Hello! I am trying to render Direct3D to DirectShow. Basically the opposite of what a lot of people want to do (video in scene) so searching for help is very difficult. I think what I need to do is render/copy a Direct3D surface into a DirectShow video object, via a filter. However, in terms of actually getting anywhere I am utterly stumped. I am not familiar with DirectShow filter/graph stuff at all, so getting my head around this is really challenging. Does anyone have any pointers/links that could get me a bit down the road? It would be greatly appreciated.

Couldn't you achieve the same result by using the same technique as bringing a video into a 3D scene? In your case your video would presumably be a fullscreen backdrop with the 3D element on top.

If that works for you, then I would recommend getting started using VMR9 and a custom allocator presenter. There's an example that should get you going in the standard DirectShow samples. I didn't find it the easiest thing to get my head around, but got there in the end.