Qt Reference Documentation

# 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;
             }
             break;
         case 16:
             switch (m_format.sampleType()) {
             case QAudioFormat::UnSignedInt:
                 m_maxAmplitude = 65535;
                 break;
             case QAudioFormat::SignedInt:
                 m_maxAmplitude = 32767;
                 break;
             default:
                 break;
             }
             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(), QVariant::fromValue(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
         if (m_input != 0) {
             disconnect(m_input, 0, this, 0);
             m_input = 0;
         }

         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();
     }