24 April 2020, 23:07 | #1 |
Registered User
Join Date: May 2017
Location: Munich/Bavaria
Posts: 2,502
|
Is the Amiga capable of Teletext?
Well ok: there are several hardware thingies, that allow decoding of teletext/videotext - that is NOT what I am talking about.
I am wondering if the other way around, producing a teletext signal for the TV, is actually possible, even if I am not aware of any such project or tool .... Here ist a RaspPi doing it (without additional hardware!) [ Show youtube player ] https://github.com/ali1234/raspi-teletext Could a ECS Amiga be tweaked to display something during the phase that would be otherwise "vblank"? Last edited by Gorf; 25 April 2020 at 04:44. |
25 April 2020, 01:05 | #2 |
Registered User
Join Date: Sep 2004
Location: Poland
Posts: 1,306
|
|
25 April 2020, 01:28 | #3 | |
Registered User
Join Date: May 2017
Location: Munich/Bavaria
Posts: 2,502
|
Quote:
And none of these programs do, what I asked for! So your comment is not helpful at all! |
|
25 April 2020, 02:12 | #4 |
Phone Homer
Join Date: Jun 2006
Location: 5150
Posts: 5,887
|
he wants to transmit it to a TV, confusing because the video shows old UK Ceefax
|
25 April 2020, 03:35 | #5 |
Registered User
Join Date: May 2017
Location: Munich/Bavaria
Posts: 2,502
|
|
25 April 2020, 04:16 | #6 |
Registered User
Join Date: Feb 2016
Location: New Forest
Posts: 196
|
My Microtext disk for my adaptor contains a drawer called developer and includes application software that allows software to be written. Such applications to be written in Lattice 'C'. It says that the routines are provided for your own private use only. There is an object file displayrow.o which provides a means of displaying teletext pages on an Amiga screen.
https://www.scuzzscink.com/amiga/scu...ary19_2603.htm You should refer to the 1976 Broadcast Teletext Specification which is published by the BBC. They give a phone number though this is 1988. I do sense that the software and developer tools are designed to work with the adaptor which is the key I guess to providing the data. Dunno. |
25 April 2020, 04:33 | #7 |
Registered User
Join Date: May 2013
Location: Grimstad / Norway
Posts: 877
|
I have this vague memory of one of the DICE games actually having a teletext signal in it? Or am I completely lost here?
|
25 April 2020, 04:40 | #8 | |
Registered User
Join Date: May 2017
Location: Munich/Bavaria
Posts: 2,502
|
Quote:
This adapter is for decoding teletext and showing the results on your Amiga. I was asking for sending out a teletext signal from the Amiga to any TV that is capable of displaying teletext. Yes I am referring to the official teletext standard. The system was called Ceefax in UK, Teletext in France and Videotext in Germany. But all three use the same standard. |
|
25 April 2020, 04:41 | #9 |
Registered User
Join Date: May 2017
Location: Munich/Bavaria
Posts: 2,502
|
|
25 April 2020, 05:55 | #10 |
Registered User
Join Date: Nov 2015
Location: Perth, Australia
Posts: 73
|
In analogue TV, Teletext, and programme guide data, is encoded in the vertical blanking period between frames.
That Raspberry Pi project fiddles with the registers of the video output hardware so that the top of the display buffer is output into the normally blank part of the video signal and then renders the teletext data as a bitmap. It only works with the analogue composite video output, not HDMI. I'm not sure if the Amiga HW can be made to do that. A good place to start is probably the stuff on overscan in the HRM like http://amigadev.elowar.com/read/ADCD.../node006F.html. Like with the RPI, this will probably only work for composite or (urgh) RF TV inputs. A few years ago I was working for a place that was still using broadcast teletext in retail locations but the broadcaster wanted to shut it down. I was on a team that won an in-house hackathon by prototyping a RPI teletext solution based on that github repo. It got picked up as a real project and I spent a couple of weeks with another guy writing a much neater version in C# that could talk to the rest of our systems but that was the end of my involvement. It was a fun bit of work Andrew |
25 April 2020, 06:29 | #11 | |||||
Registered User
Join Date: May 2017
Location: Munich/Bavaria
Posts: 2,502
|
Quote:
Quote:
Quote:
Quote:
Is there an overview what is possible with ECS timings? (OCS won’t work for sure but there are quite some strange settings possible with ECS) Quote:
I did not know that someone still actively uses teletext. My idea was, this could perhaps be a missed opportunity for the Amiga ... for applications like the one you coded for - and of course as a second display that could be used in parallel. That would be ideal for things like video-titeling ... |
|||||
25 April 2020, 08:31 | #12 | ||
Registered User
Join Date: Nov 2015
Location: Perth, Australia
Posts: 73
|
Quote:
Quote:
However in this thread there seems to be some doubt that it's possible: http://eab.abime.net/showthread.php?t=50015 As far as I know, they're one of the last users of it. They're a betting company that used it for race information displays at racecourses and in retail outlets. They're gradually phasing it out but needed a temporary solution for when the broadcaster turned it off. |
||
25 April 2020, 11:28 | #13 | |||
Registered User
Join Date: Jul 2015
Location: The Netherlands
Posts: 3,464
|
The wikipedia page on teletext says the following about teletext encoding:
Quote:
The HRM states the following on vertical blank & maximum overscan Quote:
Quote:
Edit: above is info for OCS only. I don't know about ECS/AGA here, as I've never used the extra registers mentioned in the post above. Last edited by roondar; 25 April 2020 at 11:37. |
|||
25 April 2020, 16:14 | #14 |
Semi-Retired
Join Date: Mar 2012
Location: Leiden / The Netherlands
Posts: 2,065
|
Dutch national television still uses teletext. One of the very few, I'll bet.
|
25 April 2020, 16:15 | #15 | |
Registered User
Join Date: May 2017
Location: Munich/Bavaria
Posts: 2,502
|
yes I am aware of the OCS limitation in this case ;-)
Here is the same question from a couple of years ago with a short answer from Toni: Quote:
Toni sees problems with the encoding ... but got wrong numbers there, which is discussed here: http://eab.abime.net/showthread.php?t=50015 (from comment #17 on) And here some discussion about the maximum overscan: http://eab.abime.net/showthread.php?t=45691 All in all: no definitive answer. Nobody actually tried. I don't have a CRT anymore ... got rid of them because I moved a couple of times and they are no fun to carry around Actually I do not have a TV set at all (just monitors) or anything that would be able to display teletext ... So it will probably stay a mystery forever .... Last edited by Gorf; 25 April 2020 at 22:00. |
|
25 April 2020, 19:38 | #16 | |
Registered User
Join Date: Dec 2014
Location: germany
Posts: 448
|
Quote:
|
|
25 April 2020, 20:10 | #17 | |
Registered User
Join Date: May 2017
Location: Munich/Bavaria
Posts: 2,502
|
Quote:
It is also unclear if rgb would work ... the RaspPi it the video outputs composite ... so would BW-composite be enough? PS: that link is just for "DVB-T" dongles ... they expect a digital signal to begin with... |
|
25 April 2020, 20:15 | #18 |
Registered User
Join Date: May 2013
Location: Grimstad / Norway
Posts: 877
|
|
25 April 2020, 20:16 | #19 | |
Phone Homer
Join Date: Jun 2006
Location: 5150
Posts: 5,887
|
Quote:
Although you Neighbour Belgium has some of the most cable TV in the world and I'd be surprised if there cable TV isn't with HDMI. |
|
25 April 2020, 20:23 | #20 | |
Registered User
Join Date: May 2017
Location: Munich/Bavaria
Posts: 2,502
|
Quote:
https://www.team17.com/worms-for-tel...-marvel/worms/ |
|
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests) | |
Thread Tools | |
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Zif/Lif HDD Capable to Work with Amiga? | nathanm1991 | support.Hardware | 1 | 07 May 2018 12:33 |
Things you thought the amiga was never capable of | cosmicfrog | Amiga scene | 38 | 13 March 2009 23:10 |
Broadcasting Teletext, possible? | pepzi | Coders. General | 2 | 22 September 2008 23:21 |
Amiga 1200 capable | AliasXZ | New to Emulation or Amiga scene | 7 | 21 January 2008 10:49 |
MicroText teletext adaptor (£10 posted) | Smiley | MarketPlace | 13 | 15 April 2006 17:20 |
|
|