diff --git a/include/media/IMediaPlayerService.h b/include/media/IMediaPlayerService.h
index cce9129..7956788 100644
--- a/include/media/IMediaPlayerService.h
+++ b/include/media/IMediaPlayerService.h
@@ -55,17 +55,25 @@
     virtual sp<IMemory>         decode(int fd, int64_t offset, int64_t length, uint32_t *pSampleRate, int* pNumChannels, int* pFormat) = 0;
     virtual sp<IOMX>            getOMX() = 0;
 
-    // codecs usage tracking for the battery app
+    // codecs and audio devices usage tracking for the battery app
     enum BatteryDataBits {
         // tracking audio codec
-        kBatteryDataTrackAudio          = 1,
+        kBatteryDataTrackAudio          = 0x1,
         // tracking video codec
-        kBatteryDataTrackVideo          = 2,
+        kBatteryDataTrackVideo          = 0x2,
         // codec is started, otherwise codec is paused
-        kBatteryDataCodecStarted        = 4,
+        kBatteryDataCodecStarted        = 0x4,
         // tracking decoder (for media player),
         // otherwise tracking encoder (for media recorder)
-        kBatteryDataTrackDecoder        = 8,
+        kBatteryDataTrackDecoder        = 0x8,
+        // start to play an audio on an audio device
+        kBatteryDataAudioFlingerStart   = 0x10,
+        // stop/pause the audio playback
+        kBatteryDataAudioFlingerStop    = 0x20,
+        // audio is rounted to speaker
+        kBatteryDataSpeakerOn           = 0x40,
+        // audio is rounted to devices other than speaker
+        kBatteryDataOtherAudioDeviceOn  = 0x80,
     };
 
     virtual void addBatteryData(uint32_t params) = 0;
diff --git a/media/libmediaplayerservice/MediaPlayerService.cpp b/media/libmediaplayerservice/MediaPlayerService.cpp
index ec6188f..a42cca5 100644
--- a/media/libmediaplayerservice/MediaPlayerService.cpp
+++ b/media/libmediaplayerservice/MediaPlayerService.cpp
@@ -214,6 +214,15 @@
 {
     LOGV("MediaPlayerService created");
     mNextConnId = 1;
+
+    mBatteryAudio.refCount = 0;
+    for (int i = 0; i < NUM_AUDIO_DEVICES; i++) {
+        mBatteryAudio.deviceOn[i] = 0;
+        mBatteryAudio.lastTime[i] = 0;
+        mBatteryAudio.totalTime[i] = 0;
+    }
+    // speaker is on by default
+    mBatteryAudio.deviceOn[SPEAKER] = 1;
 }
 
 MediaPlayerService::~MediaPlayerService()
@@ -1777,12 +1786,88 @@
 void MediaPlayerService::addBatteryData(uint32_t params)
 {
     Mutex::Autolock lock(mLock);
+
+    int32_t time = systemTime() / 1000000L;
+
+    // change audio output devices. This notification comes from AudioFlinger
+    if ((params & kBatteryDataSpeakerOn)
+            || (params & kBatteryDataOtherAudioDeviceOn)) {
+
+        int deviceOn[NUM_AUDIO_DEVICES];
+        for (int i = 0; i < NUM_AUDIO_DEVICES; i++) {
+            deviceOn[i] = 0;
+        }
+
+        if ((params & kBatteryDataSpeakerOn)
+                && (params & kBatteryDataOtherAudioDeviceOn)) {
+            deviceOn[SPEAKER_AND_OTHER] = 1;
+        } else if (params & kBatteryDataSpeakerOn) {
+            deviceOn[SPEAKER] = 1;
+        } else {
+            deviceOn[OTHER_AUDIO_DEVICE] = 1;
+        }
+
+        for (int i = 0; i < NUM_AUDIO_DEVICES; i++) {
+            if (mBatteryAudio.deviceOn[i] != deviceOn[i]){
+
+                if (mBatteryAudio.refCount > 0) { // if playing audio
+                    if (!deviceOn[i]) {
+                        mBatteryAudio.lastTime[i] += time;
+                        mBatteryAudio.totalTime[i] += mBatteryAudio.lastTime[i];
+                        mBatteryAudio.lastTime[i] = 0;
+                    } else {
+                        mBatteryAudio.lastTime[i] = 0 - time;
+                    }
+                }
+
+                mBatteryAudio.deviceOn[i] = deviceOn[i];
+            }
+        }
+        return;
+    }
+
+    // an sudio stream is started
+    if (params & kBatteryDataAudioFlingerStart) {
+        // record the start time only if currently no other audio
+        // is being played
+        if (mBatteryAudio.refCount == 0) {
+            for (int i = 0; i < NUM_AUDIO_DEVICES; i++) {
+                if (mBatteryAudio.deviceOn[i]) {
+                    mBatteryAudio.lastTime[i] -= time;
+                }
+            }
+        }
+
+        mBatteryAudio.refCount ++;
+        return;
+
+    } else if (params & kBatteryDataAudioFlingerStop) {
+        if (mBatteryAudio.refCount <= 0) {
+            LOGW("Battery track warning: refCount is <= 0");
+            return;
+        }
+
+        // record the stop time only if currently this is the only
+        // audio being played
+        if (mBatteryAudio.refCount == 1) {
+            for (int i = 0; i < NUM_AUDIO_DEVICES; i++) {
+                if (mBatteryAudio.deviceOn[i]) {
+                    mBatteryAudio.lastTime[i] += time;
+                    mBatteryAudio.totalTime[i] += mBatteryAudio.lastTime[i];
+                    mBatteryAudio.lastTime[i] = 0;
+                }
+            }
+        }
+
+        mBatteryAudio.refCount --;
+        return;
+    }
+
     int uid = IPCThreadState::self()->getCallingUid();
     if (uid == AID_MEDIA) {
         return;
     }
     int index = mBatteryData.indexOfKey(uid);
-    int32_t time = systemTime() / 1000000L;
 
     if (index < 0) { // create a new entry for this UID
         BatteryUsageInfo info;
@@ -1792,7 +1877,10 @@
         info.videoLastTime = 0;
         info.refCount = 0;
 
-        mBatteryData.add(uid, info);
+        if (mBatteryData.add(uid, info) == NO_MEMORY) {
+            LOGE("Battery track error: no memory for new app");
+            return;
+        }
     }
 
     BatteryUsageInfo &info = mBatteryData.editValueFor(uid);
@@ -1837,6 +1925,26 @@
 
 status_t MediaPlayerService::pullBatteryData(Parcel* reply) {
     Mutex::Autolock lock(mLock);
+
+    // audio output devices usage
+    int32_t time = systemTime() / 1000000L; //in ms
+    int32_t totalTime;
+
+    for (int i = 0; i < NUM_AUDIO_DEVICES; i++) {
+        totalTime = mBatteryAudio.totalTime[i];
+
+        if (mBatteryAudio.deviceOn[i]
+            && (mBatteryAudio.lastTime[i] != 0)) {
+                int32_t tmpTime = mBatteryAudio.lastTime[i] + time;
+                totalTime += tmpTime;
+        }
+
+        reply->writeInt32(totalTime);
+        // reset the total time
+        mBatteryAudio.totalTime[i] = 0;
+   }
+
+    // codec usage
     BatteryUsageInfo info;
     int size = mBatteryData.size();
 
diff --git a/media/libmediaplayerservice/MediaPlayerService.h b/media/libmediaplayerservice/MediaPlayerService.h
index 1175ed0..ff6ccf54 100644
--- a/media/libmediaplayerservice/MediaPlayerService.h
+++ b/media/libmediaplayerservice/MediaPlayerService.h
@@ -225,6 +225,25 @@
     };
     KeyedVector<int, BatteryUsageInfo>    mBatteryData;
 
+    enum {
+        SPEAKER,
+        OTHER_AUDIO_DEVICE,
+        SPEAKER_AND_OTHER,
+        NUM_AUDIO_DEVICES
+    };
+
+    struct BatteryAudioFlingerUsageInfo {
+        int refCount; // how many audio streams are being played
+        int deviceOn[NUM_AUDIO_DEVICES]; // whether the device is currently used
+        int32_t lastTime[NUM_AUDIO_DEVICES]; // in ms
+        // totalTime[]: total time of audio output devices usage
+        int32_t totalTime[NUM_AUDIO_DEVICES]; // in ms
+    };
+
+    // This varialble is used to record the usage of audio output device
+    // for battery app
+    BatteryAudioFlingerUsageInfo mBatteryAudio;
+
     // Collect info of the codec usage from media player and media recorder
     virtual void                addBatteryData(uint32_t params);
     // API for the Battery app to pull the data of codecs usage
diff --git a/services/audioflinger/AudioFlinger.cpp b/services/audioflinger/AudioFlinger.cpp
index a07ebfc..2b08ab5 100644
--- a/services/audioflinger/AudioFlinger.cpp
+++ b/services/audioflinger/AudioFlinger.cpp
@@ -24,6 +24,7 @@
 #include <sys/time.h>
 #include <sys/resource.h>
 
+#include <binder/IPCThreadState.h>
 #include <binder/IServiceManager.h>
 #include <utils/Log.h>
 #include <binder/Parcel.h>
@@ -35,6 +36,7 @@
 
 #include <media/AudioTrack.h>
 #include <media/AudioRecord.h>
+#include <media/IMediaPlayerService.h>
 
 #include <private/media/AudioTrackShared.h>
 #include <private/media/AudioEffectShared.h>
@@ -121,6 +123,19 @@
 #endif
 }
 
+// To collect the amplifier usage
+static void addBatteryData(uint32_t params) {
+    sp<IBinder> binder =
+        defaultServiceManager()->getService(String16("media.player"));
+    sp<IMediaPlayerService> service = interface_cast<IMediaPlayerService>(binder);
+    if (service.get() == NULL) {
+        LOGW("Cannot connect to the MediaPlayerService for battery tracking");
+        return;
+    }
+
+    service->addBatteryData(params);
+}
+
 // ----------------------------------------------------------------------------
 
 AudioFlinger::AudioFlinger()
@@ -1833,6 +1848,27 @@
             }
         }
         if (param.getInt(String8(AudioParameter::keyRouting), value) == NO_ERROR) {
+            // when changing the audio output device, call addBatteryData to notify
+            // the change
+            if (mDevice != value) {
+                uint32_t params = 0;
+                // check whether speaker is on
+                if (value & AudioSystem::DEVICE_OUT_SPEAKER) {
+                    params |= IMediaPlayerService::kBatteryDataSpeakerOn;
+                }
+
+                int deviceWithoutSpeaker
+                    = AudioSystem::DEVICE_OUT_ALL & ~AudioSystem::DEVICE_OUT_SPEAKER;
+                // check if any other device (except speaker) is on
+                if (value & deviceWithoutSpeaker ) {
+                    params |= IMediaPlayerService::kBatteryDataOtherAudioDeviceOn;
+                }
+
+                if (params != 0) {
+                    addBatteryData(params);
+                }
+            }
+
             // forward device change to effects that have requested to be
             // aware of attached audio device.
             mDevice = (uint32_t)value;
@@ -2831,6 +2867,9 @@
                     AudioSystem::stopOutput(thread->id(),
                                             (AudioSystem::stream_type)mStreamType,
                                             mSessionId);
+
+                    // to track the speaker usage
+                    addBatteryData(IMediaPlayerService::kBatteryDataAudioFlingerStop);
                 }
                 AudioSystem::releaseOutput(thread->id());
             }
@@ -2941,6 +2980,11 @@
                                               (AudioSystem::stream_type)mStreamType,
                                               mSessionId);
             thread->mLock.lock();
+
+            // to track the speaker usage
+            if (status == NO_ERROR) {
+                addBatteryData(IMediaPlayerService::kBatteryDataAudioFlingerStart);
+            }
         }
         if (status == NO_ERROR) {
             PlaybackThread *playbackThread = (PlaybackThread *)thread.get();
@@ -2976,6 +3020,9 @@
                                     (AudioSystem::stream_type)mStreamType,
                                     mSessionId);
             thread->mLock.lock();
+
+            // to track the speaker usage
+            addBatteryData(IMediaPlayerService::kBatteryDataAudioFlingerStop);
         }
     }
 }
@@ -2995,6 +3042,9 @@
                                         (AudioSystem::stream_type)mStreamType,
                                         mSessionId);
                 thread->mLock.lock();
+
+                // to track the speaker usage
+                addBatteryData(IMediaPlayerService::kBatteryDataAudioFlingerStop);
             }
         }
     }