The paper presents a model for multi-mode realtime applications and develops new techniques for the compositional analysis of systems that contain multiple such applications. An algorithm for constructing an interface for a single multimode application is presented. Then, a method for computing an interface of a composite application is presented, which uses only the interfaces of constituent applications. A case study of an adaptive streaming system demonstrates that multi-mode analysis offers more precise results compared to a unimodal worst-case analysis.