Qt Reference Documentation

spectrumanalyser.h Example File

demos/spectrum/app/spectrumanalyser.h
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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
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