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| 1 /* |
| 2 * Copyright (c) 2016 The WebRTC project authors. All Rights Reserved. |
| 3 * |
| 4 * Use of this source code is governed by a BSD-style license |
| 5 * that can be found in the LICENSE file in the root of the source |
| 6 * tree. An additional intellectual property rights grant can be found |
| 7 * in the file PATENTS. All contributing project authors may |
| 8 * be found in the AUTHORS file in the root of the source tree. |
| 9 */ |
| 10 |
| 11 #include "webrtc/video/quality_threshold.h" |
| 12 |
| 13 #include "webrtc/base/checks.h" |
| 14 #include "webrtc/base/logging.h" |
| 15 |
| 16 namespace webrtc { |
| 17 |
| 18 QualityThreshold::QualityThreshold(int low_threshold, |
| 19 int high_threshold, |
| 20 float fraction, |
| 21 int max_measurements) |
| 22 : buffer_(new int[max_measurements]), |
| 23 max_measurements_(max_measurements), |
| 24 fraction_(fraction), |
| 25 low_threshold_(low_threshold), |
| 26 high_threshold_(high_threshold), |
| 27 until_full_(max_measurements), |
| 28 next_index_(0), |
| 29 sum_(0), |
| 30 count_low_(0), |
| 31 count_high_(0) { |
| 32 RTC_CHECK_GT(fraction, 0.5f); |
| 33 RTC_CHECK_GT(max_measurements, 1); |
| 34 RTC_CHECK_LT(low_threshold, high_threshold); |
| 35 } |
| 36 |
| 37 void QualityThreshold::AddMeasurement(int measurement) { |
| 38 int prev_val = until_full_ > 0 ? 0 : buffer_[next_index_]; |
| 39 buffer_[next_index_] = measurement; |
| 40 next_index_ = (next_index_ + 1) % max_measurements_; |
| 41 |
| 42 sum_ += measurement - prev_val; |
| 43 |
| 44 if (until_full_ == 0) { |
| 45 if (prev_val <= low_threshold_) { |
| 46 --count_low_; |
| 47 } else if (prev_val >= high_threshold_) { |
| 48 --count_high_; |
| 49 } |
| 50 } |
| 51 |
| 52 if (measurement <= low_threshold_) { |
| 53 ++count_low_; |
| 54 } else if (measurement >= high_threshold_) { |
| 55 ++count_high_; |
| 56 } |
| 57 |
| 58 float sufficient_majority = fraction_ * max_measurements_; |
| 59 if (count_high_ >= sufficient_majority) { |
| 60 is_high_ = rtc::Optional<bool>(true); |
| 61 } else if (count_low_ >= sufficient_majority) { |
| 62 is_high_ = rtc::Optional<bool>(false); |
| 63 } |
| 64 |
| 65 if (until_full_ > 0) |
| 66 --until_full_; |
| 67 } |
| 68 |
| 69 rtc::Optional<bool> QualityThreshold::IsHigh() const { |
| 70 return is_high_; |
| 71 } |
| 72 |
| 73 rtc::Optional<double> QualityThreshold::CalculateVariance() const { |
| 74 if (until_full_ > 0) { |
| 75 return rtc::Optional<double>(); |
| 76 } |
| 77 |
| 78 double variance = 0; |
| 79 double mean = static_cast<double>(sum_) / max_measurements_; |
| 80 for (int i = 0; i < max_measurements_; ++i) { |
| 81 variance += (buffer_[i] - mean) * (buffer_[i] - mean); |
| 82 } |
| 83 return rtc::Optional<double>(variance / (max_measurements_ - 1)); |
| 84 } |
| 85 |
| 86 } // namespace webrtc |
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