spectrum.h Example File

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  #ifndef SPECTRUM_H
  #define SPECTRUM_H

  #include <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