audiorecorder.cpp Example File

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 #include <QtCore/qdir.h>
 #include <QtWidgets/qfiledialog.h>

 #include <qaudiorecorder.h>
 #include <qmediarecorder.h>
 #include <qaudioprobe.h>

 #include "audiorecorder.h"

 #if defined(Q_WS_MAEMO_6)
 #include "ui_audiorecorder_small.h"
 #else
 #include "ui_audiorecorder.h"
 #endif

 AudioRecorder::AudioRecorder(QWidget *parent)
     :
     QMainWindow(parent),
     ui(new Ui::AudioRecorder),
     outputLocationSet(false)
 {
     ui->setupUi(this);

     audioRecorder = new QAudioRecorder(this);
     probe = new QAudioProbe;
     connect(probe, SIGNAL(audioBufferProbed(const QAudioBuffer&)), this, SLOT(processBuffer(QAudioBuffer)));
     probe->setSource(audioRecorder);

     //audio devices
     ui->audioDeviceBox->addItem(tr("Default"), QVariant(QString()));
     foreach (const QString &device, audioRecorder->audioInputs()) {
         ui->audioDeviceBox->addItem(device, QVariant(device));
     }

     //audio codecs
     ui->audioCodecBox->addItem(tr("Default"), QVariant(QString()));
     foreach (const QString &codecName, audioRecorder->supportedAudioCodecs()) {
         ui->audioCodecBox->addItem(codecName, QVariant(codecName));
     }

     //containers
     ui->containerBox->addItem(tr("Default"), QVariant(QString()));
     foreach (const QString &containerName, audioRecorder->supportedContainers()) {
         ui->containerBox->addItem(containerName, QVariant(containerName));
     }

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

     ui->qualitySlider->setRange(0, int(QtMultimedia::VeryHighQuality));
     ui->qualitySlider->setValue(int(QtMultimedia::NormalQuality));

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

     connect(audioRecorder, SIGNAL(durationChanged(qint64)), this,
             SLOT(updateProgress(qint64)));
     connect(audioRecorder, SIGNAL(stateChanged(QMediaRecorder::State)), this,
             SLOT(updateState(QMediaRecorder::State)));
     connect(audioRecorder, SIGNAL(error(QMediaRecorder::Error)), this,
             SLOT(displayErrorMessage()));
 }

 AudioRecorder::~AudioRecorder()
 {
     delete audioRecorder;
     delete probe;
 }

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

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

 void AudioRecorder::updateState(QMediaRecorder::State state)
 {
     QString statusMessage;

     switch (state) {
         case QMediaRecorder::RecordingState:
             ui->recordButton->setText(tr("Stop"));
             ui->pauseButton->setText(tr("Pause"));
             if (audioRecorder->outputLocation().isEmpty())
                 statusMessage = tr("Recording");
             else
                 statusMessage = tr("Recording to %1").arg(
                         audioRecorder->outputLocation().toString());
             break;
         case QMediaRecorder::PausedState:
             ui->recordButton->setText(tr("Stop"));
             ui->pauseButton->setText(tr("Resume"));
             statusMessage = tr("Paused");
             break;
         case QMediaRecorder::StoppedState:
             ui->recordButton->setText(tr("Record"));
             ui->pauseButton->setText(tr("Pause"));
             statusMessage = tr("Stopped");
     }

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

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

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

     return box->itemData(idx);
 }

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

         if (!outputLocationSet)
             audioRecorder->setOutputLocation(generateAudioFilePath());

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

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

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

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

 void AudioRecorder::setOutputLocation()
 {
     QString fileName = QFileDialog::getSaveFileName();
     audioRecorder->setOutputLocation(QUrl(fileName));
     outputLocationSet = true;
 }

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

 QUrl AudioRecorder::generateAudioFilePath()
 {
     QDir outputDir(QDir::rootPath());

     int lastImage = 0;
     int fileCount = 0;
     foreach(QString fileName, outputDir.entryList(QStringList() << "testclip_*")) {
         int imgNumber = fileName.mid(5, fileName.size() - 9).toInt();
         lastImage = qMax(lastImage, imgNumber);
         if (outputDir.exists(fileName))
             fileCount += 1;
     }
     lastImage += fileCount;
     QUrl location(QDir::toNativeSeparators(outputDir.canonicalPath() + QString("/testclip_%1").arg(lastImage + 1, 4, 10, QLatin1Char('0'))));
     return location;
 }

 // This function returns the maximum possible sample value for a given audio format
 qreal AudioRecorder::GetPeakValue(const QAudioFormat& format)
 {
     // Note: Only the most common sample formats are supported
     if (!format.isValid())
         return 0.0;

     if (format.codec() != "audio/pcm")
         return 0.0;

     switch (format.sampleType()) {
     case QAudioFormat::Unknown:
         break;
     case QAudioFormat::Float:
         if (format.sampleSize() != 32) // other sample formats are not supported
             return 0.0;
         return 1.00003;
     case QAudioFormat::SignedInt:
         if (format.sampleSize() == 32)
             return 2147483648.0;
         else if (format.sampleSize() == 16)
             return 32768.0;
         else if (format.sampleSize() == 8)
             return 128.0;
         break;
     case QAudioFormat::UnSignedInt:
         // Unsigned formats are not supported in this example
         break;
     }

     return 0.0;
 }

 qreal AudioRecorder::GetBufferLevel(const QAudioBuffer& buffer)
 {
     if (!buffer.format().isValid() || buffer.format().byteOrder() != QAudioFormat::LittleEndian)
         return 0.0;

     if (buffer.format().codec() != "audio/pcm")
         return 0.0;

     qreal peak_value = GetPeakValue(buffer.format());
     if (qFuzzyCompare(peak_value, 0.0))
         return 0.0;

     switch (buffer.format().sampleType()) {
     case QAudioFormat::Unknown:
     case QAudioFormat::UnSignedInt:
         break;
     case QAudioFormat::Float:
         if (buffer.format().sampleSize() == 32)
             return GetBufferLevel(buffer.constData<float>(), buffer.sampleCount()) / peak_value;
         break;
     case QAudioFormat::SignedInt:
         if (buffer.format().sampleSize() == 32)
             return GetBufferLevel(buffer.constData<long int>(), buffer.sampleCount()) / peak_value;
         else if (buffer.format().sampleSize() == 16)
             return GetBufferLevel(buffer.constData<short int>(), buffer.sampleCount()) / peak_value;
         else if (buffer.format().sampleSize() == 8)
             return GetBufferLevel(buffer.constData<signed char>(), buffer.sampleCount()) / peak_value;
         break;
     }

     return 0.0;
 }

 template <class T>
 qreal AudioRecorder::GetBufferLevel(const T* buffer, int samples)
 {
     qreal max_value = 0.0;

     for (int i = 0; i < samples; i++) {
         qreal value = qAbs((qreal)buffer[i]);
         if (value > max_value)
             max_value = value;
     }

     return max_value;
 }

 void AudioRecorder::processBuffer(const QAudioBuffer& buffer)
 {
     qreal level = GetBufferLevel(buffer);
     ui->audioLevel->setLevel(level);
 }