| 1 | // Copyright (C) 2024 The Qt Company Ltd. |
|---|---|
| 2 | // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only |
| 3 | |
| 4 | #ifndef QSINEWAVEVALIDATOR_H |
| 5 | #define QSINEWAVEVALIDATOR_H |
| 6 | |
| 7 | // |
| 8 | // W A R N I N G |
| 9 | // ------------- |
| 10 | // |
| 11 | // This file is not part of the Qt API. It exists purely as an |
| 12 | // implementation detail. This header file may change from version to |
| 13 | // version without notice, or even be removed. |
| 14 | // |
| 15 | // We mean it. |
| 16 | // |
| 17 | |
| 18 | #include <array> |
| 19 | |
| 20 | // sine wave validator: accumulating peak value and result of passing the signal through a notch |
| 21 | // filter. A sine wave of that frequency should not pass the notch filter, so if the peak exceeds a |
| 22 | // small threshold, it we can detect discontinuities for example. |
| 23 | struct QSineWaveValidator |
| 24 | { |
| 25 | QSineWaveValidator(const QSineWaveValidator &) = delete; |
| 26 | QSineWaveValidator(QSineWaveValidator &&) = delete; |
| 27 | QSineWaveValidator &operator=(const QSineWaveValidator &) = delete; |
| 28 | QSineWaveValidator &operator=(QSineWaveValidator &&) = delete; |
| 29 | |
| 30 | QSineWaveValidator(float notchFrequency, float sampleRate); |
| 31 | |
| 32 | void feedSample(float sample); |
| 33 | |
| 34 | float peak() const { return accumPeak; } |
| 35 | float notchPeak() const; |
| 36 | |
| 37 | private: |
| 38 | float a0, a1, a2; |
| 39 | float b0, b1, b2; |
| 40 | |
| 41 | std::array<float, 3> x{}, y{}; |
| 42 | int framesBeforeAnalysis = 128; // unscientific estimate, larger than the transient response |
| 43 | // time for the IIR filter |
| 44 | int pendingFramesBeforeAnalysis = framesBeforeAnalysis; |
| 45 | |
| 46 | float accumPeak{}; |
| 47 | float accumNotchPeak{}; |
| 48 | }; |
| 49 | |
| 50 | #endif // QSINEWAVEVALIDATOR_H |
| 51 |