Set min BWE bitrate form 10kbps to 5kbps and centralize minimum bitrate.

BUG=webrtc:6522

Review-Url: https://codereview.webrtc.org/2415543002
Cr-Commit-Position: refs/heads/master@{#14947}

webrtc/modules/bitrate_controller/bitrate_controller_unittest.cc

@@ -14,7 +14,7 @@
 #include "webrtc/logging/rtc_event_log/mock/mock_rtc_event_log.h"
 #include "webrtc/modules/bitrate_controller/include/bitrate_controller.h"
 #include "webrtc/modules/pacing/mock/mock_paced_sender.h"
-#include "webrtc/modules/rtp_rtcp/include/rtp_rtcp_defines.h"
+#include "webrtc/modules/remote_bitrate_estimator/include/bwe_defines.h"
 #include "webrtc/test/field_trial.h"
 #include "webrtc/test/gtest.h"
 
@@ -98,7 +98,8 @@ TEST_F(BitrateControllerTest, DefaultMinMaxBitrate) {
   controller_->SetMinMaxBitrate(0, 0);
   EXPECT_EQ(kStartBitrateBps, bitrate_observer_.last_bitrate_);
   bandwidth_observer_->OnReceivedEstimatedBitrate(kDefaultMinBitrateBps / 2);
-  EXPECT_EQ(kDefaultMinBitrateBps, bitrate_observer_.last_bitrate_);
+  EXPECT_EQ(webrtc::congestion_controller::GetMinBitrateBps(),
+            bitrate_observer_.last_bitrate_);
   bandwidth_observer_->OnReceivedEstimatedBitrate(2 * kDefaultMaxBitrateBps);
   clock_.AdvanceTimeMilliseconds(1000);
   controller_->Process();

webrtc/modules/bitrate_controller/send_side_bandwidth_estimation.cc

@@ -16,6 +16,7 @@
 #include "webrtc/base/checks.h"
 #include "webrtc/base/logging.h"
 #include "webrtc/logging/rtc_event_log/rtc_event_log.h"
+#include "webrtc/modules/remote_bitrate_estimator/include/bwe_defines.h"
 #include "webrtc/system_wrappers/include/field_trial.h"
 #include "webrtc/system_wrappers/include/metrics.h"
 
@@ -26,7 +27,6 @@ const int64_t kBweDecreaseIntervalMs = 300;
 const int64_t kStartPhaseMs = 2000;
 const int64_t kBweConverganceTimeMs = 20000;
 const int kLimitNumPackets = 20;
-const int kDefaultMinBitrateBps = 10000;
 const int kDefaultMaxBitrateBps = 1000000000;
 const int64_t kLowBitrateLogPeriodMs = 10000;
 const int64_t kRtcEventLogPeriodMs = 5000;
@@ -53,7 +53,7 @@ SendSideBandwidthEstimation::SendSideBandwidthEstimation(RtcEventLog* event_log)
     : lost_packets_since_last_loss_update_Q8_(0),
       expected_packets_since_last_loss_update_(0),
       bitrate_(0),
-      min_bitrate_configured_(kDefaultMinBitrateBps),
+      min_bitrate_configured_(congestion_controller::GetMinBitrateBps()),
       max_bitrate_configured_(kDefaultMaxBitrateBps),
       last_low_bitrate_log_ms_(-1),
       has_decreased_since_last_fraction_loss_(false),
@@ -100,7 +100,8 @@ void SendSideBandwidthEstimation::SetSendBitrate(int bitrate) {
 void SendSideBandwidthEstimation::SetMinMaxBitrate(int min_bitrate,
                                                    int max_bitrate) {
   RTC_DCHECK_GE(min_bitrate, 0);
-  min_bitrate_configured_ = std::max(min_bitrate, kDefaultMinBitrateBps);
+  min_bitrate_configured_ =
+      std::max(min_bitrate, congestion_controller::GetMinBitrateBps());
   if (max_bitrate > 0) {
     max_bitrate_configured_ =
         std::max<uint32_t>(min_bitrate_configured_, max_bitrate);

webrtc/modules/congestion_controller/congestion_controller.cc

@@ -20,6 +20,7 @@
 #include "webrtc/base/socket.h"
 #include "webrtc/modules/bitrate_controller/include/bitrate_controller.h"
 #include "webrtc/modules/congestion_controller/probe_controller.h"
+#include "webrtc/modules/remote_bitrate_estimator/include/bwe_defines.h"
 #include "webrtc/modules/remote_bitrate_estimator/remote_bitrate_estimator_abs_send_time.h"
 #include "webrtc/modules/remote_bitrate_estimator/remote_bitrate_estimator_single_stream.h"
 #include "webrtc/system_wrappers/include/critical_section_wrapper.h"
@@ -37,9 +38,8 @@ static void ClampBitrates(int* bitrate_bps,
   // TODO(holmer): We should make sure the default bitrates are set to 10 kbps,
   // and that we don't try to set the min bitrate to 0 from any applications.
   // The congestion controller should allow a min bitrate of 0.
-  const int kMinBitrateBps = 10000;
-  if (*min_bitrate_bps < kMinBitrateBps)
-    *min_bitrate_bps = kMinBitrateBps;
+  if (*min_bitrate_bps < congestion_controller::GetMinBitrateBps())
+    *min_bitrate_bps = congestion_controller::GetMinBitrateBps();
   if (*max_bitrate_bps > 0)
     *max_bitrate_bps = std::max(*min_bitrate_bps, *max_bitrate_bps);
   if (*bitrate_bps > 0)
@@ -55,7 +55,7 @@ class WrappingBitrateEstimator : public RemoteBitrateEstimator {
         rbe_(new RemoteBitrateEstimatorSingleStream(observer_, clock_)),
         using_absolute_send_time_(false),
         packets_since_absolute_send_time_(0),
-        min_bitrate_bps_(RemoteBitrateEstimator::kDefaultMinBitrateBps) {}
+        min_bitrate_bps_(congestion_controller::GetMinBitrateBps()) {}
 
   virtual ~WrappingBitrateEstimator() {}
 
@@ -166,7 +166,7 @@ CongestionController::CongestionController(
           new RateLimiter(clock, kRetransmitWindowSizeMs)),
       remote_estimator_proxy_(clock_, packet_router_.get()),
       transport_feedback_adapter_(clock_, bitrate_controller_.get()),
-      min_bitrate_bps_(RemoteBitrateEstimator::kDefaultMinBitrateBps),
+      min_bitrate_bps_(congestion_controller::GetMinBitrateBps()),
       max_bitrate_bps_(0),
       last_reported_bitrate_bps_(0),
       last_reported_fraction_loss_(0),
@@ -197,7 +197,7 @@ CongestionController::CongestionController(
           new RateLimiter(clock, kRetransmitWindowSizeMs)),
       remote_estimator_proxy_(clock_, packet_router_.get()),
       transport_feedback_adapter_(clock_, bitrate_controller_.get()),
-      min_bitrate_bps_(RemoteBitrateEstimator::kDefaultMinBitrateBps),
+      min_bitrate_bps_(congestion_controller::GetMinBitrateBps()),
       max_bitrate_bps_(0),
       last_reported_bitrate_bps_(0),
       last_reported_fraction_loss_(0),

webrtc/modules/congestion_controller/congestion_controller_unittest.cc

@@ -13,6 +13,7 @@
 #include "webrtc/modules/congestion_controller/include/congestion_controller.h"
 #include "webrtc/modules/congestion_controller/include/mock/mock_congestion_controller.h"
 #include "webrtc/modules/pacing/mock/mock_paced_sender.h"
+#include "webrtc/modules/remote_bitrate_estimator/include/bwe_defines.h"
 #include "webrtc/modules/remote_bitrate_estimator/include/mock/mock_remote_bitrate_observer.h"
 #include "webrtc/system_wrappers/include/clock.h"
 #include "webrtc/test/gmock.h"
@@ -135,10 +136,11 @@ TEST_F(CongestionControllerTest, ResetBweAndBitrates) {
   controller_->ResetBweAndBitrates(new_bitrate, -1, -1);
 
   // If the bitrate is reset to -1, the new starting bitrate will be
-  // the minimum default bitrate 10000bps.
-  int min_default_bitrate = 10000;
-  EXPECT_CALL(observer_, OnNetworkChanged(min_default_bitrate, _, _));
-  EXPECT_CALL(*pacer_, SetEstimatedBitrate(min_default_bitrate));
+  // the minimum default bitrate kMinBitrateBps.
+  EXPECT_CALL(observer_, OnNetworkChanged(
+                             congestion_controller::GetMinBitrateBps(), _, _));
+  EXPECT_CALL(*pacer_,
+              SetEstimatedBitrate(congestion_controller::GetMinBitrateBps()));
   controller_->ResetBweAndBitrates(-1, -1, -1);
 }
 

webrtc/modules/remote_bitrate_estimator/aimd_rate_control.cc

@@ -17,6 +17,7 @@
 #include "webrtc/base/checks.h"
 
 #include "webrtc/modules/remote_bitrate_estimator/overuse_detector.h"
+#include "webrtc/modules/remote_bitrate_estimator/include/bwe_defines.h"
 #include "webrtc/modules/remote_bitrate_estimator/include/remote_bitrate_estimator.h"
 #include "webrtc/modules/remote_bitrate_estimator/test/bwe_test_logging.h"
 
@@ -27,8 +28,7 @@ static const double kWithinIncomingBitrateHysteresis = 1.05;
 static const int64_t kMaxFeedbackIntervalMs = 1000;
 
 AimdRateControl::AimdRateControl()
-    : min_configured_bitrate_bps_(
-          RemoteBitrateEstimator::kDefaultMinBitrateBps),
+    : min_configured_bitrate_bps_(congestion_controller::GetMinBitrateBps()),
       max_configured_bitrate_bps_(30000000),
       current_bitrate_bps_(max_configured_bitrate_bps_),
       avg_max_bitrate_kbps_(-1.0f),

webrtc/modules/remote_bitrate_estimator/bwe_defines.cc

@@ -7,7 +7,23 @@
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
+
+#include "webrtc/system_wrappers/include/field_trial.h"
+
 namespace webrtc {
 
 const char* kBweTypeHistogram = "WebRTC.BWE.Types";
+
+namespace congestion_controller {
+int GetMinBitrateBps() {
+  constexpr int kAudioMinBitrateBps = 5000;
+  constexpr int kMinBitrateBps = 10000;
+  if (webrtc::field_trial::FindFullName("WebRTC-Audio-SendSideBwe") ==
+      "Enabled") {
+    return kAudioMinBitrateBps;
+  }
+  return kMinBitrateBps;
+}
+
+}  // namespace congestion_controller
 }  // namespace webrtc

webrtc/modules/remote_bitrate_estimator/include/bwe_defines.h

@@ -19,6 +19,10 @@
 
 namespace webrtc {
 
+namespace congestion_controller {
+int GetMinBitrateBps();
+}  // namespace congestion_controller
+
 static const int64_t kBitrateWindowMs = 1000;
 
 extern const char* kBweTypeHistogram;

webrtc/modules/remote_bitrate_estimator/include/remote_bitrate_estimator.h

@@ -44,7 +44,6 @@ struct ReceiveBandwidthEstimatorStats {};
 
 class RemoteBitrateEstimator : public CallStatsObserver, public Module {
  public:
-  static const int kDefaultMinBitrateBps = 30000;
   virtual ~RemoteBitrateEstimator() {}
 
   virtual void IncomingPacketFeedbackVector(