Da da da da da da-da-da da da! Freeze Frame!
January 17, 2008 9:02 AM   Subscribe

Help me freeze my VGA video signal...as cheaply as possible.

In a saturated market of switchers and projectors, what's the cheapest possible way to freeze a 1280x1024 24-bit color analog (RGBHV) image? How much circuitry is required for a device inline in a video feed that can toggle between "hold" or "pass" modes? I don't need it scaled, color-corrected, distorted, brightened or otherwise modified - just froze. Has anyone taken on this problem as a microcontroller project? Or is there a device that "just" freezes video?

Lots of projectors do this, but some plasma screens and LCDs don't have the feature...and I want it and I'm willing to throw money at the problem, but I thought since AskMe saved me thousands of dollars by directing me to a certain online retailer (after I asked about putting HDMI 'ends' on cheap Cat5 cable) I thought, you know, maybe...

If it's too hard to build or guaranteed to be expensive, I understand. Thanks!
posted by ostranenie to Computers & Internet (1 answer total)
Simple answer: some video scalers have the ability to freeze the image. AFAIK, that'd be the simplest & cheapest off-the-shelf option (where 'cheapest' is a relative term).

What's required, circuit-wise? A video ADC, RAM to store the digitised image (& support stuff like address/data decoding & registers, latching, refresh, etc), a video DAC, and a microcontroller + code to run it all. Years ago there were a few circuits/kits for composite video ones, but I haven't seen anything lately. (Not that there may not be - I haven't been looking).

Part of the reason why you'd be unlikely to find a stand-alone freeze-frame unit is that, having built something like that, you've got all the necessaries to do so much more - scaling, mixing, effects, etc, are just a matter of writing the microcontroller software to do it. The market for effects boxes, or even just a basic video scaler, is so much larger than for a single-purpose unit. And, as you mention, some displays have this feature built-in due to the fact that they've already got an ADC & memory for other reasons e.g. converting/scaling various input formats/sizes to the screen's native resolution - adding freeze-frame is just a matter of writing code to stop updating the stored image each frame, & clocking it out over and over again.
posted by Pinback at 3:51 PM on January 17, 2008

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