qtmultimedia/examples/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