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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
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Posted: Sat Feb 02, 2008 11:57 pm Post subject:
Voltage Controlled Video Processing Modules Subject description: Do they exist? |
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I've come across a few people experimenting with voltage controlled analog video processing, but have been unsuccessful in finding much information on how to manipulate a video signal or schematics/circuits for anything similar.
I'm mainly interested in processing (hue, saturation, etc) and distorting (static and noise patterns) analog video signals with the LFO's and EG's of my synth modules.
I've got a couple of old video source mixers to experiment with, but before I do... I'd like to collect as much information as possible. Anyone know where to find schematics or circuits for this kind of stuff? Even just general information or datasheets on ICs that process video signals. |
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Pehr
Joined: Aug 14, 2005 Posts: 1307 Location: Björkvik, Sweden
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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
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Posted: Sun Feb 03, 2008 1:52 am Post subject:
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Yep!! And I've got an early 80's tube-powered studio camera that sends out RGB video... I want to use this and a VCR as video inputs for live performances. I guess I need to learn more about how to manipulate a video signal, and what it contains... |
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bugbrand
Joined: Nov 27, 2005 Posts: 846 Location: Bristol, UK
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Danno Gee Ray
Joined: Sep 25, 2005 Posts: 1351 Location: Telford, PA USA
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Posted: Sun Feb 03, 2008 7:56 am Post subject:
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Radio Shack used to sell simple video processors and enhancers. If you can find one, try replaceing the control pots on one with some vactrol circuits and have a ball. Last edited by Danno Gee Ray on Sat Mar 15, 2008 4:04 pm; edited 1 time in total |
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mistercooper
Joined: Jul 17, 2006 Posts: 62 Location: Seattle
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Posted: Tue Feb 05, 2008 11:48 am Post subject:
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iirc, one of the hard parts is maintaining the sync signal, which is nowhere near audio bandwidth. |
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CJ Miller
Joined: Jan 07, 2007 Posts: 368 Location: 127.0.0.1
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Posted: Sat Mar 15, 2008 12:46 am Post subject:
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There definately have been analog video synths! I got turned on to analog video art in the late 1980s, way after it became a bit obscure. Public television stations used to show a lot of video art in the 1970s... Anyway, it is not easy to find much information on how it is done.
If you know which end of a soldering iron to hold and can understand analog audio synthesis then you already have some advantage over many of the trailblazers, who knew video but not electronics. And then one needs to know video. The biggest difference is not that video runs in the MHz range, it is that video signals are composite. In music, we get a voltage that varies in frequency and amplitude over time. But for video the horizontal sync, vertical sync, and picture data are all lumped together. B&W is easier because the picture is just a varying level. Color packs more data. So the first useful things to figure out are how to strip the sync from picture signals. Then you can put the picture through whatever you want. And then make sure it has proper sync when it leaves so it can work on a regular TV, VCR or whatever. Luckily it is easy to find info on these kinds of circuits because they are commonplace in video electronics.
I'm dropping the bomb here. There is more information on video synthesis here than anywhere else on the web:
http://www.vasulka.org/archive/
Enjoy! It took me weeks to read it all, and months later I am still trying to digest what I read. Lots of info on the ins and outs of video. And there are schematics for the Paik-Abe, Sandin, and others. Most of these synths used ICs which are long obselete though, so the schematics are probably more for educational value of the principles than anything else. It is an amazing resource.
I wish you luck. I am still stuggling to finish four years worth of audio PCBs into a working synth. Still I really look forward to playing with video soon also. |
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toppobrillo
Joined: Dec 10, 2005 Posts: 766 Location: oakland, ca
G2 patch files: 1
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Posted: Sat Mar 15, 2008 2:11 am Post subject:
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Quote: | I'm dropping the bomb here. |
you certainly have. thanks very much, i am going to be up all nite |
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bugbrand
Joined: Nov 27, 2005 Posts: 846 Location: Bristol, UK
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Clack
Joined: Aug 08, 2005 Posts: 438 Location: Walthamstow - london
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Danno Gee Ray
Joined: Sep 25, 2005 Posts: 1351 Location: Telford, PA USA
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Posted: Sat Mar 15, 2008 4:15 pm Post subject:
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Does anybody have schematics for that kind of stuff? |
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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
Audio files: 4
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Posted: Sat Mar 15, 2008 11:00 pm Post subject:
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That link is great, thank you... man, yeah, little sleep for me...
Wow, good timing for this thread to become active again!
I just last night stayed up REAL late working on some video-related experiments. I've got a couple of 1980's video FX units (just hue/saturation/contrast adjusters basically) that I'm in the process of making voltage controllable. I've had great luck w/the hue and saturation especially so far... but haven't got it tweaked perfectly yet. I also made a basic passive panel w/audio inputs and pots ala the schematic on Karl's site. Have gotten some very interesting, predictable effects, especially with LFO's with audio-->video modulation, but it mainly seems to be screwing w/the sync signals rather than color information.
I also started playing with the dozens and dozens of adjustment trimmers inside my Ikegami tube video camera. Voltage control of the camera itself could yield some CRAZY results. (My act uses a live camera feed for projections at shows.) Or even just filmmaking... live soundtrack-controlled cameras anyone?
I want to be able to split the image into several value ranges and manipulate each separately in a modular/patchable fashion, like Sandin's IP. I've studied those schematics briefly, but finding modern IC equivalents is definitely neccesary... I have a feeling the obsolete encoder board he refers to is something that can be ripped out of a cheap video unit or camera very easily these days, or may be available in IC form.
Thanks for the futurlec links. One of the video fx boxes I mentioned uses the LM1881N. Unfortunately I haven't found schematics for either of these boxes.
We'll see how things develop, it's a shame no one's developed more material here in a Synth DIY fashion. |
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snufkin
Joined: Apr 06, 2007 Posts: 57 Location: the world
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toybox
Joined: Aug 03, 2005 Posts: 176 Location: chicago/peru,illinois usa
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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
Audio files: 4
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Posted: Mon Mar 17, 2008 7:52 am Post subject:
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Yeah, I wish there were full schematics for that VS001 available.
One of those Futurlec IC's, the LM1203N, looks like it could definitely be implemented w/voltage control as an RGB controller module. Just need some kind of Composite-->VGA circuit, which I'm not having much luck finding.
I'm not really interested in video-synths so much as voltage-controlled analog video manipulation from camera/VCR sources. I want the keying and amplitude classifying capabilities of something like the Sandin, which you won't get with just voltage-control of Red/Green/Blue/Brightness/Contrast. I really wish I knew what I was doing enough to find replacements for the two IC's used throughout the Sandin IP... the MC1445 and CA3030 (these are nowhere to be found, but I'd be willing to buy lots of 50 pieces each if I could find them anywhere.) If I were to try to redocument and do board layouts for the Sandin, though... I'd want to try to find IC replacements still in production. It looks like a lot of the more complex Sandin IP boards could be replaced by chips (Sync Separator, Color VGA-->NTSC Encoder, etc.) If anyone's interested in giving me a hand trying to find workable replacements for those ICs, lemme know. It's probably right under my nose... |
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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
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TheAncientOne
Joined: Dec 26, 2006 Posts: 144 Location: United Kingdom
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Posted: Thu Mar 20, 2008 7:44 pm Post subject:
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"The Daddy" of all analogue video synths was the EMS "Spectron". I saw one once as youngster and wanted it!
http://members.tripod.com/werdav/spectron.html
The Spectron is probably unclonable - it needs about half an acre of Ghialmetti patchboards for a start.
The Sandin is probably still do-able. For me, I'd have to change a lot of the I/O and timing because I'm in Europe, and the analogue video standard is not NTSC, (said by techs to stand for "Never Twice Same Colour"). but PAL, with a higher line count, (625 not 5252) and a lower frame rate, (50Hz not 60Hz).
I think a lot of the obsolete logic and counter chips could be mashed into PAL's or CPLD's. I'd do the standard video amps as neat little surface mount modules with 4 pins, and treat them as a chip.
It would be a way cool project - and there is lots of old analogue video gear floating around due to the move to HighDef.
Mr Bugs: I'm coming down to see a friend in your area next week, I hope. Perhaps we should meet up and plot.... _________________ Mike |
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bugbrand
Joined: Nov 27, 2005 Posts: 846 Location: Bristol, UK
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Posted: Fri Mar 21, 2008 2:48 am Post subject:
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TheProf wrote: | "The Daddy" of all analogue video synths was the EMS "Spectron". I saw one once as youngster and wanted it!
http://members.tripod.com/werdav/spectron.html
The Spectron is probably unclonable - it needs about half an acre of Ghialmetti patchboards for a start.
The Sandin is probably still do-able. For me, I'd have to change a lot of the I/O and timing because I'm in Europe, and the analogue video standard is not NTSC, (said by techs to stand for "Never Twice Same Colour"). but PAL, with a higher line count, (625 not 5252) and a lower frame rate, (50Hz not 60Hz).
I think a lot of the obsolete logic and counter chips could be mashed into PAL's or CPLD's. I'd do the standard video amps as neat little surface mount modules with 4 pins, and treat them as a chip.
It would be a way cool project - and there is lots of old analogue video gear floating around due to the move to HighDef.
Mr Bugs: I'm coming down to see a friend in your area next week, I hope. Perhaps we should meet up and plot.... |
Nice one Mike - PM'ing you.. _________________ http://www.bugbrand.co.uk
http://www.bugbrand.blogspot.com |
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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
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Posted: Fri Mar 21, 2008 7:53 am Post subject:
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Wow, yeah the Spectron looks amazing!
I am a film school grad so I'm familiar with all the NTSC/PAL stuff (not that they taught us anything about actual video equipment, hah.)
Anyway, I found the MC1377... this chip is exactly what I was looking for, and an NTE replacement is still available from Mouser for $6. It is an RGB-to-NTSC/PAL encoder and can be used to generate all the necessary standard sync/blanking, etc. I think this was used in the Commodore. There are probably some surface-mount modern equivalents.... but the difference between PAL & NTSC is a simple matter of connecting a pin to ground!!
With a few "input modules" to filter out the sync, and an output module based around the NE1203 (RGB Amplifier System IC from Futurlec) + the MC1377, you've got the potential for a pretty damn complex "Voltage Controlled Video Enhancer/Colorizer"... and then adding redesigned clones of the logic/processing modules in the Sandin should be fairly straightforward. They only use two ICs, one as a 4-quadrant multiplier and the other as a standard wideband op-amp.
What's gonna happen if I use a normal op-amp w/video (like the TL072)? Is there just going to be a quality decrease? |
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bugbrand
Joined: Nov 27, 2005 Posts: 846 Location: Bristol, UK
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jondent
Joined: Oct 04, 2013 Posts: 8 Location: Australia
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Posted: Sat Jan 26, 2019 1:17 am Post subject:
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bugbrand wrote: | Someone emailed me to ask about the circuit I mentioned, so I'm going to share what little info I have... I did this back pre-2010 I think and had zero idea about video signals so the approach is shonky as anything! But the results (with, I think, a Time Base Corrector) were interesting - the box was used by a video guy for Portishead live visuals. The only documentation I have is a schematic I drew a month or two later. I used various different opamps with the same pinouts & had a switch to select different ones.
Looking at the schematic today, I'm not really sure why it works - it is clearly f***y as anything! But that's roughly what I did, so sharing it if anyone wants to try it out.
Nice to see, 10 years down the line, just how far LZX Video works have come! |
It's great to see these old circuits again.
and how far video synths have developed over the last decade |
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