2. The system recited in claim 1 , wherein the memory stores a predetermined threshold, and wherein the garbled close captioning detector includes a percentage threshold detector that determines the metric as a percentage of data elements having the particular data element characteristic in the closed captioning data as the ratio of the total data element characteristic count to the total data element count, and the alert generator generates the alert when the metric exceeds the predetermined threshold.
2. The system recited in claim 1 , wherein the memory stores a predetermined threshold, and wherein the garbled close captioning detector includes a percentage threshold detector that determines the metric as a percentage of data elements having the particular data element characteristic in the closed captioning data as the ratio of the total data element characteristic count to the total data element count, and the alert generator generates the alert when the metric exceeds the predetermined threshold. 9. The system recited in claim 2 , wherein the predetermined threshold varies depending upon at least one of time of day, day of week, and time of year.