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

media/cast/audio_sender/audio_sender.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/cast/audio_sender/audio_sender.h"
 
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/message_loop/message_loop.h"
 #include "media/cast/audio_sender/audio_encoder.h"
@@ skipping 88 matching lines @@
   }
 
   frame_id_to_rtp_timestamp_[audio_frame->frame_id & 0xff] =
       audio_frame->rtp_timestamp;
   transport_sender_->InsertCodedAudioFrame(*audio_frame);
 }
 
 void AudioSender::ResendPackets(
     const MissingFramesAndPacketsMap& missing_frames_and_packets) {
   DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
-  transport_sender_->ResendPackets(true, missing_frames_and_packets, false);
+
+  base::TimeDelta rtt;
+  base::TimeDelta avg_rtt;
+  base::TimeDelta min_rtt;
+  base::TimeDelta max_rtt;
+  rtcp_.Rtt(&rtt, &avg_rtt, &min_rtt, &max_rtt);
+
+  // It would probably be better to use the 10% percentile rtt
+  // rather than the min.
+  transport_sender_->ResendPackets(
+      true, missing_frames_and_packets, false, min_rtt);

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

In VideoSender we used rtt and avg_rtt while min_rtt is used here. They should
be consistent.

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

Done.

 }
 
 void AudioSender::IncomingRtcpPacket(scoped_ptr<Packet> packet) {
   DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
   rtcp_.IncomingRtcpPacket(&packet->front(), packet->size());
 }
 
 void AudioSender::ScheduleNextRtcpReport() {
   DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
   base::TimeDelta time_to_next =
@@ skipping 47 matching lines @@
   uint32 acked_frame_id = static_cast<uint32>(cast_feedback.ack_frame_id_);
   VLOG(2) << "Received audio ACK: " << acked_frame_id;
   cast_environment_->Logging()->InsertFrameEvent(
         cast_environment_->Clock()->NowTicks(),
         FRAME_ACK_RECEIVED, AUDIO_EVENT,
         frame_id_to_rtp_timestamp_[acked_frame_id & 0xff], acked_frame_id);
 }
 
 }  // namespace cast
 }  // namespace media