Patent ID: 7894533

Claim:
A method of monitoring a transport stream of a compressed video signal comprising the steps of: extracting an information element from the transport stream; generating a message of a predetermined type dependent on the extracted information element; assigning a priority to the message, the priority being dependent on a predetermined criticality of the predetermined type to the integrity of the compressed video signal; adding the message to a message queue if the priority of the message exceeds a variable threshold priority level; adjusting the variable threshold priority level in dependence upon whether a size of the message queue is within a predetermined range to obtain an adjusted variable threshold priority level, discarding messages in the message queue having a priority less than the adjusted variable threshold priority level; analyzing a next message from the message queue according to the predetermined type of the next message; wherein the adjusting step comprises the steps of: increasing the variable threshold priority level to a higher level as the adjusted variable threshold priority level if a size of the message queue exceeds a predetermined maximum size; discarding the messages in the message queue having a priority less than the adjusted variable threshold priority level; otherwise reducing the variable threshold priority level to a lower level as the adjusted variable threshold priority level if the size of the message queue is less than a predetermined minimum size; whereing the reducing step comprises the steps of: determining an elapsed time since the level of the variable threshold priority level was last changed; and reducing the level of the variable threshold priority level as the adjusted variable threshold priority level if the elapsed time exceeds a predetermined hysteresis time.