  In this paper, we investigate Bauer's method for the matrix spectral
factorization of an r-channel matrix product filter which is a halfband
autocorrelation matrix. We regularize the resulting matrix spectral factors by
an averaging approach and by multiplication by a unitary matrix. This leads to
the approximate and exact orthogonal SA4 multiscaling functions. We also find
the corresponding orthogonal multiwavelet functions, based on the QR
decomposition.
