What's best for E-Prime video timing accuracy: Mirror mode, VGA splitter, or Display Port splitter?

[Scott]

Hi David,

Actually, I submitted this basic question to E-Prime support a couple of 
hours after I posted here. Unfortunately, the body of my support request 
did not get submitted; don't know why but guess I goofed somehow. Even without 
the detailed explanation I posted here, I did get a decent response to only 
the title of my support request (nothing else got submitted): "What's 
better: mirror mode or splitter?"
Reply:

> Cloning or mirroring can cause timing issues since vertical blank 
> synchronization is not accurate between multiple displays. Determining 
> which display is considered primary can cause confusion and may not be 
> consistent between computer configurations. Instead of cloning the display 
> through software, it is better to split it physically using a VGA splitter 
> cable. If it is necessary for you to view the experiment on multiple 
> screens, you should use a splitter to direct the output.
>
> I hope this helps. Please let me know if you have any other questions.
>
> Sincerely,
> David Nicholson, Technical Consultant
>
I've asked for clarification and amended my request as follows:

> Thanks. You more or less answered my question from the support title, even 
> though (for reasons I don't understand) the actual text of the question was 
> not submitted.
>
> I'd like a little clarification and an answer to another part of my 
> question (which did not get posted). You are saying if I use a splitter, 
> then E-Prime will see only one monitor (connected to the display card) and 
> thus only one vertical blank signal; is that correct? Part of my question 
> that wasn't posted was that I will be using two LCD monitors. Considering 
> this, will it make any difference whether I divide the analog signal from 
> my display card, using a VGA splitter or the digital signal, using a DVI or 
> Display Port splitter? A digital connection can transmit additional 
> information about the display; I wonder if this might cause any 
> synchronization problems. On the other hand, the VGA signal will have to be 
> converted to digital data by the LCD display, possibly increasing the lag. 
> -- Thanks for clarification & recommendations regarding the preferred type 
> of splitter.
>
I'll post this support response whenever I get it. 

Thanks.

Scott
 
On Monday, December 10, 2012 12:49:02 PM UTC-6, McFarlane, David wrote:
>
> Scott, 
>
> Good questions, wish I had an answer, hope someone else does.  You 
> should submit this to PST Web Support at 
> http://support.pstnet.com/e%2Dprime/support/login.asp , after all it 
> is their business to know these things.  Then please post back here 
> with the answer. 
>
> Thanks, 
> -- David McFarlane 
>
>
> At 12/9/2012 05:08 PM Sunday, Scott wrote: 
> >I don't expect perfection, but would like feedback to help choose 
> >how to setup a new lab using E-Prime using physiological equipment 
> >in two rooms. One room has two PCs, one recording physiological 
> >measurements, connected (via the parallel port) to a second PC 
> >running E-Prime. Each will be monitored by experimenters in that 
> >room. The other room has the subject's video display and button box. 
> >My question has to do ONLY with the E-Prime PC. We want 
> >experimenters to be able to see what the subject sees, while they 
> >monitor physiological recording, so we want the E-Prime video 
> >mirrored on LCD displays in the two rooms. Of course this is a very 
> >common situation for such labs (using EEG, fMRI, EDR, etc). Our 
> >E-Prime computer has a video card (AMD RADEON HD 7470) with one 
> >Display Port and one VGA port. Using this computer and display card, 
> >there are 3 simple ways (afaik) to accomplish what I want and 
> >display the same thing on two monitors: 
> >    * Connect one LCD to the Display Port and the other to the VGA 
> > port, and set the display card to clone mode; 
> >    * Connect a VGA Y-splitter to the computer's VGA port, and 
> > connect one LCD monitor to each side of the splitter; or 
> >    * Connect a Display Port Y-splitter to the computer's VGA port, 
> > and connect one LCD monitor (via Display Port-to-HDMI or -to-VGA 
> > converter) to each side of the splitter. 
> > 
> >Using method #1, the E-Prime 2.0.10.184 or later Experiment Advisor 
> >will warn that "Mirroring can cause timing issues since vertical 
> >blank synchronization is not accurate between multiple displays..." 
> >(see <http://www.pstnet.com/support/kb.asp?TopicID=5014>KB 5014 - 
> >FEATURE: Experiment Advisor Module - Display adapter set to clone 
> >mode). However, I do not know whether using a splitter will actually 
> >improve timing consistency or solve any issues related to vertical 
> >blank synchronization. If a splitter would be better, Also, I don't 
> >know whether the type of splitter would make any difference in this 
> >regard. (I do know that video resolution and quality might differ). 
> >Note that I am aware of various issues (eg., input lag, rise time) 
> >that can compromise timing accuracy of LCD displays. As a said at 
> >the outset, I'm not expecting perfection, or even anything close to 
> >the accuracy of a single CRT monitor. My goal is simply to minimize 
> >the variability of the time between the onset sync, detected by 
> >E-Prime, and the onset of the visual display seen by the subject. A 
> >constant lag does not concern me. Also, the two monitors to do NOT 
> >need to be synchronized with each other, except to the extent 
> >necessary for even one to be (relatively) synchronized to the 
> >vertical blank. Also note that I am NOT concerned or asking about 
> >synchronization between physiological recordings and the vertical 
> >blank time detected by E-Prime, signaled via the parallel port; 
> >that's a different and less troublesome issue, imho. Also, I 
> >understand that timing accuracy is more or less critical, depending 
> >on experimental paradigms and physiological measures. All I'm asking 
> >about is which of the 3 methods listed above can be expected to 
> >yield the most consistent and reliable (or least bad) timings, as a 
> >general rule, when connecting two LCD displays, both showing the 
> >same content,  to one PC running E-Prime. If anyone knows any better 
> >methods, other than these 3, I'd like to hear about them as well. 
> > 
> >Thanks, in advance, for sharing relevant experience, knowledge, and 
> >advice. --Scott 
>
>

-- 
You received this message because you are subscribed to the Google Groups "E-Prime" group.
To post to this group, send email to e-prime at googlegroups.com.
To unsubscribe from this group, send email to e-prime+unsubscribe at googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msg/e-prime/-/O3aKng3xoVsJ.
For more options, visit https://groups.google.com/groups/opt_out.


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://listserv.linguistlist.org/pipermail/eprime/attachments/20121211/d0d2fb04/attachment.htm>