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Voice Call v4.0.0 Beta

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Start a Voice Call

Last updated 2022/09/15 11:33:07

Real-time voice chatting immerses people in the sights and sounds of human connections, keeping them engaged in your app longer.

This page shows the minimum code you need to integrate high-quality, low-latency Voice Call function into your app using the SDK.

Understand the tech

The following figure shows the workflow you need to integrate into your app in order to achieve Voice Call functionality.

To start voice call, implement the following steps in your app:

1. Set the role

Set both app clients as the host.

2. Join a channel

Call joinChannel to create and join a channel. When using the same App ID, users who pass in the same channel name enter the same channel.

3 and 4. Publish and subscribe to audio in the channel

After joining a channel, both hosts can publish audio stream to the channel and subscribe to each other.

Prerequisites

Android Studio 4.1 or later.
Android SDK API Level 16 or higher.
Two mobile devices that run Android 4.1 or later.
A computer that can access the Internet. Ensure that no firewall is deployed in your network environment, otherwise the project fails.
A valid Agora account and an Agora project, please refer to Start using the Agora platform and get the following information from Agora Console:
- The App ID: A randomly generated string provided by Agora for identifying your app.
- A temporary token: A token is the credential that authenticates a user when your app client joins a channel. A temporary token is valid for 24 hours.
- The channel name: A string that identifies the channel.

Project setup

In order to create the environment necessary to integrate Voice Call into your app, do the following:

For new projects, in Android Studio, create a Phone and Tablet Android project with an Empty Activity.

After creating the project, Android Studio automatically starts gradle sync. Ensure that the sync succeeds before you continue.
Integrate the Video SDK into your project with Maven Central.
1. In /Gradle Scripts/build.gradle(Project: <projectname>), add the following lines to add the Maven Central dependency:
```
 buildscript {
     repositories {
         ...
         mavenCentral()
     }
     ...
}

  allprojects {
     repositories {
         ...
         mavenCentral()
     }
}
```

The way to add the Maven Central dependency can be different if you set dependencyResolutionManagement in your Android project.

In /Gradle Scripts/build.gradle(Module: <projectname>.app), add the following lines to integrate the Agora Video SDK into your Android project.
```
...
 dependencies {
     ...
       // Fill in a specific SDK version number (get the latest version from the SDK download). For example, 4.0.0 or 4.0.0.4
       implementation 'io.agora.rtc:voice-sdk:x.y.z' 
  }
```
For more integration methods, see Other approaches to integrate the SDK.

Add permissions for network and device access.

In /app/Manifests/AndroidManifest.xml, add the following permissions after </application>:

 <uses-permission android:name="android.permission.INTERNET" />
 <uses-permission android:name="android.permission.CAMERA" />
 <uses-permission android:name="android.permission.RECORD_AUDIO" />
 <uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS" />
 <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
 <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
 <uses-permission android:name="android.permission.BLUETOOTH" />

To prevent obfuscating the code in the SDK, add the following line in /Gradle Scripts/proguard-rules.pro file:
```
 -keep class io.agora.**{*;}
```

Implement a client for Voice Call

This section shows how to use the Agora Video SDK to implement Voice Call into your app step by step.

Create the UI

In the interface, create one frame for local video and another for remote video. In /app/res/layout/activity_main.xml, replace the content with the following:

<?xml version="1.0" encoding="UTF-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

      <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@android:color/darker_gray">

        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginBottom="40dp"
            android:layout_marginLeft="16dp"
            android:layout_marginStart="16dp"
            android:layout_gravity="center_vertical|start"
            android:text="Welcome to the Agora Voice Call channel."/>

      </FrameLayout>
</RelativeLayout>

Handle the Android system logic

Import the necessary Android classes and handle the Android permissions.

Import Android classes

In /app/java/com.example.<projectname>/MainActivity, add the following lines after package com.example.<projectname>:

import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;

import android.Manifest;
import android.content.pm.PackageManager;
import android.view.SurfaceView;
import android.widget.FrameLayout;

Handle the Android permissions

When your app launches, check if the permissions necessary to insert Voice Call functionality into the app are granted. If the permissions are not granted, use the built-in Android functionality to request them; if they are, return true.

In /app/java/com.example.<projectname>/MainActivity, add the following lines before the onCreate function:

private static final int PERMISSION_REQ_ID = 22;
private static final String[] REQUESTED_PERMISSIONS = {
        Manifest.permission.RECORD_AUDIO,
        Manifest.permission.CAMERA
};
private boolean checkSelfPermission(String permission, int requestCode) {
    if (ContextCompat.checkSelfPermission(this, permission) !=
            PackageManager.PERMISSION_GRANTED) {
        ActivityCompat.requestPermissions(this, REQUESTED_PERMISSIONS, requestCode);
        return false;
        }
    return true;
}

Implement the Voice Call logic

The following figure and steps show the API call sequence of implementing Voice Call.

To implement this logic, take the following steps:

Import the Agora classes.

In /app/java/com.example.<projectname>/MainActivity, add the following lines after import android.os.Bundle;:

import io.agora.rtc2.Constants;
import io.agora.rtc2.IRtcEngineEventHandler;
import io.agora.rtc2.RtcEngine;
import io.agora.rtc2.RtcEngineConfig;
import io.agora.rtc2.ChannelMediaOptions;

Create the variables that you use to create and join channel.

In /app/java/com.example.<projectname>/MainActivity, add the following lines after AppCompatActivity {:

 // Fill the App ID of your project generated on Agora Console.
 private String appId = "";
 // Fill the channel name.
 private String channelName = "";
 // Fill the temp token generated on Agora Console.
 private String token = "";

 private RtcEngine mRtcEngine;

 private final IRtcEngineEventHandler mRtcEventHandler = new IRtcEngineEventHandler() {
     @Override
     // Listen for the remote host joining the channel to get the uid of the host.
     public void onUserJoined(int uid, int elapsed) {
 };

Initialize the app and join the channel.

Call the core methods for joining a channel in the MainActivity class, pass in your App ID, channel name, and temp token.

In the following reference code, the core methods are included in the initializeAndJoinChannel function.

private void initializeAndJoinChannel() {
  try {
      RtcEngineConfig config = new RtcEngineConfig();
      config.mContext = getBaseContext();
      config.mAppId = appId;
      config.mEventHandler = mRtcEventHandler;
      mRtcEngine = RtcEngine.create(config);
  } catch (Exception e) {
      throw new RuntimeException("Check the error.");
  }

  ChannelMediaOptions options = new ChannelMediaOptions();
  // Set both clients as the BROADCASTER.
  options.clientRoleType = Constants.CLIENT_ROLE_BROADCASTER;
  // Set the channel profile as BROADCASTING.
  options.channelProfile = Constants.CHANNEL_PROFILE_LIVE_BROADCASTING;

  // Join the channel with a temp token.
  // You need to specify the user ID yourself, and ensure that it is unique in the channel.
  mRtcEngine.joinChannel(token, channelName, 0, options);
}

Start and stop your app

Now you have created the Voice Call functionality. In this implementation, a video call starts when the user opens your app. The video call ends when the user closes your app.

Check that the app has the correct permissions. If permissions are granted, call initializeAndJoinChannel to join channel.

In /app/java/com.example.<projectname>/MainActivity, replace onCreate with the following code in the MainActivity class.

@Override
protected void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
   setContentView(R.layout.activity_main);

   // If all the permissions are granted, initialize the RtcEngine object and join a channel.
   if (checkSelfPermission(REQUESTED_PERMISSIONS[0], PERMISSION_REQ_ID) &&
           checkSelfPermission(REQUESTED_PERMISSIONS[1], PERMISSION_REQ_ID)) {
       initializeAndJoinChannel();
   }
}

When the user closes this app, call leaveChannel to release all resources related to the session. In /app/java/com.example.<projectname>/MainActivity, add the following code in the MainActivity class.

If you want to release all resources used by the Agora SDK, call destroy to clean up all the resources you created in initializeAndJoinChannel.
```
  mRtcEngine.leaveChannel();
```

Test your app

Please follow the test procedure as shown in the example.

Connect the Android devices to the computer.
Click Run 'app' on your Android Studio. A moment later you can see the project installed on your device.
Grant microphone and camera access to your app.
When the app launches, ask a friend to use a second device to join the channel with the same App ID, token, and channel name.

You can hear each other.

Next steps

In a test or production environment, use a token server to generate token is recommended to ensure communication security, see Authenticate Your Users with Tokens for details.

File or subfolder	Path of your project
`agora-rtc-sdk.jar` file	`/app/libs/`
`arm64-v8a` folder	`/app/src/main/jniLibs/`
`armeabi-v7a` folder	`/app/src/main/jniLibs/`
`x86` folder	`/app/src/main/jniLibs/`
`x86_64` folder	`/app/src/main/jniLibs/`
`include` folder in `high_level_api`	`/app/src/main/jniLibs/`