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audioinput.cpp Example File
multimedia/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"

 #define BUFFER_SIZE 4096

 AudioInfo::AudioInfo(QObject* parent, QAudioInput* device)
     :QIODevice( parent )
 {
     input = device;

     m_maxValue = 0;
 }

 AudioInfo::~AudioInfo()
 {
 }

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

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

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

     return 0;
 }

 qint64 AudioInfo::writeData(const char *data, qint64 len)
 {
     int samples = len/2; // 2 bytes per sample
     int maxAmp = 32768; // max for S16 samples
     bool clipping = false;

     m_maxValue = 0;

     qint16* s = (qint16*)data;

     // sample format is S16LE, only!

     for(int i=0;i<samples;i++) {
         qint16 sample = *s;
         s++;
         if(abs(sample) > m_maxValue) m_maxValue = abs(sample);
     }
     // check for clipping
     if(m_maxValue>=(maxAmp-1)) clipping = true;

     float value = ((float)m_maxValue/(float)maxAmp);
     if(clipping) m_maxValue = 100;
     else m_maxValue = (int)(value*100);

     emit update();

     return len;
 }

 int AudioInfo::LinearMax()
 {
     return m_maxValue;
 }

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

     level = 0;
     setMinimumHeight(30);
     setMinimumWidth(200);
 }

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

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

     if(level == 0)
         return;

     painter.setPen(Qt::red);

     int pos = ((painter.viewport().right()-20)-(painter.viewport().left()+11))*level/100;
     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().left()+20+pos;
         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));
     }
 }

 void RenderArea::setLevel(int value)
 {
     level = value;
     repaint();
 }

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

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

     deviceBox = new QComboBox(this);
     QList<QAudioDeviceInfo> devices = QAudioDeviceInfo::availableDevices(QAudio::AudioInput);
     for(int i = 0; i < devices.size(); ++i) {
         deviceBox->addItem(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];

     pullMode = true;

     // AudioInfo class only supports mono S16LE samples!
     format.setFrequency(8000);
     format.setChannels(1);
     format.setSampleSize(16);
     format.setSampleType(QAudioFormat::SignedInt);
     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)));
     audioinfo  = new AudioInfo(this,audioInput);
     connect(audioinfo,SIGNAL(update()),SLOT(refreshDisplay()));
     audioinfo->start();
     audioInput->start(audioinfo);
 }

 InputTest::~InputTest() {}

 void InputTest::status()
 {
     qWarning()<<"bytesReady = "<<audioInput->bytesReady()<<" bytes, elapsedUSecs = "<<audioInput->elapsedUSecs()<<", processedUSecs = "<<audioInput->processedUSecs();
 }

 void InputTest::readMore()
 {
     if(!audioInput)
         return;
     qint64 len = audioInput->bytesReady();
     if(len > 4096)
         len = 4096;
     qint64 l = input->read(buffer,len);
     if(l > 0) {
         audioinfo->write(buffer,l);
     }
 }

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

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

 void InputTest::toggleSuspend()
 {
     // toggle suspend/resume
     if(audioInput->state() == QAudio::SuspendedState) {
         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::StoppedState) {
         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->setLevel(audioinfo->LinearMax());
     canvas->repaint();
 }

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

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