Make the BWE threshold adaptive.

webrtc/modules/remote_bitrate_estimator/aimd_rate_control.cc

Index: webrtc/modules/remote_bitrate_estimator/aimd_rate_control.cc
diff --git a/webrtc/modules/remote_bitrate_estimator/aimd_rate_control.cc b/webrtc/modules/remote_bitrate_estimator/aimd_rate_control.cc
index 81ab97367bb5ce322fb6e74368120bf9f1136ca4..bcb71d6db891db222bdfbee7e43fef629598ff85 100644
--- a/webrtc/modules/remote_bitrate_estimator/aimd_rate_control.cc
+++ b/webrtc/modules/remote_bitrate_estimator/aimd_rate_control.cc
@@ -14,6 +14,7 @@
 #include <cassert>
 #include <cmath>
 
+#include "webrtc/modules/remote_bitrate_estimator/overuse_detector.h"
 #include "webrtc/modules/remote_bitrate_estimator/test/bwe_test_logging.h"
 
 namespace webrtc {
@@ -27,20 +28,20 @@ AimdRateControl::AimdRateControl(uint32_t min_bitrate_bps)
     : min_configured_bitrate_bps_(min_bitrate_bps),
       max_configured_bitrate_bps_(30000000),
       current_bitrate_bps_(max_configured_bitrate_bps_),
-      max_hold_rate_bps_(0),
       avg_max_bitrate_kbps_(-1.0f),
       var_max_bitrate_kbps_(0.4f),
       rate_control_state_(kRcHold),
-      came_from_state_(kRcDecrease),
       rate_control_region_(kRcMaxUnknown),
       time_last_bitrate_change_(-1),
       current_input_(kBwNormal, 0, 1.0),
       updated_(false),
       time_first_incoming_estimate_(-1),
       bitrate_is_initialized_(false),
-      beta_(0.9f),
+      beta_(0.85f),
       rtt_(kDefaultRttMs),
-      time_of_last_log_(-1) {}
+      time_of_last_log_(-1),
+      in_experiment_(AdaptiveThresholdExperimentIsEnabled()) {
+}
 
 uint32_t AimdRateControl::GetMinBitrate() const {
   return min_configured_bitrate_bps_;
@@ -95,8 +96,7 @@ void AimdRateControl::SetRtt(int64_t rtt) {
   rtt_ = rtt;
 }
 
-RateControlRegion AimdRateControl::Update(const RateControlInput* input,
-                                          int64_t now_ms) {
+void AimdRateControl::Update(const RateControlInput* input, int64_t now_ms) {
   assert(input);
 
   // Set the initial bit rate value to what we're receiving the first half
@@ -122,7 +122,6 @@ RateControlRegion AimdRateControl::Update(const RateControlInput* input,
     updated_ = true;
     current_input_ = *input;
   }
-  return rate_control_region_;
 }
 
 void AimdRateControl::SetEstimate(int bitrate_bps, int64_t now_ms) {
@@ -145,22 +144,16 @@ uint32_t AimdRateControl::ChangeBitrate(uint32_t current_bitrate_bps,
   // variance and the current incoming bit rate.
   const float std_max_bit_rate = sqrt(var_max_bitrate_kbps_ *
                                       avg_max_bitrate_kbps_);
-  bool fast_recovery_after_hold = false;
   switch (rate_control_state_) {
-    case kRcHold: {
-      max_hold_rate_bps_ = std::max(max_hold_rate_bps_, incoming_bitrate_bps);
+    case kRcHold:
       break;
-    }
-    case kRcIncrease: {
-      if (avg_max_bitrate_kbps_ >= 0) {
-        if (incoming_bitrate_kbps > avg_max_bitrate_kbps_ +
-            3 * std_max_bit_rate) {
-          ChangeRegion(kRcMaxUnknown);
-          avg_max_bitrate_kbps_ = -1.0;
-        } else if (incoming_bitrate_kbps > avg_max_bitrate_kbps_ +
-            2.5 * std_max_bit_rate) {
-          ChangeRegion(kRcAboveMax);
-        }
+
+    case kRcIncrease:
+      if (avg_max_bitrate_kbps_ >= 0 &&
+          incoming_bitrate_kbps >
+              avg_max_bitrate_kbps_ + 3 * std_max_bit_rate) {
+        ChangeRegion(kRcMaxUnknown);
+        avg_max_bitrate_kbps_ = -1.0;
       }
       if (rate_control_region_ == kRcNearMax) {
         // Approximate the over-use estimator delay to 100 ms.
@@ -175,18 +168,10 @@ uint32_t AimdRateControl::ChangeBitrate(uint32_t current_bitrate_bps,
         current_bitrate_bps += multiplicative_increase_bps;
       }
 
-      if (max_hold_rate_bps_ > 0 &&
-          beta_ * max_hold_rate_bps_ > current_bitrate_bps) {
-        current_bitrate_bps = static_cast<uint32_t>(beta_ * max_hold_rate_bps_);
-        avg_max_bitrate_kbps_ = beta_ * max_hold_rate_bps_ / 1000.0f;
-        ChangeRegion(kRcNearMax);
-        fast_recovery_after_hold = true;
-      }
-      max_hold_rate_bps_ = 0;
       time_last_bitrate_change_ = now_ms;
       break;
-    }
-    case kRcDecrease: {
+
+    case kRcDecrease:
       if (incoming_bitrate_bps < min_configured_bitrate_bps_) {
         current_bitrate_bps = min_configured_bitrate_bps_;
       } else {
@@ -216,12 +201,11 @@ uint32_t AimdRateControl::ChangeBitrate(uint32_t current_bitrate_bps,
       ChangeState(kRcHold);
       time_last_bitrate_change_ = now_ms;
       break;
-    }
+
     default:
       assert(false);
   }
-  if (!fast_recovery_after_hold && (incoming_bitrate_bps > 100000 ||
-      current_bitrate_bps > 150000) &&
+  if ((incoming_bitrate_bps > 100000 || current_bitrate_bps > 150000) &&
       current_bitrate_bps > 1.5 * incoming_bitrate_bps) {
     // Allow changing the bit rate if we are operating at very low rates
     // Don't change the bit rate if the send side is too far off
@@ -249,8 +233,10 @@ uint32_t AimdRateControl::AdditiveRateIncrease(
   assert(response_time_ms > 0);
   double beta = 0.0;
   if (last_ms > 0) {
-    beta = std::min((now_ms - last_ms) /
-                    static_cast<double>(response_time_ms), 1.0);
+    beta = std::min((now_ms - last_ms) / static_cast<double>(response_time_ms),
+                    1.0);
+    if (in_experiment_)
+      beta /= 2.0;
   }
   double bits_per_frame = static_cast<double>(current_bitrate_bps_) / 30.0;
   double packets_per_frame = std::ceil(bits_per_frame / (8.0 * 1200.0));
@@ -308,21 +294,9 @@ void AimdRateControl::ChangeState(const RateControlInput& input,
 
 void AimdRateControl::ChangeRegion(RateControlRegion region) {
   rate_control_region_ = region;
-  switch (rate_control_region_) {
-    case kRcAboveMax:
-    case kRcMaxUnknown:
-      beta_ = 0.9f;
-      break;
-    case kRcNearMax:
-      beta_ = 0.95f;
-      break;
-    default:
-      assert(false);
-  }
 }
 
 void AimdRateControl::ChangeState(RateControlState new_state) {
-  came_from_state_ = rate_control_state_;
   rate_control_state_ = new_state;
 }
 }  // namespace webrtc