VC1 encoder with Windows 7 SDK (Media Foundation)

Hi,

I'd like to develop "vc1 encoder" with Windows 7 SDK.

So, I created an instance of the IMFTransform. And, the input subtype of the instance was set to "MFVideoFormat_I420" (YUV file is used as an input source.).

I also created an instance of the IMFMediaSource. Then, I wish to connect an YUV file(input source) to the instance. but I can connect them. I think IMFMediaSource is created with a compressed input file only.(is it right?)

How does an YUV file use as an input of IMFTransform?

Please help me.