Monitoring audio-visual content with captions

A system for monitoring audio-visual content which includes a succession of video images and a plurality of caption events, each caption event comprising a plurality of words, each word formed from one or more characters, each caption event being associated with and intended to be co-timed with a respective string of successive images, the system comprising:

• at least first and second fingerprint generators operating in a content delivery chain at respective locations upstream and downstream of defined content manipulation process or processes, each fingerprint generator serving to process a caption event to derive a caption event fingerprint from a length of each word in the caption event, without regard to the identity of the character or characters forming the word;
• and
• a fingerprint processor serving to compare caption event fingerprints from the respective first and second fingerprint generators to identify matching caption events;
• and to measure any caption event error selected from the group consisting of a missing caption event;
• a caption event timing error and a caption discrepancy.

A non-transient computer readable medium containing instructions causing a processor to implement a method of monitoring audio-visual content which includes a succession of video images and a plurality of caption events, each caption event being associated with and intended to be co-timed with a respective string of successive images, the method comprising the steps in at least one processor of:

• processing a caption event to derive a caption event fingerprint;
• searching audio-visual content to identify a caption event matching a defined caption event fingerprint;
• analysing any matching caption event;
• and
• measuring any caption event error, where the measured caption event error is selected from the group consisting of a missing caption event;
• a caption event timing error and a caption discrepancy.