camera tracking. how do i render video background

Doing a bit of camera tracking with cycles.
how do i composite to render the video background as well as my object, in blender render i used render layers and movie clip nodes going through a alpha over node into a composite which worked fine,

but doesnt in cycles.

can it even be done in cycles?

First guess is that you need to check Film->Transparent in the Render panels in the Cycles scene. If it’s not that you’ll need to provide more info as screenshots or the .blend.

i get really fustrated with blender at times,
one simple click after hours of messing around with nodes and trying to use the movie as a background image even textures all sorts of ways.

thanks for help (he says sheepishly :o )

i would recommend checking out andrew prices tutorial here

The thing is, Andrew’s tutorial is for Blender Internal, the rendering stage is different for Cycles.

i got it working fine in blender internal. new to cycles thats my problem