69 lines
1.7 KiB
C
69 lines
1.7 KiB
C
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/*
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* Copyright 2020 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef ANALYZER_PEAK_DETECTOR_H
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#define ANALYZER_PEAK_DETECTOR_H
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#include <math.h>
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/**
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* Measure a peak envelope by rising with the peaks,
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* and decaying exponentially after each peak.
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* The absolute value of the input signal is used.
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*/
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class PeakDetector {
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public:
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void reset() {
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mLevel = 0.0;
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}
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double process(double input) {
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mLevel *= mDecay; // exponential decay
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input = fabs(input);
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// never fall below the input signal
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if (input > mLevel) {
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mLevel = input;
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}
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return mLevel;
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}
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double getLevel() const {
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return mLevel;
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}
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double getDecay() const {
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return mDecay;
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}
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/**
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* Multiply the level by this amount on every iteration.
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* This provides an exponential decay curve.
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* A value just under 1.0 is best, for example, 0.99;
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* @param decay scale level for each input
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*/
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void setDecay(double decay) {
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mDecay = decay;
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}
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private:
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static constexpr double kDefaultDecay = 0.99f;
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double mLevel = 0.0;
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double mDecay = kDefaultDecay;
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};
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#endif //ANALYZER_PEAK_DETECTOR_H
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