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audioinput.cpp Example File
multimedia/audio/audioinput/audioinput.cpp

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 #include <stdlib.h>
 #include <math.h>

 #include <QDebug>
 #include <QPainter>
 #include <QVBoxLayout>

 #include <QAudioDeviceInfo>
 #include <QAudioInput>
 #include "audioinput.h"

 #ifndef M_PI
 #define M_PI 3.14159265358979323846
 #endif

 Spectrum::Spectrum(QObject* parent, QAudioInput* device, float* out)
     :QIODevice( parent )
 {
     input = device;
     output = out;

     unsigned int i;

     // Allocate sample buffer and initialize sin and cos lookup tables
     fftState = (fft_state *) malloc (sizeof(fft_state));

     for(i = 0; i < BUFFER_SIZE; i++) {
         bitReverse[i] = reverseBits(i);
     }
     for(i = 0; i < BUFFER_SIZE / 2; i++) {
         float j = 2 * M_PI * i / BUFFER_SIZE;
         costable[i] = cos(j);
         sintable[i] = sin(j);
     }
 }

 Spectrum::~Spectrum()
 {
 }

 void Spectrum::start()
 {
     open(QIODevice::WriteOnly);
 }

 void Spectrum::stop()
 {
     close();
 }

 qint64 Spectrum::readData(char *data, qint64 maxlen)
 {
     Q_UNUSED(data)
     Q_UNUSED(maxlen)

     return 0;
 }

 qint64 Spectrum::writeData(const char *data, qint64 len)
 {
     performFFT((sound_sample*)data);
     emit update();

     return len;
 }

 int Spectrum::reverseBits(unsigned int initial) {
     // BIT-REVERSE-COPY(a,A)

     unsigned int reversed = 0, loop;
     for(loop = 0; loop < BUFFER_SIZE_LOG; loop++) {
         reversed <<= 1;
         reversed += (initial & 1);
         initial >>= 1;
     }
     return reversed;
 }

 void Spectrum::performFFT(const sound_sample *input) {
     /* Convert to reverse bit order for FFT */
     prepFFT(input, fftState->real, fftState->imag);

     /* Calculate FFT */
     calcFFT(fftState->real, fftState->imag);

     /* Convert FFT to intensities */
     outputFFT(fftState->real, fftState->imag);
 }

 void Spectrum::prepFFT(const sound_sample *input, float * re, float * im) {
     unsigned int i;
     float *realptr = re;
     float *imagptr = im;

     /* Get input, in reverse bit order */
     for(i = 0; i < BUFFER_SIZE; i++) {
         *realptr++ = input[bitReverse[i]];
         *imagptr++ = 0;
     }
 }

 void Spectrum::calcFFT(float * re, float * im) {
     unsigned int i, j, k;
     unsigned int exchanges;
     float fact_real, fact_imag;
     float tmp_real, tmp_imag;
     unsigned int factfact;

     /* Set up some variables to reduce calculation in the loops */
     exchanges = 1;
     factfact = BUFFER_SIZE / 2;

     /* divide and conquer method */
     for(i = BUFFER_SIZE_LOG; i != 0; i--) {
         for(j = 0; j != exchanges; j++) {
             fact_real = costable[j * factfact];
             fact_imag = sintable[j * factfact];
             for(k = j; k < BUFFER_SIZE; k += exchanges << 1) {
                 int k1 = k + exchanges;
                 tmp_real = fact_real * re[k1] - fact_imag * im[k1];
                 tmp_imag = fact_real * im[k1] + fact_imag * re[k1];
                 re[k1] = re[k] - tmp_real;
                 im[k1] = im[k] - tmp_imag;
                 re[k]  += tmp_real;
                 im[k]  += tmp_imag;
             }
         }
         exchanges <<= 1;
         factfact >>= 1;
     }
 }

 void Spectrum::outputFFT(const float * re, const float * im) {
     const float *realptr   = re;
     const float *imagptr   = im;
     float       *outputptr = output;

     float *endptr    = output + BUFFER_SIZE / 2;

     /* Convert FFT to intensities */

     while(outputptr <= endptr) {
         *outputptr = (*realptr * *realptr) + (*imagptr * *imagptr);
         outputptr++; realptr++; imagptr++;
     }
     *output /= 4;
     *endptr /= 4;
 }

 RenderArea::RenderArea(QWidget *parent)
     : QWidget(parent)
 {
     setBackgroundRole(QPalette::Base);
     setAutoFillBackground(true);

     samples = 0;
     sampleSize = 0;
     setMinimumHeight(30);
     setMinimumWidth(200);
 }

 void RenderArea::paintEvent(QPaintEvent * /* event */)
 {
     QPainter painter(this);

     if(sampleSize == 0)
         return;

     painter.setPen(Qt::red);
     int max = 0;
     for(int i=0;i<sampleSize;i++) {
         int m = (int)(sqrt(samples[i])/32768);
         if(m > max)
             max = m;
     }
     int x1,y1,x2,y2;

     for(int i=0;i<10;i++) {
         x1 = painter.viewport().left()+11;
         y1 = painter.viewport().top()+10+i;
         x2 = painter.viewport().right()-20-max;
         y2 = painter.viewport().top()+10+i;
         if(x2 < painter.viewport().left()+10)
             x2 = painter.viewport().left()+10;

         painter.drawLine(QPoint(x1,y1),QPoint(x2,y2));
     }

     painter.setPen(Qt::black);
     painter.drawRect(QRect(painter.viewport().left()+10, painter.viewport().top()+10,
                 painter.viewport().right()-20, painter.viewport().bottom()-20));
 }

 void RenderArea::spectrum(float* output, int size)
 {
     samples = output;
     sampleSize = size;
     repaint();
 }

 InputTest::InputTest()
 {
     QWidget *window = new QWidget;
     QVBoxLayout* layout = new QVBoxLayout;

     canvas = new RenderArea;
     layout->addWidget(canvas);

     deviceBox = new QComboBox(this);
     QList<QAudioDeviceId> devices = QAudioDeviceInfo::deviceList(QAudio::AudioInput);
     for(int i = 0; i < devices.size(); ++i) {
         deviceBox->addItem(QAudioDeviceInfo(devices.at(i)).deviceName(), qVariantFromValue(devices.at(i)));
     }
     connect(deviceBox,SIGNAL(activated(int)),SLOT(deviceChanged(int)));
     layout->addWidget(deviceBox);

     button = new QPushButton(this);
     button->setText(tr("Click for Push Mode"));
     connect(button,SIGNAL(clicked()),SLOT(toggleMode()));
     layout->addWidget(button);

     button2 = new QPushButton(this);
     button2->setText(tr("Click To Suspend"));
     connect(button2,SIGNAL(clicked()),SLOT(toggleSuspend()));
     layout->addWidget(button2);

     window->setLayout(layout);
     setCentralWidget(window);
     window->show();

     buffer = new char[BUFFER_SIZE*10];
     output = new float[1024];

     pullMode = true;

     format.setFrequency(8000);
     format.setChannels(1);
     format.setSampleSize(8);
     format.setSampleType(QAudioFormat::UnSignedInt);
     format.setByteOrder(QAudioFormat::LittleEndian);
     format.setCodec("audio/pcm");

     audioInput = new QAudioInput(format,this);
     connect(audioInput,SIGNAL(notify()),SLOT(status()));
     connect(audioInput,SIGNAL(stateChanged(QAudio::State)),SLOT(state(QAudio::State)));
     spec  = new Spectrum(this,audioInput,output);
     connect(spec,SIGNAL(update()),SLOT(refreshDisplay()));
     spec->start();
     audioInput->start(spec);
 }

 InputTest::~InputTest() {}

 void InputTest::status()
 {
     qWarning()<<"bytesReady = "<<audioInput->bytesReady()<<" bytes, clock = "<<audioInput->clock()<<"ms, totalTime = "<<audioInput->totalTime()/1000<<"ms";
 }

 void InputTest::readMore()
 {
     if(!audioInput)
         return;
     qint64 len = audioInput->bytesReady();
     if(len > BUFFER_SIZE*10)
         len = BUFFER_SIZE*10;
     qint64 l = input->read(buffer,len);
     if(l > 0) {
         spec->write(buffer,l);
     }
 }

 void InputTest::toggleMode()
 {
     // Change bewteen pull and push modes
     audioInput->stop();

     if(pullMode) {
         button->setText(tr("Click for Push Mode"));
         input = audioInput->start(0);
         connect(input,SIGNAL(readyRead()),SLOT(readMore()));
         pullMode = false;
     } else {
         button->setText(tr("Click for Pull Mode"));
         pullMode = true;
         audioInput->start(spec);
     }
 }

 void InputTest::toggleSuspend()
 {
     // toggle suspend/resume
     if(audioInput->state() == QAudio::SuspendState) {
         qWarning()<<"status: Suspended, resume()";
         audioInput->resume();
         button2->setText("Click To Suspend");
     } else if (audioInput->state() == QAudio::ActiveState) {
         qWarning()<<"status: Active, suspend()";
         audioInput->suspend();
         button2->setText("Click To Resume");
     } else if (audioInput->state() == QAudio::StopState) {
         qWarning()<<"status: Stopped, resume()";
         audioInput->resume();
         button2->setText("Click To Suspend");
     } else if (audioInput->state() == QAudio::IdleState) {
         qWarning()<<"status: IdleState";
     }
 }

 void InputTest::state(QAudio::State state)
 {
     qWarning()<<" state="<<state;
 }

 void InputTest::refreshDisplay()
 {
     canvas->spectrum(output,256);
     canvas->repaint();
 }

 void InputTest::deviceChanged(int idx)
 {
     spec->stop();
     audioInput->stop();
     audioInput->disconnect(this);
     delete audioInput;

     device = deviceBox->itemData(idx).value<QAudioDeviceId>();
     audioInput = new QAudioInput(device, format, this);
     connect(audioInput,SIGNAL(notify()),SLOT(status()));
     connect(audioInput,SIGNAL(stateChanged(QAudio::State)),SLOT(state(QAudio::State)));
     spec->start();
     audioInput->start(spec);
 }