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/*
* Copyright (c) 2012 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/remote_bitrate_estimator/overuse_detector.h"
#include <math.h>
#include <stdio.h>
#include <algorithm>
#include <cstdint>
#include "api/transport/bandwidth_usage.h"
#include "rtc_base/numerics/safe_minmax.h"
namespace webrtc {
namespace {
constexpr double kMaxAdaptOffsetMs = 15.0;
constexpr double kOverUsingTimeThreshold = 10;
constexpr int kMaxNumDeltas = 60;
constexpr double kUp = 0.0087;
constexpr double kDown = 0.039;
} // namespace
OveruseDetector::OveruseDetector() = default;
BandwidthUsage OveruseDetector::State() const {
return hypothesis_;
}
BandwidthUsage OveruseDetector::Detect(double offset,
double ts_delta,
int num_of_deltas,
int64_t now_ms) {
if (num_of_deltas < 2) {
return BandwidthUsage::kBwNormal;
}
const double T = std::min(num_of_deltas, kMaxNumDeltas) * offset;
if (T > threshold_) {
if (time_over_using_ == -1) {
// Initialize the timer. Assume that we've been
// over-using half of the time since the previous
// sample.
time_over_using_ = ts_delta / 2;
} else {
// Increment timer
time_over_using_ += ts_delta;
}
overuse_counter_++;
if (time_over_using_ > kOverUsingTimeThreshold && overuse_counter_ > 1) {
if (offset >= prev_offset_) {
time_over_using_ = 0;
overuse_counter_ = 0;
hypothesis_ = BandwidthUsage::kBwOverusing;
}
}
} else if (T < -threshold_) {
time_over_using_ = -1;
overuse_counter_ = 0;
hypothesis_ = BandwidthUsage::kBwUnderusing;
} else {
time_over_using_ = -1;
overuse_counter_ = 0;
hypothesis_ = BandwidthUsage::kBwNormal;
}
prev_offset_ = offset;
UpdateThreshold(T, now_ms);
return hypothesis_;
}
void OveruseDetector::UpdateThreshold(double modified_offset, int64_t now_ms) {
if (last_update_ms_ == -1)
last_update_ms_ = now_ms;
if (fabs(modified_offset) > threshold_ + kMaxAdaptOffsetMs) {
// Avoid adapting the threshold to big latency spikes, caused e.g.,
// by a sudden capacity drop.
last_update_ms_ = now_ms;
return;
}
const double k = fabs(modified_offset) < threshold_ ? kDown : kUp;
const int64_t kMaxTimeDeltaMs = 100;
int64_t time_delta_ms = std::min(now_ms - last_update_ms_, kMaxTimeDeltaMs);
threshold_ += k * (fabs(modified_offset) - threshold_) * time_delta_ms;
threshold_ = SafeClamp(threshold_, 6.f, 600.f);
last_update_ms_ = now_ms;
}
} // namespace webrtc
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