Wire up trial for alternative EncoderBitrateAdjuster behavior.

Behind a flag, the new behavior changes how the "media rate" utilization
is calculated:

* Instead of per spatial & temporal layer, it's per spatial layer only.
* Overshoot is compared to real target vs adjusted target.
* Window takes quite periods/frame drops more into consideration.

This should lead to less push-back when not network constrained and
complex content is used causing bursty behavior.

Bug: b/349561566
Change-Id: I402e6531183493c963fec48ae363ce0b859b396a
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/356480
Commit-Queue: Erik Språng <sprang@webrtc.org>
Reviewed-by: Philip Eliasson <philipel@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#42593}

experiments/field_trials.py

@@ -59,6 +59,9 @@ ACTIVE_FIELD_TRIALS: FrozenSet[FieldTrial] = frozenset([
     FieldTrial('WebRTC-Av1-GetEncoderInfoOverride',
                42225234,
                date(2024, 4, 1)),
+    FieldTrial('WebRTC-BitrateAdjusterUseNewfangledHeadroomAdjustment',
+               349561566,
+               date(2025, 8, 26)),
     FieldTrial('WebRTC-Bwe-LimitPacingFactorByUpperLinkCapacityEstimate',
                42220543,
                date(2025, 1, 1)),

video/encoder_bitrate_adjuster.cc

@@ -41,19 +41,23 @@ struct LayerRateInfo {
   }
 };
 }  // namespace
-constexpr int64_t EncoderBitrateAdjuster::kWindowSizeMs;
+constexpr TimeDelta EncoderBitrateAdjuster::kWindowSize;
 constexpr size_t EncoderBitrateAdjuster::kMinFramesSinceLayoutChange;
 constexpr double EncoderBitrateAdjuster::kDefaultUtilizationFactor;
 
 EncoderBitrateAdjuster::EncoderBitrateAdjuster(
     const VideoCodec& codec_settings,
-    const FieldTrialsView& field_trials)
+    const FieldTrialsView& field_trials,
+    Clock& clock)
     : utilize_bandwidth_headroom_(RateControlSettings(field_trials)
                                       .BitrateAdjusterCanUseNetworkHeadroom()),
+      use_newfangled_headroom_adjustment_(field_trials.IsEnabled(
+          "WebRTC-BitrateAdjusterUseNewfangledHeadroomAdjustment")),
       frames_since_layout_change_(0),
       min_bitrates_bps_{},
       codec_(codec_settings.codecType),
-      codec_mode_(codec_settings.mode) {
+      codec_mode_(codec_settings.mode),
+      clock_(clock) {
   // TODO(https://crbug.com/webrtc/14891): If we want to support simulcast of
   // SVC streams, EncoderBitrateAdjuster needs to be updated to care about both
   // `simulcastStream` and `spatialLayers` at the same time.
@@ -94,6 +98,7 @@ EncoderBitrateAdjuster::~EncoderBitrateAdjuster() = default;
 VideoBitrateAllocation EncoderBitrateAdjuster::AdjustRateAllocation(
     const VideoEncoder::RateControlParameters& rates) {
   current_rate_control_parameters_ = rates;
+  const Timestamp now = clock_.CurrentTime();
 
   // First check that overshoot detectors exist, and store per simulcast/spatial
   // layer how many active temporal layers we have.
@@ -109,7 +114,7 @@ VideoBitrateAllocation EncoderBitrateAdjuster::AdjustRateAllocation(
         if (!overshoot_detectors_[si][ti]) {
           overshoot_detectors_[si][ti] =
               std::make_unique<EncoderOvershootDetector>(
-                  kWindowSizeMs, codec_,
+                  kWindowSize.ms(), codec_,
                   codec_mode_ == VideoCodecMode::kScreensharing);
           frames_since_layout_change_ = 0;
         }
@@ -119,10 +124,26 @@ VideoBitrateAllocation EncoderBitrateAdjuster::AdjustRateAllocation(
         frames_since_layout_change_ = 0;
       }
     }
+    if (use_newfangled_headroom_adjustment_) {
+      // Instantiate average media rate trackers, one per active spatial layer.
+
+      DataRate spatial_layer_rate =
+          DataRate::BitsPerSec(rates.bitrate.GetSpatialLayerSum(si));
+      if (spatial_layer_rate.IsZero()) {
+        media_rate_trackers_[si].reset();
+      } else {
+        if (media_rate_trackers_[si] == nullptr) {
+          constexpr int kMaxDataPointsInUtilizationTrackers = 100;
+          media_rate_trackers_[si] = std::make_unique<RateUtilizationTracker>(
+              kMaxDataPointsInUtilizationTrackers, kWindowSize);
+        }
+        // Media rate trackers use the unadjusted target rate.
+        media_rate_trackers_[si]->OnDataRateChanged(spatial_layer_rate, now);
+      }
+    }
   }
 
   // Next poll the overshoot detectors and populate the adjusted allocation.
-  const int64_t now_ms = rtc::TimeMillis();
   VideoBitrateAllocation adjusted_allocation;
   std::vector<LayerRateInfo> layer_infos;
   DataRate wanted_overshoot_sum = DataRate::Zero();
@@ -153,11 +174,15 @@ VideoBitrateAllocation EncoderBitrateAdjuster::AdjustRateAllocation(
       RTC_DCHECK(overshoot_detectors_[si][0]);
       layer_info.link_utilization_factor =
           overshoot_detectors_[si][0]
-              ->GetNetworkRateUtilizationFactor(now_ms)
+              ->GetNetworkRateUtilizationFactor(now.ms())
               .value_or(kDefaultUtilizationFactor);
       layer_info.media_utilization_factor =
-          overshoot_detectors_[si][0]
+          use_newfangled_headroom_adjustment_
-              ->GetMediaRateUtilizationFactor(now_ms)
+              ? media_rate_trackers_[si]
+                    ->GetRateUtilizationFactor(now)
+                    .value_or(kDefaultUtilizationFactor)
+              : overshoot_detectors_[si][0]
+                    ->GetMediaRateUtilizationFactor(now.ms())
                     .value_or(kDefaultUtilizationFactor);
     } else if (layer_info.target_rate > DataRate::Zero()) {
       // Multiple temporal layers enabled for this simulcast/spatial layer.
@@ -170,9 +195,11 @@ VideoBitrateAllocation EncoderBitrateAdjuster::AdjustRateAllocation(
         RTC_DCHECK(overshoot_detectors_[si][ti]);
         const absl::optional<double> ti_link_utilization_factor =
             overshoot_detectors_[si][ti]->GetNetworkRateUtilizationFactor(
-                now_ms);
+                now.ms());
+
         const absl::optional<double> ti_media_utilization_factor =
-            overshoot_detectors_[si][ti]->GetMediaRateUtilizationFactor(now_ms);
+            overshoot_detectors_[si][ti]->GetMediaRateUtilizationFactor(
+                now.ms());
         if (!ti_link_utilization_factor || !ti_media_utilization_factor) {
           layer_info.link_utilization_factor = kDefaultUtilizationFactor;
           layer_info.media_utilization_factor = kDefaultUtilizationFactor;
@@ -186,14 +213,17 @@ VideoBitrateAllocation EncoderBitrateAdjuster::AdjustRateAllocation(
         layer_info.media_utilization_factor +=
             weight * ti_media_utilization_factor.value();
       }
+
+      if (use_newfangled_headroom_adjustment_) {
+        layer_info.media_utilization_factor =
+            media_rate_trackers_[si]->GetRateUtilizationFactor(now).value_or(
+                kDefaultUtilizationFactor);
+      }
     } else {
       RTC_DCHECK_NOTREACHED();
     }
 
     if (layer_info.link_utilization_factor < 1.0) {
-      // TODO(sprang): Consider checking underuse and allowing it to cancel some
-      // potential overuse by other streams.
-
       // Don't boost target bitrate if encoder is under-using.
       layer_info.link_utilization_factor = 1.0;
     } else {
@@ -313,7 +343,7 @@ VideoBitrateAllocation EncoderBitrateAdjuster::AdjustRateAllocation(
 
         overshoot_detectors_[si][ti]->SetTargetRate(
             DataRate::BitsPerSec(layer_bitrate_bps),
-            fps_fraction * rates.framerate_fps, now_ms);
+            fps_fraction * rates.framerate_fps, now.ms());
       }
     }
   }
@@ -345,6 +375,10 @@ void EncoderBitrateAdjuster::OnEncodedFrame(DataSize size,
   if (detector) {
     detector->OnEncodedFrame(size.bytes(), rtc::TimeMillis());
   }
+  if (media_rate_trackers_[stream_index]) {
+    media_rate_trackers_[stream_index]->OnDataProduced(size,
+                                                       clock_.CurrentTime());
+  }
 }
 
 void EncoderBitrateAdjuster::Reset() {
@@ -352,6 +386,7 @@ void EncoderBitrateAdjuster::Reset() {
     for (size_t ti = 0; ti < kMaxTemporalStreams; ++ti) {
       overshoot_detectors_[si][ti].reset();
     }
+    media_rate_trackers_[si].reset();
   }
   // Call AdjustRateAllocation() with the last know bitrate allocation, so that
   // the appropriate overuse detectors are immediately re-created.

video/encoder_bitrate_adjuster.h

@@ -14,17 +14,20 @@
 #include <memory>
 
 #include "api/field_trials_view.h"
+#include "api/units/time_delta.h"
 #include "api/video/encoded_image.h"
 #include "api/video/video_bitrate_allocation.h"
 #include "api/video_codecs/video_encoder.h"
+#include "system_wrappers/include/clock.h"
 #include "video/encoder_overshoot_detector.h"
+#include "video/rate_utilization_tracker.h"
 
 namespace webrtc {
 
 class EncoderBitrateAdjuster {
  public:
   // Size of sliding window used to track overshoot rate.
-  static constexpr int64_t kWindowSizeMs = 3000;
+  static constexpr TimeDelta kWindowSize = TimeDelta::Seconds(3);
   // Minimum number of frames since last layout change required to trust the
   // overshoot statistics. Otherwise falls back to default utilization.
   // By layout change, we mean any simulcast/spatial/temporal layer being either
@@ -36,7 +39,8 @@ class EncoderBitrateAdjuster {
   static constexpr double kDefaultUtilizationFactor = 1.2;
 
   EncoderBitrateAdjuster(const VideoCodec& codec_settings,
-                         const FieldTrialsView& field_trials);
+                         const FieldTrialsView& field_trials,
+                         Clock& clock);
   ~EncoderBitrateAdjuster();
 
   // Adjusts the given rate allocation to make it paceable within the target
@@ -59,6 +63,7 @@ class EncoderBitrateAdjuster {
 
  private:
   const bool utilize_bandwidth_headroom_;
+  const bool use_newfangled_headroom_adjustment_;
 
   VideoEncoder::RateControlParameters current_rate_control_parameters_;
   // FPS allocation of temporal layers, per simulcast/spatial layer. Represented
@@ -73,6 +78,10 @@ class EncoderBitrateAdjuster {
   std::unique_ptr<EncoderOvershootDetector>
       overshoot_detectors_[kMaxSpatialLayers][kMaxTemporalStreams];
 
+  // Per spatial layer track of average media utilization.
+  std::unique_ptr<RateUtilizationTracker>
+      media_rate_trackers_[kMaxSpatialLayers];
+
   // Minimum bitrates allowed, per spatial layer.
   uint32_t min_bitrates_bps_[kMaxSpatialLayers];
 
@@ -81,6 +90,8 @@ class EncoderBitrateAdjuster {
 
   // Codec mode: { kRealtimeVideo, kScreensharing }.
   VideoCodecMode codec_mode_;
+
+  Clock& clock_;
 };
 
 }  // namespace webrtc

video/encoder_bitrate_adjuster_unittest.cc

@@ -11,19 +11,26 @@
 #include "video/encoder_bitrate_adjuster.h"
 
 #include <memory>
+#include <string>
 #include <vector>
 
 #include "api/field_trials_view.h"
 #include "api/units/data_rate.h"
-#include "rtc_base/fake_clock.h"
+#include "rtc_base/logging.h"
 #include "rtc_base/numerics/safe_conversions.h"
 #include "test/gtest.h"
 #include "test/scoped_key_value_config.h"
+#include "test/time_controller/simulated_time_controller.h"
 
 namespace webrtc {
 namespace test {
 
-class EncoderBitrateAdjusterTest : public ::testing::Test {
+using ::testing::Test;
+using ::testing::Values;
+using ::testing::WithParamInterface;
+
+class EncoderBitrateAdjusterTest : public Test,
+                                   public WithParamInterface<std::string> {
  public:
   static constexpr int64_t kWindowSizeMs = 3000;
   static constexpr int kDefaultBitrateBps = 300000;
@@ -35,10 +42,12 @@ class EncoderBitrateAdjusterTest : public ::testing::Test {
   static_assert(kSequenceLength % 2 == 0, "Sequence length must be even.");
 
   EncoderBitrateAdjusterTest()
-      : target_bitrate_(DataRate::BitsPerSec(kDefaultBitrateBps)),
+      : time_controller_(/*start_time=*/Timestamp::Millis(123)),
+        target_bitrate_(DataRate::BitsPerSec(kDefaultBitrateBps)),
         target_framerate_fps_(kDefaultFrameRateFps),
         tl_pattern_idx_{},
-        sequence_idx_{} {}
+        sequence_idx_{},
+        scoped_field_trial_(GetParam()) {}
 
  protected:
   void SetUpAdjusterWithCodec(size_t num_spatial_layers,
@@ -55,8 +64,8 @@ class EncoderBitrateAdjusterTest : public ::testing::Test {
       }
     }
 
-    adjuster_ =
+    adjuster_ = std::make_unique<EncoderBitrateAdjuster>(
-        std::make_unique<EncoderBitrateAdjuster>(codec_, scoped_field_trial_);
+        codec_, scoped_field_trial_, *time_controller_.GetClock());
     adjuster_->OnEncoderInfo(encoder_info_);
     current_adjusted_allocation_ =
         adjuster_->AdjustRateAllocation(VideoEncoder::RateControlParameters(
@@ -112,7 +121,8 @@ class EncoderBitrateAdjusterTest : public ::testing::Test {
     const int64_t start_us = rtc::TimeMicros();
     while (rtc::TimeMicros() <
            start_us + (duration_ms * rtc::kNumMicrosecsPerMillisec)) {
-      clock_.AdvanceTime(TimeDelta::Seconds(1) / target_framerate_fps_);
+      time_controller_.AdvanceTime(TimeDelta::Seconds(1) /
+                                   target_framerate_fps_);
       for (size_t si = 0; si < NumSpatialLayers(); ++si) {
         const std::vector<int>& tl_pattern =
             kTlPatterns[NumTemporalLayers(si) - 1];
@@ -231,12 +241,14 @@ class EncoderBitrateAdjusterTest : public ::testing::Test {
     return multiplied_allocation;
   }
 
+  GlobalSimulatedTimeController time_controller_;
+
   VideoCodec codec_;
   VideoEncoder::EncoderInfo encoder_info_;
   std::unique_ptr<EncoderBitrateAdjuster> adjuster_;
   VideoBitrateAllocation current_input_allocation_;
   VideoBitrateAllocation current_adjusted_allocation_;
-  rtc::ScopedFakeClock clock_;
+
   DataRate target_bitrate_;
   double target_framerate_fps_;
   int tl_pattern_idx_[kMaxSpatialLayers];
@@ -250,7 +262,7 @@ class EncoderBitrateAdjusterTest : public ::testing::Test {
       {0, 3, 2, 3, 1, 3, 2, 3}};
 };
 
-TEST_F(EncoderBitrateAdjusterTest, SingleLayerOptimal) {
+TEST_P(EncoderBitrateAdjusterTest, SingleLayerOptimal) {
   // Single layer, well behaved encoder.
   current_input_allocation_.SetBitrate(0, 0, 300000);
   target_framerate_fps_ = 30;
@@ -264,7 +276,7 @@ TEST_F(EncoderBitrateAdjusterTest, SingleLayerOptimal) {
   ExpectNear(current_input_allocation_, current_adjusted_allocation_, 0.01);
 }
 
-TEST_F(EncoderBitrateAdjusterTest, SingleLayerOveruse) {
+TEST_P(EncoderBitrateAdjusterTest, SingleLayerOveruse) {
   // Single layer, well behaved encoder.
   current_input_allocation_.SetBitrate(0, 0, 300000);
   target_framerate_fps_ = 30;
@@ -278,7 +290,7 @@ TEST_F(EncoderBitrateAdjusterTest, SingleLayerOveruse) {
              current_adjusted_allocation_, 0.01);
 }
 
-TEST_F(EncoderBitrateAdjusterTest, SingleLayerUnderuse) {
+TEST_P(EncoderBitrateAdjusterTest, SingleLayerUnderuse) {
   // Single layer, well behaved encoder.
   current_input_allocation_.SetBitrate(0, 0, 300000);
   target_framerate_fps_ = 30;
@@ -291,7 +303,7 @@ TEST_F(EncoderBitrateAdjusterTest, SingleLayerUnderuse) {
   ExpectNear(current_input_allocation_, current_adjusted_allocation_, 0.00);
 }
 
-TEST_F(EncoderBitrateAdjusterTest, ThreeTemporalLayersOptimalSize) {
+TEST_P(EncoderBitrateAdjusterTest, ThreeTemporalLayersOptimalSize) {
   // Three temporal layers, 60%/20%/20% bps distro, well behaved encoder.
   current_input_allocation_.SetBitrate(0, 0, 180000);
   current_input_allocation_.SetBitrate(0, 1, 60000);
@@ -305,7 +317,7 @@ TEST_F(EncoderBitrateAdjusterTest, ThreeTemporalLayersOptimalSize) {
   ExpectNear(current_input_allocation_, current_adjusted_allocation_, 0.01);
 }
 
-TEST_F(EncoderBitrateAdjusterTest, ThreeTemporalLayersOvershoot) {
+TEST_P(EncoderBitrateAdjusterTest, ThreeTemporalLayersOvershoot) {
   // Three temporal layers, 60%/20%/20% bps distro.
   // 10% overshoot on all layers.
   current_input_allocation_.SetBitrate(0, 0, 180000);
@@ -322,7 +334,7 @@ TEST_F(EncoderBitrateAdjusterTest, ThreeTemporalLayersOvershoot) {
              current_adjusted_allocation_, 0.01);
 }
 
-TEST_F(EncoderBitrateAdjusterTest, ThreeTemporalLayersUndershoot) {
+TEST_P(EncoderBitrateAdjusterTest, ThreeTemporalLayersUndershoot) {
   // Three temporal layers, 60%/20%/20% bps distro, undershoot all layers.
   current_input_allocation_.SetBitrate(0, 0, 180000);
   current_input_allocation_.SetBitrate(0, 1, 60000);
@@ -337,7 +349,7 @@ TEST_F(EncoderBitrateAdjusterTest, ThreeTemporalLayersUndershoot) {
   ExpectNear(current_input_allocation_, current_adjusted_allocation_, 0.0);
 }
 
-TEST_F(EncoderBitrateAdjusterTest, ThreeTemporalLayersSkewedOvershoot) {
+TEST_P(EncoderBitrateAdjusterTest, ThreeTemporalLayersSkewedOvershoot) {
   // Three temporal layers, 60%/20%/20% bps distro.
   // 10% overshoot on base layer, 20% on higher layers.
   current_input_allocation_.SetBitrate(0, 0, 180000);
@@ -355,7 +367,7 @@ TEST_F(EncoderBitrateAdjusterTest, ThreeTemporalLayersSkewedOvershoot) {
              current_adjusted_allocation_, 0.01);
 }
 
-TEST_F(EncoderBitrateAdjusterTest, ThreeTemporalLayersNonLayeredEncoder) {
+TEST_P(EncoderBitrateAdjusterTest, ThreeTemporalLayersNonLayeredEncoder) {
   // Three temporal layers, 60%/20%/20% bps allocation, 10% overshoot,
   // encoder does not actually support temporal layers.
   current_input_allocation_.SetBitrate(0, 0, 180000);
@@ -376,7 +388,7 @@ TEST_F(EncoderBitrateAdjusterTest, ThreeTemporalLayersNonLayeredEncoder) {
   ExpectNear(expected_allocation, current_adjusted_allocation_, 0.01);
 }
 
-TEST_F(EncoderBitrateAdjusterTest, IgnoredStream) {
+TEST_P(EncoderBitrateAdjusterTest, IgnoredStream) {
   // Encoder with three temporal layers, but in a mode that does not support
   // deterministic frame rate. Those are ignored, even if bitrate overshoots.
   current_input_allocation_.SetBitrate(0, 0, 180000);
@@ -395,7 +407,7 @@ TEST_F(EncoderBitrateAdjusterTest, IgnoredStream) {
   ExpectNear(current_input_allocation_, current_adjusted_allocation_, 0.00);
 }
 
-TEST_F(EncoderBitrateAdjusterTest, DifferentSpatialOvershoots) {
+TEST_P(EncoderBitrateAdjusterTest, DifferentSpatialOvershoots) {
   // Two streams, both with three temporal layers.
   // S0 has 5% overshoot, S1 has 25% overshoot.
   current_input_allocation_.SetBitrate(0, 0, 180000);
@@ -427,13 +439,14 @@ TEST_F(EncoderBitrateAdjusterTest, DifferentSpatialOvershoots) {
   }
 }
 
-TEST_F(EncoderBitrateAdjusterTest, HeadroomAllowsOvershootToMediaRate) {
+TEST_P(EncoderBitrateAdjusterTest, HeadroomAllowsOvershootToMediaRate) {
+  if (GetParam() == "WebRTC-VideoRateControl/adjuster_use_headroom:false/") {
+    // This test does not make sense without headroom adjustment.
+    GTEST_SKIP();
+  }
+
   // Two streams, both with three temporal layers.
   // Media rate is 1.0, but network rate is higher.
-  test::ScopedKeyValueConfig field_trial(
-      scoped_field_trial_,
-      "WebRTC-VideoRateControl/adjuster_use_headroom:true/");
-
   const uint32_t kS0Bitrate = 300000;
   const uint32_t kS1Bitrate = 900000;
   current_input_allocation_.SetBitrate(0, 0, kS0Bitrate / 3);
@@ -470,12 +483,14 @@ TEST_F(EncoderBitrateAdjusterTest, HeadroomAllowsOvershootToMediaRate) {
   }
 }
 
-TEST_F(EncoderBitrateAdjusterTest, DontExceedMediaRateEvenWithHeadroom) {
+TEST_P(EncoderBitrateAdjusterTest, DontExceedMediaRateEvenWithHeadroom) {
+  if (GetParam() == "WebRTC-VideoRateControl/adjuster_use_headroom:false/") {
+    // This test does not make sense without headroom adjustment.
+    GTEST_SKIP();
+  }
+
   // Two streams, both with three temporal layers.
   // Media rate is 1.1, but network rate is higher.
-  test::ScopedKeyValueConfig field_trial(
-      scoped_field_trial_,
-      "WebRTC-VideoRateControl/adjuster_use_headroom:true/");
 
   const uint32_t kS0Bitrate = 300000;
   const uint32_t kS1Bitrate = 900000;
@@ -489,32 +504,37 @@ TEST_F(EncoderBitrateAdjusterTest, DontExceedMediaRateEvenWithHeadroom) {
   target_framerate_fps_ = 30;
 
   // Run twice, once configured as simulcast and once as VP9 SVC.
-  for (int i = 0; i < 2; ++i) {
+  for (const bool is_svc : {false, true}) {
-    SetUpAdjuster(2, 3, i == 0);
+    SetUpAdjuster(/*num_spatial_layers=*/2,
-    // Network rate has 30% overshoot, media rate has 10% overshoot.
+                  /*num_temporal_layers=*/3, is_svc);
-    InsertFrames({{1.1, 1.1, 1.1}, {1.1, 1.1, 1.1}},
-                 {{1.3, 1.3, 1.3}, {1.3, 1.3, 1.3}},
-                 kWindowSizeMs * kSequenceLength);
 
-    // Push back by 30%.
+    // First insert frames with no overshoot.
+    InsertFrames({{1.0, 1.0, 1.0}}, kWindowSizeMs * kSequenceLength);
+    // Verify encoder is not pushed backed.
     current_adjusted_allocation_ =
         adjuster_->AdjustRateAllocation(VideoEncoder::RateControlParameters(
             current_input_allocation_, target_framerate_fps_));
     // The up-down causes a bit more noise, allow slightly more error margin.
-    ExpectNear(MultiplyAllocation(current_input_allocation_, 1 / 1.3),
+    ExpectNear(MultiplyAllocation(current_input_allocation_, 1.0),
                current_adjusted_allocation_, 0.015);
 
+    // Change network rate to 30% overshoot, media rate has 10% overshoot.
+    InsertFrames({{1.1, 1.1, 1.1}, {1.1, 1.1, 1.1}},
+                 {{1.3, 1.3, 1.3}, {1.3, 1.3, 1.3}},
+                 kWindowSizeMs * kSequenceLength);
+
     // Add 100% link headroom, overshoot from network to media rate is allowed.
     current_adjusted_allocation_ =
         adjuster_->AdjustRateAllocation(VideoEncoder::RateControlParameters(
             current_input_allocation_, target_framerate_fps_,
             DataRate::BitsPerSec(current_input_allocation_.get_sum_bps() * 2)));
+
     ExpectNear(MultiplyAllocation(current_input_allocation_, 1 / 1.1),
-               current_adjusted_allocation_, 0.015);
+               current_adjusted_allocation_, 0.02);
   }
 }
 
-TEST_F(EncoderBitrateAdjusterTest, HonorsMinBitrateWithAv1) {
+TEST_P(EncoderBitrateAdjusterTest, HonorsMinBitrateWithAv1) {
   // Single layer, well behaved encoder.
   const DataRate kHighBitrate = DataRate::KilobitsPerSec(20);
   const DataRate kALowerMinBitrate = DataRate::KilobitsPerSec(15);
@@ -549,5 +569,13 @@ TEST_F(EncoderBitrateAdjusterTest, HonorsMinBitrateWithAv1) {
   ExpectNear(expected_input_allocation, current_adjusted_allocation_, 0.01);
 }
 
+INSTANTIATE_TEST_SUITE_P(
+    AdjustWithHeadroomVariations,
+    EncoderBitrateAdjusterTest,
+    Values("WebRTC-VideoRateControl/adjuster_use_headroom:false/",
+           "WebRTC-VideoRateControl/adjuster_use_headroom:true/",
+           "WebRTC-VideoRateControl/adjuster_use_headroom:true/"
+           "WebRTC-BitrateAdjusterUseNewfangledHeadroomAdjustment/Enabled/"));
+
 }  // namespace test
 }  // namespace webrtc

video/video_stream_encoder.cc

@@ -1345,8 +1345,8 @@ void VideoStreamEncoder::ReconfigureEncoder() {
 
   const VideoEncoder::EncoderInfo info = encoder_->GetEncoderInfo();
   if (rate_control_settings_.UseEncoderBitrateAdjuster()) {
-    bitrate_adjuster_ =
+    bitrate_adjuster_ = std::make_unique<EncoderBitrateAdjuster>(
-        std::make_unique<EncoderBitrateAdjuster>(codec, env_.field_trials());
+        codec, env_.field_trials(), env_.clock());
     bitrate_adjuster_->OnEncoderInfo(info);
   }
 

video/video_stream_encoder_unittest.cc

@@ -2611,8 +2611,7 @@ TEST_F(VideoStreamEncoderTest, CorrectlyAdjustsAv1Bitrate) {
               allowed_error_bps);
 
   // Insert frames until bitrate adjuster is saturated.
-  const TimeDelta runtime =
+  const TimeDelta runtime = EncoderBitrateAdjuster::kWindowSize;
-      TimeDelta::Millis(EncoderBitrateAdjuster::kWindowSizeMs);
   const Timestamp start_time = clock()->CurrentTime();
   while (clock()->CurrentTime() - start_time < runtime) {
     video_source_.IncomingCapturedFrame(