[mythtv] Bug Reports

[Jay R. Ashworth]

On Fri, May 09, 2003 at 04:04:26PM -0400, Chris Pinkham wrote:
> > I *can* find you some specs on the stuff that lives down there, though,
> > if that's what you need.
> 
> Any specs or information would be great.  I've been trying to learn by
> looking at the CC code in Myth and TVtime's as well as doing some
> google searching.

Ok, will look around.

Roughly, you can figure it as "binary code alternating between black
and white, on a specific line of the VBI".  The coding patterns, which
are, I think, usually Reed or Manning codes, look a lot like barcodes.

Different services get different lines:

	Closed captioning, of course, is on line 21, specified by
	EIA-608.  You'll probably find the following links useful:

	http://www.hynixmcu.com/download/app_note/eia608_application_note.pdf
	http://www.cpcweb.com/TechSupport/CapMaker/TroubleShootingandTips-General-Caption.pdf

	and particularly

	http://www.robson.org/gary/writing/nv-line21.html

	There's a new technology to put IFB (Interruptable FoldBack)
	audio on a VBI line, which I'll be *wildly* interested in
	seeing someone decode; it has 8 subchannels, and can be tuned
	to any line from 10 to 25, so some signature detection would
	likely be necessary (I envision this as some sort of menu you
	could pop up that shows all the VBI signals present on a
	show... and I wonder if there's anyway to get the VBI data
	*saved* into the resultant record files so you can deal with it
	*later*).

	http://www.ultechvideo.com/avbi.html

	There's teletext, but it doesn't seem to be standardized.

	And there's a whole bunch of interesting looking stuff here:

	http://www.atsc.org/guide_default.html

	and, notably, here:

	http://www.atsc.org/document_map/time_code.htm
	
and don't forget to check out RFC 2278.

I can't code, but I can research like a mother...

Cheers,
-- jra
-- 
Jay R. Ashworth                                                jra at baylink.com
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