Video Signal Splitter Issues

[niebs]

So I am having problems with video playback in our sanctuary and am wondering if our VGA video signal splitter could be to blame.

Problem#1: Video runs smoothly within presentation program (EasyWorship 2009) but appears like it skip frames on the big screen (fluid motion looks a bit jagged, for example).

Problem #2: One of the projectors sometimes has difficulty finding the VGA signal from the computer (searches for signal, eventually locks on to it).

Setup/Gear: We run two VGA signals from our video card (nVidia GTS450), one to local monitor, one to a CHEAP VGA splitter. Split signal is run via VGA cables to each projector (InFocus 2114's).

I've checked all the physical connections and they appear to be solid.

Could the problems listed above be caused by the cheap VGA splitter? If so, could someone recommend a better (budget-conscious) solution?

Thanks for your help!
-Jamie

[Brad Weber]

It could be the VGA splitter/DA. Or the VGA cable (you didn't mention how long the cable runs are). Or the settings of the computer and graphics card (are you running at the native 1024x768 resolution of the projector and at a refresh rate the projector accepts?). The last is free to address, so start there. Beyond that, knowing the length of the VGA cables and the actual splitter/DA model used would help.

[[Admin] osborn4]

If that is an unpowered splitter, I'd bet that's the problem.

[niebs]

Thanks for the replies. The VGA cable runs are 100'. The splitter is literally a no-name brand 1:4 splitter, but it is powered.

The resolutions and refresh rates are set correctly for the video card.

Thanks again.
-Jamie

[prochlea]

The first and easiest thing to try beyond making sure that your resolution is at 1024x768 would be to plug the VGA cable directly into the video card... bypassing the splitter. If that corrects the video, you know where the problem is.

Also - you should make sure you have the latest versions of your video card drivers, and any video codecs that EasyWorship uses. Maybe some EW users can chime in on proper file types and codecs...

[niebs]

Duh! Great idea...I will bypass the splitter and test the video...thanks for that!

[blonborg]

Once you get it figured out, label the connections.

We had a lot of problems along these lines in weeks leading up to Easter and afterwards. We've got a wireless DVI connection (Avocent) to our projector. While troubleshooting problems, various folks would tear things apart and not put it back the way it was in the first place.

- bill

[niebs]

Well, I've done some testing by taking the VGA splitter out of the signal path, and I get the same problems.

So the current problems are:

• Mild-to-Moderate choppy video playback
• Signal dropout (projector searches inputs), but mostly during initial acquisition of signal from computer. Seems like once it finds it, it locks on, but occasionally loses it randomly.

Questions:

• Is the VGA Multiplier/Splitter we use (see link above) the same as a distribution amplifier (DA)? I can't tell by the listed specs...
• My videocard has DVI to VGA adapters...could those degrade the signal?
• Is there signal loss expected with 100ft. VGA cable runs?

Thanks for your insights.
-Jamie

[Brad Weber]

I can't find any information that says if that device (which seems to be a VM114A) provides any gain including compensation for the split losses.

Every connection, adapter, etc. in the path potentially adds some loss or other signal degradation. A 100' cable run with several adapters and intermediate connections may be comparable to a longer cable in terms of signal losses and corruption.

It is very difficult to estimate the loss of any specific length of VGA cable since "VGA cable" can reference such a range of actual products. You'd pretty much have to test the actual cable or know the specific cable used in the construction and its characteristics in order to put specific numbers to it. And even if you were able to estimate the actual cable loss, you'd need to know the output level from the computer and the input level required by the projector in order to know if those losses were acceptable or not.

All of these factors as well as factors such as resolution are why it can be so difficult to say with any certainty what length of "VGA cable" will work or not on any general basis. Also remember that the total cable run and associated losses would include both the connection from the computer to the DA and from there to the projector. I would say that a 100' cable is typically going to be pushing it with generic VGA cable.