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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 <QtCore/qendian.h>

 #include "audioinput.h"

 const QString InputTest::PushModeLabel(tr("Enable push mode"));
 const QString InputTest::PullModeLabel(tr("Enable pull mode"));
 const QString InputTest::SuspendLabel(tr("Suspend recording"));
 const QString InputTest::ResumeLabel(tr("Resume recording"));

 const int BufferSize = 4096;

 AudioInfo::AudioInfo(const QAudioFormat &format, QObject *parent)
     :   QIODevice(parent)
     ,   m_format(format)
     ,   m_maxAmplitude(0)
     ,   m_level(0.0)

 {
     switch (m_format.sampleSize()) {
     case 8:
         switch (m_format.sampleType()) {
         case QAudioFormat::UnSignedInt:
             m_maxAmplitude = 255;
             break;
         case QAudioFormat::SignedInt:
             m_maxAmplitude = 127;
             break;
         default: ;
         }
         break;
     case 16:
         switch (m_format.sampleType()) {
         case QAudioFormat::UnSignedInt:
             m_maxAmplitude = 65535;
             break;
         case QAudioFormat::SignedInt:
             m_maxAmplitude = 32767;
             break;
         default: ;
         }
         break;
     }
 }

 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)
 {
     if (m_maxAmplitude) {
         Q_ASSERT(m_format.sampleSize() % 8 == 0);
         const int channelBytes = m_format.sampleSize() / 8;
         const int sampleBytes = m_format.channels() * channelBytes;
         Q_ASSERT(len % sampleBytes == 0);
         const int numSamples = len / sampleBytes;

         quint16 maxValue = 0;
         const unsigned char *ptr = reinterpret_cast<const unsigned char *>(data);

         for (int i = 0; i < numSamples; ++i) {
             for(int j = 0; j < m_format.channels(); ++j) {
                 quint16 value = 0;

                 if (m_format.sampleSize() == 8 && m_format.sampleType() == QAudioFormat::UnSignedInt) {
                     value = *reinterpret_cast<const quint8*>(ptr);
                 } else if (m_format.sampleSize() == 8 && m_format.sampleType() == QAudioFormat::SignedInt) {
                     value = qAbs(*reinterpret_cast<const qint8*>(ptr));
                 } else if (m_format.sampleSize() == 16 && m_format.sampleType() == QAudioFormat::UnSignedInt) {
                     if (m_format.byteOrder() == QAudioFormat::LittleEndian)
                         value = qFromLittleEndian<quint16>(ptr);
                     else
                         value = qFromBigEndian<quint16>(ptr);
                 } else if (m_format.sampleSize() == 16 && m_format.sampleType() == QAudioFormat::SignedInt) {
                     if (m_format.byteOrder() == QAudioFormat::LittleEndian)
                         value = qAbs(qFromLittleEndian<qint16>(ptr));
                     else
                         value = qAbs(qFromBigEndian<qint16>(ptr));
                 }

                 maxValue = qMax(value, maxValue);
                 ptr += channelBytes;
             }
         }

         maxValue = qMin(maxValue, m_maxAmplitude);
         m_level = qreal(maxValue) / m_maxAmplitude;
     }

     emit update();
     return len;
 }

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

     m_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 (m_level == 0.0)
         return;

     painter.setPen(Qt::red);

     int pos = ((painter.viewport().right()-20)-(painter.viewport().left()+11))*m_level;
     for (int i = 0; i < 10; ++i) {
         int x1 = painter.viewport().left()+11;
         int y1 = painter.viewport().top()+10+i;
         int x2 = painter.viewport().left()+20+pos;
         int 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(qreal value)
 {
     m_level = value;
     repaint();
 }

 InputTest::InputTest()
     :   m_canvas(0)
     ,   m_modeButton(0)
     ,   m_suspendResumeButton(0)
     ,   m_deviceBox(0)
     ,   m_device(QAudioDeviceInfo::defaultInputDevice())
     ,   m_audioInfo(0)
     ,   m_audioInput(0)
     ,   m_input(0)
     ,   m_pullMode(false)
     ,   m_buffer(BufferSize, 0)
 {
     initializeWindow();
     initializeAudio();
 }

 InputTest::~InputTest() {}

 void InputTest::initializeWindow()
 {
     QScopedPointer<QWidget> window(new QWidget);
     QScopedPointer<QVBoxLayout> layout(new QVBoxLayout);

     m_canvas = new RenderArea(this);
     layout->addWidget(m_canvas);

     m_deviceBox = new QComboBox(this);
     QList<QAudioDeviceInfo> devices = QAudioDeviceInfo::availableDevices(QAudio::AudioInput);
     for(int i = 0; i < devices.size(); ++i)
         m_deviceBox->addItem(devices.at(i).deviceName(), qVariantFromValue(devices.at(i)));

     connect(m_deviceBox, SIGNAL(activated(int)), SLOT(deviceChanged(int)));
     layout->addWidget(m_deviceBox);

     m_modeButton = new QPushButton(this);
     m_modeButton->setText(PushModeLabel);
     connect(m_modeButton, SIGNAL(clicked()), SLOT(toggleMode()));
     layout->addWidget(m_modeButton);

     m_suspendResumeButton = new QPushButton(this);
     m_suspendResumeButton->setText(SuspendLabel);
     connect(m_suspendResumeButton, SIGNAL(clicked()), SLOT(toggleSuspend()));
     layout->addWidget(m_suspendResumeButton);

     window->setLayout(layout.data());
     layout.take(); // ownership transferred

     setCentralWidget(window.data());
     QWidget *const windowPtr = window.take(); // ownership transferred
     windowPtr->show();
 }

 void InputTest::initializeAudio()
 {
     m_pullMode = true;

     m_format.setFrequency(8000);
     m_format.setChannels(1);
     m_format.setSampleSize(16);
     m_format.setSampleType(QAudioFormat::SignedInt);
     m_format.setByteOrder(QAudioFormat::LittleEndian);
     m_format.setCodec("audio/pcm");

     QAudioDeviceInfo info(QAudioDeviceInfo::defaultInputDevice());
     if (!info.isFormatSupported(m_format)) {
         qWarning() << "Default format not supported - trying to use nearest";
         m_format = info.nearestFormat(m_format);
     }

     m_audioInfo  = new AudioInfo(m_format, this);
     connect(m_audioInfo, SIGNAL(update()), SLOT(refreshDisplay()));

     createAudioInput();
 }

 void InputTest::createAudioInput()
 {
     m_audioInput = new QAudioInput(m_device, m_format, this);
     connect(m_audioInput, SIGNAL(notify()), SLOT(notified()));
     connect(m_audioInput, SIGNAL(stateChanged(QAudio::State)), SLOT(stateChanged(QAudio::State)));
     m_audioInfo->start();
     m_audioInput->start(m_audioInfo);
 }

 void InputTest::notified()
 {
     qWarning() << "bytesReady = " << m_audioInput->bytesReady()
                << ", " << "elapsedUSecs = " <<m_audioInput->elapsedUSecs()
                << ", " << "processedUSecs = "<<m_audioInput->processedUSecs();
 }

 void InputTest::readMore()
 {
     if(!m_audioInput)
         return;
     qint64 len = m_audioInput->bytesReady();
     if(len > 4096)
         len = 4096;
     qint64 l = m_input->read(m_buffer.data(), len);
     if(l > 0) {
         m_audioInfo->write(m_buffer.constData(), l);
     }
 }

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

     if (m_pullMode) {
         m_modeButton->setText(PullModeLabel);
         m_input = m_audioInput->start();
         connect(m_input, SIGNAL(readyRead()), SLOT(readMore()));
         m_pullMode = false;
     } else {
         m_modeButton->setText(PushModeLabel);
         m_pullMode = true;
         m_audioInput->start(m_audioInfo);
     }

     m_suspendResumeButton->setText(SuspendLabel);
 }

 void InputTest::toggleSuspend()
 {
     // toggle suspend/resume
     if(m_audioInput->state() == QAudio::SuspendedState) {
         qWarning() << "status: Suspended, resume()";
         m_audioInput->resume();
         m_suspendResumeButton->setText(SuspendLabel);
     } else if (m_audioInput->state() == QAudio::ActiveState) {
         qWarning() << "status: Active, suspend()";
         m_audioInput->suspend();
         m_suspendResumeButton->setText(ResumeLabel);
     } else if (m_audioInput->state() == QAudio::StoppedState) {
         qWarning() << "status: Stopped, resume()";
         m_audioInput->resume();
         m_suspendResumeButton->setText(SuspendLabel);
     } else if (m_audioInput->state() == QAudio::IdleState) {
         qWarning() << "status: IdleState";
     }
 }

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

 void InputTest::refreshDisplay()
 {
     m_canvas->setLevel(m_audioInfo->level());
     m_canvas->repaint();
 }

 void InputTest::deviceChanged(int index)
 {
     m_audioInfo->stop();
     m_audioInput->stop();
     m_audioInput->disconnect(this);
     delete m_audioInput;

     m_device = m_deviceBox->itemData(index).value<QAudioDeviceInfo>();
     createAudioInput();
 }


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Qt 4.6.3