Image Number 9 for United States Patent #7894533.
A transport stream of a compressed video signal is monitored. Information elements extracted from the transport stream prompt the generation of messages which are assigned a predetermined priority dependent upon their pre-determined criticality to integrity of the video signal. The generated messages are queued for analysis by analyzer modules only if their priority exceeds a current value of a variable threshold priority level for the queue. The variable threshold priority level is varied dependent on the current length of the queue. When the threshold level is raised, messages already in the queue having a lower priority than the new threshold priority are discarded from the queue without analysis. Thus a varying proportion of the least important messages are progressively discarded so that the apparatus continuously stabilizes at a maximum proportion of messages that the monitor can handle without overload, while always analyzing messages corresponding to the most critical parameters of the transport stream.