Originally Posted by bicker1
Actually, at that point, they're not closed
captions anymore -- they're open captions.
Beat me to it...
Over here we have a couple of different "subtitling" standards.
1. World Systems Teletext in VBI (similar to the analogue closed caption system). These are mainly used on analogue OTA, and are assigned a page number (in the UK usually p888) to select, as Teletext carries other info, like TV listings, news stories, financial news, recipes, airport arrivals etc. These are almost universally closed captions, with the TV optionally decoding / displaying them.
2. World Systems Teletext via packet. These are the same as the above, but carried via packets in an MPEG2 transport stream. They can either be inserted as open captions burned into the video output from a receiver, or transcoded to the VBI for decoding and display by a TV (see 1.), along with other WST services.
3. DVB subtitles. These are bitmap graphics (like DVD subtitles?) rather than character graphics (WST is a 1970s 40x25 or 20x25 character graphcs based system), and are also sent as packet data. They are almost universally burnt in by an external set top box, turning them into open subtitles, or decoded internally in an IDTV.
Almost every set top box or TV either has a "Subtitles" button or menu option to quickly switch them on or off.