sorry for the late reply.
Dynamic VPP output resolution change is supported without needing to call Reset() with the limitation that the dynamically selected resolution must be smaller than the resolution set during VPP initialization. If there is a need to change to greater resolution compared to Init resolution then VPP pipeline must be reinitialized and surfaces reallocated to the new resolution.
The Media SDK manual is somewhat misleading when it comes to describing this usage. We will work to improve the manual to describe this better.
To change to new output resolution at runtime the only thing you have to do is to modify the CropW and CropH values in the output surface Info field (mfxFrameSurface1). This will effectively resize the frame to the new desired resolution.