user10559: I need to set up a three-screen HD video installation with sound for a friend's art exhibition. The videos will likely be provided as separate video files, each with a different video but exactly the same length and intended to be played synchronously. I'm looking for advice on how to set up the installation so that the three screens will be synchronised correctly and played on an endless loop. What's the best way to achieve this with consumer-grade equipment?
I can hopefully borrow three HD (720p) projectors - not sure yet which model, I'll hopefully find that out soon - or can possibly purchase three cheaper projectors specifically for this. I've been told it's important to have the same model (& year?) to ensure the color will be effectively matched.
I can borrow a laptop or mac mini to drive the video or could purchase one or more cheap devices if needed. I can also borrow blu-ray players if that's any use. Again, I need advice about what device to borrow/buy.
Sound is two-track stereo, so can be played from just one of the videos. That should be the easy bit. 

user3908: Using three random laptops for this is likely to be problematic. You may find that the players get out of sync fairly quickly. If you require frame-accurate sync (or better) over a video of any length, you usually need a single computer with a triple-headed graphics card (like Matrox) playing a single video comprising all three parts. 
I don't know Syncplay (recommended in another answer), but it's worth a try if it can keep continuous sync. Often such solutions don't maintain absolute frame sync over time. And depending on internal factors, "frame sync" may not be good enough to prevent disruptions at scene changes - you also need vertical genlock.

user2178: As you want to play three different videos, daisy-chaining projectors or copying the signal using an amplifier is not viable.
Machine
While you can get one machine to play to three different projectors I think it will be quite expensive and prone to errors.
Average laptops/desktops are not equipped to output a video signal to three screens. You will need a modern GPU or an external video card, which can be quite expensive. Additionally the hard disk and CPU should be able to play three videos simultaneously. Lower end machines might stutter and syncing will be very hard.
Therefore I suggest you borrow/buy three average laptops. Nowadays almost any laptop can play an HD video and connect to a projector without a problem. Try to get three laptops with the same OS, as that makes live easier.
For sound, just connect one of the laptops to a sound system using the line-out/headphone jack.
Software
VLC seems to have several ways to sync videos over the network. A Google search for vlc sync different machines network yielded results involving multicast and the third party tool Syncplay.
Other hardware
When using projectors they need to be calibrated. Simply calibrating one and copying the settings to the other two might yield unsatisfactory results. 
Proper calibration is done using a colorimeter, but you can also calibrate by eye if precision is not very important.
I've only calibrated a projector by eye several times, so I can not tell you more about colorimeter calibration. This subject might also be suitable for a separate question.
To connect the machines you'll need a router or switch. Wired connections are more reliable than wireless connections.
Rough Bill of Materials
3 x laptop
3 x projector
3 x video cable (VGA, DVI, HDMI, whatever the projector needs)
1 x 3.5mm audio jack cable
1 x sound system (2.1 amp/speaker combo is easiest)
1 x network switch or router with min. 3 LAN ports
3 x ethernet cables
2 x 4 port power strip (to balance load if needed)


user17885: I did a 3 screen art installation in a hotel lobby some years ago. The original system used media players in a rack with converters to pass DVI over cat5 cable. There was a control computer to keep the media players in sync. It was 20U of rack space, 15K of hardware and many hours of configuration and installation. It ran 24/7 for 7 years.
When the media players started dying I replaced the system with a single server computer and a Matrox Triplehead unit.
Then the plasma screens finally wore out. The new LCD monitors did not do DVI. Converting the outputs was going to be expensive.
That is when I switched to Brightsign HD players.
They will play in sync with each other with just a simple network connection to a small switch. The HD220 players are around $350 each and mount on the back of the monitor.
Less than a grand to replace 30K worth of junk.
Now I can shoot the video for that with a 4K camcorder and use handbrake to split it up. Back in the early days we had 3 Hidef cameras on a massive plate to line them up. Editing had to be done in sync.
Now I take the camera and tripod in a small pack and go out on my bicycle to capture video.

user17560: I was in same situation when I started my project in 2014. After a lot of research i found a very good solution.
I am running three projectors and one monitor on one computer so total 4 outputs i am using and it's working quite well.
I am using mac pro black cylinder model and I bought resolume arena software which can play multiple videos at a time in sync too.
There are two options you can go for, 

if you go for Mac pro which has 6 thunderbolt and one hdmi out then buy thunderbolt to HDMI/VGA/DVI..and connect you projectors and screen you are done with hardware and now coming to software part download resolume "https://resolume.com/software"  and you are all set to play the videos in sync.
If you want to go for Windows or you already have one  then buy a graphics card with multiple display outputs. you need at least 4 outputs graphics card because 3 for projectors and one for monitor which you will need to see the resolume software interface to play the videos.
Something like this "NVIDIA NVS 510 Quad DisplayPort UHD 4K Graphics Card" pls check specifications of any graphic card you like before you buy.



user10722: The Matrox graphics card is probably the easiest and most versatile approach. I use the TripleHead2Go, which as you'd assume sends a signal(s) to up to three monitors/projectors.
Multiple computers will never stay in sync. I found this out the hard way the night of an event.
In terms of software, if you're on OS X check out VDMX. There's a fully functional demo that you can grab. Setting it up for your needs would be fairly trivial after a quick search for the right approach.
PS. I would have just commented on the other answers, but I'm new here and don't have the credentials.

10559: <p>I need to set up a three-screen HD video installation with sound for a friend's art exhibition. The videos will likely be provided as separate video files, each with a different video but exactly the same length and intended to be played synchronously. I'm looking for advice on how to set up the installation so that the three screens will be synchronised correctly and played on an endless loop. What's the best way to achieve this with consumer-grade equipment?</p>

<p>I can hopefully borrow three HD (720p) projectors - not sure yet which model, I'll hopefully find that out soon - or can possibly purchase three cheaper projectors specifically for this. I've been told it's important to have the same model (&amp; year?) to ensure the color will be effectively matched.</p>

<p>I can borrow a laptop or mac mini to drive the video or could purchase one or more cheap devices if needed. I can also borrow blu-ray players if that's any use. Again, I need advice about what device to borrow/buy.</p>

<p>Sound is two-track stereo, so can be played from just one of the videos. That should be the easy bit. </p>
 3908: <p>Using three random laptops for this is likely to be problematic. You may find that the players get out of sync fairly quickly. If you require frame-accurate sync (or better) over a video of any length, you usually need a single computer with a triple-headed graphics card (like Matrox) playing a single video comprising all three parts. </p>

<p>I don't know Syncplay (recommended in another answer), but it's worth a try if it can keep continuous sync. Often such solutions don't maintain absolute frame sync over time. And depending on internal factors, "frame sync" may not be good enough to prevent disruptions at scene changes - you also need vertical genlock.</p>
 2178: <p>As you want to play three <em>different</em> videos, daisy-chaining projectors or copying the signal using an amplifier is not viable.</p>

<h3>Machine</h3>

<p>While you can get one machine to play to three different projectors I think it will be quite expensive and prone to errors.</p>

<p>Average laptops/desktops are not equipped to output a video signal to three screens. You will need a modern GPU or an external video card, which can be quite expensive. Additionally the hard disk and CPU should be able to play three videos simultaneously. Lower end machines might stutter and syncing will be very hard.</p>

<p>Therefore I suggest you borrow/buy three average laptops. Nowadays almost any laptop can play an HD video and connect to a projector without a problem. Try to get three laptops with the same OS, as that makes live easier.</p>

<p>For sound, just connect one of the laptops to a sound system using the line-out/headphone jack.</p>

<h3>Software</h3>

<p>VLC seems to have several ways to sync videos over the network. A Google search for <code>vlc sync different machines network</code> yielded results involving <a href="https://superuser.com/q/172529/141595">multicast</a> and the third party tool <a href="http://syncplay.pl" rel="nofollow noreferrer">Syncplay</a>.</p>

<h3>Other hardware</h3>

<p>When using projectors they need to be calibrated. Simply calibrating one and copying the settings to the other two might yield unsatisfactory results. 
Proper calibration is done using a colorimeter, but you can also calibrate by eye if precision is not very important.<br>
I've only calibrated a projector by eye several times, so I can not tell you more about colorimeter calibration. This subject might also be suitable for a separate question.</p>

<p>To connect the machines you'll need a router or switch. Wired connections are more reliable than wireless connections.</p>

<h3>Rough Bill of Materials</h3>

<pre><code>3 x laptop
3 x projector
3 x video cable (VGA, DVI, HDMI, whatever the projector needs)
1 x 3.5mm audio jack cable
1 x sound system (2.1 amp/speaker combo is easiest)
1 x network switch or router with min. 3 LAN ports
3 x ethernet cables
2 x 4 port power strip (to balance load if needed)
</code></pre>
 17885: <p>I did a 3 screen art installation in a hotel lobby some years ago. The original system used media players in a rack with converters to pass DVI over cat5 cable. There was a control computer to keep the media players in sync. It was 20U of rack space, 15K of hardware and many hours of configuration and installation. It ran 24/7 for 7 years.</p>

<p>When the media players started dying I replaced the system with a single server computer and a Matrox Triplehead unit.</p>

<p>Then the plasma screens finally wore out. The new LCD monitors did not do DVI. Converting the outputs was going to be expensive.</p>

<p>That is when I switched to Brightsign HD players.</p>

<p>They will play in sync with each other with just a simple network connection to a small switch. The HD220 players are around $350 each and mount on the back of the monitor.</p>

<p>Less than a grand to replace 30K worth of junk.</p>

<p>Now I can shoot the video for that with a 4K camcorder and use handbrake to split it up. Back in the early days we had 3 Hidef cameras on a massive plate to line them up. Editing had to be done in sync.</p>

<p>Now I take the camera and tripod in a small pack and go out on my bicycle to capture video.</p>
 17560: <p>I was in same situation when I started my project in 2014. After a lot of research i found a very good solution.</p>

<p>I am running three projectors and one monitor on one computer so total 4 outputs i am using and it's working quite well.</p>

<p>I am using mac pro black cylinder model and I bought resolume arena software which can play multiple videos at a time in sync too.</p>

<p>There are two options you can go for, </p>

<ol>
<li><p>if you go for Mac pro which has 6 thunderbolt and one hdmi out then buy thunderbolt to HDMI/VGA/DVI..and connect you projectors and screen you are done with hardware and now coming to software part download resolume "<a href="https://resolume.com/software" rel="nofollow noreferrer">https://resolume.com/software</a>"  and you are all set to play the videos in sync.</p></li>
<li><p>If you want to go for Windows or you already have one  then buy a graphics card with multiple display outputs. you need at least 4 outputs graphics card because 3 for projectors and one for monitor which you will need to see the resolume software interface to play the videos.
Something like this "NVIDIA NVS 510 Quad DisplayPort UHD 4K Graphics Card" pls check specifications of any graphic card you like before you buy.</p></li>
</ol>

<p><img src="https://i.stack.imgur.com/OBAlp.jpg" alt="Pic"></p>
 10722: <p>The Matrox graphics card is probably the easiest and most versatile approach. I use the TripleHead2Go, which as you'd assume sends a signal(s) to up to three monitors/projectors.</p>

<p>Multiple computers will never stay in sync. I found this out the hard way the night of an event.</p>

<p>In terms of software, if you're on OS X check out <a href="https://vidvox.net/" rel="nofollow">VDMX</a>. There's a fully functional demo that you can grab. Setting it up for your needs would be fairly trivial after a quick search for the right approach.</p>

<p>PS. I would have just commented on the other answers, but I'm new here and don't have the credentials.</p>
