No volume control of QMediaPlayer after upgrade to Belle FP1

The followimg code, that has worked until now in Belle, doesn't work anymore after upgrading to FP1:

#include <QMediaPlayer>

QMediaPlayer * player = new QMediaPlayer;
player->setMedia(QUrl::fromLocalFile("E:/myWav.wav"));
player->setVolume(10); // <-- it doesn't matter what value is set here. The Device will play at full volume
player->play();