How can I overlay html elements over my DirectShow application?

Question

I'm working with a DirectShow application that exports as a Firefox plugin for video streaming.

To the best of my knowledge, it seems as though the plugin is being rendered on a separate window from the web page. I'd like to edit the application to allow html elements over the plugin much like flash allows with wmode='opaque' or 'transparent'. Another option that would work is to pass mouse events through the application (such as mouse move and mouse down).

I've been reading up on put_MessageDrain and put_Owner, but I'm not sure how to apply these to the application or if they will work.

I'm also aware that iframe shimming may work, but since I have access to the source code of the application I'd like to add the functionality directly rather than use a work around. Is iframe shimming my best option? It seems like the easiest option.

The application currently uses Windowless mode and is always on top of everything else on the web page.

Answer 1

The way video is displayed with DirectShow video renderers, you cannot make it transparent without providing your own video renderer filter, or custom allocator/presenter object for one of the standard video renderers. DirectShow renderers display video with DirectDraw or Direct3D surface which stands alone from hosting window and is not interacting with host in a way supposed to get you combined picture with transparent video and something else as well.

I've been reading up on put_MessageDrain and put_Owner

These are for Windowed mode, you seem to use Windowless which assumes that you are providing a hosting window and rectangle to cover opaquely. Renderless, the third mode VMR-7/9 and EVR offer you is the one where you provide allocator/presenter and override the presentation.

Windows SDK (for some you might need to look for an older version, not the latest) provides with samples: Renderless, VMR9Allocator, EVRPresenter which demo the renderless mode.