Revert 255166 "Cast: Using a min filter to compute time offset"

trunk/src/media/cast/video_receiver/video_receiver.cc

Index: trunk/src/media/cast/video_receiver/video_receiver.cc
===================================================================
--- trunk/src/media/cast/video_receiver/video_receiver.cc	(revision 255172)
+++ trunk/src/media/cast/video_receiver/video_receiver.cc	(working copy)
@@ -18,8 +18,8 @@
 namespace {
 
 static const int64 kMinSchedulingDelayMs = 1;
-static const int64 kMinTimeBetweenOffsetUpdatesMs = 1000;
-static const int kTimeOffsetMaxCounter = 10;
+static const int64 kMinTimeBetweenOffsetUpdatesMs = 2000;
+static const int kTimeOffsetFilter = 8;
 static const int64_t kMinProcessIntervalMs = 5;
 
 }  // namespace
@@ -107,7 +107,6 @@
                     incoming_payload_callback_.get()),
       rtp_video_receiver_statistics_(
           new LocalRtpReceiverStatistics(&rtp_receiver_)),
-      time_offset_counter_(0),
       decryptor_(),
       time_incoming_packet_updated_(false),
       incoming_rtp_timestamp_(0),
@@ -357,7 +356,7 @@
   base::TimeTicks rtp_timestamp_in_ticks;
 
   // Compute the time offset_in_ticks based on the incoming_rtp_timestamp_.
-  if (time_offset_counter_ == 0) {
+  if (time_offset_.InMilliseconds() == 0) {
     if (!rtcp_->RtpTimestampInSenderTime(kVideoFrequency,
                                          incoming_rtp_timestamp_,
                                          &rtp_timestamp_in_ticks)) {
@@ -365,8 +364,7 @@
       // possible.
       return now;
     }
-    ++time_offset_counter_;
-    return now;
+    time_offset_ = time_incoming_packet_ - rtp_timestamp_in_ticks;
   } else if (time_incoming_packet_updated_) {
     if (rtcp_->RtpTimestampInSenderTime(kVideoFrequency,
                                         incoming_rtp_timestamp_,
@@ -374,16 +372,8 @@
       // Time to update the time_offset.
       base::TimeDelta time_offset =
           time_incoming_packet_ - rtp_timestamp_in_ticks;
-      // Taking the minimum of the first kTimeOffsetMaxCounter values. We are
-      // assuming that we are looking for the minimum offset, which will occur
-      // when network conditions are the best. This should occur at least once
-      // within the first kTimeOffsetMaxCounter samples. Any drift should be
-      // very slow, and negligible for this use case.
-      if (time_offset_counter_ == 1)
-        time_offset_ = time_offset;
-      else if (time_offset_counter_  < kTimeOffsetMaxCounter)
-        time_offset_ = std::min(time_offset_, time_offset);
-      ++time_offset_counter_;
+      time_offset_ = ((kTimeOffsetFilter - 1) * time_offset_ + time_offset) /
+                     kTimeOffsetFilter;
     }
   }
   // Reset |time_incoming_packet_updated_| to enable a future measurement.