blob: 9e4655822d8480ec219b4302efdc2e879cb5ff45 [file] [log] [blame]
* 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.
#include <stddef.h>
#include <stdint.h>
#include <deque>
#include <utility>
#include "webrtc/rtc_base/constructormagic.h"
namespace webrtc {
class TrendlineEstimator {
// |window_size| is the number of points required to compute a trend line.
// |smoothing_coef| controls how much we smooth out the delay before fitting
// the 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.
TrendlineEstimator(size_t window_size,
double smoothing_coef,
double threshold_gain);
// 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_; }
// Parameters.
const size_t window_size_;
const double smoothing_coef_;
const double threshold_gain_;
// Used by the existing threshold.
unsigned int num_of_deltas_;
// Keep the arrival times small by using the change from the first packet.
int64_t first_arrival_time_ms;
// Exponential backoff filtering.
double accumulated_delay_;
double smoothed_delay_;
// Linear least squares regression.
std::deque<std::pair<double, double>> delay_hist_;
double trendline_;
} // namespace webrtc