audiorecorder.cpp Example File

multimedia/audiorecorder/audiorecorder.cpp 
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 #include "audiorecorder.h"
 #include "audiolevel.h"

 #include "ui_audiorecorder.h"

 #include <QAudioProbe>
 #include <QAudioRecorder>
 #include <QDir>
 #include <QFileDialog>
 #include <QMediaRecorder>
 #include <QStandardPaths>

 static qreal getPeakValue(const QAudioFormat &format);
 static QVector<qreal> getBufferLevels(const QAudioBuffer &buffer);

 template <class T>
 static QVector<qreal> getBufferLevels(const T *buffer, int frames, int channels);

 AudioRecorder::AudioRecorder()
     : ui(new Ui::AudioRecorder)
 {
     ui->setupUi(this);

     m_audioRecorder = new QAudioRecorder(this);
     m_probe = new QAudioProbe(this);
     connect(m_probe, &QAudioProbe::audioBufferProbed,
             this, &AudioRecorder::processBuffer);
     m_probe->setSource(m_audioRecorder);

     //audio devices
     ui->audioDeviceBox->addItem(tr("Default"), QVariant(QString()));
     for (auto &device: m_audioRecorder->audioInputs()) {
         ui->audioDeviceBox->addItem(device, QVariant(device));
     }

     //audio codecs
     ui->audioCodecBox->addItem(tr("Default"), QVariant(QString()));
     for (auto &codecName: m_audioRecorder->supportedAudioCodecs()) {
         ui->audioCodecBox->addItem(codecName, QVariant(codecName));
     }

     //containers
     ui->containerBox->addItem(tr("Default"), QVariant(QString()));
     for (auto &containerName: m_audioRecorder->supportedContainers()) {
         ui->containerBox->addItem(containerName, QVariant(containerName));
     }

     //sample rate
     ui->sampleRateBox->addItem(tr("Default"), QVariant(0));
     for (int sampleRate: m_audioRecorder->supportedAudioSampleRates()) {
         ui->sampleRateBox->addItem(QString::number(sampleRate), QVariant(
                 sampleRate));
     }

     //channels
     ui->channelsBox->addItem(tr("Default"), QVariant(-1));
     ui->channelsBox->addItem(QStringLiteral("1"), QVariant(1));
     ui->channelsBox->addItem(QStringLiteral("2"), QVariant(2));
     ui->channelsBox->addItem(QStringLiteral("4"), QVariant(4));

     //quality
     ui->qualitySlider->setRange(0, int(QMultimedia::VeryHighQuality));
     ui->qualitySlider->setValue(int(QMultimedia::NormalQuality));

     //bitrates:
     ui->bitrateBox->addItem(tr("Default"), QVariant(0));
     ui->bitrateBox->addItem(QStringLiteral("32000"), QVariant(32000));
     ui->bitrateBox->addItem(QStringLiteral("64000"), QVariant(64000));
     ui->bitrateBox->addItem(QStringLiteral("96000"), QVariant(96000));
     ui->bitrateBox->addItem(QStringLiteral("128000"), QVariant(128000));

     connect(m_audioRecorder, &QAudioRecorder::durationChanged, this, &AudioRecorder::updateProgress);
     connect(m_audioRecorder, &QAudioRecorder::statusChanged, this, &AudioRecorder::updateStatus);
     connect(m_audioRecorder, &QAudioRecorder::stateChanged, this, &AudioRecorder::onStateChanged);
     connect(m_audioRecorder, QOverload<QMediaRecorder::Error>::of(&QAudioRecorder::error), this,
             &AudioRecorder::displayErrorMessage);
 }

 void AudioRecorder::updateProgress(qint64 duration)
 {
     if (m_audioRecorder->error() != QMediaRecorder::NoError || duration < 2000)
         return;

     ui->statusbar->showMessage(tr("Recorded %1 sec").arg(duration / 1000));
 }

 void AudioRecorder::updateStatus(QMediaRecorder::Status status)
 {
     QString statusMessage;

     switch (status) {
     case QMediaRecorder::RecordingStatus:
         statusMessage = tr("Recording to %1").arg(m_audioRecorder->actualLocation().toString());
         break;
     case QMediaRecorder::PausedStatus:
         clearAudioLevels();
         statusMessage = tr("Paused");
         break;
     case QMediaRecorder::UnloadedStatus:
     case QMediaRecorder::LoadedStatus:
         clearAudioLevels();
         statusMessage = tr("Stopped");
     default:
         break;
     }

     if (m_audioRecorder->error() == QMediaRecorder::NoError)
         ui->statusbar->showMessage(statusMessage);
 }

 void AudioRecorder::onStateChanged(QMediaRecorder::State state)
 {
     switch (state) {
     case QMediaRecorder::RecordingState:
         ui->recordButton->setText(tr("Stop"));
         ui->pauseButton->setText(tr("Pause"));
         break;
     case QMediaRecorder::PausedState:
         ui->recordButton->setText(tr("Stop"));
         ui->pauseButton->setText(tr("Resume"));
         break;
     case QMediaRecorder::StoppedState:
         ui->recordButton->setText(tr("Record"));
         ui->pauseButton->setText(tr("Pause"));
         break;
     }

     ui->pauseButton->setEnabled(m_audioRecorder->state() != QMediaRecorder::StoppedState);
 }

 static QVariant boxValue(const QComboBox *box)
 {
     int idx = box->currentIndex();
     if (idx == -1)
         return QVariant();

     return box->itemData(idx);
 }

 void AudioRecorder::toggleRecord()
 {
     if (m_audioRecorder->state() == QMediaRecorder::StoppedState) {
         m_audioRecorder->setAudioInput(boxValue(ui->audioDeviceBox).toString());

         QAudioEncoderSettings settings;
         settings.setCodec(boxValue(ui->audioCodecBox).toString());
         settings.setSampleRate(boxValue(ui->sampleRateBox).toInt());
         settings.setBitRate(boxValue(ui->bitrateBox).toInt());
         settings.setChannelCount(boxValue(ui->channelsBox).toInt());
         settings.setQuality(QMultimedia::EncodingQuality(ui->qualitySlider->value()));
         settings.setEncodingMode(ui->constantQualityRadioButton->isChecked() ?
                                  QMultimedia::ConstantQualityEncoding :
                                  QMultimedia::ConstantBitRateEncoding);

         QString container = boxValue(ui->containerBox).toString();

         m_audioRecorder->setEncodingSettings(settings, QVideoEncoderSettings(), container);
         m_audioRecorder->record();
     }
     else {
         m_audioRecorder->stop();
     }
 }

 void AudioRecorder::togglePause()
 {
     if (m_audioRecorder->state() != QMediaRecorder::PausedState)
         m_audioRecorder->pause();
     else
         m_audioRecorder->record();
 }

 void AudioRecorder::setOutputLocation()
 {
 #ifdef Q_OS_WINRT
     // UWP does not allow to store outside the sandbox
     const QString cacheDir = QStandardPaths::writableLocation(QStandardPaths::CacheLocation);
     if (!QDir().mkpath(cacheDir)) {
         qWarning() << "Failed to create cache directory";
         return;
     }
     QString fileName = cacheDir + QLatin1String("/output.wav");
 #else
     QString fileName = QFileDialog::getSaveFileName();
 #endif
     m_audioRecorder->setOutputLocation(QUrl::fromLocalFile(fileName));
     m_outputLocationSet = true;
 }

 void AudioRecorder::displayErrorMessage()
 {
     ui->statusbar->showMessage(m_audioRecorder->errorString());
 }

 void AudioRecorder::clearAudioLevels()
 {
     for (int i = 0; i < m_audioLevels.size(); ++i)
         m_audioLevels.at(i)->setLevel(0);
 }

 // This function returns the maximum possible sample value for a given audio format
 qreal getPeakValue(const QAudioFormat& format)
 {
     // Note: Only the most common sample formats are supported
     if (!format.isValid())
         return qreal(0);

     if (format.codec() != "audio/pcm")
         return qreal(0);

     switch (format.sampleType()) {
     case QAudioFormat::Unknown:
         break;
     case QAudioFormat::Float:
         if (format.sampleSize() != 32) // other sample formats are not supported
             return qreal(0);
         return qreal(1.00003);
     case QAudioFormat::SignedInt:
         if (format.sampleSize() == 32)
             return qreal(INT_MAX);
         if (format.sampleSize() == 16)
             return qreal(SHRT_MAX);
         if (format.sampleSize() == 8)
             return qreal(CHAR_MAX);
         break;
     case QAudioFormat::UnSignedInt:
         if (format.sampleSize() == 32)
             return qreal(UINT_MAX);
         if (format.sampleSize() == 16)
             return qreal(USHRT_MAX);
         if (format.sampleSize() == 8)
             return qreal(UCHAR_MAX);
         break;
     }

     return qreal(0);
 }

 // returns the audio level for each channel
 QVector<qreal> getBufferLevels(const QAudioBuffer& buffer)
 {
     QVector<qreal> values;

     if (!buffer.format().isValid() || buffer.format().byteOrder() != QAudioFormat::LittleEndian)
         return values;

     if (buffer.format().codec() != "audio/pcm")
         return values;

     int channelCount = buffer.format().channelCount();
     values.fill(0, channelCount);
     qreal peak_value = getPeakValue(buffer.format());
     if (qFuzzyCompare(peak_value, qreal(0)))
         return values;

     switch (buffer.format().sampleType()) {
     case QAudioFormat::Unknown:
     case QAudioFormat::UnSignedInt:
         if (buffer.format().sampleSize() == 32)
             values = getBufferLevels(buffer.constData<quint32>(), buffer.frameCount(), channelCount);
         if (buffer.format().sampleSize() == 16)
             values = getBufferLevels(buffer.constData<quint16>(), buffer.frameCount(), channelCount);
         if (buffer.format().sampleSize() == 8)
             values = getBufferLevels(buffer.constData<quint8>(), buffer.frameCount(), channelCount);
         for (int i = 0; i < values.size(); ++i)
             values[i] = qAbs(values.at(i) - peak_value / 2) / (peak_value / 2);
         break;
     case QAudioFormat::Float:
         if (buffer.format().sampleSize() == 32) {
             values = getBufferLevels(buffer.constData<float>(), buffer.frameCount(), channelCount);
             for (int i = 0; i < values.size(); ++i)
                 values[i] /= peak_value;
         }
         break;
     case QAudioFormat::SignedInt:
         if (buffer.format().sampleSize() == 32)
             values = getBufferLevels(buffer.constData<qint32>(), buffer.frameCount(), channelCount);
         if (buffer.format().sampleSize() == 16)
             values = getBufferLevels(buffer.constData<qint16>(), buffer.frameCount(), channelCount);
         if (buffer.format().sampleSize() == 8)
             values = getBufferLevels(buffer.constData<qint8>(), buffer.frameCount(), channelCount);
         for (int i = 0; i < values.size(); ++i)
             values[i] /= peak_value;
         break;
     }

     return values;
 }

 template <class T>
 QVector<qreal> getBufferLevels(const T *buffer, int frames, int channels)
 {
     QVector<qreal> max_values;
     max_values.fill(0, channels);

     for (int i = 0; i < frames; ++i) {
         for (int j = 0; j < channels; ++j) {
             qreal value = qAbs(qreal(buffer[i * channels + j]));
             if (value > max_values.at(j))
                 max_values.replace(j, value);
         }
     }

     return max_values;
 }

 void AudioRecorder::processBuffer(const QAudioBuffer& buffer)
 {
     if (m_audioLevels.count() != buffer.format().channelCount()) {
         qDeleteAll(m_audioLevels);
         m_audioLevels.clear();
         for (int i = 0; i < buffer.format().channelCount(); ++i) {
             AudioLevel *level = new AudioLevel(ui->centralwidget);
             m_audioLevels.append(level);
             ui->levelsLayout->addWidget(level);
         }
     }

     QVector<qreal> levels = getBufferLevels(buffer);
     for (int i = 0; i < levels.count(); ++i)
         m_audioLevels.at(i)->setLevel(levels.at(i));
 }

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