COINIT_MULTITHREADED and mysterious crashes after using OleCreatePropertyFrame

Is there any benefit of using COINIT_MULTITHREADED in a DirectShow application? For now it has given me some troubles, but I am not sure if using CoInitializeEx(NULL, COINIT_APARTMENTTHREADED) is the right fix for the problems.

The full story: I have a pretty straightforward web camera capture application with ability to choose the capture source and call the device manufacturer settings through OleCreatePropertyFrame.

My app runs pretty stable, no memory leaks, I can switch between devices without any problems (I completely rebuild DirectShow graph each time when user chooses device).

But there is only one problem after showing the property page of the capture filter. If I just show it and close without changing anything, all continues normally. If I change any setting in the property pages and then close the property frame, also everything continues seemingly normal .. until the next 开发者_开发问答time I change the device and rebuild the graph. The previous graph gets destroyed normally, no errors, filters are being removed and released correctly. And right when I create a new graph and call graphBuilder->SetFiltergraph( pfg ), my app crashes with some weird access violation errors insde of Kernel32. But if I change COINIT_MULTITHREADED to COINIT_APARTMENTTHREADED, this error disappears.

So is that COINIT_MULTITHREADED a real problem of my application or maybe there is some other monster hiding somwhere? Has someone experince with it?

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Any thread that creates a window must be STA. Both user32 and gdi are fundamentally thread-unsafe.