Thanks for the suggestion. However, my understanding is that ffdshow tryouts doesn't have alternative codecs for Windows Media Player 12? If that's the case I could try a different file format like .avi or .mpg. However, I haven't been able to successfully play an .avi or .mpg file using my DirectRT input file. I've tried directly calling .avi files in the input file (rather than a StimList, which doesn't work either) but with no success. Again, the .avi and .mpg files play in WMP12. But they don't appear at all when running the input file. I am using Windows 7 Home Premium - could that be part of the problem?