dv: better split weight tables assignment

This is a mostly cosmetical patch in preparation for the following.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
dv: use smaller type for weight tables

Reviewed-by: Reimar Döffinger <Reimar.Doeffinger@gmx.de>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>