first of are using the interop library for direct show called directshowlib
?
http://directshownet.sourceforge.net/
I not a direct show expert but we have using direct show in .Net via
(directshowlib) to evaluate hardware recently and we used code similar to
this to create and use a graph builder. I am sure you should be able to find
an example of what you want done in C++ that you can translate into .net
using the directshowlib for .Net.
....
DirectShowLib.IGraphBuilder graphBuilder = (DirectShowLib.IGraphBuilder)new
DirectShowLib.FilterGraph();
DirectShowLib.IBaseFilter filter = (DirectShowLib.IBaseFilter)new
DirectShowLib.VideoMixingRenderer9();
hresult = graphBuilder.AddFilter(filter, "Video Mixing Renderer 9");
DirectShowLib.IVMRMonitorConfig9 vmrMonitorConfig = filter as
DirectShowLib.IVMRMonitorConfig9;
....
....
HTH
Ollie Riches
