qsinewavevalidator.cpp

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++ // Copyright (C) 2024 The Qt Company Ltd.

++ // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only

++

++ #include "qsinewavevalidator_p.h"

++

++ #include <QtCore/qmath.h>

++ #include <QtCore/QDebug>

++

++ QT_BEGIN_NAMESPACE

++

++ QSineWaveValidator::QSineWaveValidator(float notchFrequency, float sampleRate)

++ {

++     using namespace std;

++     float pi = static_cast<float>(M_PI);

++     float f0 = notchFrequency;

++     float Fs = sampleRate;

++     float Q = 1 / sqrt(2.f); // higher Q gives narrow bandwidth, but requires a larger number of

++     // frames during the transient

++

++     // compare https://webaudio.github.io/Audio-EQ-Cookbook/Audio-EQ-Cookbook.txt

++     float w0 = 2 * pi * f0 / Fs;

++     float alpha = sin(w0) / (2 * Q);

++

++     b0 = 1;

++     b1 = -2 * cos(w0);

++     b2 = 1;

++     a0 = 1 + alpha;

++     a1 = -2 * cos(w0);

++     a2 = 1 - alpha;

++ }

++

++ void QSineWaveValidator::feedSample(float sample)

++ {

++     if (pendingFramesBeforeAnalysis == framesBeforeAnalysis) {

++         x.fill(sample);

++         y.fill(b0 / a0 * sample);

++     }

++

++     x[2] = x[1];

++     x[1] = x[0];

++     x[0] = sample;

++

++     y[2] = y[1];

++     y[1] = y[0];

++     y[0] = (b0 / a0) * x[0] + (b1 / a0) * x[1] + (b2 / a0) * x[2] - (a1 / a0) * y[1]

++             - (a2 / a0) * y[2];

++

++     accumPeak = std::max(std::abs(sample), accumPeak);

++

++     if (pendingFramesBeforeAnalysis) {

++         pendingFramesBeforeAnalysis -= 1;

++         return;

++     }

++

++     accumNotchPeak = std::max(std::abs(y[0]), accumNotchPeak);

++ }

++

++ float QSineWaveValidator::notchPeak() const

++ {

++     if (pendingFramesBeforeAnalysis)

++         qWarning() << "notchPeak during initial frames. Result will not be accurate";

++     return accumNotchPeak;

++ }

++

++ QT_END_NAMESPACE