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

webrtc/modules/congestion_controller/congestion_controller.cc

 /*
  *  Copyright (c) 2012 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/congestion_controller/include/congestion_controller.h"
 
 #include <algorithm>
 #include <memory>
 #include <vector>
 
 #include "webrtc/base/checks.h"
 #include "webrtc/base/constructormagic.h"
 #include "webrtc/base/logging.h"
 #include "webrtc/base/rate_limiter.h"
 #include "webrtc/base/socket.h"
 #include "webrtc/base/thread_annotations.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/send_time_history.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/modules/utility/include/process_thread.h"
 #include "webrtc/system_wrappers/include/critical_section_wrapper.h"
+#include "webrtc/system_wrappers/include/field_trial.h"
 #include "webrtc/video/payload_router.h"
 
 namespace webrtc {
 namespace {
 
 static const uint32_t kTimeOffsetSwitchThreshold = 30;
 static const int64_t kRetransmitWindowSizeMs = 500;
 
 // Makes sure that the bitrate and the min, max values are in valid range.
 static void ClampBitrates(int* bitrate_bps,
                           int* min_bitrate_bps,
                           int* max_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 < CongestionController::GetMinBitrateBps())
+    *min_bitrate_bps = CongestionController::GetMinBitrateBps();
   if (*max_bitrate_bps > 0)
     *max_bitrate_bps = std::max(*min_bitrate_bps, *max_bitrate_bps);
   if (*bitrate_bps > 0)
     *bitrate_bps = std::max(*min_bitrate_bps, *bitrate_bps);
 }
 
 class WrappingBitrateEstimator : public RemoteBitrateEstimator {
  public:
   WrappingBitrateEstimator(RemoteBitrateObserver* observer, Clock* clock)
       : observer_(observer),
         clock_(clock),
         crit_sect_(CriticalSectionWrapper::CreateCriticalSection()),
         rbe_(new RemoteBitrateEstimatorSingleStream(observer_, clock_)),
         using_absolute_send_time_(false),
         packets_since_absolute_send_time_(0),
-        min_bitrate_bps_(RemoteBitrateEstimator::kDefaultMinBitrateBps) {}
+        min_bitrate_bps_(CongestionController::GetMinBitrateBps()) {}
 
   virtual ~WrappingBitrateEstimator() {}
 
   void IncomingPacket(int64_t arrival_time_ms,
                       size_t payload_size,
                       const RTPHeader& header) override {
     CriticalSectionScoped cs(crit_sect_.get());
     PickEstimatorFromHeader(header);
     rbe_->IncomingPacket(arrival_time_ms, payload_size, header);
   }
@@ skipping 72 matching lines @@
   std::unique_ptr<RemoteBitrateEstimator> rbe_;
   bool using_absolute_send_time_;
   uint32_t packets_since_absolute_send_time_;
   int min_bitrate_bps_;
 
   RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(WrappingBitrateEstimator);
 };
 
 }  // namespace
 
+
+int CongestionController::GetMinBitrateBps() {
+  constexpr int kAudioMinBitrateBps = 5000;
+  constexpr int kMinBitrateBps = 10000;
+  if (webrtc::field_trial::FindFullName("WebRTC-Audio-SendSideBwe") ==
+      "Enabled")

[stefan-webrtc, 2016/11/01 09:09:15]

{} since it's a multi-line if

[michaelt, 2016/11/01 09:21:55]

Done.

+    return kAudioMinBitrateBps;
+  return kMinBitrateBps;
+}
+
 CongestionController::CongestionController(
     Clock* clock,
     Observer* observer,
     RemoteBitrateObserver* remote_bitrate_observer,
     RtcEventLog* event_log)
     : clock_(clock),
       observer_(observer),
       packet_router_(new PacketRouter()),
       pacer_(new PacedSender(clock_, packet_router_.get())),
       remote_bitrate_estimator_(
           new WrappingBitrateEstimator(remote_bitrate_observer, clock_)),
       bitrate_controller_(
           BitrateController::CreateBitrateController(clock_, event_log)),
       probe_controller_(new ProbeController(pacer_.get(), clock_)),
       retransmission_rate_limiter_(
           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_(GetMinBitrateBps()),
       max_bitrate_bps_(0),
       last_reported_bitrate_bps_(0),
       last_reported_fraction_loss_(0),
       last_reported_rtt_(0),
       network_state_(kNetworkUp) {
   Init();
 }
 
 CongestionController::CongestionController(
     Clock* clock,
@@ skipping 10 matching lines @@
           new WrappingBitrateEstimator(remote_bitrate_observer, clock_)),
       // Constructed last as this object calls the provided callback on
       // construction.
       bitrate_controller_(
           BitrateController::CreateBitrateController(clock_, event_log)),
       probe_controller_(new ProbeController(pacer_.get(), clock_)),
       retransmission_rate_limiter_(
           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_(GetMinBitrateBps()),
       max_bitrate_bps_(0),
       last_reported_bitrate_bps_(0),
       last_reported_fraction_loss_(0),
       last_reported_rtt_(0),
       network_state_(kNetworkUp) {
   Init();
 }
 
 CongestionController::~CongestionController() {}
 
@@ skipping 156 matching lines @@
 bool CongestionController::IsSendQueueFull() const {
   return pacer_->ExpectedQueueTimeMs() > PacedSender::kMaxQueueLengthMs;
 }
 
 bool CongestionController::IsNetworkDown() const {
   rtc::CritScope cs(&critsect_);
   return network_state_ == kNetworkDown;
 }
 
 }  // namespace webrtc