[Interest] QMultimedia crashes or doesn't work on recent linux releases

[maitai]

Hello,

Since Ubuntu 16.04, my qt (qt5.7 official release/QWidget-based) 
application cannot play a sound (no crash, but no sound). The very same 
app works fine with Ubuntu 14.04. I get that kind of messages in the 
console when trying to play a sound (.mp3 file) with QMultimedia:

Warning: "No decoder available for type 'audio/mpeg, mpegversion=(int)1, 
mpegaudioversion=(int)1, layer=(int)3, rate=(int)44100, channels=(int)2, 
parsed=(boolean)true'."

or (depending on the machine)

defaultServiceProvider::requestService(): no service found for - 
"org.qt-project.qt.mediaplayer"

Even worst, I have a user running latest linux Manjaro 64bits who is 
reporting a crash each time a sound is played (i.e. the app works fine 
until it tries to play a sound). It crashes with this message:

  symbol lookup error: (...)/mediaservice/libgstmediaplayer.so: undefined 
symbol: gst_video_connector_get_type

He is also saying that the same app build is running fine on an older 
Manjaro machine.

I ended up for the time being by removing all sounds on all linux 
platforms, which is a bit sad as you can imagine.

I believe it's gstreamer related, but before I start digging, may be 
someone has some clues about that?

Any help welcomed
Philippe Lelong