Digitizing VGA? (take 2)

urgent asks: "In March of 2002, Ask Slashdot ran this article, wherein advice on 'hardware to digitize the VGA output of a PC' was sought. Most of the responses seemed to assume that remote administration of PC's/servers was the end goal. If you've got control of the software and/or hardware, it's pretty clear there are easier solutions for that. On the other had, there are many legacy and embedded systems where it would be nice to monitor and record display output. For instance, integrating old computerized factory equipment into a SCADA system, or recording old embedded maritime and medical displays (hint: jobs). My dream hardware would be a dongle that connected to a VGA out and could be polled over ethernet or CAN."

Comments

Bandwidth is a monkey wrench

[MBCook]

I'd be worried about the bandwidth. For a VGA sized screen (640x480) at 60hz with 8bit color you're looking at about 18 megabytes per second. If you want 24 bit color, it's about 55 megabytes per second. 1024x768x24x60 is about 1135 megabytes. Remember that 10baseT is 1.25 megabytes per second, 100baseT is 12.5, and 1000baseT is 125, so even 8 bit VGA needs gigabit ethernet.

So really you MUST have compression unless you want to kill the network (and that's assuming you have gigabit) so a simple dongle is out of the question. You are left with KVMs that do this for you (mentioned in another post) and running video over cat5e (not ethernet, it uses the cable) which is also in another post. A simple dongle isn't feasable to run VGA over an Ethernet network.

"Analog" hole

[BillyBlaze]

Monitor outputs have no DRM.

So if such hardware exists (and it could certainly be made), this is yet another obstacle to a "secure" PC. Do other standards for connecting displays have Macrovision-style restrictions? Would Palladium hardware obselete all those monitors?