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vga to ethernet converter

  • Thread starter Rune Christensen
  • Start date
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Rune Christensen

Jan 1, 1970
0
Hello

Does anyone know if it's possible to build a VGA to ethernet converter? A
device that converts a VGA signal to a digital videostream.

I want to be able to operate a computer from a remote position also when the
computer boots. So I will be able to change bios settings, starting mode of
Windows, etc.

Thanks
Rune
 
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Rene Tschaggelar

Jan 1, 1970
0
Rune said:
Hello

Does anyone know if it's possible to build a VGA to ethernet converter? A
device that converts a VGA signal to a digital videostream.

I want to be able to operate a computer from a remote position also when the
computer boots. So I will be able to change bios settings, starting mode of
Windows, etc.

That is inlikely possible. Especially when I consider the high
analog bandwidth required for comfortable viewing.
At 1600x1200 with 24bit colors, the bandwidth is in the order of
350MHz per color.

Rene
 
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Iwo Mergler

Jan 1, 1970
0
Rune said:
Hello

Does anyone know if it's possible to build a VGA to ethernet converter? A
device that converts a VGA signal to a digital videostream.

I want to be able to operate a computer from a remote position also when the
computer boots. So I will be able to change bios settings, starting mode of
Windows, etc.

Thanks
Rune

Yes it is possible.

As Rune pointed out, the easy approach is most likely
unsuccessful, as the bandwidth of a video signal may
well be several hundred MHz.

If I had to design such a beast, I would start with
a frame grabber, similar to the innards of a LCD monitor.
I would then compress the video stream for transmission
via Ethernet.

For simple applications (BIOS, simple GUI, etc.), a differential
encoding or simply a reduced frame rate would be sufficient.
A 10MBit/s ethernet link could reliably transmit about one
640x480x24 frame per second.

For complex GUIs / moving pictures, you may have to use a
real compression algorithm, maybe MPEG2.

Kind regards,

Iwo
 
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Paul Hovnanian P.E.

Jan 1, 1970
0
Rune said:
Hello

Does anyone know if it's possible to build a VGA to ethernet converter? A
device that converts a VGA signal to a digital videostream.

I want to be able to operate a computer from a remote position also when the
computer boots. So I will be able to change bios settings, starting mode of
Windows, etc.

Does it have to be Windows? There are ways to do this if you can access
bios and/or the o/s via a serial console. Not possible with Windows
AFAIK.
 
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Ian

Jan 1, 1970
0
Does anyone know if it's possible to build a VGA to ethernet converter? A
device that converts a VGA signal to a digital videostream.
I want to be able to operate a computer from a remote position also when the
computer boots. So I will be able to change bios settings, starting mode of
Windows, etc.

Some "server management" cards do just this. Needs to either snoop the bus for VGA
accesses or fully emulate a VGA adapter (i.e. they /are/ the VGA adapter for the
machine). Quite expensive to buy, quite hard to make...
 
K

Ken Taylor

Jan 1, 1970
0
Rune Christensen said:
Hello

Does anyone know if it's possible to build a VGA to ethernet converter? A
device that converts a VGA signal to a digital videostream.

I want to be able to operate a computer from a remote position also when the
computer boots. So I will be able to change bios settings, starting mode of
Windows, etc.

Thanks
Rune
Do you actually need to change BIOS settings remotely as well? Programs such
as VNC allow you to remotely take control of the PC, which also gets over
the keyboard/mouse interface that your VGA-Ethernet converter forgets. Only
applies once the OS is up and running though, hence the BIOS question.

Ken
 
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Richard

Jan 1, 1970
0
Rune said:
Does anyone know if it's possible to build a VGA to
ethernet converter?

http://www.avocent.com/ - KVM over IP $$$

If Ethernet / IP aren't required, there are Cat-5 KVM extenders for <$1K
that will run 500 feet. See Raritan or Avocent for these as well.
 
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Tim Shoppa

Jan 1, 1970
0
Rune Christensen said:
Does anyone know if it's possible to build a VGA to ethernet converter? A
device that converts a VGA signal to a digital videostream.

I want to be able to operate a computer from a remote position also when the
computer boots. So I will be able to change bios settings, starting mode of
Windows, etc.

It's not really Ethernet, but there are companies that sell
adapters that let you run VGA signals over CAT-5 cable for distances
of hundreds/thousands of feet. There's a converter box at one end,
and another converter box at the other end.

For example

http://www.compuplus.com/insidepage.php3?id=1000872

If anyone wants to spill the beans on what's inside these, I'm curious.
I would guess that of the 4 CAT-5 pairs, three are for R, G, and B, and
the fourth pair is used to carry sync info. But maybe it's much more
complicated? Or maybe it's just 3 single-ended-analog-to-differential
converters on one end and termination and differential-to-single-ended
conversion on the other for RGB? You could convert the H&V syncs to any
number of intermediate signals on their way to the other end... that's
"just" 2 digital lines.

Tim.
 
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Rune Christensen

Jan 1, 1970
0
"Ian"
Some "server management" cards do just this. Needs to either snoop the bus for VGA
accesses or fully emulate a VGA adapter (i.e. they /are/ the VGA adapter for the
machine). Quite expensive to buy, quite hard to make...

I think that this must the easiest solution to the problem. Create a VGA
card that transfer the screen to ethernet instead of a screen. Maybe a PCI
FPGA card could be used to do this.

To the people on comp.arch.fpga have anyone tried to create a VGA card on a
PCI FPGA card?

Thanks
Rune Christensen
 
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Ian Stirling

Jan 1, 1970
0
Rune Christensen said:
Hello

Does anyone know if it's possible to build a VGA to ethernet converter? A
device that converts a VGA signal to a digital videostream.

I want to be able to operate a computer from a remote position also when the
computer boots. So I will be able to change bios settings, starting mode of
Windows, etc.

Devices to do this are readily available.
Just google for network webcams.
 
Z

Zak

Jan 1, 1970
0
Devices to do this are readily available.
Just google for network webcams.

Or google for "KVM over IP". IBM and HP have servers that can do this
via an internal management card.


Thomas
 
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INS122595

Jan 1, 1970
0
We done similar projects, the critical point is if many VGA standard need be
supported

Walter


Rune Christensen said:
 
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Andrew Dyer

Jan 1, 1970
0
some 'server' type computers have a BIOS that will allow you to do
the basics over a serial port. After the computer comes up you
can run something like windows' RDP or VNC for a remote desktop.
I think that this must the easiest solution to the problem. Create a VGA
card that transfer the screen to ethernet instead of a screen. Maybe a PCI
FPGA card could be used to do this.

To the people on comp.arch.fpga have anyone tried to create a VGA card on a
PCI FPGA card?

This isn't all that simple - assume your video stream is
800x600x8bits per pixel x 60 hz (~230 mbits/sec). To make it
work, you'll have to run gigabit ethernet, drop bits or frames,
compress or some mixture of these.

Next problem is how to get at the screen data - you could implement a
whole vga subsystem (don't forget BIOS and drivers), snoop the PCI bus
(need to track the state of a real vga chip which can be tricky), get a
digital copy of the VGA output data (not all vga chips have digital out)
or recapture the data from an analog copy (probably don't have access to
the pixel clock, so you need PLLs to recapture the data).
 
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Tim Shoppa

Jan 1, 1970
0
Chuck Wozniak said:
Intersil makes some ICs for doing this. Full schematic in PDF format at:

http://www.intersil.com/data/rd/el4543/vga_transmission.pdf

Ah, not too far from what I thought. Although I am surprised at how
they only use 3 of the 4 pairs, and use a funky encoding of common
mode voltages on the red, green, and blue pairs to send the sync.

I suppose that the sync really is sent differentially, in sort-of a
three-phase way. They claim this reduces EMI, they're probably right but
I've never analyzed this situation before.

Maybe the fourth pair is reserved for a back-channel (mouse, keyboard) by
some applications?

Tim.
 
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