Cuts out part of video frame without memory copy. nFeild <= 0->both, nField=1 -> first field, nField=2 -> second field 

Sub MFCut( _
   ByVal _nField As Integer, _
   ByRef _pRect As tagRECT, _
   ByRef _ppFrameRes As IMFFrame _
) 

void MFCut( 
   int _nField,
   ref tagRECT _pRect,
   out IMFFrame _ppFrameRes
)

procedure MFCut( 
    _nField: Integer;
   var  _pRect: tagRECT;
   Out  _ppFrameRes: IMFFrame
); 

void MFCut( 
   int _nField,
   ref tagRECT _pRect,
   [PARAMFLAG::Out] IMFFrame* _ppFrameRes
)