This paper presents an approach for the safe design of data-intensive embedded systems. A multimedia application module of last generation cellular phones is considered as a case study. The OMG standard profile MARTE is used to adequately model the application. The resulting model is then transformed into a synchronous program from which a controller is synthesized by using a formal technique, in order to enforce the safe behavior of the modeled application while meeting quality of service requirements. The whole study is carried out in a design framework, GASPARD, dedicated to high-performance embedded systems.