QAudioprobe setSource returns false

[Mich64]

Hi,

I'm trying to use the QAudioProbe like this:

@
header file:
private:
QMediaPlayer *player;

cpp file:
player = new QMediaPlayer;
QAudioProbe *probe = new QAudioProbe;
qDebug() << probe->setSource(player);
@

But the probe always returns false. I'm using WinXp and/or Win7 (64bit) with Qt 5.0.2 for MinGW.

The documentation is very vague what the "false" means. What is the cause of the not working QAudioProbe? Is it a missing plugin or something?
I'm using MinGW for because the QMediaplayer does not work on Qt/VS2010 on winXP due to some directshow plugin missing. I tried to compile that but there are bugs in the sources. QMediaplayer works fine in MinGW configuration, but I wish QAudioprobe would work too.
Interesting fact is that QAudioprobe |does| work together with QAudiorecorder. So the problem must be somewhere in the QMediaplayer plugin (which claims to support the QAudioProbe class).