QMediaResource returns no media info

On different video containers and codecs this simple example returns no data.

QMediaResource mr(QUrl::fromLocalFile("test.avi"));
QMediaContent mc(mr);

QMediaPlayer player = new QMediaPlayer(this);
QVideoWidget vw = new QVideoWidget;
player->setVideoOutput(vw);
player->setMedia(mc);
vw->show();
player->play();

qDebug() << mr.resolution() << mr.videoCodec(); //etc. returns nulls or empty strings

http://qt-project.org/forums/viewthread/23022/