Reset InterArrival if arrival time clock makes a jump.

webrtc/modules/congestion_controller/delay_based_bwe_unittest.cc

 /*
  *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
+#include "testing/gtest/include/gtest/gtest.h"
+#include "webrtc/base/constructormagic.h"
+#include "webrtc/modules/pacing/paced_sender.h"
 #include "webrtc/modules/congestion_controller/delay_based_bwe.h"

[philipel, 2016/07/06 13:36:36]

Move to top

[stefan-webrtc, 2016/07/06 14:53:24]

I don't think it should be at the top since this isn't the .cc file of the .h
file. 

[philipel, 2016/07/07 08:11:38]

Right, my bad.

-
-#include "testing/gtest/include/gtest/gtest.h"
-#include "webrtc/modules/pacing/paced_sender.h"
+#include "webrtc/modules/congestion_controller/delay_based_bwe_unittest_helper.h"
 #include "webrtc/system_wrappers/include/clock.h"
 
 namespace webrtc {
 
 class TestDelayBasedBwe : public ::testing::Test, public RemoteBitrateObserver {
  public:
   static constexpr int kArrivalTimeClockOffsetMs = 60000;
   static constexpr int kNumProbes = 5;

[philipel, 2016/07/06 13:36:36]

Move both constexpr to namespace {...} and drop static.

[stefan-webrtc, 2016/07/06 14:53:24]

Done.

 
   TestDelayBasedBwe()
-      : bwe_(this), clock_(0), bitrate_updated_(false), latest_bitrate_(0) {}
+      : clock_(0),
+        bwe_(this, &clock_),
+        bitrate_updated_(false),
+        latest_bitrate_(0) {}
 
   uint32_t AbsSendTime(int64_t t, int64_t denom) {

[philipel, 2016/07/06 13:36:36]

Remove, since it's not used anymore.

[stefan-webrtc, 2016/07/06 14:53:24]

Done.

     return (((t << 18) + (denom >> 1)) / denom) & 0x00fffffful;
   }
 
-  void IncomingPacket(uint32_t ssrc,
+  void IncomingPacket(int64_t arrival_time,

[philipel, 2016/07/06 13:36:36]

Rename to AddPacketInfo or IncomingFeedback or something like that.

[stefan-webrtc, 2016/07/06 14:53:24]

Done.

+                      int64_t send_time_ms,

[philipel, 2016/07/06 13:36:36]

|arrival_time| -> |arrival_time_ms|

Nit: don't you think it would make more sense to have send_time_ms before
arrival_time_ms?

[stefan-webrtc, 2016/07/06 14:53:24]

Done.
Maybe, but this matches the class we're testing, so I'll keep as is for now.

+                      uint16_t sequence_number,
                       size_t payload_size,
-                      int64_t arrival_time,
-                      uint32_t rtp_timestamp,
-                      uint32_t absolute_send_time,
                       int probe_cluster_id) {
-    RTPHeader header;
-    memset(&header, 0, sizeof(header));
-    header.ssrc = ssrc;
-    header.timestamp = rtp_timestamp;
-    header.extension.hasAbsoluteSendTime = true;
-    header.extension.absoluteSendTime = absolute_send_time;
-    bwe_.IncomingPacket(arrival_time + kArrivalTimeClockOffsetMs, payload_size,
-                        header, probe_cluster_id);
+    std::vector<PacketInfo> packets;
+    packets.push_back(PacketInfo(arrival_time + kArrivalTimeClockOffsetMs,
+                                 send_time_ms, sequence_number, payload_size,

[philipel, 2016/07/06 13:36:36]

Sequence number is not used by delay_based_bwe, set it to 0 and remove the
|sequence_number| argument.

[stefan-webrtc, 2016/07/06 14:53:24]

I don't know, it seems like a good idea to pass in a valid sequence number if we
in the future actually decide to use it? Not too much code related to it.

[philipel, 2016/07/07 08:11:38]

That makes sense.

+                                 probe_cluster_id));
+    bwe_.IncomingPacketFeedbackVector(packets);
   }
 
   void OnReceiveBitrateChanged(const std::vector<uint32_t>& ssrcs,
                                uint32_t bitrate) {
     bitrate_updated_ = true;
     latest_bitrate_ = bitrate;
   }
 
   bool bitrate_updated() {
     bool res = bitrate_updated_;
     bitrate_updated_ = false;
     return res;
   }
 
   int latest_bitrate() { return latest_bitrate_; }
 
+ protected:
+  SimulatedClock clock_;
   DelayBasedBwe bwe_;
-  SimulatedClock clock_;
 
  private:
   bool bitrate_updated_;
   int latest_bitrate_;
 };
 
 TEST_F(TestDelayBasedBwe, ProbeDetection) {
   int64_t now_ms = clock_.TimeInMilliseconds();
+  uint16_t seq_num = 0;
 
   // First burst sent at 8 * 1000 / 10 = 800 kbps.
   for (int i = 0; i < kNumProbes; ++i) {
     clock_.AdvanceTimeMilliseconds(10);
     now_ms = clock_.TimeInMilliseconds();
-    IncomingPacket(0, 1000, now_ms, 90 * now_ms, AbsSendTime(now_ms, 1000), 0);
+    IncomingPacket(now_ms, now_ms, seq_num++, 1000, 1);

[philipel, 2016/07/06 13:36:36]

Note: 0 is a valid probe cluster id.

[stefan-webrtc, 2016/07/06 14:53:24]

Yes, I happened to change it because I thought it wasn't, but then realized what
was really wrong... Changing back.

   }
   EXPECT_TRUE(bitrate_updated());
 
   // Second burst sent at 8 * 1000 / 5 = 1600 kbps.
   for (int i = 0; i < kNumProbes; ++i) {
     clock_.AdvanceTimeMilliseconds(5);
     now_ms = clock_.TimeInMilliseconds();
-    IncomingPacket(0, 1000, now_ms, 90 * now_ms, AbsSendTime(now_ms, 1000), 1);
+    IncomingPacket(now_ms, now_ms, seq_num++, 1000, 2);
   }
 
   EXPECT_TRUE(bitrate_updated());
   EXPECT_GT(latest_bitrate(), 1500000);
 }
 
 TEST_F(TestDelayBasedBwe, ProbeDetectionNonPacedPackets) {
   int64_t now_ms = clock_.TimeInMilliseconds();
+  uint16_t seq_num = 0;
   // First burst sent at 8 * 1000 / 10 = 800 kbps, but with every other packet
   // not being paced which could mess things up.
   for (int i = 0; i < kNumProbes; ++i) {
     clock_.AdvanceTimeMilliseconds(5);
     now_ms = clock_.TimeInMilliseconds();
-    IncomingPacket(0, 1000, now_ms, 90 * now_ms, AbsSendTime(now_ms, 1000), 0);
+    IncomingPacket(now_ms, now_ms, seq_num++, 1000, 1);
     // Non-paced packet, arriving 5 ms after.
     clock_.AdvanceTimeMilliseconds(5);
-    IncomingPacket(0, PacedSender::kMinProbePacketSize + 1, now_ms, 90 * now_ms,
-                   AbsSendTime(now_ms, 1000), PacketInfo::kNotAProbe);
+    IncomingPacket(now_ms, now_ms, seq_num++,
+                   PacedSender::kMinProbePacketSize + 1,
+                   PacketInfo::kNotAProbe);
   }
 
   EXPECT_TRUE(bitrate_updated());
   EXPECT_GT(latest_bitrate(), 800000);
 }
 
 // Packets will require 5 ms to be transmitted to the receiver, causing packets
 // of the second probe to be dispersed.
 TEST_F(TestDelayBasedBwe, ProbeDetectionTooHighBitrate) {
   int64_t now_ms = clock_.TimeInMilliseconds();
   int64_t send_time_ms = 0;
+  uint16_t seq_num = 0;
   // First burst sent at 8 * 1000 / 10 = 800 kbps.
   for (int i = 0; i < kNumProbes; ++i) {
     clock_.AdvanceTimeMilliseconds(10);
     now_ms = clock_.TimeInMilliseconds();
     send_time_ms += 10;
-    IncomingPacket(0, 1000, now_ms, 90 * send_time_ms,
-                   AbsSendTime(send_time_ms, 1000), 0);
+    IncomingPacket(now_ms, send_time_ms, seq_num++, 1000, 1);
   }
 
   // Second burst sent at 8 * 1000 / 5 = 1600 kbps, arriving at 8 * 1000 / 8 =
   // 1000 kbps.
   for (int i = 0; i < kNumProbes; ++i) {
     clock_.AdvanceTimeMilliseconds(8);
     now_ms = clock_.TimeInMilliseconds();
     send_time_ms += 5;
-    IncomingPacket(0, 1000, now_ms, send_time_ms,
-                   AbsSendTime(send_time_ms, 1000), 1);
+    IncomingPacket(now_ms, send_time_ms, seq_num++, 1000, 2);
   }
 
   EXPECT_TRUE(bitrate_updated());
   EXPECT_NEAR(latest_bitrate(), 800000, 10000);
 }
 
 TEST_F(TestDelayBasedBwe, ProbeDetectionSlightlyFasterArrival) {
   int64_t now_ms = clock_.TimeInMilliseconds();
+  uint16_t seq_num = 0;
   // First burst sent at 8 * 1000 / 10 = 800 kbps.
   // Arriving at 8 * 1000 / 5 = 1600 kbps.
   int64_t send_time_ms = 0;
   for (int i = 0; i < kNumProbes; ++i) {
     clock_.AdvanceTimeMilliseconds(5);
     send_time_ms += 10;
     now_ms = clock_.TimeInMilliseconds();
-    IncomingPacket(0, 1000, now_ms, 90 * send_time_ms,
-                   AbsSendTime(send_time_ms, 1000), 23);
+    IncomingPacket(now_ms, send_time_ms, seq_num++, 1000, 23);
   }
 
   EXPECT_TRUE(bitrate_updated());
   EXPECT_GT(latest_bitrate(), 800000);
 }
 
 TEST_F(TestDelayBasedBwe, ProbeDetectionFasterArrival) {
   int64_t now_ms = clock_.TimeInMilliseconds();
+  uint16_t seq_num = 0;
   // First burst sent at 8 * 1000 / 10 = 800 kbps.
   // Arriving at 8 * 1000 / 5 = 1600 kbps.
   int64_t send_time_ms = 0;
   for (int i = 0; i < kNumProbes; ++i) {
     clock_.AdvanceTimeMilliseconds(1);
     send_time_ms += 10;
     now_ms = clock_.TimeInMilliseconds();
-    IncomingPacket(0, 1000, now_ms, 90 * send_time_ms,
-                   AbsSendTime(send_time_ms, 1000), 0);
+    IncomingPacket(now_ms, send_time_ms, seq_num++, 1000, 1);
   }
 
   EXPECT_FALSE(bitrate_updated());
 }
 
 TEST_F(TestDelayBasedBwe, ProbeDetectionSlowerArrival) {
   int64_t now_ms = clock_.TimeInMilliseconds();
+  uint16_t seq_num = 0;
   // First burst sent at 8 * 1000 / 5 = 1600 kbps.
   // Arriving at 8 * 1000 / 7 = 1142 kbps.
   int64_t send_time_ms = 0;
   for (int i = 0; i < kNumProbes; ++i) {
     clock_.AdvanceTimeMilliseconds(7);
     send_time_ms += 5;
     now_ms = clock_.TimeInMilliseconds();
-    IncomingPacket(0, 1000, now_ms, 90 * send_time_ms,
-                   AbsSendTime(send_time_ms, 1000), 1);
+    IncomingPacket(now_ms, send_time_ms, seq_num++, 1000, 1);
   }
 
   EXPECT_TRUE(bitrate_updated());
   EXPECT_NEAR(latest_bitrate(), 1140000, 10000);
 }
 
 TEST_F(TestDelayBasedBwe, ProbeDetectionSlowerArrivalHighBitrate) {
   int64_t now_ms = clock_.TimeInMilliseconds();
+  uint16_t seq_num = 0;
   // Burst sent at 8 * 1000 / 1 = 8000 kbps.
   // Arriving at 8 * 1000 / 2 = 4000 kbps.
   int64_t send_time_ms = 0;
   for (int i = 0; i < kNumProbes; ++i) {
     clock_.AdvanceTimeMilliseconds(2);
     send_time_ms += 1;
     now_ms = clock_.TimeInMilliseconds();
-    IncomingPacket(0, 1000, now_ms, 90 * send_time_ms,
-                   AbsSendTime(send_time_ms, 1000), 1);
+    IncomingPacket(now_ms, send_time_ms, seq_num++, 1000, 1);
   }
 
   EXPECT_TRUE(bitrate_updated());
   EXPECT_NEAR(latest_bitrate(), 4000000u, 10000);
 }
 
 TEST_F(TestDelayBasedBwe, ProbingIgnoresSmallPackets) {
   int64_t now_ms = clock_.TimeInMilliseconds();
+  uint16_t seq_num = 0;
   // Probing with 200 bytes every 10 ms, should be ignored by the probe
   // detection.
   for (int i = 0; i < kNumProbes; ++i) {
     clock_.AdvanceTimeMilliseconds(10);
     now_ms = clock_.TimeInMilliseconds();
-    IncomingPacket(0, PacedSender::kMinProbePacketSize, now_ms, 90 * now_ms,
-                   AbsSendTime(now_ms, 1000), 1);
+    IncomingPacket(now_ms, now_ms, seq_num++, PacedSender::kMinProbePacketSize,
+                   1);
   }
 
   EXPECT_FALSE(bitrate_updated());
 
   // Followed by a probe with 1000 bytes packets, should be detected as a
   // probe.
   for (int i = 0; i < kNumProbes; ++i) {
     clock_.AdvanceTimeMilliseconds(10);
     now_ms = clock_.TimeInMilliseconds();
-    IncomingPacket(0, 1000, now_ms, 90 * now_ms, AbsSendTime(now_ms, 1000), 1);
+    IncomingPacket(now_ms, now_ms, seq_num++, 1000, 1);
   }
 
   // Wait long enough so that we can call Process again.
   clock_.AdvanceTimeMilliseconds(1000);
 
   EXPECT_TRUE(bitrate_updated());
   EXPECT_NEAR(latest_bitrate(), 800000u, 10000);
 }
+
+TEST_F(DelayBasedBweTest, InitialBehavior) {
+  InitialBehaviorTestHelper(674840);
+}
+
+TEST_F(DelayBasedBweTest, RateIncreaseReordering) {
+  RateIncreaseReorderingTestHelper(674840);
+}
+
+TEST_F(DelayBasedBweTest, RateIncreaseRtpTimestamps) {
+  RateIncreaseRtpTimestampsTestHelper(1240);
+}
+
+TEST_F(DelayBasedBweTest, CapacityDropOneStream) {
+  CapacityDropTestHelper(1, false, 633, 0);
+}
+
+TEST_F(DelayBasedBweTest, CapacityDropPosOffsetChange) {
+  CapacityDropTestHelper(1, false, 200, 30000);
+}
+
+TEST_F(DelayBasedBweTest, CapacityDropNegOffsetChange) {
+  CapacityDropTestHelper(1, false, 733, -30000);
+}
+
+TEST_F(DelayBasedBweTest, CapacityDropOneStreamWrap) {
+  CapacityDropTestHelper(1, true, 633, 0);
+}
+
+TEST_F(DelayBasedBweTest, CapacityDropTwoStreamsWrap) {
+  CapacityDropTestHelper(2, true, 567, 0);
+}
+
+TEST_F(DelayBasedBweTest, CapacityDropThreeStreamsWrap) {
+  CapacityDropTestHelper(3, true, 633, 0);
+}
+
+TEST_F(DelayBasedBweTest, CapacityDropThirteenStreamsWrap) {
+  CapacityDropTestHelper(13, true, 733, 0);
+}
+
+TEST_F(DelayBasedBweTest, CapacityDropNineteenStreamsWrap) {
+  CapacityDropTestHelper(19, true, 667, 0);
+}
+
+TEST_F(DelayBasedBweTest, CapacityDropThirtyStreamsWrap) {
+  CapacityDropTestHelper(30, true, 667, 0);
+}
+
+TEST_F(DelayBasedBweTest, TestTimestampGrouping) {
+  TestTimestampGroupingTestHelper();
+}
+
+TEST_F(DelayBasedBweTest, TestShortTimeoutAndWrap) {
+  // Simulate a client leaving and rejoining the call after 35 seconds. This
+  // will make abs send time wrap, so if streams aren't timed out properly
+  // the next 30 seconds of packets will be out of order.
+  TestWrappingHelper(35);
+}
+
+TEST_F(DelayBasedBweTest, TestLongTimeoutAndWrap) {
+  // Simulate a client leaving and rejoining the call after some multiple of
+  // 64 seconds later. This will cause a zero difference in abs send times due
+  // to the wrap, but a big difference in arrival time, if streams aren't
+  // properly timed out.
+  TestWrappingHelper(10 * 64);
+}
+
+TEST_F(DelayBasedBweTest, TestProcessAfterTimeout) {
+  // This time constant must be equal to the ones defined for the
+  // RemoteBitrateEstimator.
+  const int64_t kStreamTimeOutMs = 2000;
+  const int64_t kProcessIntervalMs = 1000;
+  IncomingPacket(1000, clock_.TimeInMilliseconds(), 0, 0);
+  clock_.AdvanceTimeMilliseconds(kStreamTimeOutMs + 1);
+  // Trigger timeout.
+  bitrate_estimator_->Process();
+  clock_.AdvanceTimeMilliseconds(kProcessIntervalMs);
+  // This shouldn't crash.
+  bitrate_estimator_->Process();
+}
+
+TEST_F(DelayBasedBweTest, TestProbeDetection) {
+  const int kProbeLength = 5;
+  int64_t now_ms = clock_.TimeInMilliseconds();
+  uint16_t sequence_number = 0;
+  // First burst sent at 8 * 1000 / 10 = 800 kbps.
+  for (int i = 0; i < kProbeLength; ++i) {
+    clock_.AdvanceTimeMilliseconds(10);
+    now_ms = clock_.TimeInMilliseconds();
+    IncomingPacket(1000, now_ms, now_ms, sequence_number++, 1);
+  }
+
+  // Second burst sent at 8 * 1000 / 5 = 1600 kbps.
+  for (int i = 0; i < kProbeLength; ++i) {
+    clock_.AdvanceTimeMilliseconds(5);
+    now_ms = clock_.TimeInMilliseconds();
+    IncomingPacket(1000, now_ms, now_ms, sequence_number++, 2);
+  }
+
+  bitrate_estimator_->Process();
+  EXPECT_TRUE(bitrate_observer_->updated());
+  EXPECT_GT(bitrate_observer_->latest_bitrate(), 1500000u);
+}
+
+TEST_F(DelayBasedBweTest, TestProbeDetectionNonPacedPackets) {
+  const int kProbeLength = 5;
+  int64_t now_ms = clock_.TimeInMilliseconds();
+  uint16_t sequence_number = 0;
+  // First burst sent at 8 * 1000 / 10 = 800 kbps, but with every other packet
+  // not being paced which could mess things up.
+  for (int i = 0; i < kProbeLength; ++i) {
+    clock_.AdvanceTimeMilliseconds(5);
+    now_ms = clock_.TimeInMilliseconds();
+    IncomingPacket(1000, now_ms, now_ms, sequence_number++, 1);
+    // Non-paced packet, arriving 5 ms after.
+    clock_.AdvanceTimeMilliseconds(5);
+    IncomingPacket(100, now_ms, now_ms, sequence_number++,
+                   PacketInfo::kNotAProbe);
+  }
+
+  bitrate_estimator_->Process();
+  EXPECT_TRUE(bitrate_observer_->updated());
+  EXPECT_GT(bitrate_observer_->latest_bitrate(), 800000u);
+}
+
+// Packets will require 5 ms to be transmitted to the receiver, causing packets
+// of the second probe to be dispersed.
+TEST_F(DelayBasedBweTest, TestProbeDetectionTooHighBitrate) {
+  const int kProbeLength = 5;
+  int64_t now_ms = clock_.TimeInMilliseconds();
+  int64_t send_time_ms = 0;
+  uint16_t sequence_number = 0;
+  // First burst sent at 8 * 1000 / 10 = 800 kbps.
+  for (int i = 0; i < kProbeLength; ++i) {
+    clock_.AdvanceTimeMilliseconds(10);
+    now_ms = clock_.TimeInMilliseconds();
+    send_time_ms += 10;
+    IncomingPacket(1000, now_ms, send_time_ms, sequence_number++, 1);
+  }
+
+  // Second burst sent at 8 * 1000 / 5 = 1600 kbps, arriving at 8 * 1000 / 8 =
+  // 1000 kbps.
+  for (int i = 0; i < kProbeLength; ++i) {
+    clock_.AdvanceTimeMilliseconds(8);
+    now_ms = clock_.TimeInMilliseconds();
+    send_time_ms += 5;
+    IncomingPacket(1000, now_ms, send_time_ms, sequence_number++, 2);
+  }
+
+  bitrate_estimator_->Process();
+  EXPECT_TRUE(bitrate_observer_->updated());
+  EXPECT_NEAR(bitrate_observer_->latest_bitrate(), 800000u, 10000);
+}
+
+TEST_F(DelayBasedBweTest, TestProbeDetectionSlightlyFasterArrival) {
+  const int kProbeLength = 5;
+  int64_t now_ms = clock_.TimeInMilliseconds();
+  uint16_t sequence_number = 0;
+  // First burst sent at 8 * 1000 / 10 = 800 kbps.
+  // Arriving at 8 * 1000 / 5 = 1600 kbps.
+  int64_t send_time_ms = 0;
+  for (int i = 0; i < kProbeLength; ++i) {
+    clock_.AdvanceTimeMilliseconds(5);
+    send_time_ms += 10;
+    now_ms = clock_.TimeInMilliseconds();
+    IncomingPacket(1000, now_ms, send_time_ms, sequence_number++, 1);
+  }
+
+  bitrate_estimator_->Process();
+  EXPECT_TRUE(bitrate_observer_->updated());
+  EXPECT_GT(bitrate_observer_->latest_bitrate(), 800000u);
+}
+
+TEST_F(DelayBasedBweTest, TestProbeDetectionFasterArrival) {
+  const int kProbeLength = 5;
+  int64_t now_ms = clock_.TimeInMilliseconds();
+  uint16_t sequence_number = 0;
+  // First burst sent at 8 * 1000 / 10 = 800 kbps.
+  // Arriving at 8 * 1000 / 5 = 1600 kbps.
+  int64_t send_time_ms = 0;
+  for (int i = 0; i < kProbeLength; ++i) {
+    clock_.AdvanceTimeMilliseconds(1);
+    send_time_ms += 10;
+    now_ms = clock_.TimeInMilliseconds();
+    IncomingPacket(1000, now_ms, send_time_ms, sequence_number++, 1);
+  }
+
+  bitrate_estimator_->Process();
+  EXPECT_FALSE(bitrate_observer_->updated());
+}
+
+TEST_F(DelayBasedBweTest, TestProbeDetectionSlowerArrival) {
+  const int kProbeLength = 5;
+  int64_t now_ms = clock_.TimeInMilliseconds();
+  uint16_t sequence_number = 0;
+  // First burst sent at 8 * 1000 / 5 = 1600 kbps.
+  // Arriving at 8 * 1000 / 7 = 1142 kbps.
+  int64_t send_time_ms = 0;
+  for (int i = 0; i < kProbeLength; ++i) {
+    clock_.AdvanceTimeMilliseconds(7);
+    send_time_ms += 5;
+    now_ms = clock_.TimeInMilliseconds();
+    IncomingPacket(1000, now_ms, send_time_ms, sequence_number++, 1);
+  }
+
+  bitrate_estimator_->Process();
+  EXPECT_TRUE(bitrate_observer_->updated());
+  EXPECT_NEAR(bitrate_observer_->latest_bitrate(), 1140000, 10000);
+}
+
+TEST_F(DelayBasedBweTest, TestProbeDetectionSlowerArrivalHighBitrate) {
+  const int kProbeLength = 5;
+  int64_t now_ms = clock_.TimeInMilliseconds();
+  uint16_t sequence_number = 0;
+  // Burst sent at 8 * 1000 / 1 = 8000 kbps.
+  // Arriving at 8 * 1000 / 2 = 4000 kbps.
+  int64_t send_time_ms = 0;
+  for (int i = 0; i < kProbeLength; ++i) {
+    clock_.AdvanceTimeMilliseconds(2);
+    send_time_ms += 1;
+    now_ms = clock_.TimeInMilliseconds();
+    IncomingPacket(1000, now_ms, send_time_ms, sequence_number++, 1);
+  }
+
+  bitrate_estimator_->Process();
+  EXPECT_TRUE(bitrate_observer_->updated());
+  EXPECT_NEAR(bitrate_observer_->latest_bitrate(), 4000000u, 10000);
+}
+
+TEST_F(DelayBasedBweTest, ProbingIgnoresSmallPackets) {
+  const int kProbeLength = 5;
+  int64_t now_ms = clock_.TimeInMilliseconds();
+  uint16_t sequence_number = 0;
+  // Probing with 200 bytes every 10 ms, should be ignored by the probe
+  // detection.
+  for (int i = 0; i < kProbeLength; ++i) {
+    clock_.AdvanceTimeMilliseconds(10);
+    now_ms = clock_.TimeInMilliseconds();
+    IncomingPacket(200, now_ms, now_ms, sequence_number++, 1);
+  }
+
+  bitrate_estimator_->Process();
+  EXPECT_FALSE(bitrate_observer_->updated());
+
+  // Followed by a probe with 1000 bytes packets, should be detected as a
+  // probe.
+  for (int i = 0; i < kProbeLength; ++i) {
+    clock_.AdvanceTimeMilliseconds(10);
+    now_ms = clock_.TimeInMilliseconds();
+    IncomingPacket(1000, now_ms, now_ms, sequence_number++, 2);
+  }
+
+  // Wait long enough so that we can call Process again.
+  clock_.AdvanceTimeMilliseconds(1000);
+
+  bitrate_estimator_->Process();
+  EXPECT_TRUE(bitrate_observer_->updated());
+  EXPECT_NEAR(bitrate_observer_->latest_bitrate(), 800000u, 10000);
+}
 }  // namespace webrtc