Created attachment 297874 [details]
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There is a massive leak happening from calling d3d_init_swap_chains multiple times in some situations. Real life example:
1. pipeline is set to PLAYING
2. window handle is set on "prepare-window-handle", d3d_init_swap_chains is called the first time in consequence
3. set_caps is called, d3d_init_swap_chains is called the second time - at least sink->d3d.swapchain is lost. This later leads to massive resource leaks when going to NULL.

I'm attaching a gdb log showing the above and a basic patch that frees existing swap chain first - this fixes the major leak here, but perhaps d3d_init_swap_chains shouldn't be called multiple times like this in the first place.

It might as well fix some other d3dvideosink bugs related to memory leaks.

Note: all credits go to Roman Nowicki, I'm only upstreaming it.