From 6396b48b18597beb5108347421efab23c5a7bbea Mon Sep 17 00:00:00 2001
From: Christoffer Rodbro <crodbro@webrtc.org>
Date: Mon, 24 May 2021 21:20:23 +0200
Subject: [PATCH] Avoid modifying BWE internal state on reception of REMB
 feedback.
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Instead, cap the final bandwidth estimate by the last received cap. This allows fast rampup after a REMB cap is lifted.

Bug: webrtc:12306
Change-Id: Ia99707134ce145275460524b3e46923876fdf62f
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/219696
Reviewed-by: Åsa Persson <asapersson@webrtc.org>
Commit-Queue: Christoffer Rodbro <crodbro@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#34109}
---
 .../goog_cc/goog_cc_network_control_unittest.cc       |  1 -
 .../goog_cc/send_side_bandwidth_estimation.cc         | 11 ++---------
 .../goog_cc/send_side_bandwidth_estimation.h          |  1 -
 3 files changed, 2 insertions(+), 11 deletions(-)

diff --git a/modules/congestion_controller/goog_cc/goog_cc_network_control_unittest.cc b/modules/congestion_controller/goog_cc/goog_cc_network_control_unittest.cc
index 8eb4a00431..37089bc5ab 100644
--- a/modules/congestion_controller/goog_cc/goog_cc_network_control_unittest.cc
+++ b/modules/congestion_controller/goog_cc/goog_cc_network_control_unittest.cc
@@ -851,7 +851,6 @@ TEST_F(GoogCcNetworkControllerTest, IsFairToTCP) {
 }
 
 TEST(GoogCcScenario, RampupOnRembCapLifted) {
-  ScopedFieldTrials trial("WebRTC-Bwe-ReceiverLimitCapsOnly/Enabled/");
   Scenario s("googcc_unit/rampup_ramb_cap_lifted");
   NetworkSimulationConfig net_conf;
   net_conf.bandwidth = DataRate::KilobitsPerSec(2000);
diff --git a/modules/congestion_controller/goog_cc/send_side_bandwidth_estimation.cc b/modules/congestion_controller/goog_cc/send_side_bandwidth_estimation.cc
index a2865d9f5a..c8509556c6 100644
--- a/modules/congestion_controller/goog_cc/send_side_bandwidth_estimation.cc
+++ b/modules/congestion_controller/goog_cc/send_side_bandwidth_estimation.cc
@@ -226,8 +226,7 @@ SendSideBandwidthEstimation::SendSideBandwidthEstimation(
       low_loss_threshold_(kDefaultLowLossThreshold),
       high_loss_threshold_(kDefaultHighLossThreshold),
       bitrate_threshold_(kDefaultBitrateThreshold),
-      loss_based_bandwidth_estimation_(key_value_config),
-      receiver_limit_caps_only_("Enabled") {
+      loss_based_bandwidth_estimation_(key_value_config) {
   RTC_DCHECK(event_log);
   if (BweLossExperimentIsEnabled()) {
     uint32_t bitrate_threshold_kbps;
@@ -240,8 +239,6 @@ SendSideBandwidthEstimation::SendSideBandwidthEstimation(
       bitrate_threshold_ = DataRate::KilobitsPerSec(bitrate_threshold_kbps);
     }
   }
-  ParseFieldTrial({&receiver_limit_caps_only_},
-                  key_value_config->Lookup("WebRTC-Bwe-ReceiverLimitCapsOnly"));
 }
 
 SendSideBandwidthEstimation::~SendSideBandwidthEstimation() {}
@@ -310,9 +307,7 @@ int SendSideBandwidthEstimation::GetMinBitrate() const {
 }
 
 DataRate SendSideBandwidthEstimation::target_rate() const {
-  DataRate target = current_target_;
-  if (receiver_limit_caps_only_)
-    target = std::min(target, receiver_limit_);
+  DataRate target = std::min(current_target_, receiver_limit_);
   return std::max(min_bitrate_configured_, target);
 }
 
@@ -585,8 +580,6 @@ void SendSideBandwidthEstimation::UpdateMinHistory(Timestamp at_time) {
 
 DataRate SendSideBandwidthEstimation::GetUpperLimit() const {
   DataRate upper_limit = delay_based_limit_;
-  if (!receiver_limit_caps_only_)
-    upper_limit = std::min(upper_limit, receiver_limit_);
   upper_limit = std::min(upper_limit, max_bitrate_configured_);
   return upper_limit;
 }
diff --git a/modules/congestion_controller/goog_cc/send_side_bandwidth_estimation.h b/modules/congestion_controller/goog_cc/send_side_bandwidth_estimation.h
index b97b940db0..05bf10d6ff 100644
--- a/modules/congestion_controller/goog_cc/send_side_bandwidth_estimation.h
+++ b/modules/congestion_controller/goog_cc/send_side_bandwidth_estimation.h
@@ -190,7 +190,6 @@ class SendSideBandwidthEstimation {
   float high_loss_threshold_;
   DataRate bitrate_threshold_;
   LossBasedBandwidthEstimation loss_based_bandwidth_estimation_;
-  FieldTrialFlag receiver_limit_caps_only_;
 };
 }  // namespace webrtc
 #endif  // MODULES_CONGESTION_CONTROLLER_GOOG_CC_SEND_SIDE_BANDWIDTH_ESTIMATION_H_