spectrumanalyser.h Example File

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  #ifndef SPECTRUMANALYSER_H
  #define SPECTRUMANALYSER_H

  #include <QByteArray>
  #include <QObject>
  #include <QVector>

  #ifdef DUMP_SPECTRUMANALYSER
  #include <QDir>
  #include <QFile>
  #include <QTextStream>
  #endif

  #include "frequencyspectrum.h"
  #include "spectrum.h"

  #ifndef DISABLE_FFT
  #include "FFTRealFixLenParam.h"
  #endif

  QT_FORWARD_DECLARE_CLASS(QAudioFormat)
  QT_FORWARD_DECLARE_CLASS(QThread)

  class FFTRealWrapper;

  class SpectrumAnalyserThreadPrivate;

  /**
   * Implementation of the spectrum analysis which can be run in a
   * separate thread.
   */
  class SpectrumAnalyserThread : public QObject
  {
      Q_OBJECT

  public:
      SpectrumAnalyserThread(QObject *parent);
      ~SpectrumAnalyserThread();

  public slots:
      void setWindowFunction(WindowFunction type);
      void calculateSpectrum(const QByteArray &buffer,
                             int inputFrequency,
                             int bytesPerSample);

  signals:
      void calculationComplete(const FrequencySpectrum &spectrum);

  private:
      void calculateWindow();

  private:
  #ifndef DISABLE_FFT
      FFTRealWrapper*                             m_fft;
  #endif

      const int                                   m_numSamples;

      WindowFunction                              m_windowFunction;

  #ifdef DISABLE_FFT
      typedef qreal                               DataType;
  #else
      typedef FFTRealFixLenParam::DataType        DataType;
  #endif
      QVector<DataType>                           m_window;

      QVector<DataType>                           m_input;
      QVector<DataType>                           m_output;

      FrequencySpectrum                           m_spectrum;

  #ifdef SPECTRUM_ANALYSER_SEPARATE_THREAD
      QThread*                                    m_thread;
  #endif
  };

  /**
   * Class which performs frequency spectrum analysis on a window of
   * audio samples, provided to it by the Engine.
   */
  class SpectrumAnalyser : public QObject
  {
      Q_OBJECT

  public:
      SpectrumAnalyser(QObject *parent = 0);
      ~SpectrumAnalyser();

  #ifdef DUMP_SPECTRUMANALYSER
      void setOutputPath(const QString &outputPath);
  #endif

  public:
      /*
       * Set the windowing function which is applied before calculating the FFT
       */
      void setWindowFunction(WindowFunction type);

      /*
       * Calculate a frequency spectrum
       *
       * \param buffer       Audio data
       * \param format       Format of audio data
       *
       * Frequency spectrum is calculated asynchronously.  The result is returned
       * via the spectrumChanged signal.
       *
       * An ongoing calculation can be cancelled by calling cancelCalculation().
       *
       */
      void calculate(const QByteArray &buffer, const QAudioFormat &format);

      /*
       * Check whether the object is ready to perform another calculation
       */
      bool isReady() const;

      /*
       * Cancel an ongoing calculation
       *
       * Note that cancelling is asynchronous.
       */
      void cancelCalculation();

  signals:
      void spectrumChanged(const FrequencySpectrum &spectrum);

  private slots:
      void calculationComplete(const FrequencySpectrum &spectrum);

  private:
      void calculateWindow();

  private:

      SpectrumAnalyserThread*    m_thread;

      enum State {
          Idle,
          Busy,
          Cancelled
      };

      State              m_state;

  #ifdef DUMP_SPECTRUMANALYSER
      QDir                m_outputDir;
      int                 m_count;
      QFile               m_textFile;
      QTextStream         m_textStream;
  #endif
  };

  #endif // SPECTRUMANALYSER_H