Rollback of "Use small BWE period when there is a true network degradation"

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.
  */
 
@@ skipping 118 matching lines @@
   double avg_packet_size_bits = bits_per_frame / packets_per_frame;
 
   // Approximate the over-use estimator delay to 100 ms.
   const int64_t response_time = in_experiment_ ? (rtt_ + 100) * 2 : rtt_ + 100;
   constexpr double kMinIncreaseRateBps = 4000;
   return static_cast<int>(std::max(
       kMinIncreaseRateBps, (avg_packet_size_bits * 1000) / response_time));
 }
 
 int AimdRateControl::GetExpectedBandwidthPeriodMs() const {
-  constexpr int kMinPeriodMs = 500;
+  constexpr int kMinPeriodMs = 2000;
+  constexpr int kDefaultPeriodMs = 3000;
   constexpr int kMaxPeriodMs = 50000;
 
   int increase_rate = GetNearMaxIncreaseRateBps();
   if (!last_decrease_)
-    return kMinPeriodMs;
+    return kDefaultPeriodMs;
 
   return std::min(kMaxPeriodMs,
                   std::max<int>(1000 * static_cast<int64_t>(*last_decrease_) /
                                     increase_rate,
                                 kMinPeriodMs));
 }
 
 uint32_t AimdRateControl::ChangeBitrate(uint32_t new_bitrate_bps,
                                         const RateControlInput& input,
                                         int64_t now_ms) {
@@ skipping 48 matching lines @@
         if (rate_control_region_ != kRcMaxUnknown) {
           new_bitrate_bps = static_cast<uint32_t>(
               beta_ * avg_max_bitrate_kbps_ * 1000 + 0.5f);
         }
         new_bitrate_bps = std::min(new_bitrate_bps, current_bitrate_bps_);
       }
       ChangeRegion(kRcNearMax);
 
       if (bitrate_is_initialized_ &&
           incoming_bitrate_bps < current_bitrate_bps_) {
-        constexpr float kDegradationFactor = 0.9f;
-        if (new_bitrate_bps <
-            kDegradationFactor * beta_ * current_bitrate_bps_) {
-          // If bitrate decreases more than a normal back off after overuse, it
-          // indicates a real network degradation. We do not let such a decrease
-          // to determine the bandwidth estimation period.
-          last_decrease_ = rtc::Optional<int>();
-        } else {
-          last_decrease_ = rtc::Optional<int>(
-              current_bitrate_bps_ - new_bitrate_bps);
-        }
+        last_decrease_ =
+            rtc::Optional<int>(current_bitrate_bps_ - new_bitrate_bps);
       }
       if (incoming_bitrate_kbps <
           avg_max_bitrate_kbps_ - 3 * std_max_bit_rate) {
         avg_max_bitrate_kbps_ = -1.0f;
       }
 
       bitrate_is_initialized_ = true;
       UpdateMaxBitRateEstimate(incoming_bitrate_kbps);
       // Stay on hold until the pipes are cleared.
       rate_control_state_ = kRcHold;
@@ skipping 84 matching lines @@
     default:
       assert(false);
   }
 }
 
 void AimdRateControl::ChangeRegion(RateControlRegion region) {
   rate_control_region_ = region;
 }
 
 }  // namespace webrtc