Each output component (e.g., laserdisc player or output software component) has a source port associated with each type of the output signal that it can output. For example, an output component may output a video signal in RGB format through one source port and may output audio signal in AES formal through another source port. Each input component (e.g., speaker system or input software component) has a sink port associated with each type of input signal that it can input. For example, an input component may input a signal in RGB format through one sink port. The AV system models each port with a corresponding port object. The AV system has a corresponding primitive source port object for each source port and a corresponding primitive sink port object for each sink port.