By Date: <-- -->
By Thread: <-- -->

VBI Insert with own TTX?

On Wednesday 29 March 2006 18:46, Stefan de Konink wrote:
>Hello,
>
>
>I would like to know if anyone can help me with a) a hardware
>recommendation  or  b) a software solution that allows the insertion
> of TTX data into a video-output using cheap consumer hardware.
>
>So basically I want to implement two features:
>- Program guide (RSS based) TTX/100
>- using teletext/videotext as a linux terminal on a television TTX/899
>
>Normal composite TV-Out should 'just' show a normal X session on
>Composite-output.
>
>Usually this list has a lot about 'decoding' VBI data, but there must
> be ways to encode it/put it on the first few lines as well.

Generally, here in the US & Canada at least, many of the tv stations use 
a gizmo from Norpak to do this.  It was about a $1800 toy 7-8 years ago 
when the commission put us all on notice to do it or else, and when it 
crashes, which it does silently, passing the program video stream 
un-impeded, it has to reboot from a serial eprom, which takes about 22 
minutes because it never works the first 2 or 3 times you reboot it.  
By then, the newscast that generated the viewer call that its not 
working is essentially over since it took the viewer 4 or 5 mnutes to 
call in the first place.  So go see if you can find another device to 
do that if you can.  Thats the one I know about first hand.  I can't 
say as the people are bad, because they aren't, but getting one of them 
back thru customs to get it fixed, and then back thru customs again 
after they've 'fixed' it is a 2 week exersize in frustration with 
beaurocratic don't give a damn attitudes being 100% prevelant.

>So split in parts:
>- Would it be possible to insert it as pixel manipulated line of the
>normal image? (For example to use a OpenGL VSync)
>- If not is the only option to try to find out how different TV
> encoder chips work with VBI?
>- Could the zvbi be used to do the higher level encoding of data?

The so-called teletext standard is, AFAIK, a public standard.  So in 
todays world, I think you could probably put it in a FPGA and some sort 
of an analogue switch to do the mixing.  You'll need to be able to 
synth 2 different frequencies as sine waves, but I don't recall the 
frequencies off the top of my head.  Consult the standard, I believe 
its in the FCC rules & regs, part 73, which is part of the Government 
Printing Offices's 47CFR publication.  I have NDI if there are really 
major diffs between that system and ones used in pal or other tv 
systems.  My experience is of course with Never Twice Same Color only.

>Yours Sincerely,
>
>Stefan de Konink
>
>--
>video4linux-list mailing list
>Unsubscribe
> mailto:video4linux-list-request (at) redhat.com?subject=unsubscribe
> https://www.redhat.com/mailman/listinfo/video4linux-list

-- 
Cheers, Gene
People having trouble with vz bouncing email to me should add the word
'online' between the 'verizon', and the dot which bypasses vz's
stupid bounce rules.  I do use spamassassin too. :-)
Yahoo.com and AOL/TW attorneys please note, additions to the above
message by Gene Heskett are:
Copyright 2006 by Maurice Eugene Heskett, all rights reserved.

--
video4linux-list mailing list
Unsubscribe mailto:video4linux-list-request (at) redhat.com?subject=unsubscribe
https://www.redhat.com/mailman/listinfo/video4linux-list