Any ideas how to grab a VGA signal?

QNX Newsgroups (Archives) qdn.public.qnx4
1

I’d appreciate any ideas on how to do this, preferably under QNX4, but I’m
open to other methods:

I have a piece of equipment whose display I’d like to view remotely. There
is zero chance of altering the instrument’s software, so my only option is
to somehow grab the signals presented on the VGA (maybe SVGA) output. I
don’t need full motion capture, a single snapshot of the screen would do.
The snapshot would then be stored as a bmp/gif/jpeg/whatever format file,
which I could download at will over a tcp/ip link.

Any ideas on how to do this?

thanks

Julian Thornhill

2

Julian Thornhill <jth@ion.le.ac.uk> wrote:

I’d appreciate any ideas on how to do this, preferably under QNX4, but I’m
open to other methods:

I have a piece of equipment whose display I’d like to view remotely. There
is zero chance of altering the instrument’s software, so my only option is
to somehow grab the signals presented on the VGA (maybe SVGA) output. I
don’t need full motion capture, a single snapshot of the screen would do.
The snapshot would then be stored as a bmp/gif/jpeg/whatever format file,
which I could download at will over a tcp/ip link.

Any ideas on how to do this?

This “piece of equipment” – can you run an additional piece of software
on it? (Or, does that count as altering?)

If you can’t run some additional piece of software on it, then there
is probably no software/os way of doing what you want to do – and you’d
have to get into some sort of custom hardware solution.

If you can, what is it running? That is, what OS? How is it doing its
graphics output? (What windowing system, or raw vga access?)

-David

QNX Training Services
http://www.qnx.com/support/training/
Please followup in this newsgroup if you have further questions.

3

There are video capture board out there. I just don’t know of one that
would take a VGA connector’s output as it’s input.

Does you VGA card have the ability to output other than just VGA (i.e.
composit video or Super VHS). If so, there are video capture board that
can capture that. If not, you still have two choices. Can you replace
the VGA card & driver with one that does have additional outputs?

Failing that, there are devices that will convert from VGA out to composit
video or SVHS. You could get one of those devices and pipe it into a video
capture system.

“Julian Thornhill” <jth@ion.le.ac.uk> wrote in message
news:be0ufr$q0s$1@inn.qnx.com…

I’d appreciate any ideas on how to do this, preferably under QNX4, but I’m
open to other methods:

I have a piece of equipment whose display I’d like to view remotely. There
is zero chance of altering the instrument’s software, so my only option is
to somehow grab the signals presented on the VGA (maybe SVGA) output. I
don’t need full motion capture, a single snapshot of the screen would do.
The snapshot would then be stored as a bmp/gif/jpeg/whatever format file,
which I could download at will over a tcp/ip link.

Any ideas on how to do this?

thanks

Julian Thornhill

4

Julian Thornhill wrote:

I’d appreciate any ideas on how to do this, preferably under QNX4, but I’m
open to other methods:

I have a piece of equipment whose display I’d like to view remotely. There
is zero chance of altering the instrument’s software, so my only option is
to somehow grab the signals presented on the VGA (maybe SVGA) output. I
don’t need full motion capture, a single snapshot of the screen would do.
The snapshot would then be stored as a bmp/gif/jpeg/whatever format file,
which I could download at will over a tcp/ip link.

Any ideas on how to do this?

thanks

Julian Thornhill

Three options spring to mind:

  1. Use a VGA to TV adapter then feed that signal into a PC with a video
    capture card. I understand the older BT848 family-based capture card
    could be used under QNX4. Alternatively, JVC do a composite video signal
    grabber which has a serial output. Slow but OK for periodic captures.
  2. Use a webcam pointed at the instruments display, take regular
    snapshots streamed to a file and hope the camera and instrument dont
    move
  3. Source or build some electronics to capture the VGA signals - sounds
    interesting but expensive and time consuming.

I’d go for option 1.
Good luck.
D Allinson

www.candidsystems.co.uk