  In this paper, the problem of providing a complete parametrization of the
minimal spectral factors of a discrete-time rational spectral density is
considered. The desired parametrization, given in terms of the all-pass
divisors of a certain all-pass function, is established in the most general
setting: after several partial results, mostly in the continuous-time case,
this is indeed the first complete parametrization obtained without resorting to
any facilitating assumption. This result provides a positive answer to a
conjecture raised in [Baggio and Ferrante, 2016].
