Req: Info on line 21 cc encoding?

[FredThompson]

Can anyone provide technical details on line 21 data formats? I'm also interested in the British system of encoding CC in broadcasts. Looking for technical details which can be used to decode the data, not overview stuff.

(FWIW, yes, I tried to search "21" is too short a term and gets bounced by the search function, just like "DV" gets bounced. "Line" returns far too many false hits.)

[SAFE_Dives]

I hope I am right in thinking you want to know details of "Closed Captions" on UK broadcasts?

Over here, the equivalent to "Closed Captions" are subtitles and are transmitted in what is called Teletext. I, therefore, suggest that you search for technical details for teletext. To start you off, though, you might want to take a look at this page :

http://teletext.mb21.co.uk/faq.shtml

Especially, near the bottom of the page, under "I'm writing some software to do with teletext, where can I get more specific information?", where there are a couple of pointers to other sites and a links page.

Hope this helps and good luck.:)

[FredThompson]

I'll take a look, thanks. Working on CC and subtitling authoring for DVD. The challenge is we don't seem to have full specs.

[slk001]

McPoodle (do a forum search) has some details on the Line 21 closed captioning format.

[McPoodle]

If I remember correctly, the UK uses closed caption-style formatting on line 22 of the PAL signal (or whichever is the line right before the first displayed line in PAL). This system is especially used on videotapes. Therefore, if you can get the right filters together on GraphEdit, you can extract a binary file containing the captions. I've then got a whole bunch of tools for manipulating this file: convert it into the SCC format that Sonic Scenarist, Spruce DVDMaestro, and Apple DVDStudio Pro use; into a readable format for editing; or into a subtitle format for putting on a non-NTSC DVD. I've got everything documented and available for download at http://www.geocities.com/mcpoodle43/SCC_TOOLS/DOCS/SCC_TOOLS.HTML. The package includes all of my source code (which I suppose would be useful if you're fluent in Perl).