AudioFocusChangeListener cannot listen

Question

I encounter a problem using the AudioFocusChangeListener, but still cannot listen to the audio focus change. Could someone help me find the reasons? Here is what I do:

1. In my FM app, when FM starts in startFM, I place requestAudioFocus() to get resources:

   int result = mAudioManager.requestAudioFocus(mAudioFocusListener, AudioManager.STREAM_FM,AudioManager.AUDIOFOCUS_GAIN_TRANSIENT);
   if (result == AudioManager.AUDIOFOCUS_REQUEST_GRANTED) {
       Log.d(LOGTAG, "Successfull to request audioFocus listener");
   } else {
       Log.d(LOGTAG, "Failure to request focus listener");
   }
   

2. When quitting the App in onDestroy(), I used abandonAudioFocus() to release resouces.

3. The member variable mAudioFocusListener is as follows:

   private OnAudioFocusChangeListener mAudioFocusListener = new OnAudioFocusChangeListener() {
   public void onAudioFocusChange(int focusChange) {
       switch (focusChange) {
           case AudioManager.AUDIOFOCUS_LOSS:
               Log.v(LOGTAG, "AudioFocus: received AUDIOFOCUS_LOSS, turning FM off");
   
               if (isFmOn()) {
                   fmOff();
               }
               break;
           case AudioManager.AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK:
               Log.v(LOGTAG, "AudioFocus: received AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK");
   
               if (isFmOn()) {
                   Log.d(LOGTAG, "AudioFocus: FM is on, turning off");
                   mute();
                   stopFM();
               }
               break;
           case AudioManager.AUDIOFOCUS_LOSS_TRANSIENT:
               Log.v(LOGTAG, "AudioFocus: received AUDIOFOCUS_LOSS_TRANSIENT");
   
               if (isFmOn()) {
                   Log.d(LOGTAG, "AudioFocus: FM is on, turning off");
                   mute();
                   stopFM();
               }
               break;
           case AudioManager.AUDIOFOCUS_GAIN:
               Log.v(LOGTAG, "AudioFocus: received AUDIOFOCUS_GAIN");
   
               if (isFmOn()) {
                   Log.d(LOGTAG, "AudioFocus: FM is off, turning back on");
                   unMute();
                   startFM();
               }
               break;
           default:
               Log.e(LOGTAG, "Unknown audio focus change code " + focusChange);
       }
   }
   };
   

4. According to the log, it prints "Successfull to request audioFocus listener", but doesn't print any AudioForcus change log when alarm is on or other audio-changed events. Could anyone figure out what is wrong with it?

5. On the other hand, I place log in AudioService.java and AudioManger.java, where in AudioService.java, requestAudioFocus(): if (!mFocusStack.empty() && (mFocusStack.peek().mFocusDispatcher != null)) {

          try {  
   
               mFocusStack.peek().mFocusDispatcher.dispatchAudioFocusChange(  
   
                        -1 * focusChangeHint, // loss and gain codes are inverse of each other  
   
                        mFocusStack.peek().mClientId);  // This doesn't excute
   
           } catch (RemoteException e) {  
   
               Log.e(TAG, " Failure to signal loss of focus due to "+ e);  
               e.printStackTrace();  
   
            }  
   
        }  
   

6. in AudioManager.java, Here doesn't excute either: private IAudioFocusDispatcher mAudioFocusDispatcher = new IAudioFocusDispatcher.Stub() {

   public void dispatchAudioFocusChange(int focusChange, String id) {  
   
       Message m = mAudioFocusEventHandlerDelegate.getHandler().obtainMessage(focusChange, id);  
   
        mAudioFocusEventHandlerDelegate.getHandler().sendMessage(m);  
   
    }  
   

That's all my question. Could anybody tell me why this listener cannot listen to alarm events and other audiofocus-changed events? By the way, how could I successfully listen to the events? Maybe I missed some step or used a incorrect way? Many thanks.

Answer 1

DeerCoder,

I believe that if you are requesting the audio focus for the type AudioManager.STREAM_MUSIC, you would only receive events affecting this specific audio stream.

mAudioManager.requestAudioFocus(new MyService(), AudioManager.STREAM_MUSIC, AudioManager.AUDIOFOCUS_GAIN);

The alarms and notifications are managed on separate audio stream such as AudioManager.STREAM_NOTIFICATION, AudioManager.STREAM_ALARM, AudioManager.STREAM_RING, etc...

Answer 2

Try this:

private class MyService extends Service implements AudioManager.OnAudioFocusChangeListener {
    public void onAudioFocusChange(int focusChange) {
        switch (focusChange) {
            case AudioManager.AUDIOFOCUS_LOSS:
                Log.e(TAG, "AudioFocus: received AUDIOFOCUS_LOSS, turning FM off");
                break;
            case AudioManager.AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK:
                Log.e(TAG, "AudioFocus: received AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK");
                break;
            case AudioManager.AUDIOFOCUS_LOSS_TRANSIENT:
                Log.e(TAG, "AudioFocus: received AUDIOFOCUS_LOSS_TRANSIENT");
                break;
            case AudioManager.AUDIOFOCUS_GAIN:
                Log.v(TAG, "AudioFocus: received AUDIOFOCUS_GAIN");
                break;
            default:
                Log.e(TAG, "Unknown audio focus change code " + focusChange);
        }
    }

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

and...

mAudioManager.requestAudioFocus(new MyService(), AudioManager.STREAM_MUSIC, AudioManager.AUDIOFOCUS_GAIN);

Its works for me.