Date   : Mon, 06 Mar 2006 19:44:18 +0000
From   : Jules Richardson <julesrichardsonuk@...>
Subject: Re: Warning: Sad case on list!

Phil Blundell wrote:
> On Mon, 2006-03-06 at 17:53 +0000, Jules Richardson wrote:
>> Hmm, too slow to have a camera hooked up to it producing colour images
>> and then reducing colour depth / dithering [1] before splitting into
>> chunks and farming off to each BBC for subsequent display.
> 
> Mmm.  I hadn't thought about the dithering thing.  Still, it kind of
> feels like the dissemination of data to the Beebs is going to be the
> limiting factor.  What sort of data link did you plan on using for that?

Not sure as such - I was thinking Econet, but after talking to Mike the other 
weeks about his fractal array maybe the User port's the way to go - assuming 
that a suitable multiplexer can be bodged at the controller side.

Note I'm not looking for real-time video or anything :-) Given Econet speeds I 
think I figured out that I might be able to get an image from camera to image 
wall in about ten seconds - which with some creative "fading in" from previous 
image to current should be about the right sort of time. If it was instant 
then it just looks like it's all being faked by a PC behind the scenes, and 
much longer than that and people would just get bored!

This is for a 4x4 array; 3x3 obviously speeds things up no end, but it 
wouldn't look as impressive!

>> I'm suspecting that the controller needs to be pretty pokey - maybe a RiscPC 
>> or somesuch. (how to actually attach a camera is still a total unknown, which 
>> may mean I'm better off with something like an SGI Indy)
> 
> Video digitizers for RiscPCs ought to be pretty easy to come by.  Here's
> one on ebay, though I have no idea of its capabilities:

Hmm, I think the ones I've come across in the past tend to be 16 colour only; 
ideally I'd like something that gave we a 256 colour image (at least!) and at 
least the theoretical max resolution of the image wall (640x1024). That's 
possibly outside the capabilities of the average "home market" Acorn add-on of 
the time. Still, needs looking into at some point...

cheers

Jules