function movefield(clip c, int field, int x, int y) {
   separatefields(c)
   a=selectodd()
   b=selecteven()
   d = (field==0) ? a : b
   d= (x>0) ? crop(d,0,0,-x,0).addborders(x,0,0,0) : crop(d,-x,0,0,0).addborders(0,0,-x,0)
   d= (y>0) ? crop(d,0,y,0,0).addborders(0,0,0,y)  : crop(d,0,0,0,y).addborders(0,-y,0,0)
   d = (field==0) ? interleave(d,b) : interleave(a,d)
   d=weave(d)
   return d
}