mirror of
https://github.com/mollyim/webrtc.git
synced 2025-05-13 05:40:42 +01:00
c4a205c7fa
Bug: None Change-Id: I5388bc018d7ddd285d154436b5fc52a15469a97d Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/319220 Reviewed-by: Erik Språng <sprang@webrtc.org> Reviewed-by: Per Kjellander <perkj@webrtc.org> Commit-Queue: Björn Terelius <terelius@webrtc.org> Cr-Commit-Position: refs/heads/main@{#40710}
79 lines
2.7 KiB
C++
79 lines
2.7 KiB
C++
/*
|
|
* Copyright 2018 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/goog_cc/link_capacity_estimator.h"
|
|
|
|
#include <algorithm>
|
|
#include <cmath>
|
|
|
|
#include "api/units/data_rate.h"
|
|
#include "rtc_base/numerics/safe_minmax.h"
|
|
|
|
namespace webrtc {
|
|
LinkCapacityEstimator::LinkCapacityEstimator() {}
|
|
|
|
DataRate LinkCapacityEstimator::UpperBound() const {
|
|
if (estimate_kbps_.has_value())
|
|
return DataRate::KilobitsPerSec(estimate_kbps_.value() +
|
|
3 * deviation_estimate_kbps());
|
|
return DataRate::Infinity();
|
|
}
|
|
|
|
DataRate LinkCapacityEstimator::LowerBound() const {
|
|
if (estimate_kbps_.has_value())
|
|
return DataRate::KilobitsPerSec(
|
|
std::max(0.0, estimate_kbps_.value() - 3 * deviation_estimate_kbps()));
|
|
return DataRate::Zero();
|
|
}
|
|
|
|
void LinkCapacityEstimator::Reset() {
|
|
estimate_kbps_.reset();
|
|
}
|
|
|
|
void LinkCapacityEstimator::OnOveruseDetected(DataRate acknowledged_rate) {
|
|
Update(acknowledged_rate, 0.05);
|
|
}
|
|
|
|
void LinkCapacityEstimator::OnProbeRate(DataRate probe_rate) {
|
|
Update(probe_rate, 0.5);
|
|
}
|
|
|
|
void LinkCapacityEstimator::Update(DataRate capacity_sample, double alpha) {
|
|
double sample_kbps = capacity_sample.kbps();
|
|
if (!estimate_kbps_.has_value()) {
|
|
estimate_kbps_ = sample_kbps;
|
|
} else {
|
|
estimate_kbps_ = (1 - alpha) * estimate_kbps_.value() + alpha * sample_kbps;
|
|
}
|
|
// Estimate the variance of the link capacity estimate and normalize the
|
|
// variance with the link capacity estimate.
|
|
const double norm = std::max(estimate_kbps_.value(), 1.0);
|
|
double error_kbps = estimate_kbps_.value() - sample_kbps;
|
|
deviation_kbps_ =
|
|
(1 - alpha) * deviation_kbps_ + alpha * error_kbps * error_kbps / norm;
|
|
// 0.4 ~= 14 kbit/s at 500 kbit/s
|
|
// 2.5f ~= 35 kbit/s at 500 kbit/s
|
|
deviation_kbps_ = rtc::SafeClamp(deviation_kbps_, 0.4f, 2.5f);
|
|
}
|
|
|
|
bool LinkCapacityEstimator::has_estimate() const {
|
|
return estimate_kbps_.has_value();
|
|
}
|
|
|
|
DataRate LinkCapacityEstimator::estimate() const {
|
|
return DataRate::KilobitsPerSec(*estimate_kbps_);
|
|
}
|
|
|
|
double LinkCapacityEstimator::deviation_estimate_kbps() const {
|
|
// Calculate the max bit rate std dev given the normalized
|
|
// variance and the current throughput bitrate. The standard deviation will
|
|
// only be used if estimate_kbps_ has a value.
|
|
return sqrt(deviation_kbps_ * estimate_kbps_.value());
|
|
}
|
|
} // namespace webrtc
|