audioinput.cpp Example File

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  #include "audioinput.h"

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

  #include <QDateTime>
  #include <QDebug>
  #include <QPainter>
  #include <QVBoxLayout>
  #include <QAudioDeviceInfo>
  #include <QAudioInput>
  #include <qendian.h>

  AudioInfo::AudioInfo(const QAudioFormat &format)
      : m_format(format)
  {
      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;

      case 32:
          switch (m_format.sampleType()) {
          case QAudioFormat::UnSignedInt:
              m_maxAmplitude = 0xffffffff;
              break;
          case QAudioFormat::SignedInt:
              m_maxAmplitude = 0x7fffffff;
              break;
          case QAudioFormat::Float:
              m_maxAmplitude = 0x7fffffff; // Kind of
          default:
              break;
          }
          break;

      default:
          break;
      }
  }

  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.channelCount() * channelBytes;
          Q_ASSERT(len % sampleBytes == 0);
          const int numSamples = len / sampleBytes;

          quint32 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.channelCount(); ++j) {
                  quint32 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));
                  } else if (m_format.sampleSize() == 32 && m_format.sampleType() == QAudioFormat::UnSignedInt) {
                      if (m_format.byteOrder() == QAudioFormat::LittleEndian)
                          value = qFromLittleEndian<quint32>(ptr);
                      else
                          value = qFromBigEndian<quint32>(ptr);
                  } else if (m_format.sampleSize() == 32 && m_format.sampleType() == QAudioFormat::SignedInt) {
                      if (m_format.byteOrder() == QAudioFormat::LittleEndian)
                          value = qAbs(qFromLittleEndian<qint32>(ptr));
                      else
                          value = qAbs(qFromBigEndian<qint32>(ptr));
                  } else if (m_format.sampleSize() == 32 && m_format.sampleType() == QAudioFormat::Float) {
                      value = qAbs(*reinterpret_cast<const float*>(ptr) * 0x7fffffff); // assumes 0-1.0
                  }

                  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);

      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;

      int pos = ((painter.viewport().right()-20)-(painter.viewport().left()+11))*m_level;
      painter.fillRect(painter.viewport().left()+11,
                       painter.viewport().top()+10,
                       pos,
                       painter.viewport().height()-21,
                       Qt::red);
  }

  void RenderArea::setLevel(qreal value)
  {
      m_level = value;
      update();
  }

  InputTest::InputTest()
  {
      initializeWindow();
      initializeAudio(QAudioDeviceInfo::defaultInputDevice());
  }

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

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

      m_deviceBox = new QComboBox(this);
      const QAudioDeviceInfo &defaultDeviceInfo = QAudioDeviceInfo::defaultInputDevice();
      m_deviceBox->addItem(defaultDeviceInfo.deviceName(), qVariantFromValue(defaultDeviceInfo));
      for (auto &deviceInfo: QAudioDeviceInfo::availableDevices(QAudio::AudioInput)) {
          if (deviceInfo != defaultDeviceInfo)
              m_deviceBox->addItem(deviceInfo.deviceName(), qVariantFromValue(deviceInfo));
      }

      connect(m_deviceBox, QOverload<int>::of(&QComboBox::activated), this, &InputTest::deviceChanged);
      layout->addWidget(m_deviceBox);

      m_volumeSlider = new QSlider(Qt::Horizontal, this);
      m_volumeSlider->setRange(0, 100);
      m_volumeSlider->setValue(100);
      connect(m_volumeSlider, &QSlider::valueChanged, this, &InputTest::sliderChanged);
      layout->addWidget(m_volumeSlider);

      m_modeButton = new QPushButton(this);
      connect(m_modeButton, &QPushButton::clicked, this, &InputTest::toggleMode);
      layout->addWidget(m_modeButton);

      m_suspendResumeButton = new QPushButton(this);
      connect(m_suspendResumeButton, &QPushButton::clicked, this, &InputTest::toggleSuspend);
      layout->addWidget(m_suspendResumeButton);

      window->setLayout(layout);

      setCentralWidget(window);
      window->show();
  }

  void InputTest::initializeAudio(const QAudioDeviceInfo &deviceInfo)
  {
      QAudioFormat format;
      format.setSampleRate(8000);
      format.setChannelCount(1);
      format.setSampleSize(16);
      format.setSampleType(QAudioFormat::SignedInt);
      format.setByteOrder(QAudioFormat::LittleEndian);
      format.setCodec("audio/pcm");

      if (!deviceInfo.isFormatSupported(format)) {
          qWarning() << "Default format not supported - trying to use nearest";
          format = deviceInfo.nearestFormat(format);
      }

      m_audioInfo.reset(new AudioInfo(format));
      connect(m_audioInfo.data(), &AudioInfo::update, [this]() {
          m_canvas->setLevel(m_audioInfo->level());
      });

      m_audioInput.reset(new QAudioInput(deviceInfo, format));
      qreal initialVolume = QAudio::convertVolume(m_audioInput->volume(),
                                                  QAudio::LinearVolumeScale,
                                                  QAudio::LogarithmicVolumeScale);
      m_volumeSlider->setValue(qRound(initialVolume * 100));
      m_audioInfo->start();
      toggleMode();
  }

  void InputTest::toggleMode()
  {
      m_audioInput->stop();
      toggleSuspend();

      // Change bewteen pull and push modes
      if (m_pullMode) {
          m_modeButton->setText(tr("Enable push mode"));
          m_audioInput->start(m_audioInfo.data());
      } else {
          m_modeButton->setText(tr("Enable pull mode"));
          auto io = m_audioInput->start();
          connect(io, &QIODevice::readyRead,
              [&, io]() {
                  qint64 len = m_audioInput->bytesReady();
                  const int BufferSize = 4096;
                  if (len > BufferSize)
                      len = BufferSize;

                  QByteArray buffer(len, 0);
                  qint64 l = io->read(buffer.data(), len);
                  if (l > 0)
                      m_audioInfo->write(buffer.constData(), l);
              });
      }

      m_pullMode = !m_pullMode;
  }

  void InputTest::toggleSuspend()
  {
      // toggle suspend/resume
      if (m_audioInput->state() == QAudio::SuspendedState || m_audioInput->state() == QAudio::StoppedState) {
          m_audioInput->resume();
          m_suspendResumeButton->setText(tr("Suspend recording"));
      } else if (m_audioInput->state() == QAudio::ActiveState) {
          m_audioInput->suspend();
          m_suspendResumeButton->setText(tr("Resume recording"));
      } else if (m_audioInput->state() == QAudio::IdleState) {
          // no-op
      }
  }

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

      initializeAudio(m_deviceBox->itemData(index).value<QAudioDeviceInfo>());
  }

  void InputTest::sliderChanged(int value)
  {
      qreal linearVolume = QAudio::convertVolume(value / qreal(100),
                                                 QAudio::LogarithmicVolumeScale,
                                                 QAudio::LinearVolumeScale);

      m_audioInput->setVolume(linearVolume);
  }