WebRTCAudio

public void updateAudioDeviceState() {
    ThreadUtils.checkIsOnMainThread();
//    Log.d(TAG, "--- updateAudioDeviceState: "
//        + "wired headset=" + hasWiredHeadset + ", "
//        + "BT state=" + bluetoothManager.getState());
    Log.d(TAG, "Device status: "
        + "available=" + audioDevices + ", "
        + "selected=" + selectedAudioDevice + ", "
        + "user selected=" + userSelectedAudioDevice);

    // Check if any Bluetooth headset is connected. The internal BT state will
    // change accordingly.
    // TODO(henrika): perhaps wrap required state into BT manager.
//    if (bluetoothManager.getState() == AppRTCBluetoothManager.State.HEADSET_AVAILABLE
//        || bluetoothManager.getState() == AppRTCBluetoothManager.State.HEADSET_UNAVAILABLE
//        || bluetoothManager.getState() == AppRTCBluetoothManager.State.SCO_DISCONNECTING) {
//      bluetoothManager.updateDevice();
//    }

    // Update the set of available audio devices.
    Set<AudioDevice> newAudioDevices = new HashSet<>();

//    if (bluetoothManager.getState() == AppRTCBluetoothManager.State.SCO_CONNECTED
//        || bluetoothManager.getState() == AppRTCBluetoothManager.State.SCO_CONNECTING
//        || bluetoothManager.getState() == AppRTCBluetoothManager.State.HEADSET_AVAILABLE) {
//      newAudioDevices.add(AudioDevice.BLUETOOTH);
//    }

    if (hasWiredHeadset) {
      // If a wired headset is connected, then it is the only possible option.
      newAudioDevices.add(AudioDevice.WIRED_HEADSET);
    } else {
      // No wired headset, hence the audio-device list can contain speaker
      // phone (on a tablet), or speaker phone and earpiece (on mobile phone).
      newAudioDevices.add(AudioDevice.SPEAKER_PHONE);
      if (hasEarpiece()) {
        newAudioDevices.add(AudioDevice.EARPIECE);
      }
    }
    // Store state which is set to true if the device list has changed.
    boolean audioDeviceSetUpdated = !audioDevices.equals(newAudioDevices);
    // Update the existing audio device set.
    audioDevices = newAudioDevices;
    // Correct user selected audio devices if needed.
//    if (bluetoothManager.getState() == AppRTCBluetoothManager.State.HEADSET_UNAVAILABLE
//        && userSelectedAudioDevice == AudioDevice.BLUETOOTH) {
//      // If BT is not available, it can't be the user selection.
//      userSelectedAudioDevice = AudioDevice.NONE;
//    }
    if (hasWiredHeadset && userSelectedAudioDevice == AudioDevice.SPEAKER_PHONE) {
      // If user selected speaker phone, but then plugged wired headset then make
      // wired headset as user selected device.
      userSelectedAudioDevice = AudioDevice.WIRED_HEADSET;
    }
    if (!hasWiredHeadset && userSelectedAudioDevice == AudioDevice.WIRED_HEADSET) {
      // If user selected wired headset, but then unplugged wired headset then make
      // speaker phone as user selected device.
      userSelectedAudioDevice = AudioDevice.SPEAKER_PHONE;
    }

    // Need to start Bluetooth if it is available and user either selected it explicitly or
    // user did not select any output device.
//    boolean needBluetoothAudioStart =
//        bluetoothManager.getState() == AppRTCBluetoothManager.State.HEADSET_AVAILABLE
//            && (userSelectedAudioDevice == AudioDevice.NONE
//            || userSelectedAudioDevice == AudioDevice.BLUETOOTH);

    // Need to stop Bluetooth audio if user selected different device and
    // Bluetooth SCO connection is established or in the process.
//    boolean needBluetoothAudioStop =
//        (bluetoothManager.getState() == AppRTCBluetoothManager.State.SCO_CONNECTED
//            || bluetoothManager.getState() == AppRTCBluetoothManager.State.SCO_CONNECTING)
//            && (userSelectedAudioDevice != AudioDevice.NONE
//            && userSelectedAudioDevice != AudioDevice.BLUETOOTH);

//    if (bluetoothManager.getState() == AppRTCBluetoothManager.State.HEADSET_AVAILABLE
//        || bluetoothManager.getState() == AppRTCBluetoothManager.State.SCO_CONNECTING
//        || bluetoothManager.getState() == AppRTCBluetoothManager.State.SCO_CONNECTED) {
//      Log.d(TAG, "Need BT audio: start=" + needBluetoothAudioStart + ", "
//          + "stop=" + needBluetoothAudioStop + ", "
//          + "BT state=" + bluetoothManager.getState());
//    }

    // Start or stop Bluetooth SCO connection given states set earlier.
//    if (needBluetoothAudioStop) {
//      bluetoothManager.stopScoAudio();
//      bluetoothManager.updateDevice();
//    }

//    if (needBluetoothAudioStart && !needBluetoothAudioStop) {
      // Attempt to start Bluetooth SCO audio (takes a few second to start).
//      if (!bluetoothManager.startScoAudio()) {
//        // Remove BLUETOOTH from list of available devices since SCO failed.
//        audioDevices.remove(AudioDevice.BLUETOOTH);
//        audioDeviceSetUpdated = true;
//      }
//    }

    // Update selected audio device.
    final AudioDevice newAudioDevice;

//    if (bluetoothManager.getState() == AppRTCBluetoothManager.State.SCO_CONNECTED) {
//      // If a Bluetooth is connected, then it should be used as output audio
//      // device. Note that it is not sufficient that a headset is available;
//      // an active SCO channel must also be up and running.
//      newAudioDevice = AudioDevice.BLUETOOTH;
//    } else
    if (hasWiredHeadset) {
      // If a wired headset is connected, but Bluetooth is not, then wired headset is used as
      // audio device.
      newAudioDevice = AudioDevice.WIRED_HEADSET;
    } else {
      // No wired headset and no Bluetooth, hence the audio-device list can contain speaker
      // phone (on a tablet), or speaker phone and earpiece (on mobile phone).
      // |defaultAudioDevice| contains either AudioDevice.SPEAKER_PHONE or AudioDevice.EARPIECE
      // depending on the user's selection.
      newAudioDevice = defaultAudioDevice;
    }
    // Switch to new device but only if there has been any changes.
    if (newAudioDevice != selectedAudioDevice || audioDeviceSetUpdated) {
      // Do the required device switch.
      setAudioDeviceInternal(newAudioDevice);
      Log.d(TAG, "New device status: "
          + "available=" + audioDevices + ", "
          + "selected=" + newAudioDevice);
      if (audioManagerEvents != null) {
        // Notify a listening client that audio device has been changed.
        audioManagerEvents.onAudioDeviceChanged(selectedAudioDevice, audioDevices);
      }
    }
    Log.d(TAG, "--- updateAudioDeviceState done");
  }