Cast: Avoid retransmit if we sent the same packet recently (less than RTT)

media/cast/video_sender/video_sender.cc

Index: media/cast/video_sender/video_sender.cc
diff --git a/media/cast/video_sender/video_sender.cc b/media/cast/video_sender/video_sender.cc
index cc8b158950ee871e0716fb28549d6781b097c267..03a29c556a47a6b9ca7c4d44aa5be75c88734717 100644
--- a/media/cast/video_sender/video_sender.cc
+++ b/media/cast/video_sender/video_sender.cc
@@ -321,7 +321,7 @@ void VideoSender::OnReceivedCastFeedback(const RtcpCastMessage& cast_feedback) {
 
     // A NACK is also used to cancel pending re-transmissions.
     transport_sender_->ResendPackets(
-        false, cast_feedback.missing_frames_and_packets_, true);
+        false, cast_feedback.missing_frames_and_packets_, true, rtt);
   }
 
   base::TimeTicks now = cast_environment_->Clock()->NowTicks();
@@ -348,7 +348,8 @@ void VideoSender::OnReceivedCastFeedback(const RtcpCastMessage& cast_feedback) {
       latest_acked_frame_id_++;
       missing_frames_and_packets[latest_acked_frame_id_] = missing;
     }
-    transport_sender_->ResendPackets(false, missing_frames_and_packets, true);
+    transport_sender_->ResendPackets(
+        false, missing_frames_and_packets, true, rtt);
     latest_acked_frame_id_ = cast_feedback.ack_frame_id_;
   }
 }
@@ -382,10 +383,16 @@ void VideoSender::ResendForKickstart() {
       std::make_pair(last_sent_frame_id_, missing));
   last_send_time_ = cast_environment_->Clock()->NowTicks();
 
+  base::TimeDelta rtt;
+  base::TimeDelta avg_rtt;
+  base::TimeDelta min_rtt;
+  base::TimeDelta max_rtt;
+  rtcp_.Rtt(&rtt, &avg_rtt, &min_rtt, &max_rtt);
+
   // Sending this extra packet is to kick-start the session. There is
   // no need to optimize re-transmission for this case.
   transport_sender_->ResendPackets(false, missing_frames_and_packets,
-                                   false);
+                                   false, avg_rtt);

[Alpha Left Google, 2014/06/18 01:43:32]

We use rtt in other places why using avg_rtt here?

[hubbe, 2014/06/18 20:22:28]

Done.

 }
 
 }  // namespace cast