Date   : Sun, 04 Feb 2001 15:03:30 +0000
From   : jgh@... (Jonathan Graham Harston)
Subject: Re: Genlock

Tim Fardell <timf@...> wrote:
> Chris Richardson wrote:
> > I have a Genlock board
> > I have fitted it into my Master 128 as per the instructions I received.
The
> > guy that removed it from his own Master noted where all the bits went
> > It seems to fire up OK (the LED's show it knows when a signal is being
sent
> > to it).
> > The question is. Is it a video input device? The second is, if so, do you
 
It's an output device.  Well... it mixes the Beeb's video output with that
from another source, so I'm using 'output device' in the sense that the
it's not an input device.  The computer doesn't "see" any input in the
same way that the computer can "see" the input coming in from the
keyboard.
 
> > know how I use it? I have tried my video recorder out, cable box out, digi
> > camera out and PC video out. They all make the BBC screen jump now and
again
> > and the 'REF' LED on the Genlock board light up when connected to a video
> > source.
 
           Video Source ->------\
eg, camera, VID-OUT of VCD, etc |
                                |
+---------------------+         |
|                     |<--------/
| Computer--->GenLock |
|                     |------> Video out --> to video terminal, eg
+---------------------+                    monitor, VID-IN of VCR, etc
 
> The idea of a Genlock is that it locks one video source to another, in
> this case it locks the BBC's output to an external source, so you can
> superimpose titles generated by the Beeb onto the video.
 
Remember how the Domesday was genlock'd in reverse?  The external source
(the laserdisc player) was locked to the computer, so that users (ie
schools) wouldn't have to modifiy the computer.
 
> Having said that, I can't see from the picture where you feed the
> external video in, and where the mixed video comes out. I suspect the
> BBC picture 'jumps' as it locks on to the external video source?
 
I'll have to go into work and look at the picture on the website ;) and
take a closer look.
 
-- 
J.G.Harston (JGH BBC PD Library) 70 Camm Street, Walkley, SHEFFIELD S6 3TR
jgh@...                - Running on BBCs & Masters with SJ MDFS FileServer
Z80+6502/CoPro+Tubes/Econet+SJ - - - - - - - http://www.mdfs.net/User/JGH/
                             Et In Arcadia Ego