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Digitizing VGA?
mvidal01 writes: "I have been looking for hardware to digitize the VGA output of a PC. After searching for a long time I have found a few solutions but nothing really great. If possible I would like to avoid converting the VGA signal to NTSC or PAL video with a scan converter because the quality tends to suck. So how about it Slashdot readers. Anyone know of hardware that will allow hires VGA to be digitized?"
This might be it
(1) Ice ballet and (2) dial-up through IP-telephony. I believe VGA digitizing qualifies as third although it's very like the second.
Sorry folks, this is composite/S-video input only. This is not going to be able to input VGA.
Though it probably won't get too close to what you're after, HD on DVHS is a step in the right direction. Unfortunately, these recorders usually accept only the pre-digitized bitstream (already conpressed w/MPEG-2) coming off a set-top box... so unless you're ready to drop a truckload of cash on an HD MPEG-2 digitizer, you're pretty much right where you started.
Most likely it's for long distance transmission. While an analog signal fades when sent over long distances, bits don't and can be amplified without losing any signal quality. I wish there was a KVM-type switch and signal amplifier available that would let me run one cable from my server in the garage to my bedroom ;-).
That's it. I'm no longer part of Team Sanity.
The reason you find very few options for doing this is because there is almost always a better, cheaper, faster way of grabbing a screen without actually reading and interpretting the output.
A better Ask Slashdot tells us what you're trying to accomplish, and why you've dismissed the 'obvious' solutions (such as software, or a card inside the computer, etc).
The only reason I can see where you'd have to do it this way is if you don't have full access to the computer (can't load software, can't open case, trying to circumvent digital copyright protection, etc), but you still want to see what's on the screen.
I've been thinking about this for awhile mainly because I have to monitor hundreds of computers remotely. In some cases I need to control them before the system completes the boot-up process (ie, before software can be loaded), and in other cases I'm using operating systems for which inexpensive software is not available even after boot up. The solution I'm leaning toward is custom hardware (everything runs at 640x480 or less) which compresses and sends the signal over modem or tcp/ip. I haven't implemented it yet, but I enjoy thinking about it. Capturing higher resolution pictures is more involved.
Speaking of which, what do you need to do, exaclty? Do you just want to capture screen shots, or are you interested in spying on the stream in real (or near real) time? Do you need to capture those streams? How much color depth do you need? What's your budget? Does it need to be user friendly, or geek friendly?
-Adam
"Why would you like to do this?"
....), use mpeg4 compression and stream it over the internet or capture it on DVD-R.
Maybe to transport it over a longer distance than analog cables allow? While I agree that maybe it is a bit silly to do a AD conversion after a DA conversion has already taken place it does make me wonder why monitors don't do their own (presumably optimized) DA conversion and receive their signal in a digital form only.
It has always puzzled me that my monitor has to tell my PC what signal it needs (you needed to look up the proper refreshrates yourself before plug and play monitors arrived). Surely, modern gigabit network interfaces are fast enough to transfer the signal digitally? A 1600*1024 screen amounts to about 1.6 million pixels. In 24 bit color this requires about 4.7 MB for one screen (uncompressed). At 60 screen refreshes per second that's 300 MB/s. That is pretty much for a 1 gigabit line, so lets use two lines or do some compression (at this rate most frames will have a lot in common).
What would be the advantages? Simpler video cards in the PC. Better performing displays since the DA conversion can be tuned to the specific display. Better connectivity to e.g. alternative types of displays (beamers, tv's, etc.). Longer distance between PC and display and input devices (might as well tunnel USB signals over it too!), postprocessing of the signal in the monitor (digitally resize, display signals from 2 PCs on one screen and switch between them or show scaled versions,
There's a lot to be said in favor of getting rid of the analog transmission of video signals between PC and display. There's already standards for the digital transmission of audio (e.g. spdif) so why not do the same for video?
Jilles
This isn't just the 'Cat5 Video extender' product which has been around for years, this is something entirely new, with frame grabber and video compression, SSL, RADIUS authentication, etc.
The client runs only on MS-Windows 98+, at a minumum of 20Kbps. The server to be remotely controlled can be anything that supports VGA and PS/2 keyboards, including some Sun products.
So far, I have no complaints. We haven't tried all of the advanced features yet.
I do not deploy Linux. Ever.
At 300 MB/s there's nothing to decode because the video is already uncompressed and surely the cost of the necessary hardware for a point to point connection of 300 MB/s will drop if there's enough hardware being deployed (just like 100 mbit hw is dirt cheap these days).
Besides, 300 MB/s would be a worst case scenario assuming no compression whatsoever. I'd be surprised if it weren't possible to cut that by at least a factor 2-5 using lossless compression (bringing it within range of gigabit ethernet and other relevant standards (maybe even ieee1394 or a successor of it)
Jilles
There's already a standard for digital video transmission: DVI. All you have to do is convince manufacturers to use it for CRTs.
A little less clear in this instance is who gets top billing. Ordinarily you would list yourself and a second party as "...foo and I...", but in this case the "...someone else here..." isn't someone acting in concert with you, but as a second source only to be called upon in the event of your failure to help satisfactorily, so I believe the "first one and then perhaps the other" sequence makes "...perhaps I or someone else here..." the better choice of wording in this particular case.
I see even classic Slashdot is now pretty much unusable on dial up anymore.
Instead of looking for customized hardware, just buy a KVM designed for use over TCP/IP. Then just capture the screens from the remote control software. Search Google for "KVM over IP". One such example is Dakota.
LOAD "SIG",8,1
LOADING...
READY.
RUN
"Do you realize how much current is charged up inside that box ?"
An imac (the old type) has the entire PC in once case together with the CRT so I think that is a non issue. The DA conversion needs to be done anyway so you might as well do it inside the monitor.
Jilles
Here's one by Extron.
(VGA, SVGA, XVGA, etc. are all RGB, for those who don't know.)
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