use directshow, question asf to avi, can you help me?

[lyf-ljh]

thank you for reading this email about how change asf to avi!
asf format:mpeg4
asf format:RAW data(uncompress)
RGB24
framerate 30m/s
no sound
not use DIB & Indx
graphedit:asf（raw video 1, wm asf reader)－》Mpeg4s Decoder DMO－》Color Converter－》AVI Mux－》avi(file writer)
program:use SampleGrabber filter replace Color Converter filter,can receive RGB24, not use SampleGrabber and use Color Converter only receive RGB32, now in the program I don't know how to set framerate to 30m/s!!!
I use directshow for write this program , How can I change framerate to 30m/s? can you help me?
I wish you can help me!vexation waiting ............
my msn:lyf-ljh@hotmail.com