Abstract: Process models for multimedia computing must allow applications to adapt their pattern of execution as resources become scarce or abundant. As processes adapt, they should be able to express their desired performance in terms of application-defined data units or events. We propose a process model wherein processes execute according to a general rate specification of x process executions every y time units. In addition, a separate parameter is used to specify the desired response time for the completion of each execution. In all cases the real-time performance of a rate-based process is predictable. The model is general enough to encompass or extend many of the existing models proposed for multimedia systems. Our model of rate-based execution is described along with an implementation that detects when processes should adapt their execution rate and minimizes latency in interprocess communication.