diff --git a/media/libmediaplayerservice/nuplayer/GenericSource.cpp b/media/libmediaplayerservice/nuplayer/GenericSource.cpp
index 9a0db30..f4dbdeb 100644
--- a/media/libmediaplayerservice/nuplayer/GenericSource.cpp
+++ b/media/libmediaplayerservice/nuplayer/GenericSource.cpp
@@ -42,6 +42,7 @@
 
 static int64_t kLowWaterMarkUs = 2000000ll;  // 2secs
 static int64_t kHighWaterMarkUs = 5000000ll;  // 5secs
+static int64_t kHighWaterMarkRebufferUs = 15000000ll;  // 15secs
 static const ssize_t kLowWaterMarkBytes = 40000;
 static const ssize_t kHighWaterMarkBytes = 200000;
 
@@ -66,11 +67,8 @@
       mFd(-1),
       mDrmManagerClient(NULL),
       mBitrate(-1ll),
-      mPollBufferingGeneration(0),
-      mPendingReadBufferTypes(0),
-      mBuffering(false),
-      mPrepareBuffering(false),
-      mPrevBufferPercentage(-1) {
+      mPendingReadBufferTypes(0) {
+    mBufferingMonitor = new BufferingMonitor(notify);
     resetDataSource();
     DataSource::RegisterDefaultSniffers();
 }
@@ -91,6 +89,13 @@
     mDrmManagerClient = NULL;
     mStarted = false;
     mStopRead = true;
+
+    if (mBufferingMonitorLooper != NULL) {
+        mBufferingMonitorLooper->unregisterHandler(mBufferingMonitor->id());
+        mBufferingMonitorLooper->stop();
+        mBufferingMonitorLooper = NULL;
+    }
+    mBufferingMonitor->stop();
 }
 
 status_t NuPlayer::GenericSource::setDataSource(
@@ -338,6 +343,10 @@
     return mIsStreaming;
 }
 
+void NuPlayer::GenericSource::setOffloadAudio(bool offload) {
+    mBufferingMonitor->setOffloadAudio(offload);
+}
+
 NuPlayer::GenericSource::~GenericSource() {
     if (mLooper != NULL) {
         mLooper->unregisterHandler(id());
@@ -466,10 +475,18 @@
     }
 
     if (mIsStreaming) {
-        mPrepareBuffering = true;
+        if (mBufferingMonitorLooper == NULL) {
+            mBufferingMonitor->prepare(mCachedSource, mWVMExtractor, mDurationUs, mBitrate,
+                    mIsStreaming);
 
-        ensureCacheIsFetching();
-        restartPollBuffering();
+            mBufferingMonitorLooper = new ALooper;
+            mBufferingMonitorLooper->setName("GSBMonitor");
+            mBufferingMonitorLooper->start();
+            mBufferingMonitorLooper->registerHandler(mBufferingMonitor);
+        }
+
+        mBufferingMonitor->ensureCacheIsFetching();
+        mBufferingMonitor->restartPollBuffering();
     } else {
         notifyPrepared();
     }
@@ -492,7 +509,7 @@
         }
         mBitrate = -1;
 
-        cancelPollBuffering();
+        mBufferingMonitor->cancelPollBuffering();
     }
     notifyPrepared(err);
 }
@@ -571,182 +588,6 @@
     return OK;
 }
 
-void NuPlayer::GenericSource::schedulePollBuffering() {
-    sp<AMessage> msg = new AMessage(kWhatPollBuffering, this);
-    msg->setInt32("generation", mPollBufferingGeneration);
-    msg->post(1000000ll);
-}
-
-void NuPlayer::GenericSource::cancelPollBuffering() {
-    mBuffering = false;
-    ++mPollBufferingGeneration;
-    mPrevBufferPercentage = -1;
-}
-
-void NuPlayer::GenericSource::restartPollBuffering() {
-    if (mIsStreaming) {
-        cancelPollBuffering();
-        onPollBuffering();
-    }
-}
-
-void NuPlayer::GenericSource::notifyBufferingUpdate(int32_t percentage) {
-    // Buffering percent could go backward as it's estimated from remaining
-    // data and last access time. This could cause the buffering position
-    // drawn on media control to jitter slightly. Remember previously reported
-    // percentage and don't allow it to go backward.
-    if (percentage < mPrevBufferPercentage) {
-        percentage = mPrevBufferPercentage;
-    } else if (percentage > 100) {
-        percentage = 100;
-    }
-
-    mPrevBufferPercentage = percentage;
-
-    ALOGV("notifyBufferingUpdate: buffering %d%%", percentage);
-
-    sp<AMessage> msg = dupNotify();
-    msg->setInt32("what", kWhatBufferingUpdate);
-    msg->setInt32("percentage", percentage);
-    msg->post();
-}
-
-void NuPlayer::GenericSource::startBufferingIfNecessary() {
-    ALOGV("startBufferingIfNecessary: mPrepareBuffering=%d, mBuffering=%d",
-            mPrepareBuffering, mBuffering);
-
-    if (mPrepareBuffering) {
-        return;
-    }
-
-    if (!mBuffering) {
-        mBuffering = true;
-
-        ensureCacheIsFetching();
-        sendCacheStats();
-
-        sp<AMessage> notify = dupNotify();
-        notify->setInt32("what", kWhatPauseOnBufferingStart);
-        notify->post();
-    }
-}
-
-void NuPlayer::GenericSource::stopBufferingIfNecessary() {
-    ALOGV("stopBufferingIfNecessary: mPrepareBuffering=%d, mBuffering=%d",
-            mPrepareBuffering, mBuffering);
-
-    if (mPrepareBuffering) {
-        mPrepareBuffering = false;
-        notifyPrepared();
-        return;
-    }
-
-    if (mBuffering) {
-        mBuffering = false;
-
-        sendCacheStats();
-
-        sp<AMessage> notify = dupNotify();
-        notify->setInt32("what", kWhatResumeOnBufferingEnd);
-        notify->post();
-    }
-}
-
-void NuPlayer::GenericSource::sendCacheStats() {
-    int32_t kbps = 0;
-    status_t err = UNKNOWN_ERROR;
-
-    if (mWVMExtractor != NULL) {
-        err = mWVMExtractor->getEstimatedBandwidthKbps(&kbps);
-    } else if (mCachedSource != NULL) {
-        err = mCachedSource->getEstimatedBandwidthKbps(&kbps);
-    }
-
-    if (err == OK) {
-        sp<AMessage> notify = dupNotify();
-        notify->setInt32("what", kWhatCacheStats);
-        notify->setInt32("bandwidth", kbps);
-        notify->post();
-    }
-}
-
-void NuPlayer::GenericSource::ensureCacheIsFetching() {
-    if (mCachedSource != NULL) {
-        mCachedSource->resumeFetchingIfNecessary();
-    }
-}
-
-void NuPlayer::GenericSource::onPollBuffering() {
-    status_t finalStatus = UNKNOWN_ERROR;
-    int64_t cachedDurationUs = -1ll;
-    ssize_t cachedDataRemaining = -1;
-
-    ALOGW_IF(mWVMExtractor != NULL && mCachedSource != NULL,
-            "WVMExtractor and NuCachedSource both present");
-
-    if (mWVMExtractor != NULL) {
-        cachedDurationUs =
-                mWVMExtractor->getCachedDurationUs(&finalStatus);
-    } else if (mCachedSource != NULL) {
-        cachedDataRemaining =
-                mCachedSource->approxDataRemaining(&finalStatus);
-
-        if (finalStatus == OK) {
-            off64_t size;
-            int64_t bitrate = 0ll;
-            if (mDurationUs > 0 && mCachedSource->getSize(&size) == OK) {
-                bitrate = size * 8000000ll / mDurationUs;
-            } else if (mBitrate > 0) {
-                bitrate = mBitrate;
-            }
-            if (bitrate > 0) {
-                cachedDurationUs = cachedDataRemaining * 8000000ll / bitrate;
-            }
-        }
-    }
-
-    if (finalStatus != OK) {
-        ALOGV("onPollBuffering: EOS (finalStatus = %d)", finalStatus);
-
-        if (finalStatus == ERROR_END_OF_STREAM) {
-            notifyBufferingUpdate(100);
-        }
-
-        stopBufferingIfNecessary();
-        return;
-    } else if (cachedDurationUs >= 0ll) {
-        if (mDurationUs > 0ll) {
-            int64_t cachedPosUs = getLastReadPosition() + cachedDurationUs;
-            int percentage = 100.0 * cachedPosUs / mDurationUs;
-            if (percentage > 100) {
-                percentage = 100;
-            }
-
-            notifyBufferingUpdate(percentage);
-        }
-
-        ALOGV("onPollBuffering: cachedDurationUs %.1f sec",
-                cachedDurationUs / 1000000.0f);
-
-        if (cachedDurationUs < kLowWaterMarkUs) {
-            startBufferingIfNecessary();
-        } else if (cachedDurationUs > kHighWaterMarkUs) {
-            stopBufferingIfNecessary();
-        }
-    } else if (cachedDataRemaining >= 0) {
-        ALOGV("onPollBuffering: cachedDataRemaining %zd bytes",
-                cachedDataRemaining);
-
-        if (cachedDataRemaining < kLowWaterMarkBytes) {
-            startBufferingIfNecessary();
-        } else if (cachedDataRemaining > kHighWaterMarkBytes) {
-            stopBufferingIfNecessary();
-        }
-    }
-
-    schedulePollBuffering();
-}
-
 void NuPlayer::GenericSource::onMessageReceived(const sp<AMessage> &msg) {
     switch (msg->what()) {
       case kWhatPrepareAsync:
@@ -834,17 +675,7 @@
       case kWhatStart:
       case kWhatResume:
       {
-          restartPollBuffering();
-          break;
-      }
-
-      case kWhatPollBuffering:
-      {
-          int32_t generation;
-          CHECK(msg->findInt32("generation", &generation));
-          if (generation == mPollBufferingGeneration) {
-              onPollBuffering();
-          }
+          mBufferingMonitor->restartPollBuffering();
           break;
       }
 
@@ -1045,6 +876,10 @@
 
 status_t NuPlayer::GenericSource::dequeueAccessUnit(
         bool audio, sp<ABuffer> *accessUnit) {
+    if (!mStarted) {
+        return -EWOULDBLOCK;
+    }
+
     Track *track = audio ? &mAudioTrack : &mVideoTrack;
 
     if (track->mSource == NULL) {
@@ -1091,6 +926,7 @@
     CHECK((*accessUnit)->meta()->findInt64("timeUs", &timeUs));
     if (audio) {
         mAudioLastDequeueTimeUs = timeUs;
+        mBufferingMonitor->updateDequeuedBufferTime(timeUs);
     } else {
         mVideoLastDequeueTimeUs = timeUs;
     }
@@ -1377,6 +1213,8 @@
 }
 
 status_t NuPlayer::GenericSource::doSeek(int64_t seekTimeUs) {
+    mBufferingMonitor->updateDequeuedBufferTime(-1ll);
+
     // If the Widevine source is stopped, do not attempt to read any
     // more buffers.
     if (mStopRead) {
@@ -1403,8 +1241,8 @@
     // If currently buffering, post kWhatBufferingEnd first, so that
     // NuPlayer resumes. Otherwise, if cache hits high watermark
     // before new polling happens, no one will resume the playback.
-    stopBufferingIfNecessary();
-    restartPollBuffering();
+    mBufferingMonitor->stopBufferingIfNecessary();
+    mBufferingMonitor->restartPollBuffering();
 
     return OK;
 }
@@ -1585,8 +1423,10 @@
             CHECK(mbuf->meta_data()->findInt64(kKeyTime, &timeUs));
             if (trackType == MEDIA_TRACK_TYPE_AUDIO) {
                 mAudioTimeUs = timeUs;
+                mBufferingMonitor->updateQueuedTime(true /* isAudio */, timeUs);
             } else if (trackType == MEDIA_TRACK_TYPE_VIDEO) {
                 mVideoTimeUs = timeUs;
+                mBufferingMonitor->updateQueuedTime(false /* isAudio */, timeUs);
             }
 
             queueDiscontinuityIfNeeded(seeking, formatChange, trackType, track);
@@ -1630,4 +1470,330 @@
     }
 }
 
+NuPlayer::GenericSource::BufferingMonitor::BufferingMonitor(const sp<AMessage> &notify)
+    : mNotify(notify),
+      mDurationUs(-1ll),
+      mBitrate(-1ll),
+      mIsStreaming(false),
+      mAudioTimeUs(0),
+      mVideoTimeUs(0),
+      mPollBufferingGeneration(0),
+      mPrepareBuffering(false),
+      mBuffering(false),
+      mPrevBufferPercentage(-1),
+      mOffloadAudio(false),
+      mFirstDequeuedBufferRealUs(-1ll),
+      mFirstDequeuedBufferMediaUs(-1ll),
+      mlastDequeuedBufferMediaUs(-1ll) {
+}
+
+NuPlayer::GenericSource::BufferingMonitor::~BufferingMonitor() {
+}
+
+void NuPlayer::GenericSource::BufferingMonitor::prepare(
+        const sp<NuCachedSource2> &cachedSource,
+        const sp<WVMExtractor> &wvmExtractor,
+        int64_t durationUs,
+        int64_t bitrate,
+        bool isStreaming) {
+    Mutex::Autolock _l(mLock);
+    prepare_l(cachedSource, wvmExtractor, durationUs, bitrate, isStreaming);
+}
+
+void NuPlayer::GenericSource::BufferingMonitor::stop() {
+    Mutex::Autolock _l(mLock);
+    prepare_l(NULL /* cachedSource */, NULL /* wvmExtractor */, -1 /* durationUs */,
+            -1 /* bitrate */, false /* isStreaming */);
+}
+
+void NuPlayer::GenericSource::BufferingMonitor::cancelPollBuffering() {
+    Mutex::Autolock _l(mLock);
+    cancelPollBuffering_l();
+}
+
+void NuPlayer::GenericSource::BufferingMonitor::restartPollBuffering() {
+    Mutex::Autolock _l(mLock);
+    if (mIsStreaming) {
+        cancelPollBuffering_l();
+        onPollBuffering_l();
+    }
+}
+
+void NuPlayer::GenericSource::BufferingMonitor::stopBufferingIfNecessary() {
+    Mutex::Autolock _l(mLock);
+    stopBufferingIfNecessary_l();
+}
+
+void NuPlayer::GenericSource::BufferingMonitor::ensureCacheIsFetching() {
+    Mutex::Autolock _l(mLock);
+    ensureCacheIsFetching_l();
+}
+
+void NuPlayer::GenericSource::BufferingMonitor::updateQueuedTime(bool isAudio, int64_t timeUs) {
+    Mutex::Autolock _l(mLock);
+    if (isAudio) {
+        mAudioTimeUs = timeUs;
+    } else {
+        mVideoTimeUs = timeUs;
+    }
+}
+
+void NuPlayer::GenericSource::BufferingMonitor::setOffloadAudio(bool offload) {
+    Mutex::Autolock _l(mLock);
+    mOffloadAudio = offload;
+}
+
+void NuPlayer::GenericSource::BufferingMonitor::updateDequeuedBufferTime(int64_t mediaUs) {
+    Mutex::Autolock _l(mLock);
+    if (mediaUs < 0) {
+        mFirstDequeuedBufferRealUs = -1ll;
+        mFirstDequeuedBufferMediaUs = -1ll;
+    } else if (mFirstDequeuedBufferRealUs < 0) {
+        mFirstDequeuedBufferRealUs = ALooper::GetNowUs();
+        mFirstDequeuedBufferMediaUs = mediaUs;
+    }
+    mlastDequeuedBufferMediaUs = mediaUs;
+}
+
+void NuPlayer::GenericSource::BufferingMonitor::prepare_l(
+        const sp<NuCachedSource2> &cachedSource,
+        const sp<WVMExtractor> &wvmExtractor,
+        int64_t durationUs,
+        int64_t bitrate,
+        bool isStreaming) {
+    ALOGW_IF(wvmExtractor != NULL && cachedSource != NULL,
+            "WVMExtractor and NuCachedSource are both present when "
+            "BufferingMonitor::prepare_l is called, ignore NuCachedSource");
+
+    mCachedSource = cachedSource;
+    mWVMExtractor = wvmExtractor;
+    mDurationUs = durationUs;
+    mBitrate = bitrate;
+    mIsStreaming = isStreaming;
+    mAudioTimeUs = 0;
+    mVideoTimeUs = 0;
+    mPrepareBuffering = true;
+    cancelPollBuffering_l();
+    mOffloadAudio = false;
+    mFirstDequeuedBufferRealUs = -1ll;
+    mFirstDequeuedBufferMediaUs = -1ll;
+    mlastDequeuedBufferMediaUs = -1ll;
+}
+
+void NuPlayer::GenericSource::BufferingMonitor::cancelPollBuffering_l() {
+    mBuffering = false;
+    ++mPollBufferingGeneration;
+    mPrevBufferPercentage = -1;
+}
+
+void NuPlayer::GenericSource::BufferingMonitor::notifyBufferingUpdate_l(int32_t percentage) {
+    // Buffering percent could go backward as it's estimated from remaining
+    // data and last access time. This could cause the buffering position
+    // drawn on media control to jitter slightly. Remember previously reported
+    // percentage and don't allow it to go backward.
+    if (percentage < mPrevBufferPercentage) {
+        percentage = mPrevBufferPercentage;
+    } else if (percentage > 100) {
+        percentage = 100;
+    }
+
+    mPrevBufferPercentage = percentage;
+
+    ALOGV("notifyBufferingUpdate_l: buffering %d%%", percentage);
+
+    sp<AMessage> msg = mNotify->dup();
+    msg->setInt32("what", kWhatBufferingUpdate);
+    msg->setInt32("percentage", percentage);
+    msg->post();
+}
+
+void NuPlayer::GenericSource::BufferingMonitor::startBufferingIfNecessary_l() {
+    ALOGD("startBufferingIfNecessary_l: mPrepareBuffering=%d, mBuffering=%d",
+            mPrepareBuffering, mBuffering);
+
+    if (mPrepareBuffering) {
+        return;
+    }
+
+    if (!mBuffering) {
+        mBuffering = true;
+
+        ensureCacheIsFetching_l();
+        sendCacheStats_l();
+
+        sp<AMessage> notify = mNotify->dup();
+        notify->setInt32("what", kWhatPauseOnBufferingStart);
+        notify->post();
+    }
+}
+
+void NuPlayer::GenericSource::BufferingMonitor::stopBufferingIfNecessary_l() {
+    ALOGD("stopBufferingIfNecessary_l: mPrepareBuffering=%d, mBuffering=%d",
+            mPrepareBuffering, mBuffering);
+
+    if (mPrepareBuffering) {
+        mPrepareBuffering = false;
+
+        sp<AMessage> notify = mNotify->dup();
+        notify->setInt32("what", kWhatPrepared);
+        notify->setInt32("err", OK);
+        notify->post();
+
+        return;
+    }
+
+    if (mBuffering) {
+        mBuffering = false;
+
+        sendCacheStats_l();
+
+        sp<AMessage> notify = mNotify->dup();
+        notify->setInt32("what", kWhatResumeOnBufferingEnd);
+        notify->post();
+    }
+}
+
+void NuPlayer::GenericSource::BufferingMonitor::sendCacheStats_l() {
+    int32_t kbps = 0;
+    status_t err = UNKNOWN_ERROR;
+
+    if (mWVMExtractor != NULL) {
+        err = mWVMExtractor->getEstimatedBandwidthKbps(&kbps);
+    } else if (mCachedSource != NULL) {
+        err = mCachedSource->getEstimatedBandwidthKbps(&kbps);
+    }
+
+    if (err == OK) {
+        sp<AMessage> notify = mNotify->dup();
+        notify->setInt32("what", kWhatCacheStats);
+        notify->setInt32("bandwidth", kbps);
+        notify->post();
+    }
+}
+
+void NuPlayer::GenericSource::BufferingMonitor::ensureCacheIsFetching_l() {
+    if (mCachedSource != NULL) {
+        mCachedSource->resumeFetchingIfNecessary();
+    }
+}
+
+void NuPlayer::GenericSource::BufferingMonitor::schedulePollBuffering_l() {
+    sp<AMessage> msg = new AMessage(kWhatPollBuffering, this);
+    msg->setInt32("generation", mPollBufferingGeneration);
+    // Enquires buffering status every second.
+    msg->post(1000000ll);
+}
+
+int64_t NuPlayer::GenericSource::BufferingMonitor::getLastReadPosition_l() {
+    if (mAudioTimeUs > 0) {
+        return mAudioTimeUs;
+    } else if (mVideoTimeUs > 0) {
+        return mVideoTimeUs;
+    } else {
+        return 0;
+    }
+}
+
+void NuPlayer::GenericSource::BufferingMonitor::onPollBuffering_l() {
+    status_t finalStatus = UNKNOWN_ERROR;
+    int64_t cachedDurationUs = -1ll;
+    ssize_t cachedDataRemaining = -1;
+
+    if (mWVMExtractor != NULL) {
+        cachedDurationUs =
+                mWVMExtractor->getCachedDurationUs(&finalStatus);
+    } else if (mCachedSource != NULL) {
+        cachedDataRemaining =
+                mCachedSource->approxDataRemaining(&finalStatus);
+
+        if (finalStatus == OK) {
+            off64_t size;
+            int64_t bitrate = 0ll;
+            if (mDurationUs > 0 && mCachedSource->getSize(&size) == OK) {
+                // |bitrate| uses bits/second unit, while size is number of bytes.
+                bitrate = size * 8000000ll / mDurationUs;
+            } else if (mBitrate > 0) {
+                bitrate = mBitrate;
+            }
+            if (bitrate > 0) {
+                cachedDurationUs = cachedDataRemaining * 8000000ll / bitrate;
+            }
+        }
+    }
+
+    if (finalStatus != OK) {
+        ALOGV("onPollBuffering_l: EOS (finalStatus = %d)", finalStatus);
+
+        if (finalStatus == ERROR_END_OF_STREAM) {
+            notifyBufferingUpdate_l(100);
+        }
+
+        stopBufferingIfNecessary_l();
+        return;
+    } else if (cachedDurationUs >= 0ll) {
+        if (mDurationUs > 0ll) {
+            int64_t cachedPosUs = getLastReadPosition_l() + cachedDurationUs;
+            int percentage = 100.0 * cachedPosUs / mDurationUs;
+            if (percentage > 100) {
+                percentage = 100;
+            }
+
+            notifyBufferingUpdate_l(percentage);
+        }
+
+        ALOGV("onPollBuffering_l: cachedDurationUs %.1f sec",
+                cachedDurationUs / 1000000.0f);
+
+        if (cachedDurationUs < kLowWaterMarkUs) {
+            // Take into account the data cached in downstream components to try to avoid
+            // unnecessary pause.
+            if (mOffloadAudio && mFirstDequeuedBufferRealUs >= 0) {
+                int64_t downStreamCacheUs = mlastDequeuedBufferMediaUs - mFirstDequeuedBufferMediaUs
+                        - (ALooper::GetNowUs() - mFirstDequeuedBufferRealUs);
+                if (downStreamCacheUs > 0) {
+                    cachedDurationUs += downStreamCacheUs;
+                }
+            }
+
+            if (cachedDurationUs < kLowWaterMarkUs) {
+                startBufferingIfNecessary_l();
+            }
+        } else {
+            int64_t highWaterMark = mPrepareBuffering ? kHighWaterMarkUs : kHighWaterMarkRebufferUs;
+            if (cachedDurationUs > highWaterMark) {
+                stopBufferingIfNecessary_l();
+            }
+        }
+    } else if (cachedDataRemaining >= 0) {
+        ALOGV("onPollBuffering_l: cachedDataRemaining %zd bytes",
+                cachedDataRemaining);
+
+        if (cachedDataRemaining < kLowWaterMarkBytes) {
+            startBufferingIfNecessary_l();
+        } else if (cachedDataRemaining > kHighWaterMarkBytes) {
+            stopBufferingIfNecessary_l();
+        }
+    }
+
+    schedulePollBuffering_l();
+}
+
+void NuPlayer::GenericSource::BufferingMonitor::onMessageReceived(const sp<AMessage> &msg) {
+    switch (msg->what()) {
+      case kWhatPollBuffering:
+      {
+          int32_t generation;
+          CHECK(msg->findInt32("generation", &generation));
+          Mutex::Autolock _l(mLock);
+          if (generation == mPollBufferingGeneration) {
+              onPollBuffering_l();
+          }
+          break;
+      }
+      default:
+          TRESPASS();
+          break;
+    }
+}
+
 }  // namespace android
diff --git a/media/libmediaplayerservice/nuplayer/GenericSource.h b/media/libmediaplayerservice/nuplayer/GenericSource.h
index 2db5557..2fd703e 100644
--- a/media/libmediaplayerservice/nuplayer/GenericSource.h
+++ b/media/libmediaplayerservice/nuplayer/GenericSource.h
@@ -77,6 +77,8 @@
 
     virtual bool isStreaming() const;
 
+    virtual void setOffloadAudio(bool offload);
+
 protected:
     virtual ~GenericSource();
 
@@ -111,6 +113,83 @@
         sp<AnotherPacketSource> mPackets;
     };
 
+    // Helper to monitor buffering status. The polling happens every second.
+    // When necessary, it will send out buffering events to the player.
+    struct BufferingMonitor : public AHandler {
+    public:
+        BufferingMonitor(const sp<AMessage> &notify);
+
+        // Set up state.
+        void prepare(const sp<NuCachedSource2> &cachedSource,
+                const sp<WVMExtractor> &wvmExtractor,
+                int64_t durationUs,
+                int64_t bitrate,
+                bool isStreaming);
+        // Stop and reset buffering monitor.
+        void stop();
+        // Cancel the current monitor task.
+        void cancelPollBuffering();
+        // Restart the monitor task.
+        void restartPollBuffering();
+        // Stop buffering task and send out corresponding events.
+        void stopBufferingIfNecessary();
+        // Make sure data source is getting data.
+        void ensureCacheIsFetching();
+        // Update media time of just extracted buffer from data source.
+        void updateQueuedTime(bool isAudio, int64_t timeUs);
+
+        // Set the offload mode.
+        void setOffloadAudio(bool offload);
+        // Update media time of last dequeued buffer which is sent to the decoder.
+        void updateDequeuedBufferTime(int64_t mediaUs);
+
+    protected:
+        virtual ~BufferingMonitor();
+        virtual void onMessageReceived(const sp<AMessage> &msg);
+
+    private:
+        enum {
+            kWhatPollBuffering,
+        };
+
+        sp<AMessage> mNotify;
+
+        sp<NuCachedSource2> mCachedSource;
+        sp<WVMExtractor> mWVMExtractor;
+        int64_t mDurationUs;
+        int64_t mBitrate;
+        bool mIsStreaming;
+
+        int64_t mAudioTimeUs;
+        int64_t mVideoTimeUs;
+        int32_t mPollBufferingGeneration;
+        bool mPrepareBuffering;
+        bool mBuffering;
+        int32_t mPrevBufferPercentage;
+
+        mutable Mutex mLock;
+
+        bool mOffloadAudio;
+        int64_t mFirstDequeuedBufferRealUs;
+        int64_t mFirstDequeuedBufferMediaUs;
+        int64_t mlastDequeuedBufferMediaUs;
+
+        void prepare_l(const sp<NuCachedSource2> &cachedSource,
+                const sp<WVMExtractor> &wvmExtractor,
+                int64_t durationUs,
+                int64_t bitrate,
+                bool isStreaming);
+        void cancelPollBuffering_l();
+        void notifyBufferingUpdate_l(int32_t percentage);
+        void startBufferingIfNecessary_l();
+        void stopBufferingIfNecessary_l();
+        void sendCacheStats_l();
+        void ensureCacheIsFetching_l();
+        int64_t getLastReadPosition_l();
+        void onPollBuffering_l();
+        void schedulePollBuffering_l();
+    };
+
     Vector<sp<IMediaSource> > mSources;
     Track mAudioTrack;
     int64_t mAudioTimeUs;
@@ -147,17 +226,15 @@
     bool mStarted;
     bool mStopRead;
     int64_t mBitrate;
-    int32_t mPollBufferingGeneration;
+    sp<BufferingMonitor> mBufferingMonitor;
     uint32_t mPendingReadBufferTypes;
-    bool mBuffering;
-    bool mPrepareBuffering;
-    int32_t mPrevBufferPercentage;
     sp<ABuffer> mGlobalTimedText;
 
     mutable Mutex mReadBufferLock;
     mutable Mutex mDisconnectLock;
 
     sp<ALooper> mLooper;
+    sp<ALooper> mBufferingMonitorLooper;
 
     void resetDataSource();
 
@@ -212,16 +289,6 @@
     void queueDiscontinuityIfNeeded(
             bool seeking, bool formatChange, media_track_type trackType, Track *track);
 
-    void schedulePollBuffering();
-    void cancelPollBuffering();
-    void restartPollBuffering();
-    void onPollBuffering();
-    void notifyBufferingUpdate(int32_t percentage);
-    void startBufferingIfNecessary();
-    void stopBufferingIfNecessary();
-    void sendCacheStats();
-    void ensureCacheIsFetching();
-
     DISALLOW_EVIL_CONSTRUCTORS(GenericSource);
 };
 
diff --git a/media/libmediaplayerservice/nuplayer/NuPlayer.cpp b/media/libmediaplayerservice/nuplayer/NuPlayer.cpp
index ce68bd4..5c13633 100644
--- a/media/libmediaplayerservice/nuplayer/NuPlayer.cpp
+++ b/media/libmediaplayerservice/nuplayer/NuPlayer.cpp
@@ -1564,10 +1564,14 @@
 
         determineAudioModeChange();
         if (mOffloadAudio) {
+            mSource->setOffloadAudio(true /* offload */);
+
             const bool hasVideo = (mSource->getFormat(false /*audio */) != NULL);
             format->setInt32("has-video", hasVideo);
             *decoder = new DecoderPassThrough(notify, mSource, mRenderer);
         } else {
+            mSource->setOffloadAudio(false /* offload */);
+
             *decoder = new Decoder(notify, mSource, mPID, mRenderer);
         }
     } else {
diff --git a/media/libmediaplayerservice/nuplayer/NuPlayerDecoderPassThrough.cpp b/media/libmediaplayerservice/nuplayer/NuPlayerDecoderPassThrough.cpp
index 514ec1a..f224635 100644
--- a/media/libmediaplayerservice/nuplayer/NuPlayerDecoderPassThrough.cpp
+++ b/media/libmediaplayerservice/nuplayer/NuPlayerDecoderPassThrough.cpp
@@ -223,6 +223,11 @@
         status_t err = dequeueAccessUnit(&accessUnit);
 
         if (err == -EWOULDBLOCK) {
+            // Flush out the aggregate buffer to try to avoid underrun.
+            accessUnit = aggregateBuffer(NULL /* accessUnit */);
+            if (accessUnit != NULL) {
+                break;
+            }
             return err;
         } else if (err != OK) {
             if (err == INFO_DISCONTINUITY) {
diff --git a/media/libmediaplayerservice/nuplayer/NuPlayerSource.h b/media/libmediaplayerservice/nuplayer/NuPlayerSource.h
index 11a6a9f..fba4540 100644
--- a/media/libmediaplayerservice/nuplayer/NuPlayerSource.h
+++ b/media/libmediaplayerservice/nuplayer/NuPlayerSource.h
@@ -122,6 +122,8 @@
         return true;
     }
 
+    virtual void setOffloadAudio(bool /* offload */) {}
+
 protected:
     virtual ~Source() {}