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Hardware

Hardware Based Screen Capture? 17

Posted by Cliff from the hardware-hacks dept.
Sokie asks: "While trying to decide what screen capture software would work best for illustrating software reviews, I realized that there were many possible situations where this software just won't work. For instance, BIOS screens, Linux installs, that kind of thing. Then I got curious as to whether there might be a hardware based screen capture device available. After several searches on AltaVista and Google, I've come up empty." There may be several ways to do this, but it would be interesting to note if there's been a specific product designed for this purpose. Is there an off-the-shelf solution, or would methods like the ole camera-in-front-of-the-monitor trick work?

"What I'm thinking is a pass-through or Y connected external piece of hardware that has some sort of independent storage like a 3.5" floppy or SmartMedia card or something. Ideally, there would just be a button to press on the device that would do a screen capture and save it to the storage medium as a TIFF or similar file. Then there could even be a USB/Serial connection and software for getting the images back off the device at a later time. So does anyone know if this piece of hardware exists? Would this device be enormously complex and prohibitively expensive? Is there any easier/better way to do screen captures in the type of situations I mentioned?"
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Hardware Based Screen Capture? More

Hardware Based Screen Capture?

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  • A great idea would be a sort of 'tap' on a vga or keyboard cable that could record input and output.

    I know that the military and ny gov't uses this, but I have no idea where you can get it.
  • You should be able to get a video card with a TV-Out to show the contents of your screen while in any mode, then just hook the 'out' to a VCR and hit record then pull the screenshot back in off of tape at a later time.
  • One more thing, if you are looking to get a screen capture of the video bios stuff, i think you may be out of luck without some more advanced setup.
  • Wouldn't that entail a pretty serious quality loss? Especially dropping the image down to TV resolution. If this device proves unfeasible, a digital camera in front of the monitor is probably the best solution.

    Also, I have a Diamond Viper V550 with TV out, the problem is that I have to activate the TV out with Diamond's software from Windows. :/ Maybe the newer TV out cards don't have this limitation, in which case, yours would be a good solution if one were trying to make a video of a Linux install or something which could be useful in and of itself.

  • Capture With Computer (Score:3)

    by SEWilco ( 27983 ) on Sunday November 26, 2000 @01:33PM (#600885) Journal
    Use another computer, with a VGA capture card.

    • AccuView Linux [sprynet.com] mentions an "optional VGA input".
    • Video-Capture.Net [video-capture.net] mentions VisionRGB, although the link for it is not working at the moment.
  • That's a good idea. If one used a Y adapter type video cable, would there be a halving of the signal? I'll have to research these cards a bit more, looks like a workable solution, but it won't be as easy as a standalone solution and will require tying up another computer. I'd still like to see an external piece of hardware, but this may satiate me in the absence of such a device. Thanks. :)
  • It would sure be nice if the 'pause' key worked during boot, but I've never seen a board where it would. I have, however, had a situation where I needed to troubleshoot without any video and the combination of the 'print screen' key and a printer that doesn't need any software loaded sure comes in handy. Of course what prints depends on which fraction of a second in which you hit the 'print screen' key, so it can take several tries.

  • It would sure be nice if the 'pause' key worked during boot, but I've never seen a board where it would.

    Really? I use the Pause key a lot to pause the boot process after SCSI cards detect devices so I can see what was detected before it goes away. I've done this on numerous boards.. ABIT's the only brand name I can recall.

  • I don't remember the signal/ground paths of VGA; some circuit types do not work with a Y cable but I don't remember if VGA is one of those types of circuits. There are splitter boxes which let several VGA monitors be fed from a single input.

    Anyway, most video capture boards let you see what you're capturing so you can probably see what the target computer is showing...on the screen of the capturing computer. Of course, you should select a board which lets you see the display in realtime -- if the capture is every 30 seconds and you need to play Doom to capture the desired images then you'll find your Doom character shot between updates...

  • considering the original question is about "software reviews" and the like, i would think that a hardware emulator such as vmware [vmware.com] or plex86 [plex86.org] would be a reasonable way to accomplish most of this without necessitating lots of hardware. the host os should be able to capture most of what one would be after: boot sequences and everything following . only in the case of testing say motherboards and their bioses would this be unreasonable.

    the hardware described would be cool, but i havn't seen anything like it. (unfortunately!)

    # cat .sig

  • This is exactly one of the uses [vmware.com] VMWare quotes.

  • Some video out cards (or external boxes) allow for HDTV resolutions. I'm not sure of any off the top of my head, but it may be worth looking into. For simple text screens, that should be good enough.
  • It doesn't matter if the quality drops to even 320x480 (TV out is a little bit better than this) since this is about what resolution most normal BIOSes output their messages in, also with a linux console this is about the same.
  • The primary loss of quality I was talking about was the digital -> analog -> VHS -> digital process, but also many Linux installs are no longer console based and I believe run at higher than TV resolution (although I may be wrong about that). Like I said, I think this system would be a decent solution as long as you weren't planning on bringing it back to a digital format from the VHS. Also, when someone views the screenshot at 1280x1024, a 320x480 pic wouldn't give you much detail.
  • Even though some other solutions have been presented, I'm still curious about the feasibility of a device as I described. How would you folks go about hacking together a device like this? What all do you need to interpret a VGA signal and convert it back to a usable format? I assume that VGA LCD projectors do something similar to this, but instead of saving the converted input, they send it to the LCD unit. But maybe I'm wrong on this, anyone have some insight?
  • Well, apparently VGA can be split with a cable. I was looking for something else and noticed a Y-cable on eBay [ebay.com]. Do a search for "splitter monitor" to find current auctions of such items.

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