

For real-time communication, initialize an RtcEngine instance. Use RtcEngineContext to specify the App ID, and other configuration parameters. In your dart file, add the following code:

// Set up the Agora RTC engine instance
Future<void> _initializeAgoraVoiceSDK() async {
 _engine = createAgoraRtcEngine();
 await _engine.initialize(const RtcEngineContext(
  appId: "<-- Insert app Id -->",
  channelProfile: ChannelProfileType.channelProfileCommunication,
 ));
}

Join a channel

To join a channel, call joinChannel with the following parameters:

• Channel name: The name of the channel to join. Clients that pass the same channel name join the same channel. If a channel with the specified name does not exist, it is created when the first user joins.

• Authentication token: A dynamic key that authenticates a user when the client joins a channel. In a production environment, you obtain a token from a token server in your security infrastructure. For the purpose of this guide Generate a temporary token.

• User ID: A 32-bit signed integer that identifies a user in the channel. You can specify a unique user ID for each user yourself. If you set the user ID to 0 when joining a channel, the SDK generates a random number for the user ID and returns the value in the onJoinChannelSuccess callback.

• Channel media options: Configure ChannelMediaOptions to define publishing and subscription settings, optimize performance for your specific use-case, and set optional parameters.

For Voice Calling, set the clientRoleType to clientRoleBroadcaster.

// Join a channel
Future<void> _joinChannel() async {
 await _engine.joinChannel(
  token: token,
  channelId: channel,
  options: const ChannelMediaOptions(
   autoSubscribeAudio: true, // Automatically subscribe to all audio streams
   publishMicrophoneTrack: true, // Publish microphone-captured audio
   // Use clientRoleBroadcaster to act as a host or clientRoleAudience for audience
   clientRoleType: ClientRoleType.clientRoleBroadcaster,
  ),
  uid: 0,
 );
}

Subscribe to RTC SDK events

The SDK provides the RtcEngineEventHandler for subscribing to channel events. To use it, pass an instance of RtcEngineEventHandler to registerEventHandler and implement the event methods you want to handle.

Call registerEventHandler to bind the event handler to the SDK.

// Register an event handler for Agora RTC
void _setupEventHandlers() {
 _engine.registerEventHandler(
  RtcEngineEventHandler(
   onJoinChannelSuccess: (RtcConnection connection, int elapsed) {
    debugPrint("Local user ${connection.localUid} joined");
   },
   onUserJoined: (RtcConnection connection, int remoteUid, int elapsed) {
    debugPrint("Remote user $remoteUid joined");
    setState(() {
     _remoteUid = remoteUid; // Store remote user ID
    });
   },
   onUserOffline: (RtcConnection connection, int remoteUid, UserOfflineReasonType reason) {
    debugPrint("Remote user $remoteUid left");
    setState(() {
     _remoteUid = null; // Remove remote user ID
    });
   },
  ),
 );
}

Handle permissions

Request the microphone permission for Voice Calling.

// Requests microphone permission
Future<void> _requestPermissions() async {
 await [Permission.microphone].request();
}

Start and close the app

To start Voice Calling, request microphone permission, initialize the Agora SDK instance, set up an event handler, and join a channel.

await _requestPermissions();
await _initializeAgoraVoiceSDK();
_setupEventHandlers();
await _joinChannel();

To stop Voice Calling, leave the channel and release the engine instance.

// Leaves the channel and releases resources
Future<void> _cleanupAgoraEngine() async {
 await _engine.leaveChannel();
 await _engine.release();
}

Complete sample code

A complete code sample demonstrating the basic process of real-time interaction is provided for your reference. To use the sample code, copy the following code to replace the entire contents of the .dart file in your project.

Create a user interface

To connect the sample code to your existing UI, ensure that your widget tree includes the _remoteVideo and _localVideo widgets used to Display the local video and Display remote video.

Alternatively, use the following sample code to generate a basic user interface:

Sample code to create the user interface

Use the following code sample to build a basic user interface:

// Build UI
@override
Widget build(BuildContext context) {
 return MaterialApp(
  title: 'Agora Voice Call',
  home: Scaffold(
   appBar: AppBar(
    title: const Text('Agora Voice Call'),
   ),
   body: Center(
    child: Text(
     _remoteUid != null
       ? "Remote user $_remoteUid joined"
       : "No remote user in the channel", // Show appropriate message
     style: const TextStyle(fontSize: 18),
    ),
   ),
  ),
 );
}

Test the sample code

Take the following steps to test the sample code:

1. In main.dart update the values for appId, and token with values from Agora Console. Fill in the same channel name you used to generate the token.

2. Connect a target device to your development computer.

3. Open Terminal and execute the following command in the project folder to run the sample project:

   flutter run

4. Launch the App, grant microphone permission.

5. On a second target device, repeat the previous steps to install and launch the app. Test the following use-cases:

   • If users on both devices join the channel as hosts, they can hear each other.
   • If one user joins as host and the other as audience, the audience can hear the host.

Reference

This section contains content that completes the information on this page, or points you to documentation that explains other aspects to this product.

• If a firewall is deployed in your network environment, refer to Connect with Cloud Proxy to use Agora services normally.

Next steps

After implementing the quickstart sample, read the following documents to learn more:

• To ensure communication security in a test or production environment, best practice is to obtain and use a token from an authentication server. For details, see Secure authentication with tokens.

Sample project

Agora provides open source sample projects on GitHub for your reference. Download or view join_channel_audio.dart for a more detailed example.

API reference

• registerEventHandler

• setClientRole

• setChannelProfile

• joinChannel

• leaveChannel

Frequently asked questions

• How can I listen for audience joining or leaving a channel?
• How can I solve channel-related issues?
• How can I set the log file?

See also

• Error codes

• Connection status management