modules/remote_bitrate_estimator/aimd_rate_control_unittest.cc - src - Git at Google

 /*
  *  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 "modules/remote_bitrate_estimator/aimd_rate_control.h"

 #include <memory>

 #include "api/transport/field_trial_based_config.h"
 #include "system_wrappers/include/clock.h"
 #include "test/field_trial.h"
 #include "test/gtest.h"

 namespace webrtc {
 namespace {

 constexpr int64_t kClockInitialTime = 123456;

 constexpr int kMinBwePeriodMsSmoothingExp = 500;
 constexpr int kMinBwePeriodMsNoSmoothingExp = 2000;
 constexpr int kDefaultPeriodMsNoSmoothingExp = 3000;
 constexpr int kMaxBwePeriodMs = 50000;
 constexpr char kSmoothingExpFieldTrial[] =
     "WebRTC-Audio-BandwidthSmoothing/Enabled/";

 // After an overuse, we back off to 85% to the received bitrate.
 constexpr double kFractionAfterOveruse = 0.85;

 struct AimdRateControlStates {
   std::unique_ptr<AimdRateControl> aimd_rate_control;
   std::unique_ptr<SimulatedClock> simulated_clock;
   FieldTrialBasedConfig field_trials;
 };

 AimdRateControlStates CreateAimdRateControlStates(bool send_side = false) {
   AimdRateControlStates states;
   states.aimd_rate_control.reset(
       new AimdRateControl(&states.field_trials, send_side));
   states.simulated_clock.reset(new SimulatedClock(kClockInitialTime));
   return states;
 }
 absl::optional<DataRate> OptionalRateFromOptionalBps(
     absl::optional<int> bitrate_bps) {
   if (bitrate_bps) {
     return DataRate::bps(*bitrate_bps);
   } else {
     return absl::nullopt;
   }
 }
 void UpdateRateControl(const AimdRateControlStates& states,
                        const BandwidthUsage& bandwidth_usage,
                        absl::optional<uint32_t> throughput_estimate,
                        int64_t now_ms) {
   RateControlInput input(bandwidth_usage,
                          OptionalRateFromOptionalBps(throughput_estimate));
   states.aimd_rate_control->Update(&input, Timestamp::ms(now_ms));
 }
 void SetEstimate(const AimdRateControlStates& states, int bitrate_bps) {
   states.aimd_rate_control->SetEstimate(DataRate::bps(bitrate_bps),
                                         states.simulated_clock->CurrentTime());
 }

 }  // namespace

 TEST(AimdRateControlTest, MinNearMaxIncreaseRateOnLowBandwith) {
   auto states = CreateAimdRateControlStates();
   constexpr int kBitrate = 30000;
   SetEstimate(states, kBitrate);
   EXPECT_EQ(4000,
             states.aimd_rate_control->GetNearMaxIncreaseRateBpsPerSecond());
 }

 TEST(AimdRateControlTest, NearMaxIncreaseRateIs5kbpsOn90kbpsAnd200msRtt) {
   auto states = CreateAimdRateControlStates();
   constexpr int kBitrate = 90000;
   SetEstimate(states, kBitrate);
   EXPECT_EQ(5000,
             states.aimd_rate_control->GetNearMaxIncreaseRateBpsPerSecond());
 }

 TEST(AimdRateControlTest, NearMaxIncreaseRateIs5kbpsOn60kbpsAnd100msRtt) {
   auto states = CreateAimdRateControlStates();
   constexpr int kBitrate = 60000;
   SetEstimate(states, kBitrate);
   states.aimd_rate_control->SetRtt(TimeDelta::ms(100));
   EXPECT_EQ(5000,
             states.aimd_rate_control->GetNearMaxIncreaseRateBpsPerSecond());
 }

 TEST(AimdRateControlTest, GetIncreaseRateAndBandwidthPeriod) {
   // Smoothing experiment disabled
   auto states = CreateAimdRateControlStates();
   constexpr int kBitrate = 300000;
   SetEstimate(states, kBitrate);
   UpdateRateControl(states, BandwidthUsage::kBwOverusing, kBitrate,
                     states.simulated_clock->TimeInMilliseconds());
   EXPECT_NEAR(14000,
               states.aimd_rate_control->GetNearMaxIncreaseRateBpsPerSecond(),
               1000);
   EXPECT_EQ(kDefaultPeriodMsNoSmoothingExp,
             states.aimd_rate_control->GetExpectedBandwidthPeriod().ms());
 }

 TEST(AimdRateControlTest, GetIncreaseRateAndBandwidthPeriodSmoothingExp) {
   // Smoothing experiment enabled
   test::ScopedFieldTrials override_field_trials(kSmoothingExpFieldTrial);
   auto states = CreateAimdRateControlStates();
   constexpr int kBitrate = 300000;
   SetEstimate(states, kBitrate);
   UpdateRateControl(states, BandwidthUsage::kBwOverusing, kBitrate,
                     states.simulated_clock->TimeInMilliseconds());
   EXPECT_NEAR(14000,
               states.aimd_rate_control->GetNearMaxIncreaseRateBpsPerSecond(),
               1000);
   EXPECT_EQ(kMinBwePeriodMsSmoothingExp,
             states.aimd_rate_control->GetExpectedBandwidthPeriod().ms());
 }

 TEST(AimdRateControlTest, BweLimitedByAckedBitrate) {
   auto states = CreateAimdRateControlStates();
   constexpr int kAckedBitrate = 10000;
   SetEstimate(states, kAckedBitrate);
   while (states.simulated_clock->TimeInMilliseconds() - kClockInitialTime <
          20000) {
     UpdateRateControl(states, BandwidthUsage::kBwNormal, kAckedBitrate,
                       states.simulated_clock->TimeInMilliseconds());
     states.simulated_clock->AdvanceTimeMilliseconds(100);
   }
   ASSERT_TRUE(states.aimd_rate_control->ValidEstimate());
   EXPECT_EQ(static_cast<uint32_t>(1.5 * kAckedBitrate + 10000),
             states.aimd_rate_control->LatestEstimate().bps());
 }

 TEST(AimdRateControlTest, BweNotLimitedByDecreasingAckedBitrate) {
   auto states = CreateAimdRateControlStates();
   constexpr int kAckedBitrate = 100000;
   SetEstimate(states, kAckedBitrate);
   while (states.simulated_clock->TimeInMilliseconds() - kClockInitialTime <
          20000) {
     UpdateRateControl(states, BandwidthUsage::kBwNormal, kAckedBitrate,
                       states.simulated_clock->TimeInMilliseconds());
     states.simulated_clock->AdvanceTimeMilliseconds(100);
   }
   ASSERT_TRUE(states.aimd_rate_control->ValidEstimate());
   // If the acked bitrate decreases the BWE shouldn't be reduced to 1.5x
   // what's being acked, but also shouldn't get to increase more.
   uint32_t prev_estimate = states.aimd_rate_control->LatestEstimate().bps();
   UpdateRateControl(states, BandwidthUsage::kBwNormal, kAckedBitrate / 2,
                     states.simulated_clock->TimeInMilliseconds());
   uint32_t new_estimate = states.aimd_rate_control->LatestEstimate().bps();
   EXPECT_NEAR(new_estimate, static_cast<uint32_t>(1.5 * kAckedBitrate + 10000),
               2000);
   EXPECT_EQ(new_estimate, prev_estimate);
 }

 TEST(AimdRateControlTest, DefaultPeriodUntilFirstOveruse) {
   // Smoothing experiment disabled
   auto states = CreateAimdRateControlStates();
   states.aimd_rate_control->SetStartBitrate(DataRate::kbps(300));
   EXPECT_EQ(kDefaultPeriodMsNoSmoothingExp,
             states.aimd_rate_control->GetExpectedBandwidthPeriod().ms());
   states.simulated_clock->AdvanceTimeMilliseconds(100);
   UpdateRateControl(states, BandwidthUsage::kBwOverusing, 280000,
                     states.simulated_clock->TimeInMilliseconds());
   EXPECT_NE(kDefaultPeriodMsNoSmoothingExp,
             states.aimd_rate_control->GetExpectedBandwidthPeriod().ms());
 }

 TEST(AimdRateControlTest, MinPeriodUntilFirstOveruseSmoothingExp) {
   // Smoothing experiment enabled
   test::ScopedFieldTrials override_field_trials(kSmoothingExpFieldTrial);
   auto states = CreateAimdRateControlStates();
   states.aimd_rate_control->SetStartBitrate(DataRate::kbps(300));
   EXPECT_EQ(kMinBwePeriodMsSmoothingExp,
             states.aimd_rate_control->GetExpectedBandwidthPeriod().ms());
   states.simulated_clock->AdvanceTimeMilliseconds(100);
   UpdateRateControl(states, BandwidthUsage::kBwOverusing, 280000,
                     states.simulated_clock->TimeInMilliseconds());
   EXPECT_NE(kMinBwePeriodMsSmoothingExp,
             states.aimd_rate_control->GetExpectedBandwidthPeriod().ms());
 }

 TEST(AimdRateControlTest, ExpectedPeriodAfter20kbpsDropAnd5kbpsIncrease) {
   auto states = CreateAimdRateControlStates();
   constexpr int kInitialBitrate = 110000;
   SetEstimate(states, kInitialBitrate);
   states.simulated_clock->AdvanceTimeMilliseconds(100);
   // Make the bitrate drop by 20 kbps to get to 90 kbps.
   // The rate increase at 90 kbps should be 5 kbps, so the period should be 4 s.
   constexpr int kAckedBitrate =
       (kInitialBitrate - 20000) / kFractionAfterOveruse;
   UpdateRateControl(states, BandwidthUsage::kBwOverusing, kAckedBitrate,
                     states.simulated_clock->TimeInMilliseconds());
   EXPECT_EQ(5000,
             states.aimd_rate_control->GetNearMaxIncreaseRateBpsPerSecond());
   EXPECT_EQ(4000, states.aimd_rate_control->GetExpectedBandwidthPeriod().ms());
 }

 TEST(AimdRateControlTest, MinPeriodAfterLargeBitrateDecreaseSmoothingExp) {
   // Smoothing experiment enabled
   test::ScopedFieldTrials override_field_trials(kSmoothingExpFieldTrial);
   auto states = CreateAimdRateControlStates();
   constexpr int kInitialBitrate = 110000;
   SetEstimate(states, kInitialBitrate);
   states.simulated_clock->AdvanceTimeMilliseconds(100);
   // Make such a large drop in bitrate that should be treated as network
   // degradation.
   constexpr int kAckedBitrate = kInitialBitrate * 3 / 4 / kFractionAfterOveruse;
   UpdateRateControl(states, BandwidthUsage::kBwOverusing, kAckedBitrate,
                     states.simulated_clock->TimeInMilliseconds());
   EXPECT_EQ(kMinBwePeriodMsSmoothingExp,
             states.aimd_rate_control->GetExpectedBandwidthPeriod().ms());
 }

 TEST(AimdRateControlTest, BandwidthPeriodIsNotBelowMin) {
   auto states = CreateAimdRateControlStates();
   constexpr int kInitialBitrate = 10000;
   SetEstimate(states, kInitialBitrate);
   states.simulated_clock->AdvanceTimeMilliseconds(100);
   // Make a small (1.5 kbps) bitrate drop to 8.5 kbps.
   UpdateRateControl(states, BandwidthUsage::kBwOverusing, kInitialBitrate - 1,
                     states.simulated_clock->TimeInMilliseconds());
   EXPECT_EQ(kMinBwePeriodMsNoSmoothingExp,
             states.aimd_rate_control->GetExpectedBandwidthPeriod().ms());
 }

 TEST(AimdRateControlTest, BandwidthPeriodIsNotAboveMaxSmoothingExp) {
   // Smoothing experiment enabled
   test::ScopedFieldTrials override_field_trials(kSmoothingExpFieldTrial);
   auto states = CreateAimdRateControlStates();
   constexpr int kInitialBitrate = 50000000;
   SetEstimate(states, kInitialBitrate);
   states.simulated_clock->AdvanceTimeMilliseconds(100);
   // Make a large (10 Mbps) bitrate drop to 10 kbps.
   constexpr int kAckedBitrate = 40000000 / kFractionAfterOveruse;
   UpdateRateControl(states, BandwidthUsage::kBwOverusing, kAckedBitrate,
                     states.simulated_clock->TimeInMilliseconds());
   EXPECT_EQ(kMaxBwePeriodMs,
             states.aimd_rate_control->GetExpectedBandwidthPeriod().ms());
 }

 TEST(AimdRateControlTest, BandwidthPeriodIsNotAboveMaxNoSmoothingExp) {
   auto states = CreateAimdRateControlStates();
   constexpr int kInitialBitrate = 10010000;
   SetEstimate(states, kInitialBitrate);
   states.simulated_clock->AdvanceTimeMilliseconds(100);
   // Make a large (10 Mbps) bitrate drop to 10 kbps.
   constexpr int kAckedBitrate = 10000 / kFractionAfterOveruse;
   UpdateRateControl(states, BandwidthUsage::kBwOverusing, kAckedBitrate,
                     states.simulated_clock->TimeInMilliseconds());
   EXPECT_EQ(kMaxBwePeriodMs,
             states.aimd_rate_control->GetExpectedBandwidthPeriod().ms());
 }

 TEST(AimdRateControlTest, SendingRateBoundedWhenThroughputNotEstimated) {
   auto states = CreateAimdRateControlStates();
   constexpr int kInitialBitrateBps = 123000;
   UpdateRateControl(states, BandwidthUsage::kBwNormal, kInitialBitrateBps,
                     states.simulated_clock->TimeInMilliseconds());
   // AimdRateControl sets the initial bit rate to what it receives after
   // five seconds has passed.
   // TODO(bugs.webrtc.org/9379): The comment in the AimdRateControl does not
   // match the constant.
   constexpr int kInitializationTimeMs = 5000;
   states.simulated_clock->AdvanceTimeMilliseconds(kInitializationTimeMs + 1);
   UpdateRateControl(states, BandwidthUsage::kBwNormal, kInitialBitrateBps,
                     states.simulated_clock->TimeInMilliseconds());
   for (int i = 0; i < 100; ++i) {
     UpdateRateControl(states, BandwidthUsage::kBwNormal, absl::nullopt,
                       states.simulated_clock->TimeInMilliseconds());
     states.simulated_clock->AdvanceTimeMilliseconds(100);
   }
   EXPECT_LE(states.aimd_rate_control->LatestEstimate().bps(),
             kInitialBitrateBps * 1.5 + 10000);
 }

 TEST(AimdRateControlTest, EstimateDoesNotIncreaseInAlr) {
   // When alr is detected, the delay based estimator is not allowed to increase
   // bwe since there will be no feedback from the network if the new estimate
   // is correct.
   test::ScopedFieldTrials override_field_trials(
       "WebRTC-DontIncreaseDelayBasedBweInAlr/Enabled/");
   auto states = CreateAimdRateControlStates(/*send_side=*/true);
   constexpr int kInitialBitrateBps = 123000;
   SetEstimate(states, kInitialBitrateBps);
   states.aimd_rate_control->SetInApplicationLimitedRegion(true);
   UpdateRateControl(states, BandwidthUsage::kBwNormal, kInitialBitrateBps,
                     states.simulated_clock->TimeInMilliseconds());
   ASSERT_EQ(states.aimd_rate_control->LatestEstimate().bps(),
             kInitialBitrateBps);

   for (int i = 0; i < 100; ++i) {
     UpdateRateControl(states, BandwidthUsage::kBwNormal, absl::nullopt,
                       states.simulated_clock->TimeInMilliseconds());
     states.simulated_clock->AdvanceTimeMilliseconds(100);
   }
   EXPECT_EQ(states.aimd_rate_control->LatestEstimate().bps(),
             kInitialBitrateBps);
 }

 TEST(AimdRateControlTest, SetEstimateIncreaseBweInAlr) {
   test::ScopedFieldTrials override_field_trials(
       "WebRTC-DontIncreaseDelayBasedBweInAlr/Enabled/");
   auto states = CreateAimdRateControlStates(/*send_side=*/true);
   constexpr int kInitialBitrateBps = 123000;
   SetEstimate(states, kInitialBitrateBps);
   states.aimd_rate_control->SetInApplicationLimitedRegion(true);
   ASSERT_EQ(states.aimd_rate_control->LatestEstimate().bps(),
             kInitialBitrateBps);
   SetEstimate(states, 2 * kInitialBitrateBps);
   EXPECT_EQ(states.aimd_rate_control->LatestEstimate().bps(),
             2 * kInitialBitrateBps);
 }

 TEST(AimdRateControlTest, EstimateIncreaseWhileNotInAlr) {
   // Allow the estimate to increase as long as alr is not detected to ensure
   // tha BWE can not get stuck at a certain bitrate.
   test::ScopedFieldTrials override_field_trials(
       "WebRTC-DontIncreaseDelayBasedBweInAlr/Enabled/");
   auto states = CreateAimdRateControlStates(/*send_side=*/true);
   constexpr int kInitialBitrateBps = 123000;
   SetEstimate(states, kInitialBitrateBps);
   states.aimd_rate_control->SetInApplicationLimitedRegion(false);
   UpdateRateControl(states, BandwidthUsage::kBwNormal, kInitialBitrateBps,
                     states.simulated_clock->TimeInMilliseconds());
   for (int i = 0; i < 100; ++i) {
     UpdateRateControl(states, BandwidthUsage::kBwNormal, absl::nullopt,
                       states.simulated_clock->TimeInMilliseconds());
     states.simulated_clock->AdvanceTimeMilliseconds(100);
   }
   EXPECT_GT(states.aimd_rate_control->LatestEstimate().bps(),
             kInitialBitrateBps);
 }

 }  // namespace webrtc
	/*
	* 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 "modules/remote_bitrate_estimator/aimd_rate_control.h"

	#include <memory>

	#include "api/transport/field_trial_based_config.h"
	#include "system_wrappers/include/clock.h"
	#include "test/field_trial.h"
	#include "test/gtest.h"

	namespace webrtc {
	namespace {

	constexpr int64_t kClockInitialTime = 123456;

	constexpr int kMinBwePeriodMsSmoothingExp = 500;
	constexpr int kMinBwePeriodMsNoSmoothingExp = 2000;
	constexpr int kDefaultPeriodMsNoSmoothingExp = 3000;
	constexpr int kMaxBwePeriodMs = 50000;
	constexpr char kSmoothingExpFieldTrial[] =
	"WebRTC-Audio-BandwidthSmoothing/Enabled/";

	// After an overuse, we back off to 85% to the received bitrate.
	constexpr double kFractionAfterOveruse = 0.85;

	struct AimdRateControlStates {
	std::unique_ptr<AimdRateControl> aimd_rate_control;
	std::unique_ptr<SimulatedClock> simulated_clock;
	FieldTrialBasedConfig field_trials;
	};

	AimdRateControlStates CreateAimdRateControlStates(bool send_side = false) {
	AimdRateControlStates states;
	states.aimd_rate_control.reset(
	new AimdRateControl(&states.field_trials, send_side));
	states.simulated_clock.reset(new SimulatedClock(kClockInitialTime));
	return states;
	}
	absl::optional<DataRate> OptionalRateFromOptionalBps(
	absl::optional<int> bitrate_bps) {
	if (bitrate_bps) {
	return DataRate::bps(*bitrate_bps);
	} else {
	return absl::nullopt;
	}
	}
	void UpdateRateControl(const AimdRateControlStates& states,
	const BandwidthUsage& bandwidth_usage,
	absl::optional<uint32_t> throughput_estimate,
	int64_t now_ms) {
	RateControlInput input(bandwidth_usage,
	OptionalRateFromOptionalBps(throughput_estimate));
	states.aimd_rate_control->Update(&input, Timestamp::ms(now_ms));
	}
	void SetEstimate(const AimdRateControlStates& states, int bitrate_bps) {
	states.aimd_rate_control->SetEstimate(DataRate::bps(bitrate_bps),
	states.simulated_clock->CurrentTime());
	}

	} // namespace

	TEST(AimdRateControlTest, MinNearMaxIncreaseRateOnLowBandwith) {
	auto states = CreateAimdRateControlStates();
	constexpr int kBitrate = 30000;
	SetEstimate(states, kBitrate);
	EXPECT_EQ(4000,
	states.aimd_rate_control->GetNearMaxIncreaseRateBpsPerSecond());
	}

	TEST(AimdRateControlTest, NearMaxIncreaseRateIs5kbpsOn90kbpsAnd200msRtt) {
	auto states = CreateAimdRateControlStates();
	constexpr int kBitrate = 90000;
	SetEstimate(states, kBitrate);
	EXPECT_EQ(5000,
	states.aimd_rate_control->GetNearMaxIncreaseRateBpsPerSecond());
	}

	TEST(AimdRateControlTest, NearMaxIncreaseRateIs5kbpsOn60kbpsAnd100msRtt) {
	auto states = CreateAimdRateControlStates();
	constexpr int kBitrate = 60000;
	SetEstimate(states, kBitrate);
	states.aimd_rate_control->SetRtt(TimeDelta::ms(100));
	EXPECT_EQ(5000,
	states.aimd_rate_control->GetNearMaxIncreaseRateBpsPerSecond());
	}

	TEST(AimdRateControlTest, GetIncreaseRateAndBandwidthPeriod) {
	// Smoothing experiment disabled
	auto states = CreateAimdRateControlStates();
	constexpr int kBitrate = 300000;
	SetEstimate(states, kBitrate);
	UpdateRateControl(states, BandwidthUsage::kBwOverusing, kBitrate,
	states.simulated_clock->TimeInMilliseconds());
	EXPECT_NEAR(14000,
	states.aimd_rate_control->GetNearMaxIncreaseRateBpsPerSecond(),
	1000);
	EXPECT_EQ(kDefaultPeriodMsNoSmoothingExp,
	states.aimd_rate_control->GetExpectedBandwidthPeriod().ms());
	}

	TEST(AimdRateControlTest, GetIncreaseRateAndBandwidthPeriodSmoothingExp) {
	// Smoothing experiment enabled
	test::ScopedFieldTrials override_field_trials(kSmoothingExpFieldTrial);
	auto states = CreateAimdRateControlStates();
	constexpr int kBitrate = 300000;
	SetEstimate(states, kBitrate);
	UpdateRateControl(states, BandwidthUsage::kBwOverusing, kBitrate,
	states.simulated_clock->TimeInMilliseconds());
	EXPECT_NEAR(14000,
	states.aimd_rate_control->GetNearMaxIncreaseRateBpsPerSecond(),
	1000);
	EXPECT_EQ(kMinBwePeriodMsSmoothingExp,
	states.aimd_rate_control->GetExpectedBandwidthPeriod().ms());
	}

	TEST(AimdRateControlTest, BweLimitedByAckedBitrate) {
	auto states = CreateAimdRateControlStates();
	constexpr int kAckedBitrate = 10000;
	SetEstimate(states, kAckedBitrate);
	while (states.simulated_clock->TimeInMilliseconds() - kClockInitialTime <
	20000) {
	UpdateRateControl(states, BandwidthUsage::kBwNormal, kAckedBitrate,
	states.simulated_clock->TimeInMilliseconds());
	states.simulated_clock->AdvanceTimeMilliseconds(100);
	}
	ASSERT_TRUE(states.aimd_rate_control->ValidEstimate());
	EXPECT_EQ(static_cast<uint32_t>(1.5 * kAckedBitrate + 10000),
	states.aimd_rate_control->LatestEstimate().bps());
	}

	TEST(AimdRateControlTest, BweNotLimitedByDecreasingAckedBitrate) {
	auto states = CreateAimdRateControlStates();
	constexpr int kAckedBitrate = 100000;
	SetEstimate(states, kAckedBitrate);
	while (states.simulated_clock->TimeInMilliseconds() - kClockInitialTime <
	20000) {
	UpdateRateControl(states, BandwidthUsage::kBwNormal, kAckedBitrate,
	states.simulated_clock->TimeInMilliseconds());
	states.simulated_clock->AdvanceTimeMilliseconds(100);
	}
	ASSERT_TRUE(states.aimd_rate_control->ValidEstimate());
	// If the acked bitrate decreases the BWE shouldn't be reduced to 1.5x
	// what's being acked, but also shouldn't get to increase more.
	uint32_t prev_estimate = states.aimd_rate_control->LatestEstimate().bps();
	UpdateRateControl(states, BandwidthUsage::kBwNormal, kAckedBitrate / 2,
	states.simulated_clock->TimeInMilliseconds());
	uint32_t new_estimate = states.aimd_rate_control->LatestEstimate().bps();
	EXPECT_NEAR(new_estimate, static_cast<uint32_t>(1.5 * kAckedBitrate + 10000),
	2000);
	EXPECT_EQ(new_estimate, prev_estimate);
	}

	TEST(AimdRateControlTest, DefaultPeriodUntilFirstOveruse) {
	// Smoothing experiment disabled
	auto states = CreateAimdRateControlStates();
	states.aimd_rate_control->SetStartBitrate(DataRate::kbps(300));
	EXPECT_EQ(kDefaultPeriodMsNoSmoothingExp,
	states.aimd_rate_control->GetExpectedBandwidthPeriod().ms());
	states.simulated_clock->AdvanceTimeMilliseconds(100);
	UpdateRateControl(states, BandwidthUsage::kBwOverusing, 280000,
	states.simulated_clock->TimeInMilliseconds());
	EXPECT_NE(kDefaultPeriodMsNoSmoothingExp,
	states.aimd_rate_control->GetExpectedBandwidthPeriod().ms());
	}

	TEST(AimdRateControlTest, MinPeriodUntilFirstOveruseSmoothingExp) {
	// Smoothing experiment enabled
	test::ScopedFieldTrials override_field_trials(kSmoothingExpFieldTrial);
	auto states = CreateAimdRateControlStates();
	states.aimd_rate_control->SetStartBitrate(DataRate::kbps(300));
	EXPECT_EQ(kMinBwePeriodMsSmoothingExp,
	states.aimd_rate_control->GetExpectedBandwidthPeriod().ms());
	states.simulated_clock->AdvanceTimeMilliseconds(100);
	UpdateRateControl(states, BandwidthUsage::kBwOverusing, 280000,
	states.simulated_clock->TimeInMilliseconds());
	EXPECT_NE(kMinBwePeriodMsSmoothingExp,
	states.aimd_rate_control->GetExpectedBandwidthPeriod().ms());
	}

	TEST(AimdRateControlTest, ExpectedPeriodAfter20kbpsDropAnd5kbpsIncrease) {
	auto states = CreateAimdRateControlStates();
	constexpr int kInitialBitrate = 110000;
	SetEstimate(states, kInitialBitrate);
	states.simulated_clock->AdvanceTimeMilliseconds(100);
	// Make the bitrate drop by 20 kbps to get to 90 kbps.
	// The rate increase at 90 kbps should be 5 kbps, so the period should be 4 s.
	constexpr int kAckedBitrate =
	(kInitialBitrate - 20000) / kFractionAfterOveruse;
	UpdateRateControl(states, BandwidthUsage::kBwOverusing, kAckedBitrate,
	states.simulated_clock->TimeInMilliseconds());
	EXPECT_EQ(5000,
	states.aimd_rate_control->GetNearMaxIncreaseRateBpsPerSecond());
	EXPECT_EQ(4000, states.aimd_rate_control->GetExpectedBandwidthPeriod().ms());
	}

	TEST(AimdRateControlTest, MinPeriodAfterLargeBitrateDecreaseSmoothingExp) {
	// Smoothing experiment enabled
	test::ScopedFieldTrials override_field_trials(kSmoothingExpFieldTrial);
	auto states = CreateAimdRateControlStates();
	constexpr int kInitialBitrate = 110000;
	SetEstimate(states, kInitialBitrate);
	states.simulated_clock->AdvanceTimeMilliseconds(100);
	// Make such a large drop in bitrate that should be treated as network
	// degradation.
	constexpr int kAckedBitrate = kInitialBitrate * 3 / 4 / kFractionAfterOveruse;
	UpdateRateControl(states, BandwidthUsage::kBwOverusing, kAckedBitrate,
	states.simulated_clock->TimeInMilliseconds());
	EXPECT_EQ(kMinBwePeriodMsSmoothingExp,
	states.aimd_rate_control->GetExpectedBandwidthPeriod().ms());
	}

	TEST(AimdRateControlTest, BandwidthPeriodIsNotBelowMin) {
	auto states = CreateAimdRateControlStates();
	constexpr int kInitialBitrate = 10000;
	SetEstimate(states, kInitialBitrate);
	states.simulated_clock->AdvanceTimeMilliseconds(100);
	// Make a small (1.5 kbps) bitrate drop to 8.5 kbps.
	UpdateRateControl(states, BandwidthUsage::kBwOverusing, kInitialBitrate - 1,
	states.simulated_clock->TimeInMilliseconds());
	EXPECT_EQ(kMinBwePeriodMsNoSmoothingExp,
	states.aimd_rate_control->GetExpectedBandwidthPeriod().ms());
	}

	TEST(AimdRateControlTest, BandwidthPeriodIsNotAboveMaxSmoothingExp) {
	// Smoothing experiment enabled
	test::ScopedFieldTrials override_field_trials(kSmoothingExpFieldTrial);
	auto states = CreateAimdRateControlStates();
	constexpr int kInitialBitrate = 50000000;
	SetEstimate(states, kInitialBitrate);
	states.simulated_clock->AdvanceTimeMilliseconds(100);
	// Make a large (10 Mbps) bitrate drop to 10 kbps.
	constexpr int kAckedBitrate = 40000000 / kFractionAfterOveruse;
	UpdateRateControl(states, BandwidthUsage::kBwOverusing, kAckedBitrate,
	states.simulated_clock->TimeInMilliseconds());
	EXPECT_EQ(kMaxBwePeriodMs,
	states.aimd_rate_control->GetExpectedBandwidthPeriod().ms());
	}

	TEST(AimdRateControlTest, BandwidthPeriodIsNotAboveMaxNoSmoothingExp) {
	auto states = CreateAimdRateControlStates();
	constexpr int kInitialBitrate = 10010000;
	SetEstimate(states, kInitialBitrate);
	states.simulated_clock->AdvanceTimeMilliseconds(100);
	// Make a large (10 Mbps) bitrate drop to 10 kbps.
	constexpr int kAckedBitrate = 10000 / kFractionAfterOveruse;
	UpdateRateControl(states, BandwidthUsage::kBwOverusing, kAckedBitrate,
	states.simulated_clock->TimeInMilliseconds());
	EXPECT_EQ(kMaxBwePeriodMs,
	states.aimd_rate_control->GetExpectedBandwidthPeriod().ms());
	}

	TEST(AimdRateControlTest, SendingRateBoundedWhenThroughputNotEstimated) {
	auto states = CreateAimdRateControlStates();
	constexpr int kInitialBitrateBps = 123000;
	UpdateRateControl(states, BandwidthUsage::kBwNormal, kInitialBitrateBps,
	states.simulated_clock->TimeInMilliseconds());
	// AimdRateControl sets the initial bit rate to what it receives after
	// five seconds has passed.
	// TODO(bugs.webrtc.org/9379): The comment in the AimdRateControl does not
	// match the constant.
	constexpr int kInitializationTimeMs = 5000;
	states.simulated_clock->AdvanceTimeMilliseconds(kInitializationTimeMs + 1);
	UpdateRateControl(states, BandwidthUsage::kBwNormal, kInitialBitrateBps,
	states.simulated_clock->TimeInMilliseconds());
	for (int i = 0; i < 100; ++i) {
	UpdateRateControl(states, BandwidthUsage::kBwNormal, absl::nullopt,
	states.simulated_clock->TimeInMilliseconds());
	states.simulated_clock->AdvanceTimeMilliseconds(100);
	}
	EXPECT_LE(states.aimd_rate_control->LatestEstimate().bps(),
	kInitialBitrateBps * 1.5 + 10000);
	}

	TEST(AimdRateControlTest, EstimateDoesNotIncreaseInAlr) {
	// When alr is detected, the delay based estimator is not allowed to increase
	// bwe since there will be no feedback from the network if the new estimate
	// is correct.
	test::ScopedFieldTrials override_field_trials(
	"WebRTC-DontIncreaseDelayBasedBweInAlr/Enabled/");
	auto states = CreateAimdRateControlStates(/send_side=/true);
	constexpr int kInitialBitrateBps = 123000;
	SetEstimate(states, kInitialBitrateBps);
	states.aimd_rate_control->SetInApplicationLimitedRegion(true);
	UpdateRateControl(states, BandwidthUsage::kBwNormal, kInitialBitrateBps,
	states.simulated_clock->TimeInMilliseconds());
	ASSERT_EQ(states.aimd_rate_control->LatestEstimate().bps(),
	kInitialBitrateBps);

	for (int i = 0; i < 100; ++i) {
	UpdateRateControl(states, BandwidthUsage::kBwNormal, absl::nullopt,
	states.simulated_clock->TimeInMilliseconds());
	states.simulated_clock->AdvanceTimeMilliseconds(100);
	}
	EXPECT_EQ(states.aimd_rate_control->LatestEstimate().bps(),
	kInitialBitrateBps);
	}

	TEST(AimdRateControlTest, SetEstimateIncreaseBweInAlr) {
	test::ScopedFieldTrials override_field_trials(
	"WebRTC-DontIncreaseDelayBasedBweInAlr/Enabled/");
	auto states = CreateAimdRateControlStates(/send_side=/true);
	constexpr int kInitialBitrateBps = 123000;
	SetEstimate(states, kInitialBitrateBps);
	states.aimd_rate_control->SetInApplicationLimitedRegion(true);
	ASSERT_EQ(states.aimd_rate_control->LatestEstimate().bps(),
	kInitialBitrateBps);
	SetEstimate(states, 2 * kInitialBitrateBps);
	EXPECT_EQ(states.aimd_rate_control->LatestEstimate().bps(),
	2 * kInitialBitrateBps);
	}

	TEST(AimdRateControlTest, EstimateIncreaseWhileNotInAlr) {
	// Allow the estimate to increase as long as alr is not detected to ensure
	// tha BWE can not get stuck at a certain bitrate.
	test::ScopedFieldTrials override_field_trials(
	"WebRTC-DontIncreaseDelayBasedBweInAlr/Enabled/");
	auto states = CreateAimdRateControlStates(/send_side=/true);
	constexpr int kInitialBitrateBps = 123000;
	SetEstimate(states, kInitialBitrateBps);
	states.aimd_rate_control->SetInApplicationLimitedRegion(false);
	UpdateRateControl(states, BandwidthUsage::kBwNormal, kInitialBitrateBps,
	states.simulated_clock->TimeInMilliseconds());
	for (int i = 0; i < 100; ++i) {
	UpdateRateControl(states, BandwidthUsage::kBwNormal, absl::nullopt,
	states.simulated_clock->TimeInMilliseconds());
	states.simulated_clock->AdvanceTimeMilliseconds(100);
	}
	EXPECT_GT(states.aimd_rate_control->LatestEstimate().bps(),
	kInitialBitrateBps);
	}

	} // namespace webrtc