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

[Scott]

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:

   1. Connect one LCD to the Display Port and the other to the VGA port, 
   and set the display card to clone mode;
   2. Connect a VGA Y-splitter to the computer's VGA port, and connect one 
   LCD monitor to each side of the splitter; or
   3. 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 KB 5014 
- FEATURE: Experiment Advisor Module - Display adapter set to clone mode<http://www.pstnet.com/support/kb.asp?TopicID=5014>). 
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/-/wEhDBYyoJ_oJ.
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/20121209/a46cc893/attachment.htm>