Help on slow screen update

[Robin Hill]

On Wed Nov 26, 2008 at 01:00:47PM +0100, Egil Solgerd wrote:

> Hi,
> 
> I am an inexperienced user who are running realVNC server on a PC to update
> two remote monitors with the same screen picture.
> 
> An Intouch application is running as an HMI system on the PC, and the Intouch
> picture are displayed on both Remote Monitors.
> 
> The problem is that the refresh time on the screen seems to be approximately 5
> seconds.
> 
> This is shown by alarm banners blinking very slowly, and there is also a clock
> on the screen that only updates every 5-6 seconds.
> 
> We have tested the connection form the PC to the Remote Monitors by pinging
> with 20000 bytes, and get a response time of 3ms, which should be good.
> 
> Any suggestions on what might be causing this slow screen update would be much
> appreciated.
> 
There's several ways for apps to update windows, and not all of these
can be picked up in the same way.  If this is a Windows system, then you
should be able to improve the performance by using a mirror driver (a
dummy graphics card driver that passes any updates to the VNC server).
I'd suggest trying with TightVNC (http://www.tightvnc.org/), which is
VNC compatible, and the DFMirage mirror driver
(http://www.demoforge.com/dfmirage.htm).  I think the commercial
versions of RealVNC also support a mirror driver.

Alternately, you can try changing the Capture Method within the VNC
Server Properties dialogue (see
http://www.realvnc.com/products/free/4.1/winvnc.html#Hooks) - polling
may work better for your use case.

HTH,
    Robin
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    ( ' }     |       Robin Hill        <robin "at" robinhill.me.uk> |
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