--- a/liveMedia/RTPSource.cpp	2008-06-23 13:55:51.000000000 -0400
+++ b/liveMedia/RTPSource.cpp	2008-06-24 07:43:45.000000000 -0400
@@ -363,12 +363,54 @@
 
   gettimeofday(&fLastReceivedSR_time, NULL);
 
-  // Use this SR to update time synchronization information:
-  fSyncTimestamp = rtpTimestamp;
-  fSyncTime.tv_sec = ntpTimestampMSW - 0x83AA7E80; // 1/1/1900 -> 1/1/1970
-  double microseconds = (ntpTimestampLSW*15625.0)/0x04000000; // 10^6/2^32
-  fSyncTime.tv_usec = (unsigned)(microseconds+0.5);
-  fHasBeenSynchronized = True;
+  struct timeval delta, newSyncTime, normalized;
+
+
+  int timestampDiff = rtpTimestamp - fSyncTimestamp;
+  if (rtpTimestamp >= 0 && (ntpTimestampMSW || ntpTimestampLSW)) {
+    // Normalize the last Sync time since there has been a delay since it was
+    // last recorded
+    double timeDiff
+      = timestampDiff/(double)(fOurRTPSource.timestampFrequency());
+  
+    normalized.tv_sec = fSyncTime.tv_sec + (unsigned)timeDiff;
+    normalized.tv_usec = fSyncTime.tv_usec +
+                         (unsigned)((timeDiff - (unsigned)timeDiff)*MILLION);
+    if (normalized.tv_usec >= MILLION) {
+      normalized.tv_usec -= MILLION;
+      ++normalized.tv_sec;
+    }
+
+    // Convert the NTP Timestamp into a UNIX epoch timeval
+    newSyncTime.tv_sec = ntpTimestampMSW - 0x83AA7E80; // 1/1/1900 -> 1/1/1970
+    double microseconds = (ntpTimestampLSW*15625.0)/0x04000000; // 10^6/2^32
+    newSyncTime.tv_usec = (unsigned)(microseconds+0.5);
+  
+    // Compare the last synchronized time to the new NTP time
+    delta.tv_sec = newSyncTime.tv_sec - normalized.tv_sec;
+    delta.tv_usec = newSyncTime.tv_usec - normalized.tv_usec;
+    if (delta.tv_usec < 0) {
+      delta.tv_sec--;
+      delta.tv_usec += MILLION;
+    }
+  
+    // We need to limit how far we're willing to adjust an already established
+    // clock in the name of synchronization. Decreasing the time may cause the
+    // receiver to reject new "old" packets. Increasing the time may result in
+    // an equivalent delay in playback.
+    //
+    // The sender is not even required to send a NTP timestamp derived from NTP
+    // or any other accurate clock. Some cameras will derive their timestamp as
+    // time since boot up which works out to some time in the early 1970s.
+#define	MAX_SR_TIME_SKEW	5	// Clocks must be within 5s to sync
+    if ((fSyncTime.tv_sec == 0 && fSyncTime.tv_usec == 0) ||
+        abs(delta.tv_sec) < MAX_SR_TIME_SKEW) {
+      // Use this SR to update time synchronization information:
+      fSyncTimestamp = rtpTimestamp;
+      fSyncTime = newSyncTime;
+      fHasBeenSynchronized = True;
+    }
+  }
 }
 
 double RTPReceptionStats::totNumKBytesReceived() const {