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da0222b3fc
The new controller behaves mostly like before, but increases the target rate on timer update rather than when feedback is received. This makes the behavior easier to predict. It also uses a duration parameter to track the increase, removing the meed for the minimum rate increase constants that exists in the previous solution. Bug: webrtc:9718 Change-Id: Iae31a9ba2d6474a8236f8eb72f86ff434f1d1fc6 Reviewed-on: https://webrtc-review.googlesource.com/c/114681 Commit-Queue: Sebastian Jansson <srte@webrtc.org> Reviewed-by: Christoffer Rodbro <crodbro@webrtc.org> Cr-Commit-Position: refs/heads/master@{#26088}
77 lines
2.6 KiB
C++
77 lines
2.6 KiB
C++
/*
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* Copyright 2018 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "modules/congestion_controller/goog_cc/link_capacity_estimator.h"
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#include <algorithm>
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#include "rtc_base/numerics/safe_minmax.h"
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namespace webrtc {
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LinkCapacityEstimator::LinkCapacityEstimator() {}
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DataRate LinkCapacityEstimator::UpperBound() const {
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if (estimate_kbps_.has_value())
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return DataRate::kbps(estimate_kbps_.value() +
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3 * deviation_estimate_kbps());
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return DataRate::Infinity();
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}
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DataRate LinkCapacityEstimator::LowerBound() const {
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if (estimate_kbps_.has_value())
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return DataRate::kbps(
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std::max(0.0, estimate_kbps_.value() - 3 * deviation_estimate_kbps()));
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return DataRate::Zero();
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}
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void LinkCapacityEstimator::Reset() {
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estimate_kbps_.reset();
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}
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void LinkCapacityEstimator::OnOveruseDetected(DataRate acknowledged_rate) {
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Update(acknowledged_rate, 0.05);
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}
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void LinkCapacityEstimator::OnProbeRate(DataRate probe_rate) {
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Update(probe_rate, 0.5);
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}
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void LinkCapacityEstimator::Update(DataRate capacity_sample, double alpha) {
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double sample_kbps = capacity_sample.kbps();
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if (!estimate_kbps_.has_value()) {
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estimate_kbps_ = sample_kbps;
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} else {
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estimate_kbps_ = (1 - alpha) * estimate_kbps_.value() + alpha * sample_kbps;
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}
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// Estimate the variance of the link capacity estimate and normalize the
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// variance with the link capacity estimate.
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const double norm = std::max(estimate_kbps_.value(), 1.0);
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double error_kbps = estimate_kbps_.value() - sample_kbps;
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deviation_kbps_ =
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(1 - alpha) * deviation_kbps_ + alpha * error_kbps * error_kbps / norm;
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// 0.4 ~= 14 kbit/s at 500 kbit/s
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// 2.5f ~= 35 kbit/s at 500 kbit/s
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deviation_kbps_ = rtc::SafeClamp(deviation_kbps_, 0.4f, 2.5f);
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}
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bool LinkCapacityEstimator::has_estimate() const {
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return estimate_kbps_.has_value();
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}
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DataRate LinkCapacityEstimator::estimate() const {
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return DataRate::kbps(*estimate_kbps_);
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}
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double LinkCapacityEstimator::deviation_estimate_kbps() const {
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// Calculate the max bit rate std dev given the normalized
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// variance and the current throughput bitrate. The standard deviation will
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// only be used if estimate_kbps_ has a value.
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return sqrt(deviation_kbps_ * estimate_kbps_.value());
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}
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} // namespace webrtc
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