Index: webrtc/modules/congestion_controller/acknowledge_bitrate_estimator.cc |
diff --git a/webrtc/modules/congestion_controller/acknowledge_bitrate_estimator.cc b/webrtc/modules/congestion_controller/acknowledge_bitrate_estimator.cc |
new file mode 100644 |
index 0000000000000000000000000000000000000000..74a5d721ad036784c81fce2209d8c58d51af9bb8 |
--- /dev/null |
+++ b/webrtc/modules/congestion_controller/acknowledge_bitrate_estimator.cc |
@@ -0,0 +1,99 @@ |
+/* |
+ * Copyright (c) 2017 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/acknowledge_bitrate_estimator.h" |
+ |
+namespace webrtc { |
+ |
+namespace { |
+constexpr int kInitialRateWindowMs = 500; |
+constexpr int kRateWindowMs = 150; |
+} // namespace |
+ |
+AcknowledgedBitrateEstimator::AcknowledgedBitrateEstimator() |
+ : sum_(0), |
+ current_win_ms_(0), |
+ prev_time_ms_(-1), |
+ bitrate_estimate_(-1.0f), |
+ bitrate_estimate_var_(50.0f) {} |
+ |
+void AcknowledgedBitrateEstimator::IncomingPacketFeedbackVector( |
+ const std::vector<PacketFeedback>& packet_feedback_vector) { |
+ for (const auto& packet : packet_feedback_vector) { |
philipel
2017/06/02 12:32:40
remove {}
tschumi
2017/06/02 13:13:04
Done.
|
+ Update(packet.arrival_time_ms, packet.payload_size); |
+ } |
+} |
+ |
+void AcknowledgedBitrateEstimator::Update(int64_t now_ms, int bytes) { |
+ int rate_window_ms = kRateWindowMs; |
+ // We use a larger window at the beginning to get a more stable sample that |
+ // we can use to initialize the estimate. |
+ if (bitrate_estimate_ < 0.f) |
+ rate_window_ms = kInitialRateWindowMs; |
+ float bitrate_sample = UpdateWindow(now_ms, bytes, rate_window_ms); |
+ if (bitrate_sample < 0.0f) |
+ return; |
+ if (bitrate_estimate_ < 0.0f) { |
+ // This is the very first sample we get. Use it to initialize the estimate. |
+ bitrate_estimate_ = bitrate_sample; |
+ return; |
+ } |
+ // Define the sample uncertainty as a function of how far away it is from the |
+ // current estimate. |
+ float sample_uncertainty = |
+ 10.0f * std::abs(bitrate_estimate_ - bitrate_sample) / bitrate_estimate_; |
+ float sample_var = sample_uncertainty * sample_uncertainty; |
+ // Update a bayesian estimate of the rate, weighting it lower if the sample |
+ // uncertainty is large. |
+ // The bitrate estimate uncertainty is increased with each update to model |
+ // that the bitrate changes over time. |
+ float pred_bitrate_estimate_var = bitrate_estimate_var_ + 5.f; |
+ bitrate_estimate_ = (sample_var * bitrate_estimate_ + |
+ pred_bitrate_estimate_var * bitrate_sample) / |
+ (sample_var + pred_bitrate_estimate_var); |
+ bitrate_estimate_var_ = sample_var * pred_bitrate_estimate_var / |
+ (sample_var + pred_bitrate_estimate_var); |
+} |
+ |
+float AcknowledgedBitrateEstimator::UpdateWindow(int64_t now_ms, |
+ int bytes, |
+ int rate_window_ms) { |
+ // Reset if time moves backwards. |
+ if (now_ms < prev_time_ms_) { |
+ prev_time_ms_ = -1; |
+ sum_ = 0; |
+ current_win_ms_ = 0; |
+ } |
+ if (prev_time_ms_ >= 0) { |
+ current_win_ms_ += now_ms - prev_time_ms_; |
+ // Reset if nothing has been received for more than a full window. |
+ if (now_ms - prev_time_ms_ > rate_window_ms) { |
+ sum_ = 0; |
+ current_win_ms_ %= rate_window_ms; |
+ } |
+ } |
+ prev_time_ms_ = now_ms; |
+ float bitrate_sample = -1.0f; |
+ if (current_win_ms_ >= rate_window_ms) { |
+ bitrate_sample = 8.0f * sum_ / static_cast<float>(rate_window_ms); |
+ current_win_ms_ -= rate_window_ms; |
+ sum_ = 0; |
+ } |
+ sum_ += bytes; |
+ return bitrate_sample; |
+} |
+ |
+rtc::Optional<uint32_t> AcknowledgedBitrateEstimator::bitrate_bps() const { |
+ if (bitrate_estimate_ < 0.f) |
+ return rtc::Optional<uint32_t>(); |
+ return rtc::Optional<uint32_t>(bitrate_estimate_ * 1000); |
+} |
+ |
+} // namespace webrtc |