This article introduces a new technique to minimize the memory footprints of Digital Signal Processing (DSP) applications specified with Synchronous Dataflow (SDF) graphs and implemented on shared-memory Multiprocessor Systems-on-Chips (MPSoCs). In addition to the SDF specification, which captures data dependencies between coarse-grained tasks called actors, the proposed technique relies on two optional inputs abstracting the internal data dependencies of actors: annotations of the ports of actors, and script-based specifications of merging opportunities between input and output buffers of actors. Experimental results on a set of applications show a reduction of the memory footprint by 48% compared to state-of-the-art minimization techniques.