the system for containing the words which are to be considered obviously as irrelevant whatever will be the tv program for example the common verbs articles conjunctions etc according to this embodiment the current word is searched in that list test 22 common word if the current word is a common one the system increments by one its number of occurrences selects the next word bloc 23 next and returns to the bloc 21 for the new current word if not or if the test 22 is omitted the current word is taken into account bloc 24 storage or updating count in the pre list of words to be processed in order to determine their relevance the pre list contains also the number of occurrences of the stored words if it is the first occurrence of the word in the tv program the current word is added to the pre list if the word is already present in the pre list its number of occurrences is incremented then again in real time for each word the system determines if the current word has to be considered as relevant bloc 25 relevant if yes the scroll line area a 2 is updated to incorporate the current word and eventually suppress another word from the extracted list according to the present invention the relevance of a word is based on the number of occurrences of that word in the tv program the system uses two thresholds between which the number of occurrences is considered as representing a.