spectrum.h Example File

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 #ifndef SPECTRUM_H
 #define SPECTRUM_H

 #include <QtCore/qglobal.h>
 #include "utils.h"
 #include "fftreal_wrapper.h" // For FFTLengthPowerOfTwo

 //-----------------------------------------------------------------------------
 // Constants
 //-----------------------------------------------------------------------------

 // Number of audio samples used to calculate the frequency spectrum
 const int    SpectrumLengthSamples  = PowerOfTwo<FFTLengthPowerOfTwo>::Result;

 // Number of bands in the frequency spectrum
 const int    SpectrumNumBands       = 10;

 // Lower bound of first band in the spectrum
 const qreal  SpectrumLowFreq        = 0.0; // Hz

 // Upper band of last band in the spectrum
 const qreal  SpectrumHighFreq       = 1000.0; // Hz

 // Waveform window size in microseconds
 const qint64 WaveformWindowDuration = 500 * 1000;

 // Length of waveform tiles in bytes
 // Ideally, these would match the QAudio*::bufferSize(), but that isn't
 // available until some time after QAudio*::start() has been called, and we
 // need this value in order to initialize the waveform display.
 // We therefore just choose a sensible value.
 const int   WaveformTileLength      = 4096;

 // Fudge factor used to calculate the spectrum bar heights
 const qreal SpectrumAnalyserMultiplier = 0.15;

 // Disable message timeout
 const int   NullMessageTimeout      = -1;

 //-----------------------------------------------------------------------------
 // Types and data structures
 //-----------------------------------------------------------------------------

 enum WindowFunction {
     NoWindow,
     HannWindow
 };

 const WindowFunction DefaultWindowFunction = HannWindow;

 struct Tone {
     Tone(qreal freq = 0.0, qreal amp = 0.0)
     :   frequency(freq), amplitude(amp)
     { }

     // Start and end frequencies for swept tone generation
     qreal   frequency;

     // Amplitude in range [0.0, 1.0]
     qreal   amplitude;
 };

 struct SweptTone {
     SweptTone(qreal start = 0.0, qreal end = 0.0, qreal amp = 0.0)
     :   startFreq(start), endFreq(end), amplitude(amp)
     { Q_ASSERT(end >= start); }

     SweptTone(const Tone &tone)
     :   startFreq(tone.frequency), endFreq(tone.frequency), amplitude(tone.amplitude)
     { }

     // Start and end frequencies for swept tone generation
     qreal   startFreq;
     qreal   endFreq;

     // Amplitude in range [0.0, 1.0]
     qreal   amplitude;
 };

 //-----------------------------------------------------------------------------
 // Macros
 //-----------------------------------------------------------------------------

 // Macro which connects a signal to a slot, and which causes application to
 // abort if the connection fails.  This is intended to catch programming errors
 // such as mis-typing a signal or slot name.  It is necessary to write our own
 // macro to do this - the following idiom
 //     Q_ASSERT(connect(source, signal, receiver, slot));
 // will not work because Q_ASSERT compiles to a no-op in release builds.

 #define CHECKED_CONNECT(source, signal, receiver, slot) \
     if(!connect(source, signal, receiver, slot)) \
         qt_assert_x(Q_FUNC_INFO, "CHECKED_CONNECT failed", __FILE__, __LINE__);

 // Handle some dependencies between macros defined in the .pro file

 #ifdef DISABLE_WAVEFORM
 #undef SUPERIMPOSE_PROGRESS_ON_WAVEFORM
 #endif

 #endif // SPECTRUM_H