1 files changed, 63 insertions, 0 deletions
diff --git a/modules/congestion_controller/remb_throttler.cc b/modules/congestion_controller/remb_throttler.cc
new file mode 100644
index 0000000000..fcc30af9a8
--- /dev/null
+++ b/modules/congestion_controller/remb_throttler.cc
@@ -0,0 +1,63 @@
+/*
+ *  Copyright (c) 2021 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 "modules/congestion_controller/remb_throttler.h"
+
+#include <algorithm>
+#include <utility>
+
+namespace webrtc {
+
+namespace {
+constexpr TimeDelta kRembSendInterval = TimeDelta::Millis(200);
+}  // namespace
+
+RembThrottler::RembThrottler(RembSender remb_sender, Clock* clock)
+    : remb_sender_(std::move(remb_sender)),
+      clock_(clock),
+      last_remb_time_(Timestamp::MinusInfinity()),
+      last_send_remb_bitrate_(DataRate::PlusInfinity()),
+      max_remb_bitrate_(DataRate::PlusInfinity()) {}
+
+void RembThrottler::OnReceiveBitrateChanged(const std::vector<uint32_t>& ssrcs,
+                                            uint32_t bitrate_bps) {
+  DataRate receive_bitrate = DataRate::BitsPerSec(bitrate_bps);
+  Timestamp now = clock_->CurrentTime();
+  {
+    MutexLock lock(&mutex_);
+    // % threshold for if we should send a new REMB asap.
+    const int64_t kSendThresholdPercent = 103;
+    if (receive_bitrate * kSendThresholdPercent / 100 >
+            last_send_remb_bitrate_ &&
+        now < last_remb_time_ + kRembSendInterval) {
+      return;
+    }
+    last_remb_time_ = now;
+    last_send_remb_bitrate_ = receive_bitrate;
+    receive_bitrate = std::min(last_send_remb_bitrate_, max_remb_bitrate_);
+  }
+  remb_sender_(receive_bitrate.bps(), ssrcs);
+}
+
+void RembThrottler::SetMaxDesiredReceiveBitrate(DataRate bitrate) {
+  Timestamp now = clock_->CurrentTime();
+  {
+    MutexLock lock(&mutex_);
+    max_remb_bitrate_ = bitrate;
+    if (now - last_remb_time_ < kRembSendInterval &&
+        !last_send_remb_bitrate_.IsZero() &&
+        last_send_remb_bitrate_ <= max_remb_bitrate_) {
+      return;
+    }
+  }
+  remb_sender_(bitrate.bps(), /*ssrcs=*/{});
+}
+
+}  // namespace webrtc