Qt 4.6: audioinput.h Example File (multimedia/audio/audioinput/audioinput.h)

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# audioinput.h Example File
multimedia/audio/audioinput/audioinput.h

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     ** This file is part of the examples of the Qt Toolkit.
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     #include <QPixmap>
     #include <QWidget>
     #include <QObject>
     #include <QMainWindow>
     #include <QPushButton>
     #include <QComboBox>

     #include <qaudioinput.h>

     #define BUFFER_SIZE_LOG 9
     #define BUFFER_SIZE (1 << BUFFER_SIZE_LOG)

     struct _struct_fft_state {
         float real[BUFFER_SIZE];
         float imag[BUFFER_SIZE];
     };
     typedef _struct_fft_state   fft_state;
     typedef short int           sound_sample;

     class Spectrum : public QIODevice
     {
         Q_OBJECT
     public:
         Spectrum(QObject* parent, QAudioInput* device, float* out);
         ~Spectrum();

         void start();
         void stop();

         qint64 readData(char *data, qint64 maxlen);
         qint64 writeData(const char *data, qint64 len);

         QAudioInput*   input;
         float*         output;
         fft_state*     fftState;

         unsigned int bitReverse[BUFFER_SIZE];
         float        sintable[BUFFER_SIZE / 2];
         float        costable[BUFFER_SIZE / 2];

         void prepFFT (const sound_sample *input, float *re, float *im);
         void calcFFT (float *re, float *im);
         void outputFFT (const float *re, const float *im);
         int  reverseBits (unsigned int initial);
         void performFFT (const sound_sample *input);

     signals:
         void update();
     };

     class RenderArea : public QWidget
     {
         Q_OBJECT

     public:
         RenderArea(QWidget *parent = 0);

         void spectrum(float* output, int size);

     protected:
         void paintEvent(QPaintEvent *event);

     private:
         QPixmap pixmap;

         float*  samples;
         int     sampleSize;
     };

     class InputTest : public QMainWindow
     {
         Q_OBJECT
     public:
         InputTest();
         ~InputTest();

         QAudioDeviceId device;
         QAudioFormat   format;
         QAudioInput*   audioInput;
         Spectrum*      spec;
         QIODevice*     input;
         RenderArea*    canvas;

         bool           pullMode;

         QPushButton*   button;
         QPushButton*   button2;
         QComboBox*     deviceBox;

         char*          buffer;
         float*         output;

     private slots:
         void refreshDisplay();
         void status();
         void readMore();
         void toggleMode();
         void toggleSuspend();
         void state(QAudio::State s);
         void deviceChanged(int idx);
     };