Methods and apparatus for processing media signals. In one embodiment, a data processing device processes fixed and variable rate data using a first and second processing unit. The processing comprises real-time processing of audio/video signals by a graphics processing unit (GPU) and/or central processing unit (CPU). The processing units process data efficiently by establishing one processor as always processing variable rate data, and using one or more schemes for determining processor will process fixed rate data. A shared memory enables the processors to communicate with one another in order to determine which will process the fixed rate data. In one scheme for determining which of the processors will process the fixed rate data the second processor need merely be unlocked. In another embodiment, the second processor must be unlocked and immediately available.