Forums > Jitter

4 screens with one computer

May 07 2006 | 12:26 pm

Hello there,

I wonder if Jitter can manage 4 video projectors with different content on a single computer?
Thank you for your help!

May 07 2006 | 8:33 pm

i am also struggling with this, the recommended method, as discussed
previously on the list is to output a single high res matrix (or plane) and
split into 4 parts using a hardware quad-splitter.
i am searching for a hardware configuration to enable me to work with 2
video cards. an AGP based video card and one on the pci slot. ati do not
support opengl simultaneously on two cards, but as i understand nvidia cards
do <> (this method will soon be
replaced as some newer motherboards can accommodate two and even more
pci-express video cards working together.).
i am waiting for a PCI card and will report soon.
anyone else with enlightenment>?

May 07 2006 | 10:45 pm

I’m working on the same issue myself-I just bought 2 Matrox
DualHead2Go boxes ($150 each) to use a dual head ATI 9800 card with.
Send the 2 outs to the DualHead2Go boxes, then get 4 outs from that.
In theory it should work fine, although I’ve been too busy to hook it
all up to try it. I’ll report when I get to it. Should be easy to
send 2 double wide windows to the outs, play back 2 movies in sync.
Maybe I’ll get to it tonight now that it’s fresh in my mind.


May 07 2006 | 11:52 pm

i haven’t heard of this hack for the matrox dualhead. it is certainly not
mentioned in the features. creative gheto thinking. good luck man

May 08 2006 | 3:46 am

It’s not a hack. Maybe I wasn’t clear-I propose to use 2 of them to
create a 4 screen show on one machine with a dual head card-no
trickery involved. Matrox is also coming out this month with a 3
head and a 4 head box. So, maybe that will work better anyway? Not
sure until testing….


May 08 2006 | 4:07 am

We have several machines running 2 Nvidia Quadro FX 1400 cards each
driving 4 monitors, so it can definitely be done. I’m not sure how
much performance you’re going to get out of one machine doing this in
jitter though. The machines we have are running Debian and
XDMX/Xcinerama for seamless displays. So, it is definitely possible
to get 4 distinct monitors out of one machine.


May 08 2006 | 10:55 am

Depends on what the content is. I am outputting to 3 projectors using a 3Ghz Pentium with two dual head NVIDIA PCI Express cards and lots of OpenGL objects and it works fairly well on high resolution.If you want to play 4 different video clips at the same time, it’s more likely that your harddrive becomes the bottle neck, unless you can load all clips into your RAM.

May 08 2006 | 2:07 pm

Using a G5 Quad with 2 SATA harddrives and four nvidia 6600 I was successful
in outputting 7 PAL sized different movies. (Photo JPEG 75%).
The bottleneck was the decompression of the clips. This could be solved by
using the direct to window feature.

For what its worth. John.

May 08 2006 | 2:22 pm

correction deKron ;)
the cpu still has to read and decompress a frame to display it
regardless if you are using direct to window mode… frame
decompression is a function of quicktime not jitter

(however direct to window bypasses all the jitter matrix stuff, and
is faster)


May 08 2006 | 8:24 pm

Ah, good to know.actually I was not sure about that, it was just my
explanation of direct to window working much better.

Actually taking a very close look on playback of quicktime movie files is
that I did not succeed in just playing only one movie from harddisk when
using the "jitter matrix stuff" smoothly. After some loops I seem to loose
frames. I did test on mac and pc, small and big movies. Fast and slow
computers, openGL and not. VGA and s-video, different monitor settings. Only
direct to window looks just as playing a clip in quicktime.

When using effects and so this is not noticeable, but when playing clips
with smooth movement it appears all the time.

Any hint how to avoid this would be appreciated.

I also want to throw in a feature request, or question. Could it be possible
to have something like "direct to openGL"? Where a movie clip would be
directed to the openGL world and like that avoid the "jitter matrix stuff"?

Maybe using has the same effect, has it?

Thanks John.

May 10 2006 | 12:16 pm

i just got my second geforce PCI 5200fx and i along with the geforce 5200fx
AGP card i get opengl on all three screens.

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