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Thread: Video Tape to Laser projector! Image Engineering units

  1. #1
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    Default Video Tape to Laser projector! Image Engineering units

    At SELEM I was lucky enough to purchase a unit and a collection of video tapes. The video tapes contain laser show data, the unit decodes (and two encoders) the data from the tape and turns it into galvo, color and shutter controls for two projectors.

    So far I've figured out the DACs, sort of where they get their chip enable from, and how the memory is tied to the DACs. I don't yet know how the data gets serialized into the memory or what triggers the chip select/write state for the DACs.

    But anyways, I made a ~14 minute video of my progress so far:

    https://www.youtube.com/watch?v=OLTajuHGd54


    I'll probably get my Beta and editing VHS deck from Norfolk this weekend as well as SGI Octane workstation which has lightpipe in and out, and firewire bridge(s).

    My goal is to convert direct-digital the data from the tape to computer then convert that into WAV or PCM audio that can be played back on ADATs, sound card setups and more.

    I also plan to capture the data videos to MPEG2-TS.

    I've also talked to a friend about trying to make a utility that can play wav files straight to RIYA and Etherdream DACs over USB and ethernet (And maybe the OpenLase ardunio shield as well!?)

  2. #2
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    Very cool!!!!! I'm glad there are people like you out there, preserving all of these older shows on modern media.

    P.S. That, sir, is a "proper" garage! No need to put a car in there. The space is much better used to house our lightshow obsessions!
    Those who fail to grasp art are the ones who criticize it.

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    Sure brings back some memories. Back in the day (mid-late '80's), I had three full time artists cranking out frames that would become shows recorded with this system. We had quite a library of shows and modules set to music. Back then, one computer could not do real and abstract graphics. This gear was great for hooking up your analog abstracts console and recording performances with music. 2 RGB scan heads. We used super VHS hifi decks. I'll dig around and see if I still have some docs for the I.E.C. DVE/DVD system. I think this was Fred Fenning's baby (as in the "Fenning Award"). I'll be watching your progress with great interest. Thanks for posting!
    Click image for larger version. 

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    Nice work! I was wondering what you were going to talk about for 14 minutes, but then it was over and I was just thinking "awesome!"

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    Dv Designer Fred Fenning passed away almost two decades ago. Odds of finding DV (Digital Video) schematics are thus restricted to a few customers who may have fragments. The current Image Engineering bought the company name and a few assets.

    There is a reason the ILDA award for Technological Innovation is the "Fenning Award".

    Mr. Fenning's Obit from MIT:
    Quote:
    We begin this month by relating news of the death of Frederick Fenning. Fred’s plane crashed over a lake in Idaho as he was piloting his plane across country to visit family in August 1997. Fred was a hardware electrical engineering consultant, whose work involved assembly guidance systems, lasers for manufacturing, and laser graphics for the entertainment industry. Fred also worked with Grumman Aircraft, and regularly participated in "fly-ins." Fred lived in Medford, Massachusetts, and remained active with his fraternity, Tau Epsilon Phi, visiting often on Sunday mornings, and flying pledges to Cape Cod during Rush Week. Fred had also participated in Dramashop, Musical Theater Guild, and academic committees as a student. The oldest of eight children, Fred is survived by seven siblings, numerous nieces and nephews, and his parents. A scholarship fund, Fred Fenning (77), has been established; contact Bonnie Kellerman in the MIT Office of the Treasurer for more information. Special thanks to Fred’s brother, Dr. Walter Fenning, who graciously provided information to us.
    End Quote.

    Since MIT has him as a 72, and 77 Alumni, Its Probably Dr. Fred Fenning....

    Link to a PIC: http://incendiaryarts.org/6obliquities/fred/fred.html

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    Haha.. That's me standing next to Fred. We had a blast (and a few headaches) on that show! Watching him troubleshoot under pressure was inspiring.

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    Wow! really cool. Maybe the artifacts on the projection are a result of the tape aging?

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    MixedGas - thanks for the history. Kind of grim.

    Status report : Still slowly working through the circuitry. I'm drawing it all out using a web based electronics cad thing called EasyEDA. It's just my goal to document for my own sanity to get enough information to find a decent place to pick the data off.

    I've figured out the data path of the DACs back to the SRAM. I've now found shift registers that are tied to the memory, this is kind of a break thru. I know how they're inverted I believe then tied to the data bus. I missed them earlier because the print was dark and because they're 4 bit. I'm used to the 8 bit ones so the part numbers didn't register (knee slap.) Now that I've got some idea as to how the data is taken serially and written to parallel the next piece of information I'm after is to make sure the shift registers are wired in series. If this is the case then 2 or 3 wires can get me the data into the MCU. From there the next big piece of information I need to find is some sort of marker as to when a frame of data is coming across. After that I'll probably cobble together a C program that takes each set of data via USB (serial speed of haul ass), and write it with the time as a "frame" (So if there is some drop out it might be detectable if the time is too wide) Then come up with something to make a WAV/PCM file out of this.

    I thought about it and NTSC, 483 * 29.97 gets close to the 14kpps if each scan line contains X+Y+R+G+B+8bits

    Over the weekend I managed to get to Norfolk and retrieved from storage a SuperBeta deck, a SuperVHS deck, and a SGI Octane computer which has lightpipe in and out. Over the weekend I ended up with 3 x black ADAT machines. This should give me some additional capability to test output with. I don't remember if Sound Recorder on IRIX can handle WAV though, might have to deal raw PCM.

    I forgot to look for firewire bridge, which is kind of a bummer. Don't think I could of found it given the amount of time anyhow.

    That's the update so far! Back to work!

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    Really looking forward to seeing what you're able to come up with from those old tapes. I drooled a little, looking at the boxes of those sitting on the floor at the back of the stage and lamented that I had neither the equipment or expertise to have attempted the preservation. Glad someone is working on it and hope you find a gem. I know from experience that sometimes you work all those hours to end up with very little but perhaps that one nugget that makes it all worth while.

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    I have been doing this for a couple years now, have bothe encoder and decoders for tape and 8 / 16 track. If you have any questions feel free to PM me. Click image for larger version. 

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    Captured back to ADAT hd24 then ripped to Wav.
    leading in trailing technology

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