105 lines
2.8 KiB
C++
105 lines
2.8 KiB
C++
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/*
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* Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "video/quality_threshold.h"
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#include "rtc_base/checks.h"
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namespace webrtc {
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QualityThreshold::QualityThreshold(int low_threshold,
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int high_threshold,
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float fraction,
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int max_measurements)
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: buffer_(new int[max_measurements]),
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max_measurements_(max_measurements),
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fraction_(fraction),
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low_threshold_(low_threshold),
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high_threshold_(high_threshold),
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until_full_(max_measurements),
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next_index_(0),
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sum_(0),
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count_low_(0),
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count_high_(0),
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num_high_states_(0),
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num_certain_states_(0) {
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RTC_CHECK_GT(fraction, 0.5f);
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RTC_CHECK_GT(max_measurements, 1);
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RTC_CHECK_LT(low_threshold, high_threshold);
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}
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QualityThreshold::~QualityThreshold() = default;
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void QualityThreshold::AddMeasurement(int measurement) {
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int prev_val = until_full_ > 0 ? 0 : buffer_[next_index_];
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buffer_[next_index_] = measurement;
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next_index_ = (next_index_ + 1) % max_measurements_;
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sum_ += measurement - prev_val;
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if (until_full_ == 0) {
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if (prev_val <= low_threshold_) {
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--count_low_;
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} else if (prev_val >= high_threshold_) {
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--count_high_;
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}
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}
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if (measurement <= low_threshold_) {
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++count_low_;
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} else if (measurement >= high_threshold_) {
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++count_high_;
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}
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float sufficient_majority = fraction_ * max_measurements_;
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if (count_high_ >= sufficient_majority) {
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is_high_ = true;
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} else if (count_low_ >= sufficient_majority) {
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is_high_ = false;
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}
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if (until_full_ > 0)
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--until_full_;
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if (is_high_) {
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if (*is_high_)
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++num_high_states_;
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++num_certain_states_;
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}
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}
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absl::optional<bool> QualityThreshold::IsHigh() const {
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return is_high_;
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}
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absl::optional<double> QualityThreshold::CalculateVariance() const {
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if (until_full_ > 0) {
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return absl::nullopt;
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}
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double variance = 0;
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double mean = static_cast<double>(sum_) / max_measurements_;
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for (int i = 0; i < max_measurements_; ++i) {
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variance += (buffer_[i] - mean) * (buffer_[i] - mean);
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}
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return variance / (max_measurements_ - 1);
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}
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absl::optional<double> QualityThreshold::FractionHigh(
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int min_required_samples) const {
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RTC_DCHECK_GT(min_required_samples, 0);
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if (num_certain_states_ < min_required_samples)
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return absl::nullopt;
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return static_cast<double>(num_high_states_) / num_certain_states_;
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}
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} // namespace webrtc
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