1. A method of processing an interactive service at a receiver, the method comprising: receiving an uncompressed audio content or an uncompressed video content from an external decoding unit; generating signatures of frames of the received content periodically; sending requests containing the signatures of the frames to an ACR (Auto Content Recognition) server to identify the uncompressed content currently being viewed, wherein the frames represented by the signatures are identified by the ACR server by being checked against a database of signatures of frames; and receiving triggers for the content from the ACR server, wherein the types of the triggers are decided by the ACR server based on the frames represented by the signatures, wherein the trigger indicates the current time of the content, or references a particular interactive event in an application parameter table and signals that the event is to be executed now or at a specified future time, wherein the application parameter table includes at least one of application elements having information about applications, wherein each of the application elements include first identifiers identifying each of the applications, wherein each of the application elements include at least one of event elements having information about the events, wherein each of the event elements include second identifiers identifying each of the events, wherein each of the event elements include at least one of data elements having information about data to be used for the corresponding event, wherein each of the data elements include third identifiers identifying each of the data, wherein the trigger is an activation trigger when an activation for one of the events is due to take place, wherein the activation trigger sets an activation time for the one of the events, wherein the activation time is indicated by a timing value term in the activation trigger, relative to a time of a segment, wherein the activation trigger includes an application term, an event term, and a data term, wherein the application term matches the first identifier to identify the application that the activation is targeting, wherein the event term matches the second identifier to identify the event that the activation is targeting, and wherein the data term matches the third identifier to identify the data to be used for the event that the activation is targeting.