VMD D3D DirectDraw support in Display Driver


I have developed a Virtual Display Driver, which acts as and extended
display. As far as normal driver operations are concerned everything
works perfectly. I have also added DirectDraw overlay support. My driver
only supports Destination color key.

The way I handle the overlay is that I capture the overlay in the
application, convert it from YUV422 to RGB and paste it over the main
video memory where the destination color key value is present which is
the window of the player (media player or winDVD etc). The problem is
that on some systems this does not work and the screen of the media
player or divx player is blank. It seems that no rendering is being on
the overlay suface. Could it be that the player is using some
capabilities that my driver does not support. i.e it is using bob
interleaved or some other capability that the primary driver supports
and my driver does not support.

Also there are some application that use VMR. I have read that VMR uses
D3D. My driver does not support D3D as well. What would be a good source
to learn how I can add support of D3D in the driver. Again as it is a
virtual display driver so there is no hardware and I have to emulate
things in software in order to add that support. I want to get some
understanding of this whole VMR, D3D, Display Driver architecture and

Any help would be highly appreciated