| /* |
| * Copyright (c) 2017 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. |
| */ |
| |
| #ifndef RTC_BASE_NUMERICS_MOVING_MEDIAN_FILTER_H_ |
| #define RTC_BASE_NUMERICS_MOVING_MEDIAN_FILTER_H_ |
| |
| #include <stddef.h> |
| |
| #include <cstddef> |
| #include <list> |
| |
| #include "rtc_base/checks.h" |
| #include "rtc_base/numerics/percentile_filter.h" |
| |
| namespace webrtc { |
| |
| // Class to efficiently get moving median filter from a stream of samples. |
| template <typename T> |
| class MovingMedianFilter { |
| public: |
| // Construct filter. `window_size` is how many latest samples are stored and |
| // used to take median. `window_size` must be positive. |
| explicit MovingMedianFilter(size_t window_size); |
| |
| MovingMedianFilter(const MovingMedianFilter&) = delete; |
| MovingMedianFilter& operator=(const MovingMedianFilter&) = delete; |
| |
| // Insert a new sample. |
| void Insert(const T& value); |
| |
| // Removes all samples; |
| void Reset(); |
| |
| // Get median over the latest window. |
| T GetFilteredValue() const; |
| |
| // The number of samples that are currently stored. |
| size_t GetNumberOfSamplesStored() const; |
| |
| private: |
| PercentileFilter<T> percentile_filter_; |
| std::list<T> samples_; |
| size_t samples_stored_; |
| const size_t window_size_; |
| }; |
| |
| template <typename T> |
| MovingMedianFilter<T>::MovingMedianFilter(size_t window_size) |
| : percentile_filter_(0.5f), samples_stored_(0), window_size_(window_size) { |
| RTC_CHECK_GT(window_size, 0); |
| } |
| |
| template <typename T> |
| void MovingMedianFilter<T>::Insert(const T& value) { |
| percentile_filter_.Insert(value); |
| samples_.emplace_back(value); |
| ++samples_stored_; |
| if (samples_stored_ > window_size_) { |
| percentile_filter_.Erase(samples_.front()); |
| samples_.pop_front(); |
| --samples_stored_; |
| } |
| } |
| |
| template <typename T> |
| T MovingMedianFilter<T>::GetFilteredValue() const { |
| return percentile_filter_.GetPercentileValue(); |
| } |
| |
| template <typename T> |
| void MovingMedianFilter<T>::Reset() { |
| percentile_filter_.Reset(); |
| samples_.clear(); |
| samples_stored_ = 0; |
| } |
| |
| template <typename T> |
| size_t MovingMedianFilter<T>::GetNumberOfSamplesStored() const { |
| return samples_stored_; |
| } |
| |
| } // namespace webrtc |
| #endif // RTC_BASE_NUMERICS_MOVING_MEDIAN_FILTER_H_ |