audio_service 0.7.0

Flutter plugin to play audio in the background while the screen is off.

audio_service

Play audio in the background.

• Continues playing while the screen is off or the app is in the background
• Control playback from your Flutter UI, notifications, lock screen, headset, Wear OS or Android Auto
• Drive audio playback from Dart code

This plugin wraps around your existing Dart audio code to allow it to run in the background, and also respond to media button clicks on the lock screen, notifications, control center, headphone buttons and other supported remote control devices. This is necessary for a whole range of media applications such as music and podcast players, text-to-speech readers, navigators, etc.

This plugin is audio agnostic. It is designed to allow you to use your favourite audio plugins, such as just_audio, flutter_radio, flutter_tts, and others. It simply wraps a special isolate around your existing audio code so that it can run in the background and enable remote control interfaces.

Note that because your app's UI and your background audio task will run in separate isolates, they do not share memory. They communicate through the message passing APIs provided by audio_service.

NEW: This release includes a partially working "alpha" iOS implementation. If you'd like to help with any missing features, join us on GitHub issue #10.

Feature	Android	iOS
start/stop	✅	✅
play/pause	✅	✅
headset click	✅	✅
seek	✅	✅
skip next/prev	✅	✅
FF/rewind	✅	✅
rate	✅	✅
custom actions	✅	(untested)
notifications/control center	✅	(partial)
lock screen controls	✅	(partial)
album art	✅	✅
queue management	✅	✅
runs in background	✅	✅
Handle phonecall interruptions	✅
Android Auto	(untested)

Example

audio_service provides two sets of APIs: one for your main UI isolate (AudioService), and one for your background audio isolate (AudioServiceBackground).

UI code

This code runs in the main UI isolate:

AudioService.connect();    // When UI becomes visible
AudioService.start(        // When user clicks button to start playback
  backgroundTaskEntrypoint: myBackgroundTaskEntrypoint,
  androidNotificationChannelName: 'Music Player',
  androidNotificationIcon: "mipmap/ic_launcher",
);
AudioService.pause();      // When user clicks button to pause playback
AudioService.play();       // When user clicks button to resume playback
AudioService.disconnect(); // When UI is gone

The full example on GitHub should be consulted for tips on how to hook connect and disconnect into your widget's lifecycle.

Background code

This code runs in a background isolate, and is the code that is guaranteed to continue running even if your UI is gone:

void myBackgroundTaskEntrypoint() {
  AudioServiceBackground.run(() => MyBackgroundTask());
}

class MyBackgroundTask extends BackgroundAudioTask {
  @override
  Future<void> onStart() async {
    // Your custom dart code to start audio playback.
    // NOTE: The background audio task will shut down
    // as soon as this async function completes.
  }
  @override
  void onStop() {
    // Your custom dart code to stop audio playback.
  }
  @override
  void onPlay() {
    // Your custom dart code to resume audio playback.
  }
  @override
  void onPause() {
    // Your custom dart code to pause audio playback.
  }
  @override
  void onClick(MediaButton button) {
    // Your custom dart code to handle a media button click.
  }
}

The full example on GitHub demonstrates how to fill in these callbacks to do audio playback and also text-to-speech.

Android setup

These instructions assume that your project follows the new project template introduced in Flutter 1.12. If your project was created prior to 1.12 and uses the old project structure, you can either view a previous version of this README on GitHub, or update your project to follow the new project template.

1. Edit your project's AndroidManifest.xml file to declare the permission to create a wake lock, and add component entries for the <service> and <receiver>:

<manifest ...>
  <uses-permission android:name="android.permission.WAKE_LOCK"/>
  <uses-permission android:name="android.permission.FOREGROUND_SERVICE"/>
  
  <application ...>
    
    ...
    
    <service android:name="com.ryanheise.audioservice.AudioService">
      <intent-filter>
        <action android:name="android.media.browse.MediaBrowserService" />
      </intent-filter>
    </service>

    <receiver android:name="androidx.media.session.MediaButtonReceiver" >
      <intent-filter>
        <action android:name="android.intent.action.MEDIA_BUTTON" />
      </intent-filter>
    </receiver> 
  </application>
</manifest>

2. Any icons that you want to appear in the notification (see the MediaControl class) should be defined as Android resources in android/app/src/main/res. Here you will find a subdirectory for each different resolution:

drawable-hdpi
drawable-mdpi
drawable-xhdpi
drawable-xxhdpi
drawable-xxxhdpi

You can use Android Asset Studio to generate these different subdirectories for any standard material design icon.

Starting from Flutter 1.12, you will also need to disable the shrinkResources setting in your android/app/build.gradle file, otherwise your icon resources will be removed during the build:

android {
    compileSdkVersion 28

    ...

    buildTypes {
        release {
            signingConfig ...
            shrinkResources false // ADD THIS LINE
        }
    }
}

3. (Optional) Versions of Flutter since 1.12 have a memory leak that affects this plugin. It will be fixed in an upcoming Flutter release but until then you can work around it by overriding the following method in your MainActivity class:

public class MainActivity extends FlutterActivity {
  /** This is a temporary workaround to avoid a memory leak in the Flutter framework */
  @Override
  public FlutterEngine provideFlutterEngine(Context context) {
    // Instantiate a FlutterEngine.
    FlutterEngine flutterEngine = new FlutterEngine(context.getApplicationContext());

    // Start executing Dart code to pre-warm the FlutterEngine.
    flutterEngine.getDartExecutor().executeDartEntrypoint(
      DartExecutor.DartEntrypoint.createDefault()
    );

    return flutterEngine;
  }
}

Alternatively, if you use a cached flutter engine (as per these instructions), you will need to change the instantiation code from new FlutterEngine(this) to new FlutterEngine(getApplicationContext()).

iOS setup

Insert this in your Info.plist file:

	<key>UIBackgroundModes</key>
	<array>
		<string>audio</string>
	</array>

The example project may be consulted for context.