Improved RobustThroughputEstimator

- Filter out very old packets (to ensure that the estimate doesn't drop to zero if sending is paused and later resumed).
- Discard packets older than previously discarded packets (to avoid the estimate dropping after deep reordering.)
- Add tests cases for high loss, deep reordering and paused/resumed streams to unittest.
- Remove some field trial settings that have very minor effect and rename some of the others.
- Change analyzer.cc to only draw data points if the estimators have valid estimates.

Bug: webrtc:13402
Change-Id: I47ead8aa4454cced5134d10895ca061d2c3e32f4
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/236347
Commit-Queue: Björn Terelius <terelius@webrtc.org>
Reviewed-by: Per Kjellander <perkj@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#36849}
diff --git a/modules/congestion_controller/goog_cc/BUILD.gn b/modules/congestion_controller/goog_cc/BUILD.gn
index 851122e..00cd2d5 100644
--- a/modules/congestion_controller/goog_cc/BUILD.gn
+++ b/modules/congestion_controller/goog_cc/BUILD.gn
@@ -129,6 +129,8 @@
     "../../../api/rtc_event_log",
     "../../../api/transport:network_control",
     "../../../api/units:data_rate",
+    "../../../api/units:data_size",
+    "../../../api/units:time_delta",
     "../../../api/units:timestamp",
     "../../../logging:rtc_event_bwe",
     "../../../rtc_base:checks",
@@ -357,6 +359,7 @@
         "../../pacing",
         "//testing/gmock",
       ]
+      absl_deps = [ "//third_party/abseil-cpp/absl/strings:strings" ]
     }
   }
 }
diff --git a/modules/congestion_controller/goog_cc/acknowledged_bitrate_estimator_interface.cc b/modules/congestion_controller/goog_cc/acknowledged_bitrate_estimator_interface.cc
index 283c9a8..c043353 100644
--- a/modules/congestion_controller/goog_cc/acknowledged_bitrate_estimator_interface.cc
+++ b/modules/congestion_controller/goog_cc/acknowledged_bitrate_estimator_interface.cc
@@ -12,6 +12,7 @@
 
 #include <algorithm>
 
+#include "api/units/time_delta.h"
 #include "modules/congestion_controller/goog_cc/acknowledged_bitrate_estimator.h"
 #include "modules/congestion_controller/goog_cc/robust_throughput_estimator.h"
 #include "rtc_base/logging.h"
@@ -24,22 +25,36 @@
     const FieldTrialsView* key_value_config) {
   Parser()->Parse(
       key_value_config->Lookup(RobustThroughputEstimatorSettings::kKey));
-  if (min_packets < 10 || kMaxPackets < min_packets) {
-    RTC_LOG(LS_WARNING) << "Window size must be between 10 and " << kMaxPackets
-                        << " packets";
-    min_packets = 20;
+  if (window_packets < 10 || 1000 < window_packets) {
+    RTC_LOG(LS_WARNING) << "Window size must be between 10 and 1000 packets";
+    window_packets = 20;
   }
-  if (initial_packets < 10 || kMaxPackets < initial_packets) {
-    RTC_LOG(LS_WARNING) << "Initial size must be between 10 and " << kMaxPackets
-                        << " packets";
-    initial_packets = 20;
+  if (max_window_packets < 10 || 1000 < max_window_packets) {
+    RTC_LOG(LS_WARNING)
+        << "Max window size must be between 10 and 1000 packets";
+    max_window_packets = 500;
   }
-  initial_packets = std::min(initial_packets, min_packets);
-  if (window_duration < TimeDelta::Millis(100) ||
-      TimeDelta::Millis(2000) < window_duration) {
-    RTC_LOG(LS_WARNING) << "Window duration must be between 100 and 2000 ms";
-    window_duration = TimeDelta::Millis(500);
+  max_window_packets = std::max(max_window_packets, window_packets);
+
+  if (required_packets < 10 || 1000 < required_packets) {
+    RTC_LOG(LS_WARNING) << "Required number of initial packets must be between "
+                           "10 and 1000 packets";
+    required_packets = 10;
   }
+  required_packets = std::min(required_packets, window_packets);
+
+  if (min_window_duration < TimeDelta::Millis(100) ||
+      TimeDelta::Millis(3000) < min_window_duration) {
+    RTC_LOG(LS_WARNING) << "Window duration must be between 100 and 3000 ms";
+    min_window_duration = TimeDelta::Millis(750);
+  }
+  if (max_window_duration < TimeDelta::Seconds(1) ||
+      TimeDelta::Seconds(15) < max_window_duration) {
+    RTC_LOG(LS_WARNING) << "Max window duration must be between 1 and 15 s";
+    max_window_duration = TimeDelta::Seconds(5);
+  }
+  min_window_duration = std::min(min_window_duration, max_window_duration);
+
   if (unacked_weight < 0.0 || 1.0 < unacked_weight) {
     RTC_LOG(LS_WARNING)
         << "Weight for prior unacked size must be between 0 and 1.";
@@ -49,14 +64,14 @@
 
 std::unique_ptr<StructParametersParser>
 RobustThroughputEstimatorSettings::Parser() {
-  return StructParametersParser::Create("enabled", &enabled,                  //
-                                        "reduce_bias", &reduce_bias,          //
-                                        "assume_shared_link",                 //
-                                        &assume_shared_link,                  //
-                                        "min_packets", &min_packets,          //
-                                        "window_duration", &window_duration,  //
-                                        "initial_packets", &initial_packets,  //
-                                        "unacked_weight", &unacked_weight);
+  return StructParametersParser::Create(
+      "enabled", &enabled,                          //
+      "window_packets", &window_packets,            //
+      "max_window_packets", &max_window_packets,    //
+      "window_duration", &min_window_duration,      //
+      "max_window_duration", &max_window_duration,  //
+      "required_packets", &required_packets,        //
+      "unacked_weight", &unacked_weight);
 }
 
 AcknowledgedBitrateEstimatorInterface::
diff --git a/modules/congestion_controller/goog_cc/acknowledged_bitrate_estimator_interface.h b/modules/congestion_controller/goog_cc/acknowledged_bitrate_estimator_interface.h
index 6dce69b..515af1e 100644
--- a/modules/congestion_controller/goog_cc/acknowledged_bitrate_estimator_interface.h
+++ b/modules/congestion_controller/goog_cc/acknowledged_bitrate_estimator_interface.h
@@ -11,6 +11,8 @@
 #ifndef MODULES_CONGESTION_CONTROLLER_GOOG_CC_ACKNOWLEDGED_BITRATE_ESTIMATOR_INTERFACE_H_
 #define MODULES_CONGESTION_CONTROLLER_GOOG_CC_ACKNOWLEDGED_BITRATE_ESTIMATOR_INTERFACE_H_
 
+#include <stddef.h>
+
 #include <memory>
 #include <vector>
 
@@ -18,13 +20,14 @@
 #include "api/field_trials_view.h"
 #include "api/transport/network_types.h"
 #include "api/units/data_rate.h"
+#include "api/units/time_delta.h"
+#include "api/units/timestamp.h"
 #include "rtc_base/experiments/struct_parameters_parser.h"
 
 namespace webrtc {
 
 struct RobustThroughputEstimatorSettings {
   static constexpr char kKey[] = "WebRTC-Bwe-RobustThroughputEstimatorSettings";
-  static constexpr size_t kMaxPackets = 500;
 
   RobustThroughputEstimatorSettings() = delete;
   explicit RobustThroughputEstimatorSettings(
@@ -32,30 +35,32 @@
 
   bool enabled = false;  // Set to true to use RobustThroughputEstimator.
 
-  // The estimator handles delay spikes by removing the largest receive time
-  // gap, but this introduces some bias that may lead to overestimation when
-  // there isn't any delay spike. If `reduce_bias` is true, we instead replace
-  // the largest receive time gap by the second largest. This reduces the bias
-  // at the cost of not completely removing the genuine delay spikes.
-  bool reduce_bias = true;
+  // The estimator keeps the smallest window containing at least
+  // `window_packets` and at least the packets received during the last
+  // `min_window_duration` milliseconds.
+  // (This means that it may store more than `window_packets` at high bitrates,
+  // and a longer duration than `min_window_duration` at low bitrates.)
+  // However, if will never store more than kMaxPackets (for performance
+  // reasons), and never longer than max_window_duration (to avoid very old
+  // packets influencing the estimate for example when sending is paused).
+  unsigned window_packets = 20;
+  unsigned max_window_packets = 500;
+  TimeDelta min_window_duration = TimeDelta::Seconds(1);
+  TimeDelta max_window_duration = TimeDelta::Seconds(5);
 
-  // If `assume_shared_link` is false, we ignore the size of the first packet
-  // when computing the receive rate. Otherwise, we remove half of the first
-  // and last packet's sizes.
-  bool assume_shared_link = false;
+  // The estimator window requires at least `required_packets` packets
+  // to produce an estimate.
+  unsigned required_packets = 10;
 
-  // The estimator window keeps at least `min_packets` packets and up to
-  // kMaxPackets received during the last `window_duration`.
-  unsigned min_packets = 20;
-  TimeDelta window_duration = TimeDelta::Millis(500);
-
-  // The estimator window requires at least `initial_packets` packets received
-  // over at least `initial_duration`.
-  unsigned initial_packets = 20;
-
+  // If audio packets aren't included in allocation (i.e. the
+  // estimated available bandwidth is divided only among the video
+  // streams), then `unacked_weight` should be set to 0.
   // If audio packets are included in allocation, but not in bandwidth
-  // estimation and the sent audio packets get double counted,
-  // then it might be useful to reduce the weight to 0.5.
+  // estimation (i.e. they don't have transport-wide sequence numbers,
+  // but we nevertheless divide the estimated available bandwidth among
+  // both audio and video streams), then `unacked_weight` should be set to 1.
+  // If all packets have transport-wide sequence numbers, then the value
+  // of `unacked_weight` doesn't matter.
   double unacked_weight = 1.0;
 
   std::unique_ptr<StructParametersParser> Parser();
diff --git a/modules/congestion_controller/goog_cc/robust_throughput_estimator.cc b/modules/congestion_controller/goog_cc/robust_throughput_estimator.cc
index 1169e9f..93909af 100644
--- a/modules/congestion_controller/goog_cc/robust_throughput_estimator.cc
+++ b/modules/congestion_controller/goog_cc/robust_throughput_estimator.cc
@@ -15,24 +15,55 @@
 #include <algorithm>
 #include <utility>
 
+#include "api/units/data_rate.h"
+#include "api/units/data_size.h"
+#include "api/units/time_delta.h"
+#include "api/units/timestamp.h"
 #include "rtc_base/checks.h"
 
 namespace webrtc {
 
 RobustThroughputEstimator::RobustThroughputEstimator(
     const RobustThroughputEstimatorSettings& settings)
-    : settings_(settings) {
+    : settings_(settings),
+      latest_discarded_send_time_(Timestamp::MinusInfinity()) {
   RTC_DCHECK(settings.enabled);
 }
 
 RobustThroughputEstimator::~RobustThroughputEstimator() {}
 
+bool RobustThroughputEstimator::FirstPacketOutsideWindow() {
+  if (window_.empty())
+    return false;
+  if (window_.size() > settings_.max_window_packets)
+    return true;
+  TimeDelta current_window_duration =
+      window_.back().receive_time - window_.front().receive_time;
+  if (current_window_duration > settings_.max_window_duration)
+    return true;
+  if (window_.size() > settings_.window_packets &&
+      current_window_duration > settings_.min_window_duration) {
+    return true;
+  }
+  return false;
+}
+
 void RobustThroughputEstimator::IncomingPacketFeedbackVector(
     const std::vector<PacketResult>& packet_feedback_vector) {
   RTC_DCHECK(std::is_sorted(packet_feedback_vector.begin(),
                             packet_feedback_vector.end(),
                             PacketResult::ReceiveTimeOrder()));
   for (const auto& packet : packet_feedback_vector) {
+    // Ignore packets without valid send or receive times.
+    // (This should not happen in production since lost packets are filtered
+    // out before passing the feedback vector to the throughput estimator.
+    // However, explicitly handling this case makes the estimator more robust
+    // and avoids a hard-to-detect bad state.)
+    if (packet.receive_time.IsInfinite() ||
+        packet.sent_packet.send_time.IsInfinite()) {
+      continue;
+    }
+
     // Insert the new packet.
     window_.push_back(packet);
     window_.back().sent_packet.prior_unacked_data =
@@ -45,24 +76,24 @@
          i > 0 && window_[i].receive_time < window_[i - 1].receive_time; i--) {
       std::swap(window_[i], window_[i - 1]);
     }
-    // Remove old packets.
-    while (window_.size() > settings_.kMaxPackets ||
-           (window_.size() > settings_.min_packets &&
-            packet.receive_time - window_.front().receive_time >
-                settings_.window_duration)) {
-      window_.pop_front();
-    }
+  }
+
+  // Remove old packets.
+  while (FirstPacketOutsideWindow()) {
+    latest_discarded_send_time_ = std::max(
+        latest_discarded_send_time_, window_.front().sent_packet.send_time);
+    window_.pop_front();
   }
 }
 
 absl::optional<DataRate> RobustThroughputEstimator::bitrate() const {
-  if (window_.size() < settings_.initial_packets)
+  if (window_.empty() || window_.size() < settings_.required_packets)
     return absl::nullopt;
 
   TimeDelta largest_recv_gap(TimeDelta::Millis(0));
   TimeDelta second_largest_recv_gap(TimeDelta::Millis(0));
   for (size_t i = 1; i < window_.size(); i++) {
-    // Find receive time gaps
+    // Find receive time gaps.
     TimeDelta gap = window_[i].receive_time - window_[i - 1].receive_time;
     if (gap > largest_recv_gap) {
       second_largest_recv_gap = largest_recv_gap;
@@ -72,63 +103,86 @@
     }
   }
 
-  Timestamp min_send_time = window_[0].sent_packet.send_time;
-  Timestamp max_send_time = window_[0].sent_packet.send_time;
-  Timestamp min_recv_time = window_[0].receive_time;
-  Timestamp max_recv_time = window_[0].receive_time;
-  DataSize data_size = DataSize::Bytes(0);
+  Timestamp first_send_time = Timestamp::PlusInfinity();
+  Timestamp last_send_time = Timestamp::MinusInfinity();
+  Timestamp first_recv_time = Timestamp::PlusInfinity();
+  Timestamp last_recv_time = Timestamp::MinusInfinity();
+  DataSize recv_size = DataSize::Bytes(0);
+  DataSize send_size = DataSize::Bytes(0);
+  DataSize first_recv_size = DataSize::Bytes(0);
+  DataSize last_send_size = DataSize::Bytes(0);
+  size_t num_sent_packets_in_window = 0;
   for (const auto& packet : window_) {
-    min_send_time = std::min(min_send_time, packet.sent_packet.send_time);
-    max_send_time = std::max(max_send_time, packet.sent_packet.send_time);
-    min_recv_time = std::min(min_recv_time, packet.receive_time);
-    max_recv_time = std::max(max_recv_time, packet.receive_time);
-    data_size += packet.sent_packet.size;
-    data_size += packet.sent_packet.prior_unacked_data;
+    if (packet.receive_time < first_recv_time) {
+      first_recv_time = packet.receive_time;
+      first_recv_size =
+          packet.sent_packet.size + packet.sent_packet.prior_unacked_data;
+    }
+    last_recv_time = std::max(last_recv_time, packet.receive_time);
+    recv_size += packet.sent_packet.size;
+    recv_size += packet.sent_packet.prior_unacked_data;
+
+    if (packet.sent_packet.send_time < latest_discarded_send_time_) {
+      // If we have dropped packets from the window that were sent after
+      // this packet, then this packet was reordered. Ignore it from
+      // the send rate computation (since the send time may be very far
+      // in the past, leading to underestimation of the send rate.)
+      // However, ignoring packets creates a risk that we end up without
+      // any packets left to compute a send rate.
+      continue;
+    }
+    if (packet.sent_packet.send_time > last_send_time) {
+      last_send_time = packet.sent_packet.send_time;
+      last_send_size =
+          packet.sent_packet.size + packet.sent_packet.prior_unacked_data;
+    }
+    first_send_time = std::min(first_send_time, packet.sent_packet.send_time);
+
+    send_size += packet.sent_packet.size;
+    send_size += packet.sent_packet.prior_unacked_data;
+    ++num_sent_packets_in_window;
   }
 
   // Suppose a packet of size S is sent every T milliseconds.
   // A window of N packets would contain N*S bytes, but the time difference
   // between the first and the last packet would only be (N-1)*T. Thus, we
-  // need to remove one packet.
-  DataSize recv_size = data_size;
-  DataSize send_size = data_size;
-  if (settings_.assume_shared_link) {
-    // Depending on how the bottleneck queue is implemented, a large packet
-    // may delay sending of sebsequent packets, so the delay between packets
-    // i and i+1  depends on the size of both packets. In this case we minimize
-    // the maximum error by removing half of both the first and last packet
-    // size.
-    DataSize first_last_average_size =
-        (window_.front().sent_packet.size +
-         window_.front().sent_packet.prior_unacked_data +
-         window_.back().sent_packet.size +
-         window_.back().sent_packet.prior_unacked_data) /
-        2;
-    recv_size -= first_last_average_size;
-    send_size -= first_last_average_size;
-  } else {
-    // In the simpler case where the delay between packets i and i+1 only
-    // depends on the size of packet i+1, the first packet doesn't give us
-    // any information. Analogously, we assume that the start send time
-    // for the last packet doesn't depend on the size of the packet.
-    recv_size -= (window_.front().sent_packet.size +
-                  window_.front().sent_packet.prior_unacked_data);
-    send_size -= (window_.back().sent_packet.size +
-                  window_.back().sent_packet.prior_unacked_data);
-  }
+  // need to remove the size of one packet to get the correct rate of S/T.
+  // Which packet to remove (if the packets have varying sizes),
+  // depends on the network model.
+  // Suppose that 2 packets with sizes s1 and s2, are received at times t1
+  // and t2, respectively. If the packets were transmitted back to back over
+  // a bottleneck with rate capacity r, then we'd expect t2 = t1 + r * s2.
+  // Thus, r = (t2-t1) / s2, so the size of the first packet doesn't affect
+  // the difference between t1 and t2.
+  // Analoguously, if the first packet is sent at time t1 and the sender
+  // paces the packets at rate r, then the second packet can be sent at time
+  // t2 = t1 + r * s1. Thus, the send rate estimate r = (t2-t1) / s1 doesn't
+  // depend on the size of the last packet.
+  recv_size -= first_recv_size;
+  send_size -= last_send_size;
 
-  // Remove the largest gap by replacing it by the second largest gap
-  // or the average gap.
-  TimeDelta send_duration = max_send_time - min_send_time;
-  TimeDelta recv_duration = (max_recv_time - min_recv_time) - largest_recv_gap;
-  if (settings_.reduce_bias) {
-    recv_duration += second_largest_recv_gap;
-  } else {
-    recv_duration += recv_duration / (window_.size() - 2);
-  }
-
-  send_duration = std::max(send_duration, TimeDelta::Millis(1));
+  // Remove the largest gap by replacing it by the second largest gap.
+  // This is to ensure that spurious "delay spikes" (i.e. when the
+  // network stops transmitting packets for a short period, followed
+  // by a burst of delayed packets), don't cause the estimate to drop.
+  // This could cause an overestimation, which we guard against by
+  // never returning an estimate above the send rate.
+  RTC_DCHECK(first_recv_time.IsFinite());
+  RTC_DCHECK(last_recv_time.IsFinite());
+  TimeDelta recv_duration = (last_recv_time - first_recv_time) -
+                            largest_recv_gap + second_largest_recv_gap;
   recv_duration = std::max(recv_duration, TimeDelta::Millis(1));
+
+  if (num_sent_packets_in_window < settings_.required_packets) {
+    // Too few send times to calculate a reliable send rate.
+    return recv_size / recv_duration;
+  }
+
+  RTC_DCHECK(first_send_time.IsFinite());
+  RTC_DCHECK(last_send_time.IsFinite());
+  TimeDelta send_duration = last_send_time - first_send_time;
+  send_duration = std::max(send_duration, TimeDelta::Millis(1));
+
   return std::min(send_size / send_duration, recv_size / recv_duration);
 }
 
diff --git a/modules/congestion_controller/goog_cc/robust_throughput_estimator.h b/modules/congestion_controller/goog_cc/robust_throughput_estimator.h
index b67b49f..9d89856 100644
--- a/modules/congestion_controller/goog_cc/robust_throughput_estimator.h
+++ b/modules/congestion_controller/goog_cc/robust_throughput_estimator.h
@@ -12,13 +12,12 @@
 #define MODULES_CONGESTION_CONTROLLER_GOOG_CC_ROBUST_THROUGHPUT_ESTIMATOR_H_
 
 #include <deque>
-#include <memory>
 #include <vector>
 
 #include "absl/types/optional.h"
-#include "api/field_trials_view.h"
 #include "api/transport/network_types.h"
 #include "api/units/data_rate.h"
+#include "api/units/timestamp.h"
 #include "modules/congestion_controller/goog_cc/acknowledged_bitrate_estimator_interface.h"
 
 namespace webrtc {
@@ -39,8 +38,11 @@
   void SetAlrEndedTime(Timestamp /*alr_ended_time*/) override {}
 
  private:
+  bool FirstPacketOutsideWindow();
+
   const RobustThroughputEstimatorSettings settings_;
   std::deque<PacketResult> window_;
+  Timestamp latest_discarded_send_time_ = Timestamp::MinusInfinity();
 };
 
 }  // namespace webrtc
diff --git a/modules/congestion_controller/goog_cc/robust_throughput_estimator_unittest.cc b/modules/congestion_controller/goog_cc/robust_throughput_estimator_unittest.cc
index d2e01d3..95ac525 100644
--- a/modules/congestion_controller/goog_cc/robust_throughput_estimator_unittest.cc
+++ b/modules/congestion_controller/goog_cc/robust_throughput_estimator_unittest.cc
@@ -10,158 +10,418 @@
 
 #include "modules/congestion_controller/goog_cc/robust_throughput_estimator.h"
 
-#include "api/transport/field_trial_based_config.h"
-#include "test/field_trial.h"
+#include <stddef.h>
+#include <stdint.h>
+
+#include <algorithm>
+#include <memory>
+
+#include "absl/strings/string_view.h"
+#include "api/units/data_size.h"
+#include "api/units/time_delta.h"
+#include "api/units/timestamp.h"
+#include "test/explicit_key_value_config.h"
 #include "test/gtest.h"
 
 namespace webrtc {
-namespace {
-std::vector<PacketResult> CreateFeedbackVector(size_t number_of_packets,
-                                               DataSize packet_size,
-                                               TimeDelta send_increment,
-                                               TimeDelta recv_increment,
-                                               Timestamp* send_clock,
-                                               Timestamp* recv_clock,
-                                               uint16_t* sequence_number) {
-  std::vector<PacketResult> packet_feedback_vector(number_of_packets);
-  for (size_t i = 0; i < number_of_packets; i++) {
-    packet_feedback_vector[i].receive_time = *recv_clock;
-    packet_feedback_vector[i].sent_packet.send_time = *send_clock;
-    packet_feedback_vector[i].sent_packet.sequence_number = *sequence_number;
-    packet_feedback_vector[i].sent_packet.size = packet_size;
-    *send_clock += send_increment;
-    *recv_clock += recv_increment;
-    *sequence_number += 1;
-  }
-  return packet_feedback_vector;
-}
-}  // anonymous namespace
 
-TEST(RobustThroughputEstimatorTest, SteadyRate) {
-  webrtc::test::ScopedFieldTrials field_trials(
-      "WebRTC-Bwe-RobustThroughputEstimatorSettings/"
-      "enabled:true,assume_shared_link:false,reduce_bias:true,min_packets:10,"
-      "window_duration:100ms/");
-  FieldTrialBasedConfig field_trial_config;
-  RobustThroughputEstimatorSettings settings(&field_trial_config);
-  RobustThroughputEstimator throughput_estimator(settings);
-  DataSize packet_size(DataSize::Bytes(1000));
-  Timestamp send_clock(Timestamp::Millis(100000));
-  Timestamp recv_clock(Timestamp::Millis(10000));
-  TimeDelta send_increment(TimeDelta::Millis(10));
-  TimeDelta recv_increment(TimeDelta::Millis(10));
-  uint16_t sequence_number = 100;
+RobustThroughputEstimatorSettings CreateRobustThroughputEstimatorSettings(
+    absl::string_view field_trial_string) {
+  test::ExplicitKeyValueConfig trials(field_trial_string);
+  RobustThroughputEstimatorSettings settings(&trials);
+  return settings;
+}
+
+class FeedbackGenerator {
+ public:
+  std::vector<PacketResult> CreateFeedbackVector(size_t number_of_packets,
+                                                 DataSize packet_size,
+                                                 DataRate send_rate,
+                                                 DataRate recv_rate) {
+    std::vector<PacketResult> packet_feedback_vector(number_of_packets);
+    for (size_t i = 0; i < number_of_packets; i++) {
+      packet_feedback_vector[i].sent_packet.send_time = send_clock_;
+      packet_feedback_vector[i].sent_packet.sequence_number = sequence_number_;
+      packet_feedback_vector[i].sent_packet.size = packet_size;
+      send_clock_ += packet_size / send_rate;
+      recv_clock_ += packet_size / recv_rate;
+      sequence_number_ += 1;
+      packet_feedback_vector[i].receive_time = recv_clock_;
+    }
+    return packet_feedback_vector;
+  }
+
+  Timestamp CurrentReceiveClock() { return recv_clock_; }
+
+  void AdvanceReceiveClock(TimeDelta delta) { recv_clock_ += delta; }
+
+  void AdvanceSendClock(TimeDelta delta) { send_clock_ += delta; }
+
+ private:
+  Timestamp send_clock_ = Timestamp::Millis(100000);
+  Timestamp recv_clock_ = Timestamp::Millis(10000);
+  uint16_t sequence_number_ = 100;
+};
+
+TEST(RobustThroughputEstimatorTest, InitialEstimate) {
+  FeedbackGenerator feedback_generator;
+  RobustThroughputEstimator throughput_estimator(
+      CreateRobustThroughputEstimatorSettings(
+          "WebRTC-Bwe-RobustThroughputEstimatorSettings/"
+          "enabled:true/"));
+  DataRate send_rate(DataRate::BytesPerSec(100000));
+  DataRate recv_rate(DataRate::BytesPerSec(100000));
+
+  // No estimate until the estimator has enough data.
   std::vector<PacketResult> packet_feedback =
-      CreateFeedbackVector(9, packet_size, send_increment, recv_increment,
-                           &send_clock, &recv_clock, &sequence_number);
+      feedback_generator.CreateFeedbackVector(9, DataSize::Bytes(1000),
+                                              send_rate, recv_rate);
   throughput_estimator.IncomingPacketFeedbackVector(packet_feedback);
   EXPECT_FALSE(throughput_estimator.bitrate().has_value());
 
-  packet_feedback =
-      CreateFeedbackVector(11, packet_size, send_increment, recv_increment,
-                           &send_clock, &recv_clock, &sequence_number);
+  // Estimate once `required_packets` packets have been received.
+  packet_feedback = feedback_generator.CreateFeedbackVector(
+      1, DataSize::Bytes(1000), send_rate, recv_rate);
   throughput_estimator.IncomingPacketFeedbackVector(packet_feedback);
   auto throughput = throughput_estimator.bitrate();
-  EXPECT_TRUE(throughput.has_value());
-  EXPECT_NEAR(throughput.value().bytes_per_sec<double>(), 100 * 1000.0,
-              0.05 * 100 * 1000.0);  // Allow 5% error
+  EXPECT_EQ(throughput, send_rate);
+
+  // Estimate remains stable when send and receive rates are stable.
+  packet_feedback = feedback_generator.CreateFeedbackVector(
+      15, DataSize::Bytes(1000), send_rate, recv_rate);
+  throughput_estimator.IncomingPacketFeedbackVector(packet_feedback);
+  throughput = throughput_estimator.bitrate();
+  EXPECT_EQ(throughput, send_rate);
 }
 
-TEST(RobustThroughputEstimatorTest, DelaySpike) {
-  webrtc::test::ScopedFieldTrials field_trials(
-      "WebRTC-Bwe-RobustThroughputEstimatorSettings/"
-      "enabled:true,assume_shared_link:false,reduce_bias:true,min_packets:10,"
-      "window_duration:100ms/");
-  FieldTrialBasedConfig field_trial_config;
-  RobustThroughputEstimatorSettings settings(&field_trial_config);
-  RobustThroughputEstimator throughput_estimator(settings);
-  DataSize packet_size(DataSize::Bytes(1000));
-  Timestamp send_clock(Timestamp::Millis(100000));
-  Timestamp recv_clock(Timestamp::Millis(10000));
-  TimeDelta send_increment(TimeDelta::Millis(10));
-  TimeDelta recv_increment(TimeDelta::Millis(10));
-  uint16_t sequence_number = 100;
-  std::vector<PacketResult> packet_feedback =
-      CreateFeedbackVector(20, packet_size, send_increment, recv_increment,
-                           &send_clock, &recv_clock, &sequence_number);
-  throughput_estimator.IncomingPacketFeedbackVector(packet_feedback);
-  auto throughput = throughput_estimator.bitrate();
-  EXPECT_TRUE(throughput.has_value());
-  EXPECT_NEAR(throughput.value().bytes_per_sec<double>(), 100 * 1000.0,
-              0.05 * 100 * 1000.0);  // Allow 5% error
+TEST(RobustThroughputEstimatorTest, EstimateAdapts) {
+  FeedbackGenerator feedback_generator;
+  RobustThroughputEstimator throughput_estimator(
+      CreateRobustThroughputEstimatorSettings(
+          "WebRTC-Bwe-RobustThroughputEstimatorSettings/"
+          "enabled:true/"));
 
-  // Delay spike
-  recv_clock += TimeDelta::Millis(40);
+  // 1 second, 800kbps, estimate is stable.
+  DataRate send_rate(DataRate::BytesPerSec(100000));
+  DataRate recv_rate(DataRate::BytesPerSec(100000));
+  for (int i = 0; i < 10; ++i) {
+    std::vector<PacketResult> packet_feedback =
+        feedback_generator.CreateFeedbackVector(10, DataSize::Bytes(1000),
+                                                send_rate, recv_rate);
+    throughput_estimator.IncomingPacketFeedbackVector(packet_feedback);
+    auto throughput = throughput_estimator.bitrate();
+    EXPECT_EQ(throughput, send_rate);
+  }
 
-  // Faster delivery after the gap
-  recv_increment = TimeDelta::Millis(2);
-  packet_feedback =
-      CreateFeedbackVector(5, packet_size, send_increment, recv_increment,
-                           &send_clock, &recv_clock, &sequence_number);
-  throughput_estimator.IncomingPacketFeedbackVector(packet_feedback);
-  throughput = throughput_estimator.bitrate();
-  EXPECT_TRUE(throughput.has_value());
-  EXPECT_NEAR(throughput.value().bytes_per_sec<double>(), 100 * 1000.0,
-              0.05 * 100 * 1000.0);  // Allow 5% error
+  // 1 second, 1600kbps, estimate increases
+  send_rate = DataRate::BytesPerSec(200000);
+  recv_rate = DataRate::BytesPerSec(200000);
+  for (int i = 0; i < 20; ++i) {
+    std::vector<PacketResult> packet_feedback =
+        feedback_generator.CreateFeedbackVector(10, DataSize::Bytes(1000),
+                                                send_rate, recv_rate);
+    throughput_estimator.IncomingPacketFeedbackVector(packet_feedback);
+    auto throughput = throughput_estimator.bitrate();
+    ASSERT_TRUE(throughput.has_value());
+    EXPECT_GE(throughput.value(), DataRate::BytesPerSec(100000));
+    EXPECT_LE(throughput.value(), send_rate);
+  }
 
-  // Delivery at normal rate. This will be capped by the send rate.
-  recv_increment = TimeDelta::Millis(10);
-  packet_feedback =
-      CreateFeedbackVector(5, packet_size, send_increment, recv_increment,
-                           &send_clock, &recv_clock, &sequence_number);
-  throughput_estimator.IncomingPacketFeedbackVector(packet_feedback);
-  throughput = throughput_estimator.bitrate();
-  EXPECT_TRUE(throughput.has_value());
-  EXPECT_NEAR(throughput.value().bytes_per_sec<double>(), 100 * 1000.0,
-              0.05 * 100 * 1000.0);  // Allow 5% error
+  // 1 second, 1600kbps, estimate is stable
+  for (int i = 0; i < 20; ++i) {
+    std::vector<PacketResult> packet_feedback =
+        feedback_generator.CreateFeedbackVector(10, DataSize::Bytes(1000),
+                                                send_rate, recv_rate);
+    throughput_estimator.IncomingPacketFeedbackVector(packet_feedback);
+    auto throughput = throughput_estimator.bitrate();
+    EXPECT_EQ(throughput, send_rate);
+  }
+
+  // 1 second, 400kbps, estimate decreases
+  send_rate = DataRate::BytesPerSec(50000);
+  recv_rate = DataRate::BytesPerSec(50000);
+  for (int i = 0; i < 5; ++i) {
+    std::vector<PacketResult> packet_feedback =
+        feedback_generator.CreateFeedbackVector(10, DataSize::Bytes(1000),
+                                                send_rate, recv_rate);
+    throughput_estimator.IncomingPacketFeedbackVector(packet_feedback);
+    auto throughput = throughput_estimator.bitrate();
+    ASSERT_TRUE(throughput.has_value());
+    EXPECT_LE(throughput.value(), DataRate::BytesPerSec(200000));
+    EXPECT_GE(throughput.value(), send_rate);
+  }
+
+  // 1 second, 400kbps, estimate is stable
+  send_rate = DataRate::BytesPerSec(50000);
+  recv_rate = DataRate::BytesPerSec(50000);
+  for (int i = 0; i < 5; ++i) {
+    std::vector<PacketResult> packet_feedback =
+        feedback_generator.CreateFeedbackVector(10, DataSize::Bytes(1000),
+                                                send_rate, recv_rate);
+    throughput_estimator.IncomingPacketFeedbackVector(packet_feedback);
+    auto throughput = throughput_estimator.bitrate();
+    EXPECT_EQ(throughput, send_rate);
+  }
 }
 
 TEST(RobustThroughputEstimatorTest, CappedByReceiveRate) {
-  webrtc::test::ScopedFieldTrials field_trials(
-      "WebRTC-Bwe-RobustThroughputEstimatorSettings/"
-      "enabled:true,assume_shared_link:false,reduce_bias:true,min_packets:10,"
-      "window_duration:100ms/");
-  FieldTrialBasedConfig field_trial_config;
-  RobustThroughputEstimatorSettings settings(&field_trial_config);
-  RobustThroughputEstimator throughput_estimator(settings);
-  DataSize packet_size(DataSize::Bytes(1000));
-  Timestamp send_clock(Timestamp::Millis(100000));
-  Timestamp recv_clock(Timestamp::Millis(10000));
-  TimeDelta send_increment(TimeDelta::Millis(10));
-  TimeDelta recv_increment(TimeDelta::Millis(40));
-  uint16_t sequence_number = 100;
+  FeedbackGenerator feedback_generator;
+  RobustThroughputEstimator throughput_estimator(
+      CreateRobustThroughputEstimatorSettings(
+          "WebRTC-Bwe-RobustThroughputEstimatorSettings/"
+          "enabled:true/"));
+  DataRate send_rate(DataRate::BytesPerSec(100000));
+  DataRate recv_rate(DataRate::BytesPerSec(25000));
+
   std::vector<PacketResult> packet_feedback =
-      CreateFeedbackVector(20, packet_size, send_increment, recv_increment,
-                           &send_clock, &recv_clock, &sequence_number);
+      feedback_generator.CreateFeedbackVector(20, DataSize::Bytes(1000),
+                                              send_rate, recv_rate);
   throughput_estimator.IncomingPacketFeedbackVector(packet_feedback);
   auto throughput = throughput_estimator.bitrate();
-  EXPECT_TRUE(throughput.has_value());
-  EXPECT_NEAR(throughput.value().bytes_per_sec<double>(), 25 * 1000.0,
-              0.05 * 25 * 1000.0);  // Allow 5% error
+  ASSERT_TRUE(throughput.has_value());
+  EXPECT_NEAR(throughput.value().bytes_per_sec<double>(),
+              recv_rate.bytes_per_sec<double>(),
+              0.05 * recv_rate.bytes_per_sec<double>());  // Allow 5% error
 }
 
 TEST(RobustThroughputEstimatorTest, CappedBySendRate) {
-  webrtc::test::ScopedFieldTrials field_trials(
-      "WebRTC-Bwe-RobustThroughputEstimatorSettings/"
-      "enabled:true,assume_shared_link:false,reduce_bias:true,min_packets:10,"
-      "window_duration:100ms/");
-  FieldTrialBasedConfig field_trial_config;
-  RobustThroughputEstimatorSettings settings(&field_trial_config);
-  RobustThroughputEstimator throughput_estimator(settings);
-  DataSize packet_size(DataSize::Bytes(1000));
-  Timestamp send_clock(Timestamp::Millis(100000));
-  Timestamp recv_clock(Timestamp::Millis(10000));
-  TimeDelta send_increment(TimeDelta::Millis(20));
-  TimeDelta recv_increment(TimeDelta::Millis(10));
-  uint16_t sequence_number = 100;
+  FeedbackGenerator feedback_generator;
+  RobustThroughputEstimator throughput_estimator(
+      CreateRobustThroughputEstimatorSettings(
+          "WebRTC-Bwe-RobustThroughputEstimatorSettings/"
+          "enabled:true/"));
+  DataRate send_rate(DataRate::BytesPerSec(50000));
+  DataRate recv_rate(DataRate::BytesPerSec(100000));
+
   std::vector<PacketResult> packet_feedback =
-      CreateFeedbackVector(20, packet_size, send_increment, recv_increment,
-                           &send_clock, &recv_clock, &sequence_number);
+      feedback_generator.CreateFeedbackVector(20, DataSize::Bytes(1000),
+                                              send_rate, recv_rate);
+  throughput_estimator.IncomingPacketFeedbackVector(packet_feedback);
+  auto throughput = throughput_estimator.bitrate();
+  ASSERT_TRUE(throughput.has_value());
+  EXPECT_NEAR(throughput.value().bytes_per_sec<double>(),
+              send_rate.bytes_per_sec<double>(),
+              0.05 * send_rate.bytes_per_sec<double>());  // Allow 5% error
+}
+
+TEST(RobustThroughputEstimatorTest, DelaySpike) {
+  FeedbackGenerator feedback_generator;
+  // This test uses a 500ms window to amplify the effect
+  // of a delay spike.
+  RobustThroughputEstimator throughput_estimator(
+      CreateRobustThroughputEstimatorSettings(
+          "WebRTC-Bwe-RobustThroughputEstimatorSettings/"
+          "enabled:true,window_duration:500ms/"));
+  DataRate send_rate(DataRate::BytesPerSec(100000));
+  DataRate recv_rate(DataRate::BytesPerSec(100000));
+
+  std::vector<PacketResult> packet_feedback =
+      feedback_generator.CreateFeedbackVector(20, DataSize::Bytes(1000),
+                                              send_rate, recv_rate);
+  throughput_estimator.IncomingPacketFeedbackVector(packet_feedback);
+  auto throughput = throughput_estimator.bitrate();
+  EXPECT_EQ(throughput, send_rate);
+
+  // Delay spike. 25 packets sent, but none received.
+  feedback_generator.AdvanceReceiveClock(TimeDelta::Millis(250));
+
+  // Deliver all of the packets during the next 50 ms. (During this time,
+  // we'll have sent an additional 5 packets, so we need to receive 30
+  // packets at 1000 bytes each in 50 ms, i.e. 600000 bytes per second).
+  recv_rate = DataRate::BytesPerSec(600000);
+  // Estimate should not drop.
+  for (int i = 0; i < 30; ++i) {
+    packet_feedback = feedback_generator.CreateFeedbackVector(
+        1, DataSize::Bytes(1000), send_rate, recv_rate);
+    throughput_estimator.IncomingPacketFeedbackVector(packet_feedback);
+    throughput = throughput_estimator.bitrate();
+    ASSERT_TRUE(throughput.has_value());
+    EXPECT_NEAR(throughput.value().bytes_per_sec<double>(),
+                send_rate.bytes_per_sec<double>(),
+                0.05 * send_rate.bytes_per_sec<double>());  // Allow 5% error
+  }
+
+  // Delivery at normal rate. When the packets received before the gap
+  // has left the estimator's window, the receive rate will be high, but the
+  // estimate should be capped by the send rate.
+  recv_rate = DataRate::BytesPerSec(100000);
+  for (int i = 0; i < 20; ++i) {
+    packet_feedback = feedback_generator.CreateFeedbackVector(
+        5, DataSize::Bytes(1000), send_rate, recv_rate);
+    throughput_estimator.IncomingPacketFeedbackVector(packet_feedback);
+    throughput = throughput_estimator.bitrate();
+    ASSERT_TRUE(throughput.has_value());
+    EXPECT_NEAR(throughput.value().bytes_per_sec<double>(),
+                send_rate.bytes_per_sec<double>(),
+                0.05 * send_rate.bytes_per_sec<double>());  // Allow 5% error
+  }
+}
+
+TEST(RobustThroughputEstimatorTest, HighLoss) {
+  FeedbackGenerator feedback_generator;
+  RobustThroughputEstimator throughput_estimator(
+      CreateRobustThroughputEstimatorSettings(
+          "WebRTC-Bwe-RobustThroughputEstimatorSettings/"
+          "enabled:true/"));
+  DataRate send_rate(DataRate::BytesPerSec(100000));
+  DataRate recv_rate(DataRate::BytesPerSec(100000));
+
+  std::vector<PacketResult> packet_feedback =
+      feedback_generator.CreateFeedbackVector(20, DataSize::Bytes(1000),
+                                              send_rate, recv_rate);
+
+  // 50% loss
+  for (size_t i = 0; i < packet_feedback.size(); i++) {
+    if (i % 2 == 1) {
+      packet_feedback[i].receive_time = Timestamp::PlusInfinity();
+    }
+  }
+
+  std::sort(packet_feedback.begin(), packet_feedback.end(),
+            PacketResult::ReceiveTimeOrder());
+  throughput_estimator.IncomingPacketFeedbackVector(packet_feedback);
+  auto throughput = throughput_estimator.bitrate();
+  ASSERT_TRUE(throughput.has_value());
+  EXPECT_NEAR(throughput.value().bytes_per_sec<double>(),
+              send_rate.bytes_per_sec<double>() / 2,
+              0.05 * send_rate.bytes_per_sec<double>() / 2);  // Allow 5% error
+}
+
+TEST(RobustThroughputEstimatorTest, ReorderedFeedback) {
+  FeedbackGenerator feedback_generator;
+  RobustThroughputEstimator throughput_estimator(
+      CreateRobustThroughputEstimatorSettings(
+          "WebRTC-Bwe-RobustThroughputEstimatorSettings/"
+          "enabled:true/"));
+  DataRate send_rate(DataRate::BytesPerSec(100000));
+  DataRate recv_rate(DataRate::BytesPerSec(100000));
+
+  std::vector<PacketResult> packet_feedback =
+      feedback_generator.CreateFeedbackVector(20, DataSize::Bytes(1000),
+                                              send_rate, recv_rate);
+  throughput_estimator.IncomingPacketFeedbackVector(packet_feedback);
+  auto throughput = throughput_estimator.bitrate();
+  EXPECT_EQ(throughput, send_rate);
+
+  std::vector<PacketResult> delayed_feedback =
+      feedback_generator.CreateFeedbackVector(10, DataSize::Bytes(1000),
+                                              send_rate, recv_rate);
+  packet_feedback = feedback_generator.CreateFeedbackVector(
+      10, DataSize::Bytes(1000), send_rate, recv_rate);
+
+  // Since we're missing some feedback, it's expected that the
+  // estimate will drop.
+  throughput_estimator.IncomingPacketFeedbackVector(packet_feedback);
+  throughput = throughput_estimator.bitrate();
+  ASSERT_TRUE(throughput.has_value());
+  EXPECT_LT(throughput.value(), send_rate);
+
+  // But it should completely recover as soon as we get the feedback.
+  throughput_estimator.IncomingPacketFeedbackVector(delayed_feedback);
+  throughput = throughput_estimator.bitrate();
+  EXPECT_EQ(throughput, send_rate);
+
+  // It should then remain stable (as if the feedbacks weren't reordered.)
+  for (int i = 0; i < 10; ++i) {
+    packet_feedback = feedback_generator.CreateFeedbackVector(
+        15, DataSize::Bytes(1000), send_rate, recv_rate);
+    throughput_estimator.IncomingPacketFeedbackVector(packet_feedback);
+    throughput = throughput_estimator.bitrate();
+    EXPECT_EQ(throughput, send_rate);
+  }
+}
+
+TEST(RobustThroughputEstimatorTest, DeepReordering) {
+  FeedbackGenerator feedback_generator;
+  // This test uses a 500ms window to amplify the
+  // effect of reordering.
+  RobustThroughputEstimator throughput_estimator(
+      CreateRobustThroughputEstimatorSettings(
+          "WebRTC-Bwe-RobustThroughputEstimatorSettings/"
+          "enabled:true,window_duration:500ms/"));
+  DataRate send_rate(DataRate::BytesPerSec(100000));
+  DataRate recv_rate(DataRate::BytesPerSec(100000));
+
+  std::vector<PacketResult> delayed_packets =
+      feedback_generator.CreateFeedbackVector(1, DataSize::Bytes(1000),
+                                              send_rate, recv_rate);
+
+  for (int i = 0; i < 10; i++) {
+    std::vector<PacketResult> packet_feedback =
+        feedback_generator.CreateFeedbackVector(10, DataSize::Bytes(1000),
+                                                send_rate, recv_rate);
+    throughput_estimator.IncomingPacketFeedbackVector(packet_feedback);
+    auto throughput = throughput_estimator.bitrate();
+    EXPECT_EQ(throughput, send_rate);
+  }
+
+  // Delayed packet arrives ~1 second after it should have.
+  // Since the window is 500 ms, the delayed packet was sent ~500
+  // ms before the second oldest packet. However, the send rate
+  // should not drop.
+  delayed_packets.front().receive_time =
+      feedback_generator.CurrentReceiveClock();
+  throughput_estimator.IncomingPacketFeedbackVector(delayed_packets);
+  auto throughput = throughput_estimator.bitrate();
+  ASSERT_TRUE(throughput.has_value());
+  EXPECT_NEAR(throughput.value().bytes_per_sec<double>(),
+              send_rate.bytes_per_sec<double>(),
+              0.05 * send_rate.bytes_per_sec<double>());  // Allow 5% error
+
+  // Thoughput should stay stable.
+  for (int i = 0; i < 10; i++) {
+    std::vector<PacketResult> packet_feedback =
+        feedback_generator.CreateFeedbackVector(10, DataSize::Bytes(1000),
+                                                send_rate, recv_rate);
+    throughput_estimator.IncomingPacketFeedbackVector(packet_feedback);
+    auto throughput = throughput_estimator.bitrate();
+    ASSERT_TRUE(throughput.has_value());
+    EXPECT_NEAR(throughput.value().bytes_per_sec<double>(),
+                send_rate.bytes_per_sec<double>(),
+                0.05 * send_rate.bytes_per_sec<double>());  // Allow 5% error
+  }
+}
+
+TEST(RobustThroughputEstimatorTest, StreamPausedAndResumed) {
+  FeedbackGenerator feedback_generator;
+  RobustThroughputEstimator throughput_estimator(
+      CreateRobustThroughputEstimatorSettings(
+          "WebRTC-Bwe-RobustThroughputEstimatorSettings/"
+          "enabled:true/"));
+  DataRate send_rate(DataRate::BytesPerSec(100000));
+  DataRate recv_rate(DataRate::BytesPerSec(100000));
+
+  std::vector<PacketResult> packet_feedback =
+      feedback_generator.CreateFeedbackVector(20, DataSize::Bytes(1000),
+                                              send_rate, recv_rate);
   throughput_estimator.IncomingPacketFeedbackVector(packet_feedback);
   auto throughput = throughput_estimator.bitrate();
   EXPECT_TRUE(throughput.has_value());
-  EXPECT_NEAR(throughput.value().bytes_per_sec<double>(), 50 * 1000.0,
-              0.05 * 50 * 1000.0);  // Allow 5% error
+  double expected_bytes_per_sec = 100 * 1000.0;
+  EXPECT_NEAR(throughput.value().bytes_per_sec<double>(),
+              expected_bytes_per_sec,
+              0.05 * expected_bytes_per_sec);  // Allow 5% error
+
+  // No packets sent or feedback received for 60s.
+  feedback_generator.AdvanceSendClock(TimeDelta::Seconds(60));
+  feedback_generator.AdvanceReceiveClock(TimeDelta::Seconds(60));
+
+  // Resume sending packets at the same rate as before. The estimate
+  // will initially be invalid, due to lack of recent data.
+  packet_feedback = feedback_generator.CreateFeedbackVector(
+      5, DataSize::Bytes(1000), send_rate, recv_rate);
+  throughput_estimator.IncomingPacketFeedbackVector(packet_feedback);
+  throughput = throughput_estimator.bitrate();
+  EXPECT_FALSE(throughput.has_value());
+
+  // But be back to the normal level once we have enough data.
+  for (int i = 0; i < 4; ++i) {
+    packet_feedback = feedback_generator.CreateFeedbackVector(
+        5, DataSize::Bytes(1000), send_rate, recv_rate);
+    throughput_estimator.IncomingPacketFeedbackVector(packet_feedback);
+    throughput = throughput_estimator.bitrate();
+    EXPECT_EQ(throughput, send_rate);
+  }
 }
 
-}  // namespace webrtc*/
+}  // namespace webrtc
diff --git a/rtc_tools/rtc_event_log_visualizer/analyzer.cc b/rtc_tools/rtc_event_log_visualizer/analyzer.cc
index bdbb438..f94adc2 100644
--- a/rtc_tools/rtc_event_log_visualizer/analyzer.cc
+++ b/rtc_tools/rtc_event_log_visualizer/analyzer.cc
@@ -1242,11 +1242,11 @@
     return std::numeric_limits<int64_t>::max();
   };
 
-  RateStatistics acked_bitrate(750, 8000);
+  RateStatistics raw_acked_bitrate(750, 8000);
   test::ExplicitKeyValueConfig throughput_config(
       "WebRTC-Bwe-RobustThroughputEstimatorSettings/"
-      "enabled:true,reduce_bias:true,assume_shared_link:false,initial_packets:"
-      "10,min_packets:25,window_duration:750ms,unacked_weight:0.5/");
+      "enabled:true,required_packets:10,"
+      "window_packets:25,window_duration:1000ms,unacked_weight:1.0/");
   std::unique_ptr<AcknowledgedBitrateEstimatorInterface>
       robust_throughput_estimator(
           AcknowledgedBitrateEstimatorInterface::Create(&throughput_config));
@@ -1305,7 +1305,6 @@
       auto feedback_msg = transport_feedback.ProcessTransportFeedback(
           rtcp_iterator->transport_feedback,
           Timestamp::Millis(clock.TimeInMilliseconds()));
-      absl::optional<uint32_t> bitrate_bps;
       if (feedback_msg) {
         observer.Update(goog_cc->OnTransportPacketsFeedback(*feedback_msg));
         std::vector<PacketResult> feedback =
@@ -1315,24 +1314,30 @@
               feedback);
           robust_throughput_estimator->IncomingPacketFeedbackVector(feedback);
           for (const PacketResult& packet : feedback) {
-            acked_bitrate.Update(packet.sent_packet.size.bytes(),
-                                 packet.receive_time.ms());
+            raw_acked_bitrate.Update(packet.sent_packet.size.bytes(),
+                                     packet.receive_time.ms());
           }
-          bitrate_bps = acked_bitrate.Rate(feedback.back().receive_time.ms());
+          absl::optional<uint32_t> raw_bitrate_bps =
+              raw_acked_bitrate.Rate(feedback.back().receive_time.ms());
+          float x = config_.GetCallTimeSec(clock.CurrentTime());
+          if (raw_bitrate_bps) {
+            float y = raw_bitrate_bps.value() / 1000;
+            acked_time_series.points.emplace_back(x, y);
+          }
+          absl::optional<DataRate> robust_estimate =
+              robust_throughput_estimator->bitrate();
+          if (robust_estimate) {
+            float y = robust_estimate.value().kbps();
+            robust_time_series.points.emplace_back(x, y);
+          }
+          absl::optional<DataRate> acked_estimate =
+              acknowledged_bitrate_estimator->bitrate();
+          if (acked_estimate) {
+            float y = acked_estimate.value().kbps();
+            acked_estimate_time_series.points.emplace_back(x, y);
+          }
         }
       }
-
-      float x = config_.GetCallTimeSec(clock.CurrentTime());
-      float y = bitrate_bps.value_or(0) / 1000;
-      acked_time_series.points.emplace_back(x, y);
-      y = robust_throughput_estimator->bitrate()
-              .value_or(DataRate::Zero())
-              .kbps();
-      robust_time_series.points.emplace_back(x, y);
-      y = acknowledged_bitrate_estimator->bitrate()
-              .value_or(DataRate::Zero())
-              .kbps();
-      acked_estimate_time_series.points.emplace_back(x, y);
       ++rtcp_iterator;
     }
     if (clock.TimeInMicroseconds() >= NextProcessTime()) {