rn,android: refactor audio device handling module

Separate each implementation (3 as of this writing) into each own "handler"
class.

This should make the code easier to understand, maintain and extend.

android/sdk/src/main/java/org/jitsi/meet/sdk/AudioDeviceHandlerConnectionService.java

+/*
+ * Copyright @ 2017-present 8x8, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jitsi.meet.sdk;
+
+import android.content.Context;
+import android.os.Build;
+import androidx.annotation.RequiresApi;
+
+import java.util.HashSet;
+import java.util.Set;
+
+import org.jitsi.meet.sdk.log.JitsiMeetLogger;
+
+
+/**
+ * {@link AudioModeModule.AudioDeviceHandlerInterface} module implementing device handling for
+ * Android versions >= O when ConnectionService is enabled.
+ */
+@RequiresApi(Build.VERSION_CODES.O)
+class AudioDeviceHandlerConnectionService implements
+        AudioModeModule.AudioDeviceHandlerInterface,
+        RNConnectionService.CallAudioStateListener {
+
+    private final static String TAG = AudioDeviceHandlerConnectionService.class.getSimpleName();
+
+    /**
+     * Reference to the main {@code AudioModeModule}.
+     */
+    private AudioModeModule module;
+
+    /**
+     * Converts any of the "DEVICE_" constants into the corresponding
+     * {@link android.telecom.CallAudioState} "ROUTE_" number.
+     *
+     * @param audioDevice one of the "DEVICE_" constants.
+     * @return a route number {@link android.telecom.CallAudioState#ROUTE_EARPIECE} if
+     * no match is found.
+     */
+    private static int audioDeviceToRouteInt(String audioDevice) {
+        if (audioDevice == null) {
+            return android.telecom.CallAudioState.ROUTE_EARPIECE;
+        }
+        switch (audioDevice) {
+            case AudioModeModule.DEVICE_BLUETOOTH:
+                return android.telecom.CallAudioState.ROUTE_BLUETOOTH;
+            case AudioModeModule.DEVICE_EARPIECE:
+                return android.telecom.CallAudioState.ROUTE_EARPIECE;
+            case AudioModeModule.DEVICE_HEADPHONES:
+                return android.telecom.CallAudioState.ROUTE_WIRED_HEADSET;
+            case AudioModeModule.DEVICE_SPEAKER:
+                return android.telecom.CallAudioState.ROUTE_SPEAKER;
+            default:
+                JitsiMeetLogger.e(TAG + " Unsupported device name: " + audioDevice);
+                return android.telecom.CallAudioState.ROUTE_EARPIECE;
+        }
+    }
+
+    /**
+     * Populates given route mask into the "DEVICE_" list.
+     *
+     * @param supportedRouteMask an integer coming from
+     * {@link android.telecom.CallAudioState#getSupportedRouteMask()}.
+     * @return a list of device names.
+     */
+    private static Set<String> routesToDeviceNames(int supportedRouteMask) {
+        Set<String> devices = new HashSet<>();
+        if ((supportedRouteMask & android.telecom.CallAudioState.ROUTE_EARPIECE)
+                == android.telecom.CallAudioState.ROUTE_EARPIECE) {
+            devices.add(AudioModeModule.DEVICE_EARPIECE);
+        }
+        if ((supportedRouteMask & android.telecom.CallAudioState.ROUTE_BLUETOOTH)
+                == android.telecom.CallAudioState.ROUTE_BLUETOOTH) {
+            devices.add(AudioModeModule.DEVICE_BLUETOOTH);
+        }
+        if ((supportedRouteMask & android.telecom.CallAudioState.ROUTE_SPEAKER)
+                == android.telecom.CallAudioState.ROUTE_SPEAKER) {
+            devices.add(AudioModeModule.DEVICE_SPEAKER);
+        }
+        if ((supportedRouteMask & android.telecom.CallAudioState.ROUTE_WIRED_HEADSET)
+                == android.telecom.CallAudioState.ROUTE_WIRED_HEADSET) {
+            devices.add(AudioModeModule.DEVICE_HEADPHONES);
+        }
+        return devices;
+    }
+
+    /**
+     * Used to store the most recently reported audio devices.
+     * Makes it easier to compare for a change, because the devices are stored
+     * as a mask in the {@link android.telecom.CallAudioState}. The mask is populated into
+     * the {@code availableDevices} on each update.
+     */
+    private int supportedRouteMask = -1;
+
+    public AudioDeviceHandlerConnectionService() {
+    }
+
+    @Override
+    public void onCallAudioStateChange(final android.telecom.CallAudioState callAudioState) {
+        module.runInAudioThread(new Runnable() {
+            @Override
+            public void run() {
+                boolean audioRouteChanged
+                    = audioDeviceToRouteInt(module.getSelectedDevice()) != callAudioState.getRoute();
+                int newSupportedRoutes = callAudioState.getSupportedRouteMask();
+                boolean audioDevicesChanged = supportedRouteMask != newSupportedRoutes;
+                if (audioDevicesChanged) {
+                    supportedRouteMask = newSupportedRoutes;
+                    Set<String> devices = routesToDeviceNames(supportedRouteMask);
+                    module.replaceDevices(devices);
+                    JitsiMeetLogger.i(TAG + " Available audio devices: " + devices.toString());
+                }
+
+                if (audioRouteChanged || audioDevicesChanged) {
+                    module.resetSelectedDevice();
+                    module.updateAudioRoute();
+                }
+            }
+        });
+    }
+
+    @Override
+    public void start(Context context, AudioModeModule audioModeModule) {
+        JitsiMeetLogger.i("Using " + TAG + " as the audio device handler");
+
+        module = audioModeModule;
+        RNConnectionService rcs = ReactInstanceManagerHolder.getNativeModule(RNConnectionService.class);
+        if (rcs != null) {
+            rcs.setCallAudioStateListener(this);
+        }
+    }
+
+    @Override
+    public void stop() {
+        RNConnectionService rcs = ReactInstanceManagerHolder.getNativeModule(RNConnectionService.class);
+        if (rcs != null) {
+            rcs.setCallAudioStateListener(null);
+        }
+    }
+
+    public void setAudioRoute(String audioDevice) {
+        int newAudioRoute = audioDeviceToRouteInt(audioDevice);
+
+        RNConnectionService.setAudioRoute(newAudioRoute);
+    }
+
+    @Override
+    public boolean setMode(int mode) {
+        return true;
+    }
+}

android/sdk/src/main/java/org/jitsi/meet/sdk/AudioDeviceHandlerGeneric.java

+/*
+ * Copyright @ 2017-present 8x8, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jitsi.meet.sdk;
+
+import android.content.Context;
+import android.media.AudioDeviceInfo;
+import android.media.AudioManager;
+import android.os.Build;
+import androidx.annotation.RequiresApi;
+
+import java.util.HashSet;
+import java.util.Set;
+
+import org.jitsi.meet.sdk.log.JitsiMeetLogger;
+
+
+/**
+ * {@link AudioModeModule.AudioDeviceHandlerInterface} module implementing device handling for
+ * all post-M Android versions. This handler can be used on any Android versions >= M, but by
+ * default it's only used on versions < O, since versions >= O use ConnectionService, but it
+ * can be disabled.
+ */
+@RequiresApi(Build.VERSION_CODES.M)
+class AudioDeviceHandlerGeneric implements
+        AudioModeModule.AudioDeviceHandlerInterface,
+        AudioManager.OnAudioFocusChangeListener {
+
+    private final static String TAG = AudioDeviceHandlerGeneric.class.getSimpleName();
+
+    /**
+     * Reference to the main {@code AudioModeModule}.
+     */
+    private AudioModeModule module;
+
+    /**
+     * Constant defining a USB headset. Only available on API level >= 26.
+     * The value of: AudioDeviceInfo.TYPE_USB_HEADSET
+     */
+    private static final int TYPE_USB_HEADSET = 22;
+
+    /**
+     * Indicator that we have lost audio focus.
+     */
+    private boolean audioFocusLost = false;
+
+    /**
+     * {@link AudioManager} instance used to interact with the Android audio
+     * subsystem.
+     */
+    private AudioManager audioManager;
+
+    /**
+     * {@link Runnable} for running audio device detection the main thread.
+     * This is only used on Android >= M.
+     */
+    private final Runnable onAudioDeviceChangeRunner = new Runnable() {
+        @Override
+        public void run() {
+            Set<String> devices = new HashSet<>();
+            AudioDeviceInfo[] deviceInfos = audioManager.getDevices(AudioManager.GET_DEVICES_ALL);
+
+            for (AudioDeviceInfo info: deviceInfos) {
+                switch (info.getType()) {
+                    case AudioDeviceInfo.TYPE_BLUETOOTH_SCO:
+                        devices.add(AudioModeModule.DEVICE_BLUETOOTH);
+                        break;
+                    case AudioDeviceInfo.TYPE_BUILTIN_EARPIECE:
+                        devices.add(AudioModeModule.DEVICE_EARPIECE);
+                        break;
+                    case AudioDeviceInfo.TYPE_BUILTIN_SPEAKER:
+                        devices.add(AudioModeModule.DEVICE_SPEAKER);
+                        break;
+                    case AudioDeviceInfo.TYPE_WIRED_HEADPHONES:
+                    case AudioDeviceInfo.TYPE_WIRED_HEADSET:
+                    case TYPE_USB_HEADSET:
+                        devices.add(AudioModeModule.DEVICE_HEADPHONES);
+                        break;
+                }
+            }
+
+            module.replaceDevices(devices);
+
+            JitsiMeetLogger.i(TAG + " Available audio devices: " + devices.toString());
+
+            module.updateAudioRoute();
+        }
+    };
+
+    private final android.media.AudioDeviceCallback audioDeviceCallback =
+        new android.media.AudioDeviceCallback() {
+            @Override
+            public void onAudioDevicesAdded(
+                AudioDeviceInfo[] addedDevices) {
+                JitsiMeetLogger.d(TAG + " Audio devices added");
+                onAudioDeviceChange();
+            }
+
+            @Override
+            public void onAudioDevicesRemoved(
+                AudioDeviceInfo[] removedDevices) {
+                JitsiMeetLogger.d(TAG + " Audio devices removed");
+                onAudioDeviceChange();
+            }
+        };
+
+    public AudioDeviceHandlerGeneric() {
+    }
+
+    /**
+     * Helper method to trigger an audio route update when devices change. It
+     * makes sure the operation is performed on the audio thread.
+     */
+    private void onAudioDeviceChange() {
+        module.runInAudioThread(onAudioDeviceChangeRunner);
+    }
+
+    /**
+     * {@link AudioManager.OnAudioFocusChangeListener} interface method. Called
+     * when the audio focus of the system is updated.
+     *
+     * @param focusChange - The type of focus change.
+     */
+    @Override
+    public void onAudioFocusChange(final int focusChange) {
+        module.runInAudioThread(new Runnable() {
+            @Override
+            public void run() {
+                switch (focusChange) {
+                    case AudioManager.AUDIOFOCUS_GAIN: {
+                        JitsiMeetLogger.d(TAG + " Audio focus gained");
+                        // Some other application potentially stole our audio focus
+                        // temporarily. Restore our mode.
+                        if (audioFocusLost) {
+                            module.updateAudioRoute();
+                        }
+                        audioFocusLost = false;
+                        break;
+                    }
+                    case AudioManager.AUDIOFOCUS_LOSS:
+                    case AudioManager.AUDIOFOCUS_LOSS_TRANSIENT:
+                    case AudioManager.AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK: {
+                        JitsiMeetLogger.d(TAG + " Audio focus lost");
+                        audioFocusLost = true;
+                        break;
+                    }
+                }
+            }
+        });
+    }
+
+    /**
+     * Helper method to set the output route to a Bluetooth device.
+     *
+     * @param enabled true if Bluetooth should use used, false otherwise.
+     */
+    private void setBluetoothAudioRoute(boolean enabled) {
+        if (enabled) {
+            audioManager.startBluetoothSco();
+            audioManager.setBluetoothScoOn(true);
+        } else {
+            audioManager.setBluetoothScoOn(false);
+            audioManager.stopBluetoothSco();
+        }
+    }
+
+    @Override
+    public void start(Context context, AudioModeModule audioModeModule) {
+        JitsiMeetLogger.i("Using " + TAG + " as the audio device handler");
+
+        module = audioModeModule;
+        audioManager = (AudioManager)context.getSystemService(Context.AUDIO_SERVICE);
+
+        // Setup runtime device change detection.
+        audioManager.registerAudioDeviceCallback(audioDeviceCallback, null);
+
+        // Do an initial detection.
+        onAudioDeviceChange();
+    }
+
+    @Override
+    public void stop() {
+        audioManager.unregisterAudioDeviceCallback(audioDeviceCallback);
+    }
+
+    @Override
+    public void setAudioRoute(String device) {
+        // Turn bluetooth on / off
+        setBluetoothAudioRoute(device.equals(AudioModeModule.DEVICE_BLUETOOTH));
+
+        // Turn speaker on / off
+        audioManager.setSpeakerphoneOn(device.equals(AudioModeModule.DEVICE_SPEAKER));
+    }
+
+    @Override
+    public boolean setMode(int mode) {
+        if (mode == AudioModeModule.DEFAULT) {
+            audioFocusLost = false;
+            audioManager.setMode(AudioManager.MODE_NORMAL);
+            audioManager.abandonAudioFocus(this);
+            audioManager.setSpeakerphoneOn(false);
+            setBluetoothAudioRoute(false);
+
+            return true;
+        }
+
+        audioManager.setMode(AudioManager.MODE_IN_COMMUNICATION);
+        audioManager.setMicrophoneMute(false);
+
+        if (audioManager.requestAudioFocus(this, AudioManager.STREAM_VOICE_CALL, AudioManager.AUDIOFOCUS_GAIN)
+            == AudioManager.AUDIOFOCUS_REQUEST_FAILED) {
+            JitsiMeetLogger.w(TAG + " Audio focus request failed");
+            return false;
+        }
+
+        return true;
+    }
+}

android/sdk/src/main/java/org/jitsi/meet/sdk/AudioDeviceHandlerLegacy.java

+/*
+ * Copyright @ 2017-present 8x8, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jitsi.meet.sdk;
+
+import android.content.BroadcastReceiver;
+import android.content.Context;
+import android.content.Intent;
+import android.content.IntentFilter;
+import android.content.pm.PackageManager;
+import android.media.AudioManager;
+
+import org.jitsi.meet.sdk.log.JitsiMeetLogger;
+
+
+/**
+ * {@link AudioModeModule.AudioDeviceHandlerInterface} module implementing device handling for
+ * legacy (pre-M) Android versions.
+ */
+class AudioDeviceHandlerLegacy implements
+        AudioModeModule.AudioDeviceHandlerInterface,
+        AudioManager.OnAudioFocusChangeListener,
+        BluetoothHeadsetMonitor.Listener {
+
+    private final static String TAG = AudioDeviceHandlerLegacy.class.getSimpleName();
+
+    /**
+     * Reference to the main {@code AudioModeModule}.
+     */
+    private AudioModeModule module;
+
+    /**
+     * Indicator that we have lost audio focus.
+     */
+    private boolean audioFocusLost = false;
+
+    /**
+     * {@link AudioManager} instance used to interact with the Android audio
+     * subsystem.
+     */
+    private AudioManager audioManager;
+
+    /**
+     * {@link BluetoothHeadsetMonitor} for detecting Bluetooth device changes in
+     * old (< M) Android versions.
+     */
+    private BluetoothHeadsetMonitor bluetoothHeadsetMonitor;
+
+    public AudioDeviceHandlerLegacy() {
+    }
+
+    /**
+     * Helper method to trigger an audio route update when Bluetooth devices are
+     * connected / disconnected.
+     */
+    @Override
+    public void onBluetoothDeviceChange(final boolean deviceAvailable) {
+        module.runInAudioThread(new Runnable() {
+            @Override
+            public void run() {
+                if (deviceAvailable) {
+                    module.addDevice(AudioModeModule.DEVICE_BLUETOOTH);
+                } else {
+                    module.removeDevice(AudioModeModule.DEVICE_BLUETOOTH);
+                }
+
+                module.updateAudioRoute();
+            }
+        });
+    }
+
+    /**
+     * Helper method to trigger an audio route update when a headset is plugged
+     * or unplugged.
+     */
+    private void onHeadsetDeviceChange() {
+        module.runInAudioThread(new Runnable() {
+            @Override
+            public void run() {
+                // XXX: isWiredHeadsetOn is not deprecated when used just for
+                // knowing if there is a wired headset connected, regardless of
+                // audio being routed to it.
+                //noinspection deprecation
+                if (audioManager.isWiredHeadsetOn()) {
+                    module.addDevice(AudioModeModule.DEVICE_HEADPHONES);
+                } else {
+                    module.removeDevice(AudioModeModule.DEVICE_HEADPHONES);
+                }
+
+                module.updateAudioRoute();
+            }
+        });
+    }
+
+    /**
+     * {@link AudioManager.OnAudioFocusChangeListener} interface method. Called
+     * when the audio focus of the system is updated.
+     *
+     * @param focusChange - The type of focus change.
+     */
+    @Override
+    public void onAudioFocusChange(final int focusChange) {
+        module.runInAudioThread(new Runnable() {
+            @Override
+            public void run() {
+                switch (focusChange) {
+                    case AudioManager.AUDIOFOCUS_GAIN: {
+                        JitsiMeetLogger.d(TAG + " Audio focus gained");
+                        // Some other application potentially stole our audio focus
+                        // temporarily. Restore our mode.
+                        if (audioFocusLost) {
+                            module.updateAudioRoute();
+                        }
+                        audioFocusLost = false;
+                        break;
+                    }
+                    case AudioManager.AUDIOFOCUS_LOSS:
+                    case AudioManager.AUDIOFOCUS_LOSS_TRANSIENT:
+                    case AudioManager.AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK: {
+                        JitsiMeetLogger.d(TAG + " Audio focus lost");
+                        audioFocusLost = true;
+                        break;
+                    }
+                }
+            }
+        });
+    }
+
+    /**
+     * Helper method to set the output route to a Bluetooth device.
+     *
+     * @param enabled true if Bluetooth should use used, false otherwise.
+     */
+    private void setBluetoothAudioRoute(boolean enabled) {
+        if (enabled) {
+            audioManager.startBluetoothSco();
+            audioManager.setBluetoothScoOn(true);
+        } else {
+            audioManager.setBluetoothScoOn(false);
+            audioManager.stopBluetoothSco();
+        }
+    }
+
+    @Override
+    public void start(Context context, AudioModeModule audioModeModule) {
+        JitsiMeetLogger.i("Using " + TAG + " as the audio device handler");
+
+        module = audioModeModule;
+        audioManager = (AudioManager)context.getSystemService(Context.AUDIO_SERVICE);
+
+        // Setup runtime device change detection.
+        //
+
+        // Detect changes in wired headset connections.
+        IntentFilter wiredHeadSetFilter = new IntentFilter(AudioManager.ACTION_HEADSET_PLUG);
+        BroadcastReceiver wiredHeadsetReceiver = new BroadcastReceiver() {
+            @Override
+            public void onReceive(Context context, Intent intent) {
+                JitsiMeetLogger.d(TAG + " Wired headset added / removed");
+                onHeadsetDeviceChange();
+            }
+        };
+        context.registerReceiver(wiredHeadsetReceiver, wiredHeadSetFilter);
+
+        // Detect Bluetooth device changes.
+        bluetoothHeadsetMonitor = new BluetoothHeadsetMonitor(context, this);
+
+        // On Android < M, detect if we have an earpiece.
+        PackageManager pm = context.getPackageManager();
+        if (pm.hasSystemFeature(PackageManager.FEATURE_TELEPHONY)) {
+            module.addDevice(AudioModeModule.DEVICE_EARPIECE);
+        }
+
+        // Always assume there is a speaker.
+        module.addDevice(AudioModeModule.DEVICE_SPEAKER);
+    }
+
+    @Override
+    public void stop() {
+        bluetoothHeadsetMonitor.stop();
+        bluetoothHeadsetMonitor = null;
+    }
+
+    @Override
+    public void setAudioRoute(String device) {
+        // Turn bluetooth on / off
+        setBluetoothAudioRoute(device.equals(AudioModeModule.DEVICE_BLUETOOTH));
+
+        // Turn speaker on / off
+        audioManager.setSpeakerphoneOn(device.equals(AudioModeModule.DEVICE_SPEAKER));
+    }
+
+    @Override
+    public boolean setMode(int mode) {
+        if (mode == AudioModeModule.DEFAULT) {
+            audioFocusLost = false;
+            audioManager.setMode(AudioManager.MODE_NORMAL);
+            audioManager.abandonAudioFocus(this);
+            audioManager.setSpeakerphoneOn(false);
+            setBluetoothAudioRoute(false);
+
+            return true;
+        }
+
+        audioManager.setMode(AudioManager.MODE_IN_COMMUNICATION);
+        audioManager.setMicrophoneMute(false);
+
+        if (audioManager.requestAudioFocus(this, AudioManager.STREAM_VOICE_CALL, AudioManager.AUDIOFOCUS_GAIN)
+                == AudioManager.AUDIOFOCUS_REQUEST_FAILED) {
+            JitsiMeetLogger.w(TAG + " Audio focus request failed");
+            return false;
+        }
+
+        return true;
+    }
+}

android/sdk/src/main/java/org/jitsi/meet/sdk/AudioModeModule.java

 /*
- * Copyright @ 2017-present Atlassian Pty Ltd
+ * Copyright @ 2017-present 8x8, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
 
 package org.jitsi.meet.sdk;
 
-import android.annotation.TargetApi;
-import android.content.BroadcastReceiver;
 import android.content.Context;
-import android.content.Intent;
-import android.content.IntentFilter;
-import android.content.pm.PackageManager;
-import android.media.AudioDeviceInfo;
-import android.media.AudioManager;
 import android.os.Build;
-import androidx.annotation.RequiresApi;
 
 import com.facebook.react.bridge.Arguments;
 import com.facebook.react.bridge.Promise;
  * {@code AudioModeModule.DEFAULT} mode should be used.
  */
 @ReactModule(name = AudioModeModule.NAME)
-class AudioModeModule extends ReactContextBaseJavaModule
-    implements AudioManager.OnAudioFocusChangeListener {
-
+class AudioModeModule extends ReactContextBaseJavaModule {
     public static final String NAME = "AudioMode";
 
     /**
      * - VIDEO_CALL: Used for video calls. It will use the speaker by default,
      *   unless a wired or Bluetooth headset is connected.
      */
-    private static final int DEFAULT    = 0;
-    private static final int AUDIO_CALL = 1;
-    private static final int VIDEO_CALL = 2;
-
-    /**
-     * Constant defining the action for plugging in a headset. This is used on
-     * our device detection system for API < 23.
-     */
-    private static final String ACTION_HEADSET_PLUG
-        = (Build.VERSION.SDK_INT >= 21)
-            ? AudioManager.ACTION_HEADSET_PLUG
-            : Intent.ACTION_HEADSET_PLUG;
-
-    /**
-     * Constant defining a USB headset. Only available on API level >= 26.
-     * The value of: AudioDeviceInfo.TYPE_USB_HEADSET
-     */
-    private static final int TYPE_USB_HEADSET = 22;
+    static final int DEFAULT    = 0;
+    static final int AUDIO_CALL = 1;
+    static final int VIDEO_CALL = 2;
 
     /**
      * The {@code Log} tag {@code AudioModeModule} is to log messages with.
     static final String TAG = NAME;
 
     /**
-     * Converts any of the "DEVICE_" constants into the corresponding
-     * {@link android.telecom.CallAudioState} "ROUTE_" number.
-     *
-     * @param audioDevice one of the "DEVICE_" constants.
-     * @return a route number {@link android.telecom.CallAudioState#ROUTE_EARPIECE} if
-     * no match is found.
+     * Whether or not the ConnectionService is used for selecting audio devices.
      */
-    @RequiresApi(api = Build.VERSION_CODES.M)
-    private static int audioDeviceToRouteInt(String audioDevice) {
-        if (audioDevice == null) {
-            return android.telecom.CallAudioState.ROUTE_EARPIECE;
-        }
-        switch (audioDevice) {
-            case DEVICE_BLUETOOTH:
-                return android.telecom.CallAudioState.ROUTE_BLUETOOTH;
-            case DEVICE_EARPIECE:
-                return android.telecom.CallAudioState.ROUTE_EARPIECE;
-            case DEVICE_HEADPHONES:
-                return android.telecom.CallAudioState.ROUTE_WIRED_HEADSET;
-            case DEVICE_SPEAKER:
-                return android.telecom.CallAudioState.ROUTE_SPEAKER;
-            default:
-                JitsiMeetLogger.e(TAG + " Unsupported device name: " + audioDevice);
-                return android.telecom.CallAudioState.ROUTE_EARPIECE;
-        }
-    }
 
-    /**
-     * Populates given route mask into the "DEVICE_" list.
-     *
-     * @param supportedRouteMask an integer coming from
-     * {@link android.telecom.CallAudioState#getSupportedRouteMask()}.
-     * @return a list of device names.
-     */
-    @RequiresApi(api = Build.VERSION_CODES.M)
-    private static Set<String> routesToDeviceNames(int supportedRouteMask) {
-        Set<String> devices = new HashSet<>();
-        if ((supportedRouteMask & android.telecom.CallAudioState.ROUTE_EARPIECE)
-                == android.telecom.CallAudioState.ROUTE_EARPIECE) {
-            devices.add(DEVICE_EARPIECE);
-        }
-        if ((supportedRouteMask & android.telecom.CallAudioState.ROUTE_BLUETOOTH)
-                == android.telecom.CallAudioState.ROUTE_BLUETOOTH) {
-            devices.add(DEVICE_BLUETOOTH);
-        }
-        if ((supportedRouteMask & android.telecom.CallAudioState.ROUTE_SPEAKER)
-                == android.telecom.CallAudioState.ROUTE_SPEAKER) {
-            devices.add(DEVICE_SPEAKER);
-        }
-        if ((supportedRouteMask & android.telecom.CallAudioState.ROUTE_WIRED_HEADSET)
-                == android.telecom.CallAudioState.ROUTE_WIRED_HEADSET) {
-            devices.add(DEVICE_HEADPHONES);
-        }
-        return devices;
-    }
+    private static final boolean supportsConnectionService = Build.VERSION.SDK_INT >= Build.VERSION_CODES.O;
+    private static boolean useConnectionService_ = supportsConnectionService;
 
-    /**
-     * Whether or not the ConnectionService is used for selecting audio devices.
-     */
     static boolean useConnectionService() {
-        return Build.VERSION.SDK_INT >= Build.VERSION_CODES.O;
+        return supportsConnectionService && useConnectionService_;
     }
 
-    /**
-     * Indicator that we have lost audio focus.
-     */
-    private boolean audioFocusLost = false;
-
-    /**
-     * {@link AudioManager} instance used to interact with the Android audio
-     * subsystem.
-     */
-    private final AudioManager audioManager;
-
-    /**
-     * {@link BluetoothHeadsetMonitor} for detecting Bluetooth device changes in
-     * old (< M) Android versions.
-     */
-    private BluetoothHeadsetMonitor bluetoothHeadsetMonitor;
+    private AudioDeviceHandlerInterface audioDeviceHandler;
 
     /**
      * {@link ExecutorService} for running all audio operations on a dedicated
      * thread.
      */
-    private static final ExecutorService executor
-        = Executors.newSingleThreadExecutor();
-
-    /**
-     * {@link Runnable} for running audio device detection the main thread.
-     * This is only used on Android >= M.
-     */
-    private final Runnable onAudioDeviceChangeRunner = new Runnable() {
-        @TargetApi(Build.VERSION_CODES.M)
-        @Override
-        public void run() {
-            Set<String> devices = new HashSet<>();
-            AudioDeviceInfo[] deviceInfos
-                = audioManager.getDevices(AudioManager.GET_DEVICES_ALL);
-
-            for (AudioDeviceInfo info: deviceInfos) {
-                switch (info.getType()) {
-                case AudioDeviceInfo.TYPE_BLUETOOTH_SCO:
-                    devices.add(DEVICE_BLUETOOTH);
-                    break;
-                case AudioDeviceInfo.TYPE_BUILTIN_EARPIECE:
-                    devices.add(DEVICE_EARPIECE);
-                    break;
-                case AudioDeviceInfo.TYPE_BUILTIN_SPEAKER:
-                    devices.add(DEVICE_SPEAKER);
-                    break;
-                case AudioDeviceInfo.TYPE_WIRED_HEADPHONES:
-                case AudioDeviceInfo.TYPE_WIRED_HEADSET:
-                case TYPE_USB_HEADSET:
-                    devices.add(DEVICE_HEADPHONES);
-                    break;
-                }
-            }
-
-            availableDevices = devices;
-            JitsiMeetLogger.i(TAG + " Available audio devices: " +
-                availableDevices.toString());
-
-            // Reset user selection
-            userSelectedDevice = null;
-
-            if (mode != -1) {
-                updateAudioRoute(mode);
-            }
-        }
-    };
+    private static final ExecutorService executor = Executors.newSingleThreadExecutor();
 
     /**
      * Audio mode currently in use.
     /**
      * Audio device types.
      */
-    private static final String DEVICE_BLUETOOTH  = "BLUETOOTH";
-    private static final String DEVICE_EARPIECE   = "EARPIECE";
-    private static final String DEVICE_HEADPHONES = "HEADPHONES";
-    private static final String DEVICE_SPEAKER    = "SPEAKER";
+    static final String DEVICE_BLUETOOTH  = "BLUETOOTH";
+    static final String DEVICE_EARPIECE   = "EARPIECE";
+    static final String DEVICE_HEADPHONES = "HEADPHONES";
+    static final String DEVICE_SPEAKER    = "SPEAKER";
 
     /**
      * Device change event.
      */
     private String selectedDevice;
 
-    /**
-     * Used on API >= 26 to store the most recently reported audio devices.
-     * Makes it easier to compare for a change, because the devices are stored
-     * as a mask in the {@link android.telecom.CallAudioState}. The mask is populated into
-     * the {@link #availableDevices} on each update.
-     */
-    @RequiresApi(api = Build.VERSION_CODES.O)
-    private int supportedRouteMask;
-
     /**
      * User selected device. When null the default is used depending on the
      * mode.
     public AudioModeModule(ReactApplicationContext reactContext) {
         super(reactContext);
 
-        audioManager
-            = (AudioManager)
-                reactContext.getSystemService(Context.AUDIO_SERVICE);
-
-        // Starting Oreo the ConnectionImpl from ConnectionService is used to
-        // detect the available devices.
-        if (!useConnectionService()) {
-            // Setup runtime device change detection.
-            setupAudioRouteChangeDetection();
-
-            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
-                // Do an initial detection on Android >= M.
-                onAudioDeviceChange();
-            } else {
-                // On Android < M, detect if we have an earpiece.
-                PackageManager pm = reactContext.getPackageManager();
-                if (pm.hasSystemFeature(PackageManager.FEATURE_TELEPHONY)) {
-                    availableDevices.add(DEVICE_EARPIECE);
-                }
-
-                // Always assume there is a speaker.
-                availableDevices.add(DEVICE_SPEAKER);
-            }
-        }
+        setAudioDeviceHandler();
     }
 
     /**
         return NAME;
     }
 
-    /**
-     * Helper method to trigger an audio route update when devices change. It
-     * makes sure the operation is performed on the main thread.
-     *
-     * Only used on Android >= M.
-     */
-    void onAudioDeviceChange() {
-        runInAudioThread(onAudioDeviceChangeRunner);
-    }
-
-    /**
-     * Helper method to trigger an audio route update when Bluetooth devices are
-     * connected / disconnected.
-     *
-     * Only used on Android < M. Runs on the main thread.
-     */
-    void onBluetoothDeviceChange() {
-        if (bluetoothHeadsetMonitor != null && bluetoothHeadsetMonitor.isHeadsetAvailable()) {
-            availableDevices.add(DEVICE_BLUETOOTH);
-        } else {
-            availableDevices.remove(DEVICE_BLUETOOTH);
+    private void setAudioDeviceHandler() {
+        if (audioDeviceHandler != null) {
+            audioDeviceHandler.stop();
         }
 
-        if (mode != -1) {
-            updateAudioRoute(mode);
-        }
-    }
-
-    /**
-     * Helper method to trigger an audio route update when a headset is plugged
-     * or unplugged.
-     *
-     * Only used on Android < M.
-     */
-    void onHeadsetDeviceChange() {
-        runInAudioThread(new Runnable() {
-            @Override
-            public void run() {
-                // XXX: isWiredHeadsetOn is not deprecated when used just for
-                // knowing if there is a wired headset connected, regardless of
-                // audio being routed to it.
-                //noinspection deprecation
-                if (audioManager.isWiredHeadsetOn()) {
-                    availableDevices.add(DEVICE_HEADPHONES);
-                } else {
-                    availableDevices.remove(DEVICE_HEADPHONES);
-                }
-
-                if (mode != -1) {
-                    updateAudioRoute(mode);
-                }
-            }
-        });
-    }
-
-    @RequiresApi(api = Build.VERSION_CODES.O)
-    void onCallAudioStateChange(Object callAudioState_) {
-        final android.telecom.CallAudioState callAudioState
-            = (android.telecom.CallAudioState)callAudioState_;
-        runInAudioThread(new Runnable() {
-            @Override
-            public void run() {
-                int newSupportedRoutes = callAudioState.getSupportedRouteMask();
-                boolean audioDevicesChanged
-                        = supportedRouteMask != newSupportedRoutes;
-                if (audioDevicesChanged) {
-                    supportedRouteMask = newSupportedRoutes;
-                    availableDevices = routesToDeviceNames(supportedRouteMask);
-                    JitsiMeetLogger.i(TAG + " Available audio devices: "
-                                  + availableDevices.toString());
-                }
-
-                boolean audioRouteChanged
-                    = audioDeviceToRouteInt(selectedDevice)
-                            != callAudioState.getRoute();
-
-                if (audioRouteChanged || audioDevicesChanged) {
-                    // Reset user selection
-                    userSelectedDevice = null;
-
-                    // If the OS changes the Audio Route or Devices we could have lost
-                    // the selected audio device
-                    selectedDevice = null;
-
-                    if (mode != -1) {
-                        updateAudioRoute(mode);
-                    }
-                }
-            }
-        });
-    }
-
-    /**
-     * {@link AudioManager.OnAudioFocusChangeListener} interface method. Called
-     * when the audio focus of the system is updated.
-     *
-     * @param focusChange - The type of focus change.
-     */
-    @Override
-    public void onAudioFocusChange(int focusChange) {
-        switch (focusChange) {
-        case AudioManager.AUDIOFOCUS_GAIN: {
-            JitsiMeetLogger.d(TAG + " Audio focus gained");
-            // Some other application potentially stole our audio focus
-            // temporarily. Restore our mode.
-            if (audioFocusLost) {
-                updateAudioRoute(mode);
-            }
-            audioFocusLost = false;
-            break;
-        }
-        case AudioManager.AUDIOFOCUS_LOSS:
-        case AudioManager.AUDIOFOCUS_LOSS_TRANSIENT:
-        case AudioManager.AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK: {
-            JitsiMeetLogger.d(TAG + " Audio focus lost");
-            audioFocusLost = true;
-            break;
+        if (useConnectionService()) {
+            audioDeviceHandler = new AudioDeviceHandlerConnectionService();
+        } else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
+            audioDeviceHandler = new AudioDeviceHandlerGeneric();
+        } else {
+            audioDeviceHandler = new AudioDeviceHandlerLegacy();
         }
 
-        }
+        audioDeviceHandler.start(getReactApplicationContext(), this);
     }
 
     /**
      * Helper function to run operations on a dedicated thread.
      * @param runnable
      */
-    public void runInAudioThread(Runnable runnable) {
+    void runInAudioThread(Runnable runnable) {
         executor.execute(runnable);
     }
 
         });
     }
 
-    /**
-     * The API >= 26 way of adjusting the audio route.
-     *
-     * @param audioDevice one of the "DEVICE_" names to set as the audio route.
-     */
-    @RequiresApi(api = Build.VERSION_CODES.O)
-    private void setAudioRoute(String audioDevice) {
-        int newAudioRoute = audioDeviceToRouteInt(audioDevice);
-
-        RNConnectionService.setAudioRoute(newAudioRoute);
-    }
-
-    /**
-     * The API < 26 way of adjusting the audio route.
-     *
-     * @param audioDevice one of the "DEVICE_" names to set as the audio route.
-     */
-    private void setAudioRoutePreO(String audioDevice) {
-        // Turn bluetooth on / off
-        setBluetoothAudioRoute(audioDevice.equals(DEVICE_BLUETOOTH));
-
-        // Turn speaker on / off
-        audioManager.setSpeakerphoneOn(audioDevice.equals(DEVICE_SPEAKER));
-    }
-
-    /**
-     * Helper method to set the output route to a Bluetooth device.
-     *
-     * @param enabled true if Bluetooth should use used, false otherwise.
-     */
-    private void setBluetoothAudioRoute(boolean enabled) {
-        if (enabled) {
-            audioManager.startBluetoothSco();
-            audioManager.setBluetoothScoOn(true);
-        } else {
-            audioManager.setBluetoothScoOn(false);
-            audioManager.stopBluetoothSco();
-        }
-    }
-
     /**
      * Public method to set the current audio mode.
      *
                     AudioModeModule.this.mode = mode;
                     promise.resolve(null);
                 } else {
-                    promise.reject(
-                            "setMode",
-                            "Failed to set audio mode to " + mode);
+                    promise.reject("setMode", "Failed to set audio mode to " + mode);
                 }
             }
         });
     }
 
     /**
-     * Setup the audio route change detection mechanism. We use the
-     * {@link android.media.AudioDeviceCallback} on 23 >= Android API < 26.
-     */
-    private void setupAudioRouteChangeDetection() {
-        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
-            setupAudioRouteChangeDetectionM();
-        } else {
-            setupAudioRouteChangeDetectionPreM();
-        }
-    }
-
-    /**
-     * Audio route change detection mechanism for 23 >= Android API < 26.
-     */
-    @TargetApi(Build.VERSION_CODES.M)
-    private void setupAudioRouteChangeDetectionM() {
-        android.media.AudioDeviceCallback audioDeviceCallback =
-                new android.media.AudioDeviceCallback() {
-                    @Override
-                    public void onAudioDevicesAdded(
-                            AudioDeviceInfo[] addedDevices) {
-                        JitsiMeetLogger.d(TAG + " Audio devices added");
-                        onAudioDeviceChange();
-                    }
-
-                    @Override
-                    public void onAudioDevicesRemoved(
-                            AudioDeviceInfo[] removedDevices) {
-                        JitsiMeetLogger.d(TAG + " Audio devices removed");
-                        onAudioDeviceChange();
-                    }
-                };
-
-        audioManager.registerAudioDeviceCallback(audioDeviceCallback, null);
-    }
-
-    /**
-     * Audio route change detection mechanism for Android API < 23.
+     * Sets whether ConnectionService should be used (if available) for setting the audio mode
+     * or not.
+     *
+     * @param use Boolean indicator of where it should be used or not.
      */
-    private void setupAudioRouteChangeDetectionPreM() {
-        Context context = getReactApplicationContext();
-
-        // Detect changes in wired headset connections.
-        IntentFilter wiredHeadSetFilter = new IntentFilter(ACTION_HEADSET_PLUG);
-        BroadcastReceiver wiredHeadsetReceiver = new BroadcastReceiver() {
-            @Override
-            public void onReceive(Context context, Intent intent) {
-                JitsiMeetLogger.d(TAG + " Wired headset added / removed");
-                onHeadsetDeviceChange();
-            }
-        };
-        context.registerReceiver(wiredHeadsetReceiver, wiredHeadSetFilter);
-
-        // Detect Bluetooth device changes.
-        bluetoothHeadsetMonitor = new BluetoothHeadsetMonitor(this, context);
+    @ReactMethod
+    public void setUseConnectionService(boolean use) {
+        useConnectionService_ = use;
+        setAudioDeviceHandler();
     }
 
     /**
     private boolean updateAudioRoute(int mode) {
         JitsiMeetLogger.i(TAG + " Update audio route for mode: " + mode);
 
+        if (!audioDeviceHandler.setMode(mode)) {
+            return false;
+        }
+
         if (mode == DEFAULT) {
-            if (!useConnectionService()) {
-                audioFocusLost = false;
-                audioManager.setMode(AudioManager.MODE_NORMAL);
-                audioManager.abandonAudioFocus(this);
-                audioManager.setSpeakerphoneOn(false);
-                setBluetoothAudioRoute(false);
-            }
             selectedDevice = null;
             userSelectedDevice = null;
 
             return true;
         }
 
-        if (!useConnectionService()) {
-            audioManager.setMode(AudioManager.MODE_IN_COMMUNICATION);
-            audioManager.setMicrophoneMute(false);
-
-            if (audioManager.requestAudioFocus(
-                    this,
-                    AudioManager.STREAM_VOICE_CALL,
-                    AudioManager.AUDIOFOCUS_GAIN)
-                    == AudioManager.AUDIOFOCUS_REQUEST_FAILED) {
-                JitsiMeetLogger.w(TAG + " Audio focus request failed");
-                return false;
-            }
-        }
-
         boolean bluetoothAvailable = availableDevices.contains(DEVICE_BLUETOOTH);
         boolean headsetAvailable = availableDevices.contains(DEVICE_HEADPHONES);
 
         }
 
         // Consider the user's selection
-        if (userSelectedDevice != null
-                && availableDevices.contains(userSelectedDevice)) {
+        if (userSelectedDevice != null && availableDevices.contains(userSelectedDevice)) {
             audioDevice = userSelectedDevice;
         }
 
         selectedDevice = audioDevice;
         JitsiMeetLogger.i(TAG + " Selected audio device: " + audioDevice);
 
-        if (useConnectionService()) {
-            setAudioRoute(audioDevice);
-        } else {
-            setAudioRoutePreO(audioDevice);
-        }
+        audioDeviceHandler.setAudioRoute(audioDevice);
 
         notifyDevicesChanged();
         return true;
     }
+
+    /**
+     * Gets the currently selected audio device.
+     *
+     * @return The selected audio device.
+     */
+    String getSelectedDevice() {
+        return selectedDevice;
+    }
+
+    /**
+     * Resets the current device selection.
+     */
+    void resetSelectedDevice() {
+        selectedDevice = null;
+        userSelectedDevice = null;
+    }
+
+    /**
+     * Adds a new device to the list of available devices.
+     *
+     * @param device The new device.
+     */
+    void addDevice(String device) {
+        availableDevices.add(device);
+        resetSelectedDevice();
+    }
+
+    /**
+     * Removes a device from the list of available devices.
+     *
+     * @param device The old device to the removed.
+     */
+    void removeDevice(String device) {
+        availableDevices.remove(device);
+        resetSelectedDevice();
+    }
+
+    /**
+     * Replaces the current list of available devices with a new one.
+     *
+     * @param devices The new devices list.
+     */
+    void replaceDevices(Set<String> devices) {
+        availableDevices = devices;
+        resetSelectedDevice();
+    }
+
+    /**
+     * Re-sets the current audio route. Needed when devices changes have happened.
+     */
+    void updateAudioRoute() {
+        if (mode != -1) {
+            updateAudioRoute(mode);
+        }
+    }
+
+    /**
+     * Interface for the modules implementing the actual audio device management.
+     */
+    interface AudioDeviceHandlerInterface {
+        /**
+         * Start detecting audio device changes.
+         * @param context Android {@link Context} where detection should take place.
+         * @param audioModeModule Reference to the main {@link AudioModeModule}.
+         */
+        void start(Context context, AudioModeModule audioModeModule);
+
+        /**
+         * Stop audio device detection.
+         */
+        void stop();
+
+        /**
+         * Set the appropriate route for the given audio device.
+         *
+         * @param device Audio device for which the route must be set.
+         */
+        void setAudioRoute(String device);
+
+        /**
+         * Set the given audio mode.
+         *
+         * @param mode The new audio mode to be used.
+         * @return Whether the operation was successful or not.
+         */
+        boolean setMode(int mode);
+    }
 }

android/sdk/src/main/java/org/jitsi/meet/sdk/BluetoothHeadsetMonitor.java

 /*
- * Copyright @ 2017-present Atlassian Pty Ltd
+ * Copyright @ 2017-present 8x8, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * about device changes when this occurs.
  */
 class BluetoothHeadsetMonitor {
+    private final static String TAG = BluetoothHeadsetMonitor.class.getSimpleName();
+
     /**
-     * {@link AudioModeModule} where this monitor reports.
+     * The {@link Context} in which this module executes.
      */
-    private final AudioModeModule audioModeModule;
+    private final Context context;
 
     /**
-     * The {@link Context} in which {@link #audioModeModule} executes.
+     * Reference to the {@link BluetoothAdapter} object, used to access Bluetooth functionality.
      */
-    private final Context context;
+    private BluetoothAdapter adapter;
 
     /**
      * Reference to a proxy object which allows us to query connected devices.
     private BluetoothHeadset headset;
 
     /**
-     * Flag indicating if there are any Bluetooth headset devices currently
-     * available.
+     * receiver registered for receiving Bluetooth connection state changes.
      */
-    private boolean headsetAvailable = false;
+    private BroadcastReceiver receiver;
 
     /**
-     * Helper for running Bluetooth operations on the main thread.
+     * Listener for receiving Bluetooth device change events.
      */
-    private final Runnable updateDevicesRunnable
-        = new Runnable() {
-            @Override
-            public void run() {
-                headsetAvailable
-                    = (headset != null)
-                        && !headset.getConnectedDevices().isEmpty();
-                audioModeModule.onBluetoothDeviceChange();
-            }
-        };
+    private Listener listener;
 
-    public BluetoothHeadsetMonitor(
-            AudioModeModule audioModeModule,
-            Context context) {
-        this.audioModeModule = audioModeModule;
+    public BluetoothHeadsetMonitor(Context context, Listener listener) {
         this.context = context;
-
-        AudioManager audioManager
-            = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
-
-        if (!audioManager.isBluetoothScoAvailableOffCall()) {
-            JitsiMeetLogger.w(AudioModeModule.TAG + " Bluetooth SCO is not available");
-            return;
-        }
-
-        if (getBluetoothHeadsetProfileProxy()) {
-            registerBluetoothReceiver();
-
-            // Initial detection.
-            updateDevices();
-        }
+        this.listener = listener;
     }
 
     private boolean getBluetoothHeadsetProfileProxy() {
-        BluetoothAdapter adapter = BluetoothAdapter.getDefaultAdapter();
+        adapter = BluetoothAdapter.getDefaultAdapter();
 
         if (adapter == null) {
-            JitsiMeetLogger.w(AudioModeModule.TAG + " Device doesn't support Bluetooth");
+            JitsiMeetLogger.w(TAG + " Device doesn't support Bluetooth");
             return false;
         }
 
         BluetoothProfile.ServiceListener listener
             = new BluetoothProfile.ServiceListener() {
                 @Override
-                public void onServiceConnected(
-                        int profile,
-                        BluetoothProfile proxy) {
+                public void onServiceConnected(int profile, BluetoothProfile proxy) {
                     if (profile == BluetoothProfile.HEADSET) {
                         headset = (BluetoothHeadset) proxy;
                         updateDevices();
                 }
             };
 
-        return
-            adapter.getProfileProxy(
-                    context,
-                    listener,
-                    BluetoothProfile.HEADSET);
-    }
-
-    /**
-     * Returns the current headset availability.
-     *
-     * @return {@code true} if there is a Bluetooth headset connected;
-     * {@code false}, otherwise.
-     */
-    public boolean isHeadsetAvailable() {
-        return headsetAvailable;
+        return adapter.getProfileProxy(context, listener, BluetoothProfile.HEADSET);
     }
 
     private void onBluetoothReceiverReceive(Context context, Intent intent) {
             switch (state) {
             case BluetoothHeadset.STATE_CONNECTED:
             case BluetoothHeadset.STATE_DISCONNECTED:
-                JitsiMeetLogger.d(AudioModeModule.TAG + " BT headset connection state changed: " + state);
+                JitsiMeetLogger.d(TAG + " BT headset connection state changed: " + state);
                 updateDevices();
                 break;
             }
             // XXX: This action will be fired when the connection established
             // with a Bluetooth headset (called a SCO connection) changes state.
             // When the SCO connection is active we route audio to it.
-            int state
-                = intent.getIntExtra(AudioManager.EXTRA_SCO_AUDIO_STATE, -99);
+            int state = intent.getIntExtra(AudioManager.EXTRA_SCO_AUDIO_STATE, -99);
 
             switch (state) {
             case AudioManager.SCO_AUDIO_STATE_CONNECTED:
             case AudioManager.SCO_AUDIO_STATE_DISCONNECTED:
-                JitsiMeetLogger.d(AudioModeModule.TAG + " BT SCO connection state changed: " + state);
+                JitsiMeetLogger.d(TAG + " BT SCO connection state changed: " + state);
                 updateDevices();
                 break;
             }
     }
 
     private void registerBluetoothReceiver() {
-        BroadcastReceiver receiver = new BroadcastReceiver() {
+        receiver = new BroadcastReceiver() {
             @Override
             public void onReceive(Context context, Intent intent) {
                 onBluetoothReceiverReceive(context, intent);
             }
         };
-        IntentFilter filter = new IntentFilter();
 
+        IntentFilter filter = new IntentFilter();
         filter.addAction(AudioManager.ACTION_SCO_AUDIO_STATE_UPDATED);
         filter.addAction(BluetoothHeadset.ACTION_CONNECTION_STATE_CHANGED);
+
         context.registerReceiver(receiver, filter);
     }
 
     /**
      * Detects if there are new devices connected / disconnected and fires the
-     * {@link AudioModeModule#onAudioDeviceChange()} callback.
+     * {@link Listener} registered event.
      */
     private void updateDevices() {
-        audioModeModule.runInAudioThread(updateDevicesRunnable);
+        boolean headsetAvailable = (headset != null) && !headset.getConnectedDevices().isEmpty();
+        listener.onBluetoothDeviceChange(headsetAvailable);
+    }
+
+    public void start() {
+        AudioManager audioManager = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
+
+        if (!audioManager.isBluetoothScoAvailableOffCall()) {
+            JitsiMeetLogger.w(TAG + " Bluetooth SCO is not available");
+            return;
+        }
+
+        if (!getBluetoothHeadsetProfileProxy()) {
+            JitsiMeetLogger.w(TAG + " Couldn't get BT profile proxy");
+            return;
+        }
+
+        registerBluetoothReceiver();
+
+        // Initial detection.
+        updateDevices();
+    }
+
+    public void stop() {
+        if (receiver != null) {
+            context.unregisterReceiver(receiver);
+        }
+
+        if (adapter != null && headset != null) {
+            adapter.closeProfileProxy(BluetoothProfile.HEADSET, headset);
+        }
+
+        receiver = null;
+        headset = null;
+        adapter = null;
+    }
+
+    interface Listener {
+        void onBluetoothDeviceChange(boolean deviceAvailable);
     }
 }

android/sdk/src/main/java/org/jitsi/meet/sdk/ConnectionService.java

         @Override
         public void onCallAudioStateChanged(CallAudioState state) {
             JitsiMeetLogger.d(TAG + " onCallAudioStateChanged: " + state);
-            AudioModeModule audioModeModule
-                    = ReactInstanceManagerHolder
-                    .getNativeModule(AudioModeModule.class);
-            if (audioModeModule != null) {
-                audioModeModule.onCallAudioStateChange(state);
+            RNConnectionService module = ReactInstanceManagerHolder.getNativeModule(RNConnectionService.class);
+            if (module != null) {
+                module.onCallAudioStateChange(state);
             }
         }
 

android/sdk/src/main/java/org/jitsi/meet/sdk/RNConnectionService.java

  */
 @RequiresApi(api = Build.VERSION_CODES.O)
 @ReactModule(name = RNConnectionService.NAME)
-class RNConnectionService
-    extends ReactContextBaseJavaModule {
+class RNConnectionService extends ReactContextBaseJavaModule {
 
     public static final String NAME = "ConnectionService";
 
     private static final String TAG = ConnectionService.TAG;
 
+    /**
+     * Handler for dealing with call state changes. We are acting as a proxy between ConnectionService
+     * and other modules such as {@link AudioModeModule}.
+     */
+    private CallAudioStateListener callAudioStateListener;
+
     /**
      * Sets the audio route on all existing {@link android.telecom.Connection}s
      *
     public void updateCall(String callUUID, ReadableMap callState) {
         ConnectionService.updateCall(callUUID, callState);
     }
+
+    public CallAudioStateListener getCallAudioStateListener() {
+        return callAudioStateListener;
+    }
+
+    public void setCallAudioStateListener(CallAudioStateListener callAudioStateListener) {
+        this.callAudioStateListener = callAudioStateListener;
+    }
+
+    /**
+     * Handler for call state changes. {@code ConnectionServiceImpl} will call this handler when the
+     * call audio state changes.
+     *
+     * @param callAudioState The current call's audio state.
+     */
+    void onCallAudioStateChange(android.telecom.CallAudioState callAudioState) {
+        if (callAudioStateListener != null) {
+            callAudioStateListener.onCallAudioStateChange(callAudioState);
+        }
+    }
+
+    interface CallAudioStateListener {
+        void onCallAudioStateChange(android.telecom.CallAudioState callAudioState);
+    }
 }