void AudioDemo::playAudio() {
  qDebug("Play %s", qPrintable(m_fileName));
  auto player = new QMediaPlayer;
  auto audioOutput = new QAudioOutput;
  player->setAudioOutput(audioOutput);
  player->setSource(QUrl::fromLocalFile(m_fileName));
  audioOutput->setVolume(50);
  connect(player, &QMediaPlayer::mediaStatusChanged, this,
          [this](QMediaPlayer::MediaStatus status) {
    if (status == QMediaPlayer::EndOfMedia) emit finished();
  });
  connect(player, &QMediaPlayer::positionChanged, this, [](qint64 pos) {
    qDebug("position: %lld", pos);
  });
  player->play();
}

class AudioDemo : public QObject {
  Q_OBJECT
public:
  explicit AudioDemo(const QString& fileName, QObject* parent = nullptr)
    : QObject(parent), m_fileName(fileName) {}
public slots:
  void playAudio();
signals:
  void finished();
private:
  QString m_fileName;
};

int main(int argc, char *argv[]) {
  QCoreApplication a(argc, argv);
  AudioDemo demo(argc > 1 ? argv[1] : "/some/path/to/file.mp3");
  QObject::connect(&demo, &AudioDemo::finished,
    &a, QCoreApplication::quit);
  QTimer::singleShot(0, &demo, &AudioDemo::playAudio);
  return a.exec();
}