Yeah, the graph option is better, since you can build the graph yourself and guarantee what decoder is being used. I always use either a .m2ts file or .mkv file as my source, and then run that to the desired decoder (CoreAVC for AVC, WMV Decoder DMO for VC-1). Seeking can be unstable with this method though, which is why your DGAVCIndex/DGAVCDecode program is so valuable.