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/*
* Copyright (c) 2016 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.
*/
#ifndef MODULES_CONGESTION_CONTROLLER_MEDIAN_SLOPE_ESTIMATOR_H_
#define MODULES_CONGESTION_CONTROLLER_MEDIAN_SLOPE_ESTIMATOR_H_
#include <stddef.h>
#include <stdint.h>
#include <deque>
#include <vector>
#include "rtc_base/constructormagic.h"
#include "rtc_base/numerics/percentile_filter.h"
namespace webrtc {
class MedianSlopeEstimator {
public:
// |window_size| is the number of points required to compute a trend line.
// |threshold_gain| is used to scale the trendline slope for comparison to
// the old threshold. Once the old estimator has been removed (or the
// thresholds been merged into the estimators), we can just set the
// threshold instead of setting a gain.
MedianSlopeEstimator(size_t window_size, double threshold_gain);
~MedianSlopeEstimator();
// Update the estimator with a new sample. The deltas should represent deltas
// between timestamp groups as defined by the InterArrival class.
void Update(double recv_delta_ms,
double send_delta_ms,
int64_t arrival_time_ms);
// Returns the estimated trend k multiplied by some gain.
// 0 < k < 1 -> the delay increases, queues are filling up
// k == 0 -> the delay does not change
// k < 0 -> the delay decreases, queues are being emptied
double trendline_slope() const { return trendline_ * threshold_gain_; }
// Returns the number of deltas which the current estimator state is based on.
unsigned int num_of_deltas() const { return num_of_deltas_; }
private:
struct DelayInfo {
DelayInfo(int64_t time, double delay, size_t slope_count);
~DelayInfo();
int64_t time;
double delay;
std::vector<double> slopes;
};
// Parameters.
const size_t window_size_;
const double threshold_gain_;
// Used by the existing threshold.
unsigned int num_of_deltas_;
// Theil-Sen robust line fitting
double accumulated_delay_;
std::deque<DelayInfo> delay_hist_;
PercentileFilter<double> median_filter_;
double trendline_;
RTC_DISALLOW_COPY_AND_ASSIGN(MedianSlopeEstimator);
};
} // namespace webrtc
#endif // MODULES_CONGESTION_CONTROLLER_MEDIAN_SLOPE_ESTIMATOR_H_