Cast: reduce the amount of retransmission packets

media/cast/video_sender/video_sender_unittest.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 <stdint.h>
 
 #include <vector>
 
 #include "base/bind.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 299 matching lines @@
   EXPECT_EQ(VIDEO_EVENT, frame_events.rbegin()->media_type);
   EXPECT_EQ(num_frames - 1u, frame_events.rbegin()->frame_id);
 
   cast_environment_->Logging()->RemoveRawEventSubscriber(&event_subscriber);
 }
 
 TEST_F(VideoSenderTest, StopSendingInTheAbsenceOfAck) {
   InitEncoder(false);
   // Send a stream of frames and don't ACK; by default we shouldn't have more
   // than 4 frames in flight.
-  // Store size in packets of frame 0, as it should be resent sue to timeout.
   scoped_refptr<media::VideoFrame> video_frame = GetNewVideoFrame();
   video_sender_->InsertRawVideoFrame(video_frame, testing_clock_->NowTicks());
   RunTasks(33);
-  const int size_of_frame0 = transport_.number_of_rtp_packets();
 
-  for (int i = 1; i < 4; ++i) {
+  // Send 3 more frames and record the number of packets sent.
+  for (int i = 0; i < 3; ++i) {
     scoped_refptr<media::VideoFrame> video_frame = GetNewVideoFrame();
     video_sender_->InsertRawVideoFrame(video_frame, testing_clock_->NowTicks());
     RunTasks(33);
   }
+  const int number_of_packets_sent = transport_.number_of_rtp_packets();
 
-  const int number_of_packets_sent = transport_.number_of_rtp_packets();
-  // Send 4 more frames - they should not be sent to the transport, as we have
-  // received any acks.
+  // Send 3 more frames - they should not be encoded, as we have not received
+  // any acks.
   for (int i = 0; i < 3; ++i) {
     scoped_refptr<media::VideoFrame> video_frame = GetNewVideoFrame();
     video_sender_->InsertRawVideoFrame(video_frame, testing_clock_->NowTicks());
     RunTasks(33);
   }
 
-  EXPECT_EQ(number_of_packets_sent + size_of_frame0,
+  // We expect a frame to be retransmitted because of duplicated ACKs.
+  // Only one packet of the frame is re-transmitted.
+  EXPECT_EQ(number_of_packets_sent + 1,
             transport_.number_of_rtp_packets());
 
   // Start acking and make sure we're back to steady-state.
   RtcpCastMessage cast_feedback(1);
   cast_feedback.media_ssrc_ = 2;
   cast_feedback.ack_frame_id_ = 0;
   video_sender_->OnReceivedCastFeedback(cast_feedback);
   EXPECT_LE(
       4,
       transport_.number_of_rtp_packets() + transport_.number_of_rtcp_packets());
 
   // Empty the pipeline.
   RunTasks(100);
   // Should have sent at least 7 packets.
   EXPECT_LE(
       7,
       transport_.number_of_rtp_packets() + transport_.number_of_rtcp_packets());
 }
 
+TEST_F(VideoSenderTest, DuplicateAckRetransmit) {
+  InitEncoder(false);
+  scoped_refptr<media::VideoFrame> video_frame = GetNewVideoFrame();
+  video_sender_->InsertRawVideoFrame(video_frame, testing_clock_->NowTicks());
+  RunTasks(33);
+  RtcpCastMessage cast_feedback(1);
+  cast_feedback.media_ssrc_ = 2;
+  cast_feedback.ack_frame_id_ = 0;
+
+  // Send 3 more frames but don't ACK.
+  for (int i = 0; i < 3; ++i) {
+    scoped_refptr<media::VideoFrame> video_frame = GetNewVideoFrame();
+    video_sender_->InsertRawVideoFrame(video_frame, testing_clock_->NowTicks());
+    RunTasks(33);
+  }
+  const int number_of_packets_sent = transport_.number_of_rtp_packets();
+
+  // Send duplicated ACKs and mix some invalid NACKs.
+  for (int i = 0; i < 10; ++i) {
+    RtcpCastMessage ack_feedback(1);
+    ack_feedback.media_ssrc_ = 2;
+    ack_feedback.ack_frame_id_ = 0;
+    RtcpCastMessage nack_feedback(1);
+    nack_feedback.media_ssrc_ = 2;
+    nack_feedback.missing_frames_and_packets_[255] = PacketIdSet();
+    video_sender_->OnReceivedCastFeedback(ack_feedback);
+    video_sender_->OnReceivedCastFeedback(nack_feedback);
+  }
+  EXPECT_EQ(number_of_packets_sent, transport_.number_of_rtp_packets());
+
+  // Re-transmit one packet because of duplicated ACKs.
+  for (int i = 0; i < 3; ++i) {
+    RtcpCastMessage ack_feedback(1);
+    ack_feedback.media_ssrc_ = 2;
+    ack_feedback.ack_frame_id_ = 0;
+    video_sender_->OnReceivedCastFeedback(ack_feedback);
+  }
+  EXPECT_EQ(number_of_packets_sent + 1, transport_.number_of_rtp_packets());
+}
+
 }  // namespace cast
 }  // namespace media