Record audio on Android in the background (even when screen is off)

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.myapp">

    <application android:allowBackup="true" android:icon="@mipmap/ic_launcher android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round" android:supportsRtl="true" android:theme="@style/AppTheme">

        <service android:name=".ForegroundService" android:enabled="true" android:exported="true"></service>

        <activity
            android:configChanges="orientation|keyboardHidden|keyboard|screenSize|locale"
            android:name="com.myapp.MainActivity"
            android:label="@string/title_activity_main"
            android:theme="@style/AppTheme.NoActionBarLaunch"
            android:launchMode="singleTop">
            <!-- //android:launchMode="singleTask" -->

            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>

            <intent-filter>
                <action android:name="android.intent.action.VIEW" />
                <category android:name="android.intent.category.DEFAULT" />
                <category android:name="android.intent.category.BROWSABLE" />
                <data android:scheme="@string/custom_url_scheme" />
            </intent-filter>
        </activity>

        <provider
            android:name="android.support.v4.content.FileProvider"
            android:authorities="${applicationId}.fileprovider"
            android:exported="false"
            android:grantUriPermissions="true">
            <meta-data
                android:name="android.support.FILE_PROVIDER_PATHS"
                android:resource="@xml/file_paths"></meta-data>
        </provider>
    </application>

    <!-- Permissions -->

    <uses-permission android:name="android.permission.INTERNET" />
    <!-- Camera, Photos, input file -->
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <!-- Geolocation API -->
    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
    <uses-feature android:name="android.hardware.location.gps" />
    <!-- Network API -->
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <!-- Navigator.getUserMedia -->
    <!-- Video -->
    <uses-permission android:name="android.permission.CAMERA" />
    <!-- Audio -->
    <uses-permission android:name="android.permission.RECORD_AUDIO" />
    <uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS"/>

    <!-- v-added -->
    <uses-permission android:name="android.permission.WAKE_LOCK" />
    <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
</manifest>

ForegroundService.java

package com.myapp;

import android.app.Notification;
import android.app.NotificationChannel;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.app.Service;
import android.content.Intent;
import android.media.AudioFormat;
import android.media.AudioManager;
import android.media.AudioRecord;
import android.media.AudioTrack;
import android.media.MediaRecorder;
import android.os.Build;
import android.os.IBinder;
import android.support.annotation.Nullable;
import android.support.v4.app.NotificationCompat;
import android.util.Log;

import com.getcapacitor.PluginCall;
import com.getcapacitor.PluginMethod;

public class ForegroundService extends Service {
	public static final String CHANNEL_ID = "ForegroundServiceChannel";

	@Override
	public void onCreate() {
		super.onCreate();
	}

	@Override
	public int onStartCommand(Intent intent, int flags, int startId) {
		String input = intent.getStringExtra("inputExtra");
		createNotificationChannel();
		Intent notificationIntent = new Intent(this, MainActivity.class);
		PendingIntent pendingIntent = PendingIntent.getActivity(this,
			0, notificationIntent, 0);

		Notification notification = new NotificationCompat.Builder(this, CHANNEL_ID)
			.setContentTitle("Foreground Service")
			.setContentText(input)
			.setSmallIcon(R.drawable.ic_launcher_foreground)
			.setContentIntent(pendingIntent)
			.build();

		startForeground(1, notification);

		// do heavy work on a background thread
		StartRecorder();

		//stopSelf();

		return START_NOT_STICKY;
	}

	@Override
	public void onDestroy() {
		super.onDestroy();
	}

	@Nullable
	@Override
	public IBinder onBind(Intent intent) {
		return null;
	}

	private void createNotificationChannel() {
		if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
			NotificationChannel serviceChannel = new NotificationChannel(
				CHANNEL_ID,
				"Foreground Service Channel",
				NotificationManager.IMPORTANCE_DEFAULT
			);

			NotificationManager manager = getSystemService(NotificationManager.class);
			manager.createNotificationChannel(serviceChannel);
		}
	}
































	private static String TAG = "ForegroundService";

	// the audio recording options
	private static final int RECORDING_RATE = 44100;
	private static final int CHANNEL = AudioFormat.CHANNEL_IN_MONO;
	private static final int FORMAT = AudioFormat.ENCODING_PCM_16BIT;

	// the audio recorder
	private AudioRecord recorder;
	// the minimum buffer size needed for audio recording
	private static int BUFFER_SIZE = AudioRecord.getMinBufferSize(RECORDING_RATE, CHANNEL, FORMAT);
	// are we currently sending audio data
	private boolean currentlySendingAudio = false;
	public void StartRecorder() {
		Log.i(TAG, "Starting the audio stream");
		currentlySendingAudio = true;
		startStreaming();
	}
	public void StopRecorder() {
		Log.i(TAG, "Stopping the audio stream");
		currentlySendingAudio = false;
		recorder.release();
	}

	private void startStreaming() {
		Log.i(TAG, "Starting the background thread (in this foreground service) to read the audio data");

		Thread streamThread = new Thread(() -> {
			try {
				Log.d(TAG, "Creating the buffer of size " + BUFFER_SIZE);
				//byte[] buffer = new byte[BUFFER_SIZE];
				int rate = AudioTrack.getNativeOutputSampleRate(AudioManager.STREAM_SYSTEM);
				int bufferSize = AudioRecord.getMinBufferSize(rate, AudioFormat.CHANNEL_IN_MONO, AudioFormat.ENCODING_PCM_16BIT);
				short[] buffer = new short[bufferSize];

				android.os.Process.setThreadPriority(android.os.Process.THREAD_PRIORITY_AUDIO);

				Log.d(TAG, "Creating the AudioRecord");
				//recorder = new AudioRecord(MediaRecorder.AudioSource.MIC, RECORDING_RATE, CHANNEL, FORMAT, BUFFER_SIZE * 10);
				recorder = new AudioRecord(MediaRecorder.AudioSource.MIC, rate, AudioFormat.CHANNEL_IN_MONO, AudioFormat.ENCODING_PCM_16BIT, bufferSize);

				Log.d(TAG, "AudioRecord recording...");
				recorder.startRecording();

				while (currentlySendingAudio == true) {
					// read the data into the buffer
					int readSize = recorder.read(buffer, 0, buffer.length);

					double maxAmplitude = 0;
					for (int i = 0; i < readSize; i++) {
						if (Math.abs(buffer[i]) > maxAmplitude) {
							maxAmplitude = Math.abs(buffer[i]);
						}
					}

					double db = 0;
					if (maxAmplitude != 0) {
						db = 20.0 * Math.log10(maxAmplitude / 32767.0) + 90;
					}

					Log.d(TAG, "Max amplitude: " + maxAmplitude + " ; DB: " + db);
				}

				Log.d(TAG, "AudioRecord finished recording");
			} catch (Exception e) {
				Log.e(TAG, "Exception: " + e);
			}
		});

		// start the thread
		streamThread.start();
	}
}

General.java (place that launches service)

package com.myapp;

import android.content.Context;
import android.content.Intent;
import android.media.AudioFormat;
import android.media.AudioManager;
import android.media.AudioRecord;
import android.media.AudioTrack;
import android.media.MediaRecorder;
import android.net.wifi.WifiManager;
import android.nfc.Tag;
import android.os.PowerManager;
import android.support.v4.content.ContextCompat;
import android.util.Log;
import android.widget.Button;

import com.getcapacitor.JSObject;
import com.getcapacitor.NativePlugin;
import com.getcapacitor.Plugin;
import com.getcapacitor.PluginCall;
import com.getcapacitor.PluginMethod;
import com.getcapacitor.PluginResult;

import java.net.DatagramSocket;

@NativePlugin()
public class General extends Plugin {



	private static String TAG = "V.General";
	@PluginMethod
	public void StartRecorder(PluginCall call) {
		Log.i(TAG, "Starting the foreground-thread");

		Intent serviceIntent = new Intent(getActivity().getApplicationContext(), ForegroundService.class);
		serviceIntent.putExtra("inputExtra", "Foreground Service Example in Android");
		ContextCompat.startForegroundService(getActivity(), serviceIntent);

		call.resolve();
	}
	@PluginMethod
	public void StopRecorder(PluginCall call) {
		Log.i(TAG, "Stopping the foreground-thread");

		Intent serviceIntent = new Intent(getActivity().getApplicationContext(), ForegroundService.class);
		getActivity().getApplicationContext().stopService(serviceIntent);

		call.resolve();
	}




  // From what I've seen you don't need the wake-lock or wifi-lock below for the audio-recorder to persist through screen-off.
  // However, to be on the safe side you might want to activate them anyway. (and/or if you have other functions that need them)



	private PowerManager.WakeLock wakeLock_partial = null;
	public void StartPartialWakeLock() {
		if (wakeLock_partial != null && wakeLock_partial.isHeld()) return;
		Log.i("vmain", "Starting partial wake-lock.");
		final PowerManager pm = (PowerManager) getActivity().getApplicationContext().getSystemService(Context.POWER_SERVICE);
		wakeLock_partial = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "com.myapp:partial_wake_lock");
		wakeLock_partial.acquire();
	}
	public void StopPartialWakeLock() {
		if (wakeLock_partial != null && wakeLock_partial.isHeld()) {
			Log.i("vmain", "Stopping partial wake-lock.");
			wakeLock_partial.release();
		}
	}

	private WifiManager.WifiLock wifiLock = null;
	public void StartWifiLock() {
		WifiManager wifiManager = (WifiManager) getActivity().getApplicationContext().getSystemService(Context.WIFI_SERVICE);
		wifiLock = wifiManager.createWifiLock(WifiManager.WIFI_MODE_FULL, "LockTag");
		wifiLock.acquire();
	}
	public void StopWifiLock() {
		wifiLock.release();
	}
}

Dear Stephen,
congratulations for such a great code.
Given your obvious experience, I would like, if you allow me, to ask you for some suggestions.
I'm not an expert so forgive any silly questions.
Using the microphone requires explicit permission, of course. However, I have read that internal audio could be recorded without permissions. The question is: do you think it is possible to by-pass the permissions regarding the use of the microphone, perhaps finding a way to redirect such an audio to the internal audio, or similar solutions?

Thanks a lot, and congratulations again.

Rocco Z.

Unfortunately, I've never tried to record from the internal audio, so I don't know if it can be done with fewer permissions. Good luck though!

// However, to be on the safe side you might want to activate them anyway.

hey where to stop and stop that power lock???

Seems not to work with Android 11, right?

Seems not to work with Android 11, right?

Sorry, but I have no idea; I haven't done any significant Android development for about a year now, and do not have an Android 11 device.

@bayerlse did you find any solution on android 11 ? i am also facing following issue
While user press home button or screen lock button mediaRecorder stop recording voice but keep writing bytes to file.

@bayerlse did you find any solution on android 11 ? i am also facing following issue While user press home button or screen lock button mediaRecorder stop recording voice but keep writing bytes to file.

Same here, have you come across any fix? I'm unable to get mediaRecorder to consistently record after the screen is off.

@bayerlse
@rayyan808
using the foreground service is a solution I think.
More on that here #react-native-webrtc/react-native-callkeep#274

Has anyone tried this working code?