first re-commit.

swfftcalc.h

@@ -0,0 +1,92 @@
+/***************************************************************************
+
+    source::worx raDIYo
+    Copyright © 2020-2022 c.holzheuer
+    chris@sourceworx.org
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+***************************************************************************/
+
+
+#ifndef SWFFTCALC_H
+#define SWFFTCALC_H
+
+#include <complex>
+#include <iostream>
+#include <valarray>
+
+#include <QObject>
+#include <QThread>
+#include <QAudioFormat>
+#include <QAudioProbe>
+#include <QAudioDeviceInfo>
+#include <QElapsedTimer>
+
+#include <raDIYoglobals.h>
+
+// Scale PCM value to [-1.0, 1.0]
+qreal xpcmToReal(qint16 pcm);
+
+
+
+
+/**
+ * @brief Berechnet mittels FFT ein Spectrum
+ * aus dem @see @QAudioBuffer. Das Spectrum wird beim
+ * Abspielen eines Songs angezeigt.
+ * @see SWSpectrumWidget
+ * @see SWPlayerControl
+ */
+
+class SWFFTCalc : public QObject
+{
+
+    Q_OBJECT
+
+public:
+
+    explicit SWFFTCalc( QObject* parent = nullptr );
+    virtual ~SWFFTCalc();
+
+signals:
+
+    void spectrumReady( const SWValVec& spectrum );
+
+public slots:
+
+    void onAudioProbed( const QAudioBuffer& audiobuffer );
+
+protected:
+
+    using Complex = std::complex<double>;
+    using CArray  = std::valarray<Complex>;
+
+    void bareFFT( CArray& x );
+
+    static constexpr const int SWNumSamples = 4096;
+    const double PI = 3.141592653589793238460;
+
+    // Fudge factor used to calculate the spectrum bar heights
+    //const qreal SpectrumAnalyserMultiplier = 0.15;
+    const qreal SWFudgeFactor = 0.17;
+
+
+    int           _bufferDuration = 0;
+    QElapsedTimer _timer;
+    SWValVec      _frames;
+    SWValVec      _hannWindow;
+    // überdenken: geht das so schneller?
+    // SWValVec _logscale;
+    SWValVec     _spectrum;
+    CArray       _complexFrame;
+
+};
+
+
+#endif // SWFFTCALC_H
+
+