HD closed-captioning
We here at Video Labs www.VideoLabs.net have now added HD closed-captioning to our menu of services.
Standard EIA-608 (EIA = Electronics Industries Association) is the techical name given to the format that we have all come to associate with closed-captioning over the years. You know, those white block letters within a black box.
If you work in television, you may also know that the 608 captioning information is carried in the vetical interval part of the video signal, on line 21 to be exact. (You can see the white line data if you have the ability to underscan the monitor screen.)
But there is no Line 21 in digital television (of which HDTV is part of). Instead, captions are put into a data stream with the digtal signal. And that data set is called EIA-708 captions.
708 captions offer various fonts, letter colors and a range of option for backgrounds among other features. But in reality, today’s 708 captions are basically upconverted 608 captions limited to the 32 characters per line standard of 608.
Now a digital TV user may be able to utilize some of the 708 advantages with that upconverted 608 signal, but as you can imagine, there is a lot more to 708 digital captioning heading our way down the road than exists now.