Ptterb can you post your full code please? I copied your code. Added fvidscale_cap to pipeline, with: self.player.add(self.source, self.scaler, self.fvidscale_cap, self.sink) gst.element_link_many(self.source,self.scaler, self.fvidscale_cap, self.sink) From the main program I create a new QWidget, and pass its winId() to Vid constructor. The widget start loading, but crashes. The output says: should be playing Segmentation fault