[150309] in North American Network Operators' Group
Re: Laptop with reverse VGA
daemon@ATHENA.MIT.EDU (Jay Ashworth)
Tue Feb 21 09:49:21 2012
Date: Tue, 21 Feb 2012 09:48:21 -0500 (EST)
From: Jay Ashworth <jra@baylink.com>
To: NANOG <nanog@nanog.org>
In-Reply-To: <1329781166.24342.6.camel@Decaf.NEEBU.Net>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
----- Original Message -----
> From: "Jake Khuon" <khuon@neebu.net>
> I think the form-factour is already there. I have a Motorola Atrix
> smartphone. It's available with a laptop-dock unit. This is
> essentially a USB hub and display. The display is connected by
> outputting from the phone's HDMI port. The rest of the input/output
> device (keyboard and trackpad) are seen as USB connected devices and
> interfaced via the phone's USB port (Atrix supports USB host mode).
>
> Essentially, this laptop dock is what people are talking about except
> for a generic host instead of for a phone. We would want to expose the
> HDMI input generically and probably with an additional VGA input. Of
> course there are also VGA-HDMI converters. Anyone wanna ring up
> Motorola to see if they're interesting in adapting the Atrix
> laptop-dock technology?
As someone who's done video for 20 years, I can tell you, Jake:
It ain't that easy.
The interface on the Atrix is purpose-built, and it's almost certainly
just a DVI/HDMI digital interface to a panel that expects that.
What's necessary for a standalone KVM of the sort we're talking about
is what the video people call a "genlock" circuit -- most machines that
need this at all have analog VGA out, and you have to have a chip that
can lock up to it, and extract the video from that analog signal cleanly.
This is, to quote the Jargon file, decidedly non-trivial to do well.
That's the reason why a single port unit, not on sale, is generally around
$400. If it was DVI/HDMI *only*, it could be substantially cheaper, but
I've never seen one that was.
Cheers,
- jra
--
Jay R. Ashworth Baylink jra@baylink.com
Designer The Things I Think RFC 2100
Ashworth & Associates http://baylink.pitas.com 2000 Land Rover DII
St Petersburg FL USA http://photo.imageinc.us +1 727 647 1274
