1. A method of processing an interactive service at a receiver, the method comprising: receiving uncompressed audio content or uncompressed video content from an external decoding unit; extracting identifiers of frames from the received content periodically; submitting requests containing the identifiers; and receiving a trigger for the content when a new segment is detected or when an event activation needs to be communicated to the receiver, wherein the trigger indicates the current time of the content and references a particular interactive event in an application parameter table or signals that the event is to be executed now or at a specified future time, wherein the application parameter table includes information about at least one application.