diff --git a/media/libmediaplayerservice/MediaPlayerFactory.cpp b/media/libmediaplayerservice/MediaPlayerFactory.cpp
index cd0a003..686c059 100644
--- a/media/libmediaplayerservice/MediaPlayerFactory.cpp
+++ b/media/libmediaplayerservice/MediaPlayerFactory.cpp
@@ -126,8 +126,7 @@
 
 sp<MediaPlayerBase> MediaPlayerFactory::createPlayer(
         player_type playerType,
-        const wp<IMediaPlayer> &client,
-        notify_callback_f notifyFunc,
+        const sp<MediaPlayerBase::Listener> &listener,
         pid_t pid) {
     sp<MediaPlayerBase> p;
     IFactory* factory;
@@ -152,7 +151,7 @@
 
     init_result = p->initCheck();
     if (init_result == NO_ERROR) {
-        p->setNotifyCallback(client, notifyFunc);
+        p->setNotifyCallback(listener);
     } else {
         ALOGE("Failed to create player object of type %d, initCheck failed"
               " (res = %d)", playerType, init_result);
diff --git a/media/libmediaplayerservice/MediaPlayerFactory.h b/media/libmediaplayerservice/MediaPlayerFactory.h
index 6aedeb2..e88700c 100644
--- a/media/libmediaplayerservice/MediaPlayerFactory.h
+++ b/media/libmediaplayerservice/MediaPlayerFactory.h
@@ -65,8 +65,7 @@
                                      const sp<DataSource> &source);
 
     static sp<MediaPlayerBase> createPlayer(player_type playerType,
-                                            const wp<IMediaPlayer> &client,
-                                            notify_callback_f notifyFunc,
+                                            const sp<MediaPlayerBase::Listener> &listener,
                                             pid_t pid);
 
     static void registerBuiltinFactories();
diff --git a/media/libmediaplayerservice/MediaPlayerService.cpp b/media/libmediaplayerservice/MediaPlayerService.cpp
index 6e17b8d..3445469 100644
--- a/media/libmediaplayerservice/MediaPlayerService.cpp
+++ b/media/libmediaplayerservice/MediaPlayerService.cpp
@@ -590,10 +590,11 @@
     mUid = uid;
     mRetransmitEndpointValid = false;
     mAudioAttributes = NULL;
+    mListener = new Listener(this);
 
 #if CALLBACK_ANTAGONIZER
     ALOGD("create Antagonizer");
-    mAntagonizer = new Antagonizer(notify, this);
+    mAntagonizer = new Antagonizer(mListener);
 #endif
 }
 
@@ -627,7 +628,7 @@
     // and reset the player. We assume the player will serialize
     // access to itself if necessary.
     if (p != 0) {
-        p->setNotifyCallback(0, 0);
+        p->setNotifyCallback(0);
 #if CALLBACK_ANTAGONIZER
         ALOGD("kill Antagonizer");
         mAntagonizer->kill();
@@ -652,7 +653,7 @@
         p.clear();
     }
     if (p == NULL) {
-        p = MediaPlayerFactory::createPlayer(playerType, this, notify, mPid);
+        p = MediaPlayerFactory::createPlayer(playerType, mListener, mPid);
     }
 
     if (p != NULL) {
@@ -1430,25 +1431,19 @@
 }
 
 void MediaPlayerService::Client::notify(
-        const wp<IMediaPlayer> &listener, int msg, int ext1, int ext2, const Parcel *obj)
+        int msg, int ext1, int ext2, const Parcel *obj)
 {
-    sp<IMediaPlayer> spListener = listener.promote();
-    if (spListener == NULL) {
-        return;
-    }
-    Client* client = static_cast<Client*>(spListener.get());
-
     sp<IMediaPlayerClient> c;
     sp<Client> nextClient;
     status_t errStartNext = NO_ERROR;
     {
-        Mutex::Autolock l(client->mLock);
-        c = client->mClient;
-        if (msg == MEDIA_PLAYBACK_COMPLETE && client->mNextClient != NULL) {
-            nextClient = client->mNextClient;
+        Mutex::Autolock l(mLock);
+        c = mClient;
+        if (msg == MEDIA_PLAYBACK_COMPLETE && mNextClient != NULL) {
+            nextClient = mNextClient;
 
-            if (client->mAudioOutput != NULL)
-                client->mAudioOutput->switchToNextOutput();
+            if (mAudioOutput != NULL)
+                mAudioOutput->switchToNextOutput();
 
             errStartNext = nextClient->start();
         }
@@ -1474,17 +1469,17 @@
         MEDIA_INFO_METADATA_UPDATE == ext1) {
         const media::Metadata::Type metadata_type = ext2;
 
-        if(client->shouldDropMetadata(metadata_type)) {
+        if(shouldDropMetadata(metadata_type)) {
             return;
         }
 
         // Update the list of metadata that have changed. getMetadata
         // also access mMetadataUpdated and clears it.
-        client->addNewMetadataUpdate(metadata_type);
+        addNewMetadataUpdate(metadata_type);
     }
 
     if (c != NULL) {
-        ALOGV("[%d] notify (%p, %d, %d, %d)", client->mConnId, spListener.get(), msg, ext1, ext2);
+        ALOGV("[%d] notify (%d, %d, %d)", mConnId, msg, ext1, ext2);
         c->notify(msg, ext1, ext2, obj);
     }
 }
@@ -1542,8 +1537,8 @@
 #if CALLBACK_ANTAGONIZER
 const int Antagonizer::interval = 10000; // 10 msecs
 
-Antagonizer::Antagonizer(notify_callback_f cb, const wp<IMediaPlayer> &client) :
-    mExit(false), mActive(false), mClient(client), mCb(cb)
+Antagonizer::Antagonizer(const sp<MediaPlayerBase::Listener> &listener) :
+    mExit(false), mActive(false), mListener(listener)
 {
     createThread(callbackThread, this);
 }
@@ -1563,7 +1558,7 @@
     while (!p->mExit) {
         if (p->mActive) {
             ALOGV("send event");
-            p->mCb(p->mClient, 0, 0, 0);
+            p->mListener->notify(0, 0, 0, 0);
         }
         usleep(interval);
     }
diff --git a/media/libmediaplayerservice/MediaPlayerService.h b/media/libmediaplayerservice/MediaPlayerService.h
index f043f32..34e5e2a 100644
--- a/media/libmediaplayerservice/MediaPlayerService.h
+++ b/media/libmediaplayerservice/MediaPlayerService.h
@@ -51,7 +51,7 @@
 #if CALLBACK_ANTAGONIZER
 class Antagonizer {
 public:
-    Antagonizer(notify_callback_f cb, const wp<IMediaPlayer> &client);
+    Antagonizer(const sp<MediaPlayerBase::Listener> &listener);
     void start() { mActive = true; }
     void stop() { mActive = false; }
     void kill();
@@ -59,12 +59,11 @@
     static const int interval;
     Antagonizer();
     static int callbackThread(void* cookie);
-    Mutex               mLock;
-    Condition           mCondition;
-    bool                mExit;
-    bool                mActive;
-    wp<IMediaPlayer>    mClient;
-    notify_callback_f   mCb;
+    Mutex                         mLock;
+    Condition                     mCondition;
+    bool                          mExit;
+    bool                          mActive;
+    sp<MediaPlayerBase::Listener> mListener;
 };
 #endif
 
@@ -215,7 +214,6 @@
 
     }; // AudioOutput
 
-
 public:
     static  void                instantiate();
 
@@ -365,8 +363,7 @@
         status_t                setDataSource_post(const sp<MediaPlayerBase>& p,
                                                    status_t status);
 
-        static  void            notify(const wp<IMediaPlayer> &cookie, int msg,
-                                       int ext1, int ext2, const Parcel *obj);
+                void            notify(int msg, int ext1, int ext2, const Parcel *obj);
 
                 pid_t           pid() const { return mPid; }
         virtual status_t        dump(int fd, const Vector<String16>& args);
@@ -437,23 +434,38 @@
 
         status_t setAudioAttributes_l(const Parcel &request);
 
-        mutable     Mutex                       mLock;
-                    sp<MediaPlayerBase>         mPlayer;
-                    sp<MediaPlayerService>      mService;
-                    sp<IMediaPlayerClient>      mClient;
-                    sp<AudioOutput>             mAudioOutput;
-                    pid_t                       mPid;
-                    status_t                    mStatus;
-                    bool                        mLoop;
-                    int32_t                     mConnId;
-                    audio_session_t             mAudioSessionId;
-                    audio_attributes_t *        mAudioAttributes;
-                    uid_t                       mUid;
-                    sp<ANativeWindow>           mConnectedWindow;
-                    sp<IBinder>                 mConnectedWindowBinder;
-                    struct sockaddr_in          mRetransmitEndpoint;
-                    bool                        mRetransmitEndpointValid;
-                    sp<Client>                  mNextClient;
+        class Listener : public MediaPlayerBase::Listener {
+        public:
+            Listener(const wp<Client> &client) : mClient(client) {}
+            virtual ~Listener() {}
+            virtual void notify(int msg, int ext1, int ext2, const Parcel *obj) {
+                sp<Client> client = mClient.promote();
+                if (client != NULL) {
+                    client->notify(msg, ext1, ext2, obj);
+                }
+            }
+        private:
+            wp<Client> mClient;
+        };
+
+        mutable     Mutex                         mLock;
+                    sp<MediaPlayerBase>           mPlayer;
+                    sp<MediaPlayerService>        mService;
+                    sp<IMediaPlayerClient>        mClient;
+                    sp<AudioOutput>               mAudioOutput;
+                    pid_t                         mPid;
+                    status_t                      mStatus;
+                    bool                          mLoop;
+                    int32_t                       mConnId;
+                    audio_session_t               mAudioSessionId;
+                    audio_attributes_t *          mAudioAttributes;
+                    uid_t                         mUid;
+                    sp<ANativeWindow>             mConnectedWindow;
+                    sp<IBinder>                   mConnectedWindowBinder;
+                    struct sockaddr_in            mRetransmitEndpoint;
+                    bool                          mRetransmitEndpointValid;
+                    sp<Client>                    mNextClient;
+                    sp<MediaPlayerBase::Listener> mListener;
 
         // Metadata filters.
         media::Metadata::Filter mMetadataAllow;  // protected by mLock
@@ -468,7 +480,7 @@
         sp<ServiceDeathNotifier> mExtractorDeathListener;
         sp<ServiceDeathNotifier> mCodecDeathListener;
 #if CALLBACK_ANTAGONIZER
-                    Antagonizer*                mAntagonizer;
+                    Antagonizer*                  mAntagonizer;
 #endif
     }; // Client
 
diff --git a/media/libmediaplayerservice/include/MediaPlayerInterface.h b/media/libmediaplayerservice/include/MediaPlayerInterface.h
index 34f1fe4..6d02cce 100644
--- a/media/libmediaplayerservice/include/MediaPlayerInterface.h
+++ b/media/libmediaplayerservice/include/MediaPlayerInterface.h
@@ -66,14 +66,17 @@
 // duration below which we do not allow deep audio buffering
 #define AUDIO_SINK_MIN_DEEP_BUFFER_DURATION_US 5000000
 
-// callback mechanism for passing messages to MediaPlayer object
-typedef void (*notify_callback_f)(const wp<IMediaPlayer> &listener,
-        int msg, int ext1, int ext2, const Parcel *obj);
-
 // abstract base class - use MediaPlayerInterface
 class MediaPlayerBase : public RefBase
 {
 public:
+    // callback mechanism for passing messages to MediaPlayer object
+    class Listener : public RefBase {
+    public:
+        virtual void notify(int msg, int ext1, int ext2, const Parcel *obj) = 0;
+        virtual ~Listener() {}
+    };
+
     // AudioSink: abstraction layer for audio output
     class AudioSink : public RefBase {
     public:
@@ -152,7 +155,7 @@
         virtual sp<VolumeShaper::State> getVolumeShaperState(int id);
     };
 
-                        MediaPlayerBase() : mClient(0), mNotify(0) {}
+                        MediaPlayerBase() {}
     virtual             ~MediaPlayerBase() {}
     virtual status_t    initCheck() = 0;
     virtual bool        hardwareOutput() = 0;
@@ -263,22 +266,22 @@
     };
 
     void        setNotifyCallback(
-            const wp<IMediaPlayer> &client, notify_callback_f notifyFunc) {
+            const sp<Listener> &listener) {
         Mutex::Autolock autoLock(mNotifyLock);
-        mClient = client; mNotify = notifyFunc;
+        mListener = listener;
     }
 
     void        sendEvent(int msg, int ext1=0, int ext2=0,
                           const Parcel *obj=NULL) {
-        notify_callback_f notifyCB;
-        wp<IMediaPlayer> client;
+        sp<Listener> listener;
         {
             Mutex::Autolock autoLock(mNotifyLock);
-            notifyCB = mNotify;
-            client = mClient;
+            listener = mListener;
         }
 
-        if (notifyCB) notifyCB(client, msg, ext1, ext2, obj);
+        if (listener != NULL) {
+            listener->notify(msg, ext1, ext2, obj);
+        }
     }
 
     virtual status_t dump(int /* fd */, const Vector<String16>& /* args */) const {
@@ -297,8 +300,7 @@
     friend class MediaPlayerService;
 
     Mutex               mNotifyLock;
-    wp<IMediaPlayer>    mClient;
-    notify_callback_f   mNotify;
+    sp<Listener>        mListener;
 };
 
 // Implement this class for media players that use the AudioFlinger software mixer