Make the BWE threshold adaptive.

webrtc/modules/remote_bitrate_estimator/aimd_rate_control.cc

 /*
  *  Copyright (c) 2014 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 "webrtc/modules/remote_bitrate_estimator/aimd_rate_control.h"
 
 #include <algorithm>
 #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 {
 
 static const int64_t kDefaultRttMs = 200;
 static const int64_t kLogIntervalMs = 1000;
 static const double kWithinIncomingBitrateHysteresis = 1.05;
 static const int64_t kMaxFeedbackIntervalMs = 1000;
 
 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_;
 }
 
 bool AimdRateControl::ValidEstimate() const {
   return bitrate_is_initialized_;
 }
 
 int64_t AimdRateControl::GetFeedbackInterval() const {
@@ skipping 34 matching lines @@
   if (now_ms - time_of_last_log_ > kLogIntervalMs) {
     time_of_last_log_ = now_ms;
   }
   return current_bitrate_bps_;
 }
 
 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
   // second.
   if (!bitrate_is_initialized_) {
     if (time_first_incoming_estimate_ < 0) {
       if (input->_incomingBitRate > 0) {
         time_first_incoming_estimate_ = now_ms;
       }
     } else if (now_ms - time_first_incoming_estimate_ > 500 &&
                input->_incomingBitRate > 0) {
       current_bitrate_bps_ = input->_incomingBitRate;
       bitrate_is_initialized_ = true;
     }
   }
 
   if (updated_ && current_input_._bwState == kBwOverusing) {
     // Only update delay factor and incoming bit rate. We always want to react
     // on an over-use.
     current_input_._noiseVar = input->_noiseVar;
     current_input_._incomingBitRate = input->_incomingBitRate;
   } else {
     updated_ = true;
     current_input_ = *input;
   }
-  return rate_control_region_;
 }
 
 void AimdRateControl::SetEstimate(int bitrate_bps, int64_t now_ms) {
   updated_ = true;
   bitrate_is_initialized_ = true;
   current_bitrate_bps_ = ChangeBitrate(bitrate_bps, bitrate_bps, now_ms);
 }
 
 uint32_t AimdRateControl::ChangeBitrate(uint32_t current_bitrate_bps,
                                         uint32_t incoming_bitrate_bps,
                                         int64_t now_ms) {
   if (!updated_) {
     return current_bitrate_bps_;
   }
   updated_ = false;
   ChangeState(current_input_, now_ms);
   // Calculated here because it's used in multiple places.
   const float incoming_bitrate_kbps = incoming_bitrate_bps / 1000.0f;
   // Calculate the max bit rate std dev given the normalized
   // 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.
         const int64_t response_time = rtt_ + 100;
         uint32_t additive_increase_bps = AdditiveRateIncrease(
             now_ms, time_last_bitrate_change_, response_time);
         current_bitrate_bps += additive_increase_bps;
 
       } else {
         uint32_t multiplicative_increase_bps = MultiplicativeRateIncrease(
             now_ms, time_last_bitrate_change_, 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 {
         // Set bit rate to something slightly lower than max
         // to get rid of any self-induced delay.
         current_bitrate_bps = static_cast<uint32_t>(beta_ *
                                                     incoming_bitrate_bps + 0.5);
         if (current_bitrate_bps > current_bitrate_bps_) {
           // Avoid increasing the rate when over-using.
           if (rate_control_region_ != kRcMaxUnknown) {
             current_bitrate_bps = static_cast<uint32_t>(
                 beta_ * avg_max_bitrate_kbps_ * 1000 + 0.5f);
           }
           current_bitrate_bps = std::min(current_bitrate_bps,
                                          current_bitrate_bps_);
         }
         ChangeRegion(kRcNearMax);
 
         if (incoming_bitrate_kbps < avg_max_bitrate_kbps_ -
             3 * std_max_bit_rate) {
           avg_max_bitrate_kbps_ = -1.0f;
         }
 
         UpdateMaxBitRateEstimate(incoming_bitrate_kbps);
       }
       // Stay on hold until the pipes are cleared.
       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
     current_bitrate_bps = current_bitrate_bps_;
     time_last_bitrate_change_ = now_ms;
   }
   return current_bitrate_bps;
 }
 
 uint32_t AimdRateControl::MultiplicativeRateIncrease(
     int64_t now_ms, int64_t last_ms, uint32_t current_bitrate_bps) const {
   double alpha = 1.08;
   if (last_ms > -1) {
     int time_since_last_update_ms = std::min(static_cast<int>(now_ms - last_ms),
                                              1000);
     alpha = pow(alpha,  time_since_last_update_ms / 1000.0);
   }
   uint32_t multiplicative_increase_bps = std::max(
       current_bitrate_bps * (alpha - 1.0), 1000.0);
   return multiplicative_increase_bps;
 }
 
 uint32_t AimdRateControl::AdditiveRateIncrease(
     int64_t now_ms, int64_t last_ms, int64_t response_time_ms) const {
   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));
   double avg_packet_size_bits = bits_per_frame / packets_per_frame;
   uint32_t additive_increase_bps = std::max(
       1000.0, beta * avg_packet_size_bits);
   return additive_increase_bps;
 }
 
 void AimdRateControl::UpdateMaxBitRateEstimate(float incoming_bitrate_kbps) {
@@ skipping 37 matching lines @@
     case kBwUnderusing:
       ChangeState(kRcHold);
       break;
     default:
       assert(false);
   }
 }
 
 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