The effects of wave front reversal and inversion of the time profile are observed experimentally for a dipolar spin wave pulse (carrier frequency omega(1)) interacting in a yttrium-iron garnet film with a weakly localized nonstationary parametric pumping (carrier frequency omega(p) congruent with 2omega(1)) in a three-wave process with conservation law omega(p) = omega(1)+omega(2), where omega(2) is the carrier frequency of the reversed pulse. Theoretical analysis based on the solution of the system of equations for envelopes of interacting wave packets by means of a Green's function formalism gives a quantitative description of the observed phenomena.