you could try this scriptclip instead:
Code:
scriptclip(f,""" x= freezeframe(current_frame -1,current_frame -1,first -1)
y= x.freezeframe(current_frame,current_frame,first + qty)
d= y.DePanEstimate(improve=true,zoommax=1.4)
offs= 1. / ( qty + 1.) * (current_frame - first + 1.)
DePan(x, data=d, offset=offs,info=true)
subtitle (" current_frame="+string(current_frame)+
\ " first="+string(first)+
\ " offset="+string(offs),
\ " qty="+string(qty),y=200)
""",after_frame=true)