How to reduce the time delay for the function call of "RenderFile()" in DirectShow?

Dear all,
I am writing an application for using Directshow to play video from a playlist. However, when each file is completely broadcasted, it take 1.5 to 2seconds black screen and then load the next video file. I find it is due to the time for the function call of "RenderFile()". Is there any way to reduce this black screen time for the function call of "RenderFile()"? It is extremely urgent!!!!. Please help. Thank you very much.


Paul