diff --git a/include/media/stagefright/AudioSource.h b/include/media/stagefright/AudioSource.h
index 1af4254..a5cec78 100644
--- a/include/media/stagefright/AudioSource.h
+++ b/include/media/stagefright/AudioSource.h
@@ -72,6 +72,7 @@
     int64_t mPrevSampleTimeUs;
     int64_t mTotalLostFrames;
     int64_t mPrevLostBytes;
+    int64_t mInitialReadTimeUs;
 
     MediaBufferGroup *mGroup;
 
diff --git a/include/media/stagefright/MPEG4Writer.h b/include/media/stagefright/MPEG4Writer.h
index 2412f6a..9716e98 100644
--- a/include/media/stagefright/MPEG4Writer.h
+++ b/include/media/stagefright/MPEG4Writer.h
@@ -132,7 +132,7 @@
     // Adjust other track media clock (presumably wall clock)
     // based on audio track media clock with the drift time.
     int64_t mDriftTimeUs;
-    void addDriftTimeUs(int64_t driftTimeUs);
+    void setDriftTimeUs(int64_t driftTimeUs);
     int64_t getDriftTimeUs();
 
     void lock();
diff --git a/include/media/stagefright/MetaData.h b/include/media/stagefright/MetaData.h
index 43354c2..3b31e68 100644
--- a/include/media/stagefright/MetaData.h
+++ b/include/media/stagefright/MetaData.h
@@ -48,6 +48,7 @@
     kKeyTime              = 'time',  // int64_t (usecs)
     kKeyNTPTime           = 'ntpT',  // uint64_t (ntp-timestamp)
     kKeyTargetTime        = 'tarT',  // int64_t (usecs)
+    kKeyDriftTime         = 'dftT',  // int64_t (usecs)
     kKeyDuration          = 'dura',  // int64_t (usecs)
     kKeyColorFormat       = 'colf',
     kKeyPlatformPrivate   = 'priv',  // pointer
diff --git a/media/libstagefright/AudioSource.cpp b/media/libstagefright/AudioSource.cpp
index bcae913..c2f79e8 100644
--- a/media/libstagefright/AudioSource.cpp
+++ b/media/libstagefright/AudioSource.cpp
@@ -84,6 +84,7 @@
 
     mTrackMaxAmplitude = false;
     mMaxAmplitude = 0;
+    mInitialReadTimeUs = 0;
     mStartTimeUs = 0;
     int64_t startTimeUs;
     if (params && params->findInt64(kKeyTime, &startTimeUs)) {
@@ -210,6 +211,7 @@
         return NO_INIT;
     }
 
+    int64_t readTimeUs = systemTime() / 1000;
     *out = NULL;
 
     MediaBuffer *buffer;
@@ -223,9 +225,10 @@
 
 
         if (numFramesRecorded == 0 && mPrevSampleTimeUs == 0) {
+            mInitialReadTimeUs = readTimeUs;
             // Initial delay
             if (mStartTimeUs > 0) {
-                mStartTimeUs = systemTime() / 1000 - mStartTimeUs;
+                mStartTimeUs = readTimeUs - mStartTimeUs;
             } else {
                 // Assume latency is constant.
                 mStartTimeUs += mRecord->latency() * 1000;
@@ -271,7 +274,10 @@
             }
             memset(buffer->data(), 0, numLostBytes);
             buffer->set_range(0, numLostBytes);
-            buffer->meta_data()->setInt64(kKeyTime, mPrevSampleTimeUs);
+            if (numFramesRecorded == 0) {
+                buffer->meta_data()->setInt64(kKeyTime, mStartTimeUs);
+            }
+            buffer->meta_data()->setInt64(kKeyDriftTime, readTimeUs - mInitialReadTimeUs);
             mPrevSampleTimeUs = timestampUs;
             *out = buffer;
             return OK;
@@ -309,7 +315,10 @@
             trackMaxAmplitude((int16_t *) buffer->data(), n >> 1);
         }
 
-        buffer->meta_data()->setInt64(kKeyTime, mPrevSampleTimeUs);
+        if (numFramesRecorded == 0) {
+            buffer->meta_data()->setInt64(kKeyTime, mStartTimeUs);
+        }
+        buffer->meta_data()->setInt64(kKeyDriftTime, readTimeUs - mInitialReadTimeUs);
         CHECK(timestampUs > mPrevSampleTimeUs);
         mPrevSampleTimeUs = timestampUs;
         LOGV("initial delay: %lld, sample rate: %d, timestamp: %lld",
diff --git a/media/libstagefright/MPEG4Writer.cpp b/media/libstagefright/MPEG4Writer.cpp
index a15b84e..af2b4c4 100644
--- a/media/libstagefright/MPEG4Writer.cpp
+++ b/media/libstagefright/MPEG4Writer.cpp
@@ -1430,9 +1430,6 @@
     int64_t previousPausedDurationUs = 0;
     int64_t timestampUs;
 
-    int64_t wallClockTimeUs = 0;
-    int64_t lastWallClockTimeUs = 0;
-
     sp<MetaData> meta_data;
     bool collectStats = collectStatisticalData();
 
@@ -1542,14 +1539,15 @@
             // of neighboring samples. This in turn helps reduce the track header size,
             // especially, the number of entries in the "stts" box.
             if (mNumSamples > 1) {
-                int64_t durationUs = timestampUs + mOwner->getDriftTimeUs() - lastTimestampUs;
+                int64_t currDriftTimeUs = mOwner->getDriftTimeUs();
+                int64_t durationUs = timestampUs + currDriftTimeUs - lastTimestampUs;
                 int64_t diffUs = (durationUs > lastDurationUs)
                             ? durationUs - lastDurationUs
                             : lastDurationUs - durationUs;
                 if (diffUs <= 5000) {  // XXX: Magic number 5ms
                     timestampUs = lastTimestampUs + lastDurationUs;
                 } else {
-                    timestampUs += mOwner->getDriftTimeUs();
+                    timestampUs += currDriftTimeUs;
                 }
             }
         }
@@ -1557,12 +1555,6 @@
         if (mNumSamples > 1) {
             if (timestampUs <= lastTimestampUs) {
                 LOGW("Frame arrives too late!");
-#if 0
-                // Drop the late frame.
-                copy->release();
-                copy = NULL;
-                continue;
-#else
                 // Don't drop the late frame, since dropping a frame may cause
                 // problems later during playback
 
@@ -1573,7 +1565,6 @@
                 } else {
                     timestampUs = lastTimestampUs + (1000000LL + (mTimeScale >> 1)) / mTimeScale;
                 }
-#endif
             }
         }
 
@@ -1613,12 +1604,10 @@
         lastDurationTicks = currDurationTicks;
         lastTimestampUs = timestampUs;
         if (mIsRealTimeRecording && mIsAudio) {
-            wallClockTimeUs = systemTime() / 1000;
-            int64_t wallClockDurationUs = wallClockTimeUs - lastWallClockTimeUs;
-            if (mNumSamples > 2) {
-                mOwner->addDriftTimeUs(lastDurationUs - wallClockDurationUs);
+            int64_t driftTimeUs = 0;
+            if (meta_data->findInt64(kKeyDriftTime, &driftTimeUs)) {
+                mOwner->setDriftTimeUs(driftTimeUs);
             }
-            lastWallClockTimeUs = wallClockTimeUs;
         }
 
         if (isSync != 0) {
@@ -1851,10 +1840,10 @@
     }
 }
 
-void MPEG4Writer::addDriftTimeUs(int64_t driftTimeUs) {
-    LOGV("addDriftTimeUs: %lld us", driftTimeUs);
+void MPEG4Writer::setDriftTimeUs(int64_t driftTimeUs) {
+    LOGV("setDriftTimeUs: %lld us", driftTimeUs);
     Mutex::Autolock autolock(mLock);
-    mDriftTimeUs += driftTimeUs;
+    mDriftTimeUs = driftTimeUs;
 }
 
 int64_t MPEG4Writer::getDriftTimeUs() {
diff --git a/media/libstagefright/codecs/aacenc/AACEncoder.cpp b/media/libstagefright/codecs/aacenc/AACEncoder.cpp
index 052c354..c05e3e5 100644
--- a/media/libstagefright/codecs/aacenc/AACEncoder.cpp
+++ b/media/libstagefright/codecs/aacenc/AACEncoder.cpp
@@ -208,6 +208,8 @@
     MediaBuffer *buffer;
     CHECK_EQ(mBufferGroup->acquire_buffer(&buffer), OK);
     uint8_t *outPtr = (uint8_t *)buffer->data();
+    bool readFromSource = false;
+    int64_t wallClockTimeUs = 0;
 
     if (mFrameCount == 0) {
         memcpy(outPtr, mAudioSpecificConfigData, 2);
@@ -238,9 +240,14 @@
             CHECK_EQ(align, 0);
 
             int64_t timeUs;
+            CHECK(mInputBuffer->meta_data()->findInt64(kKeyDriftTime, &timeUs));
+            wallClockTimeUs = timeUs;
             if (mInputBuffer->meta_data()->findInt64(kKeyTime, &timeUs)) {
                 mAnchorTimeUs = timeUs;
             }
+            readFromSource = true;
+        } else {
+            readFromSource = false;
         }
         size_t copy =
             (kNumSamplesPerFrame - mNumInputSamples) * sizeof(int16_t);
@@ -288,9 +295,13 @@
     CHECK(outputData.Length != 0);
     buffer->set_range(0, outputData.Length);
 
-    int64_t timestampUs = ((mFrameCount - 1) * 1000000LL * kNumSamplesPerFrame) / mSampleRate;
+    int64_t mediaTimeUs =
+        ((mFrameCount - 1) * 1000000LL * kNumSamplesPerFrame) / mSampleRate;
+    buffer->meta_data()->setInt64(kKeyTime, mAnchorTimeUs + mediaTimeUs);
+    if (readFromSource) {
+        buffer->meta_data()->setInt64(kKeyDriftTime, mediaTimeUs - wallClockTimeUs);
+    }
     ++mFrameCount;
-    buffer->meta_data()->setInt64(kKeyTime, timestampUs);
 
     *out = buffer;
     return OK;
diff --git a/media/libstagefright/codecs/amrnb/enc/AMRNBEncoder.cpp b/media/libstagefright/codecs/amrnb/enc/AMRNBEncoder.cpp
index c875426..dab1390 100644
--- a/media/libstagefright/codecs/amrnb/enc/AMRNBEncoder.cpp
+++ b/media/libstagefright/codecs/amrnb/enc/AMRNBEncoder.cpp
@@ -147,6 +147,8 @@
     int64_t seekTimeUs;
     ReadOptions::SeekMode mode;
     CHECK(options == NULL || !options->getSeekTo(&seekTimeUs, &mode));
+    bool readFromSource = false;
+    int64_t wallClockTimeUs = 0;
 
     while (mNumInputSamples < kNumSamplesPerFrame) {
         if (mInputBuffer == NULL) {
@@ -166,12 +168,16 @@
 
             size_t align = mInputBuffer->range_length() % sizeof(int16_t);
             CHECK_EQ(align, 0);
+            readFromSource = true;
 
             int64_t timeUs;
+            CHECK(mInputBuffer->meta_data()->findInt64(kKeyDriftTime, &timeUs));
+            wallClockTimeUs = timeUs;
             if (mInputBuffer->meta_data()->findInt64(kKeyTime, &timeUs)) {
                 mAnchorTimeUs = timeUs;
-                mNumFramesOutput = 0;
             }
+        } else {
+            readFromSource = false;
         }
 
         size_t copy =
@@ -217,8 +223,14 @@
     buffer->set_range(0, res);
 
     // Each frame of 160 samples is 20ms long.
+    int64_t mediaTimeUs = mNumFramesOutput * 20000LL;
     buffer->meta_data()->setInt64(
-            kKeyTime, mAnchorTimeUs + mNumFramesOutput * 20000);
+            kKeyTime, mAnchorTimeUs + mediaTimeUs);
+
+    if (readFromSource) {
+        buffer->meta_data()->setInt64(kKeyDriftTime,
+            mediaTimeUs - wallClockTimeUs);
+    }
 
     ++mNumFramesOutput;
 
diff --git a/media/libstagefright/codecs/amrwbenc/AMRWBEncoder.cpp b/media/libstagefright/codecs/amrwbenc/AMRWBEncoder.cpp
index 93304d0..b62eb5b 100644
--- a/media/libstagefright/codecs/amrwbenc/AMRWBEncoder.cpp
+++ b/media/libstagefright/codecs/amrwbenc/AMRWBEncoder.cpp
@@ -198,6 +198,8 @@
     int64_t seekTimeUs;
     ReadOptions::SeekMode mode;
     CHECK(options == NULL || !options->getSeekTo(&seekTimeUs, &mode));
+    bool readFromSource = false;
+    int64_t wallClockTimeUs = 0;
 
     while (mNumInputSamples < kNumSamplesPerFrame) {
         if (mInputBuffer == NULL) {
@@ -219,9 +221,14 @@
             CHECK_EQ(align, 0);
 
             int64_t timeUs;
+            CHECK(mInputBuffer->meta_data()->findInt64(kKeyDriftTime, &timeUs));
+            wallClockTimeUs = timeUs;
             if (mInputBuffer->meta_data()->findInt64(kKeyTime, &timeUs)) {
                 mAnchorTimeUs = timeUs;
             }
+            readFromSource = true;
+        } else {
+            readFromSource = false;
         }
 
         size_t copy =
@@ -276,10 +283,11 @@
     buffer->set_range(0, outputData.Length);
     ++mNumFramesOutput;
 
-    // XXX: fix timestamp calculation
-    int64_t timestampUs = mNumFramesOutput * 20000LL;
-
-    buffer->meta_data()->setInt64(kKeyTime, timestampUs);
+    int64_t mediaTimeUs = mNumFramesOutput * 20000LL;
+    buffer->meta_data()->setInt64(kKeyTime, mAnchorTimeUs + mediaTimeUs);
+    if (readFromSource) {
+        buffer->meta_data()->setInt64(kKeyDriftTime, mediaTimeUs - wallClockTimeUs);
+    }
 
     *out = buffer;
     return OK;