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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.
*/
#include "video/quality_threshold.h"
#include "rtc_base/checks.h"
namespace webrtc {
QualityThreshold::QualityThreshold(int low_threshold,
int high_threshold,
float fraction,
int max_measurements)
: buffer_(new int[max_measurements]),
max_measurements_(max_measurements),
fraction_(fraction),
low_threshold_(low_threshold),
high_threshold_(high_threshold),
until_full_(max_measurements),
next_index_(0),
sum_(0),
count_low_(0),
count_high_(0),
num_high_states_(0),
num_certain_states_(0) {
RTC_CHECK_GT(fraction, 0.5f);
RTC_CHECK_GT(max_measurements, 1);
RTC_CHECK_LT(low_threshold, high_threshold);
}
QualityThreshold::~QualityThreshold() = default;
void QualityThreshold::AddMeasurement(int measurement) {
int prev_val = until_full_ > 0 ? 0 : buffer_[next_index_];
buffer_[next_index_] = measurement;
next_index_ = (next_index_ + 1) % max_measurements_;
sum_ += measurement - prev_val;
if (until_full_ == 0) {
if (prev_val <= low_threshold_) {
--count_low_;
} else if (prev_val >= high_threshold_) {
--count_high_;
}
}
if (measurement <= low_threshold_) {
++count_low_;
} else if (measurement >= high_threshold_) {
++count_high_;
}
float sufficient_majority = fraction_ * max_measurements_;
if (count_high_ >= sufficient_majority) {
is_high_ = true;
} else if (count_low_ >= sufficient_majority) {
is_high_ = false;
}
if (until_full_ > 0)
--until_full_;
if (is_high_) {
if (*is_high_)
++num_high_states_;
++num_certain_states_;
}
}
absl::optional<bool> QualityThreshold::IsHigh() const {
return is_high_;
}
absl::optional<double> QualityThreshold::CalculateVariance() const {
if (until_full_ > 0) {
return absl::nullopt;
}
double variance = 0;
double mean = static_cast<double>(sum_) / max_measurements_;
for (int i = 0; i < max_measurements_; ++i) {
variance += (buffer_[i] - mean) * (buffer_[i] - mean);
}
return variance / (max_measurements_ - 1);
}
absl::optional<double> QualityThreshold::FractionHigh(
int min_required_samples) const {
RTC_DCHECK_GT(min_required_samples, 0);
if (num_certain_states_ < min_required_samples)
return absl::nullopt;
return static_cast<double>(num_high_states_) / num_certain_states_;
}
} // namespace webrtc
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