[sdiy] [AH] analog video synthesizers

[Nils Pipenbrinck]

I have to throw in some more thoughts about this topic...

*inlined*

> That's the problem--processing audio in real time on a fast PC is
> sort-of possible, but video is too much for PCs (as yet). The industry
> opinion is that the few professional video engineers who would
> want such effects, are willing to use rendering software--and wait
> for results. Sometimes a LONG wait.

This is not exactly true anymore. Any silly 3D vga-card today is able to do
a huge amount of trippy effects, and you can of cause process incomming
video-signals. This won't work out of the box, you need a cheap
framegrabber-card (50 bucks), some programming experiences and two month
time. then you can do almost everything you want in fine highres realtime on
the screen. Some VJ teams already use this with success.

> Any 'simple' IC device that can extract and/or
> restore sync and burst is disappearing, supposedly
> because it can be used to build low-cost outlaw
> cable-tv decoders....

If you not after PAL or NTSC, but you simply want video a cheapo ramdac for
VGA might be an option. You need a pic to programm the timing once, and then
you can feed analog signals through 3 ADC's right into the chip. Most
ramdacs generate their hsync and vsync on their own and expose those on the
pins (you might want to sync your EG's or VCO's to the video-timing). This
might be even ok for NTSC if you buy a scanconverter (vga can output 60Hz,
and so does NTSC. A frame aliasing free conversion should be possible.. PAL
is a different story however).

... thinking about this once more: PAL is no problem either.. Just program
the ramdac for 50fps timing and hook up a cheap PAL-modulator at the
outputs. This will give a cleaner picture than the scanconverter.

Why I'm writing this: I did part of that thing 4 month ago for the diploma
of a friend. He made an ASIC based microprocessor, and I helped him
soldering the vga adapter. It _really_ easy, a 6 hour job from scratch to a
colorfull image on the screen. If you're interested I could dig out the
part-number of the ramdac. (24 pins DIL, 5V TTL inputs, very diy-friendly
device).

> Or, make it really easy on yourself--get an old RGB analog monitor,
> feed it sync from a sync generator, and run your modular synth
> signals into the R, G and B inputs. You might need to use a
> camera to capture your results....sorry....this would be a cheap
> way to go, for your diyers.

Using a ramdac is even cheaper because old RGB's are hard to get. And you
don't run into the risk of trashing your monitor.

	Nils