I'm looking to make my own VCDs with closed captions (*not* subtitles), but I can't find any documentation on what format the closed caption file (EXT/CAPTnn.DAT) should be in. I figure if I get my hands on a VCD with closed captions, I'll be able to figure out how it's done. Does anyone know of a vendor that sells NTSC VCDs with closed captioning? For that matter, if anyone out there owns a VCD with closed captions and has the webspace to spare, could you please put your EXT/CAPT01.DAT file online and provide the link? I promise I'll return the favor by posting a detailed guide to added closed captions to (S)VCDs (assuming I can figure it out).

--McPoodle

-- McPoodle (mcpoodle@sonic.net), June 27, 2003

Answers

I'm sorry, but I don't believe that VCD support closed captions. VCD only supports non-selectable subtitles, which means that they are part of the video image and can not be turned on and off - they are always on, just like if you watch a video tape with subtitles. http://www.vcdimager.org has some docs on VCD format if you REALLY want to get into this subject. You should be able to verify that the format does not support closed captions from reading these docs, which give a VERY detailed description of what VCD format supports.

-- Root (root@yahoo.moc), June 27, 2003.

There is a distinction between closed-captions (or teletext) and subtitles. Long before DVD and SVCD captions have been there for NTSC, for example. This is in the form of digital data (with its own specs, etc. u can find out more about this) put on one of the lines without picture info (line 21 or 22 on the odd field and its counterpart on the even field). A closed-caption decoder (in the TV or VCD) will detect this data and superimpose it on the video for display as the viewer chooses. The VCD format only has a single unique field which is repeated twice for display (as opposed to two uniquely different fields in all other types of video storage and transmission formats) negating the possibility at once of using close- caption for it. Subtitles, on the other hand, at least as used in DVD and SVCD, are themselves digitized subpictures stored as distinct streams interleaved with the main video and audio streams in an MPEG program stream. A viewer can choose which subpicture (hence what subtitle) to display on the player controls. Subtitling is only one of the applications possible with using the subpicture structure MPEG- 2 program streams are allowed to have. I haven't come across a deliberately closed-caption DVD (as opposed to subtitled) and that is most likely because 1st a DVD player will value only the active picture lines (480 out of 525) and display that, and 2nd subtitling is just so much more, well, jazzy. So, dear, since the MPEG-1 program stream in VCD just allows two streams (audio and video) that's as far is it gets. :(

-- Mehmet Tekdemir (turk690@yahoo.com), June 28, 2003.