In order to efficiently implement an MP3 decoder, as presented in our project, choosing an adequate specification and code generation tool, is of great importance. The MP3 decoding algorithm requires periodic updates of parameters and dynamic functional block behavior. Given this, the Ptolemy-based PeaCE programming environment seems to be a good choice. Using the SPDF domain, PeaCE modifies the original Ptolemy SDF semantics, adding support for global states, without side-effects. In this work, and through the use of an example, we analyze and demonstrate the usefulness of PeaCE in describing signal processing systems that require periodic updates of states, and the generation of efficient code.