maybe this function:
Code:
function reducetoyv12(clip x)
{
u=x.utoy().separatefields().separatefields().selecteven().converttoyv12().weave()
v=x.vtoy().separatefields().separatefields().selecteven().converttoyv12().weave()
x=x.converttoyv12()
ytouv(u,v)
x.mergechroma(last)
}
avisource("dv.avi")
reducetoyv12()
kerneldeint(order=0,sharp=true)
removegrain(mode=2)
is good for your purposes.
the funmction reducetoyv12 reduces the YUY2 chroma to YV12 chroma using pointsampling insted of weighted blending, like converttoyv12(interlaced=true) would do.