Warping Effect / Sync Signal Manipulation

Discussion of modular and standalone video generating/processing techniques and associated hardware.

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tsintsi
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Warping Effect / Sync Signal Manipulation

Post by tsintsi » Sat Mar 09, 2019 8:32 pm

howdy folks - I'm trying to achieve this sort of warping effect, but outside of hard to replicate circuit bends of video mixers I'm not sure how to get it:

Image

I have an arduino video synth (via the TVout library) that can replicate this effect pretty well by cutting out the resistor that handles the sync signal. would that be a good place to start? are there any other specific ways of getting this effect?

(image is from a piece by the amazing Roberto Malano)

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nerdware
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Post by nerdware » Sun Mar 10, 2019 6:05 am

While I know you can do warping effects with displacement mapping, that's a software effect. I'll assume you want a hardware solution.

The example you've given looks a bit like filtering, but going in the opposite direction. So I might try cheating: flip the video vertically, lowpass filter it, then flip it back again. I've never tried that particular combination but I've combined other transformations with fun results, so I'll be interested to see what you get.

Flipping video vertically and/or horizontally can be easily done in software, of course, but you'll want video hardware for realtime use. You may be able to find a video mixer or other processor that'll do this. Many HD-SDI CCTV cameras can do it, but rescanning from a monitor is an extreme method. That'll introduce other effects - which can be useful too. :omg:
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joem
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Post by joem » Wed Mar 13, 2019 4:31 pm

As far as I can tell, if we're talking doing this to analog video in hardware, you'd need to have some way to buffer each line and output them at different than original speeds (or varying speeds within a line, depending on how you want it). So you'd likely need to digitize it (ADC), process it with something, then run that out through a DAC so that it's back into analog.

You can get an effect like this in the analog world using video synthesis by FM'ing your oscillators with an LFO, but I don't think there's a way for that method to work with video input.

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nerdware
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Post by nerdware » Thu Mar 14, 2019 5:29 am

You might get something close to what you want using a simple video resynthesis technique.

[video][/video]

The last time I tried this was with a set VWG modules like in the video, but I'd expect it to work even better with a set of PR modules because you have proper VC gain. ISTR I got closest to what you want by using a filter on the source plane to modulate the resynthesis, but I wasn't trying to do anything so subtle as the effect you're after. Also, I was using 3 independent filters, while I suspect you may get better results using a single filter on the source luminance. If I had the time this week, I'd try this right now and tell you what I discovered.

[Adds this to the already too-long TODO list.] :bang:
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joem
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Post by joem » Thu Mar 14, 2019 4:35 pm

nerdware wrote:You might get something close to what you want using a simple video resynthesis technique.
Oh nice! I had watched that video before I ever had any LZX gear and didn't really understand it at all, but now it makes a lot more sense to me. I'm going to have to try a budget version using my Cadet modules! I think I have just enough to try to warp some monochrome video. If I succeed, I'll post some results here.

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