Rudgey
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Multiple displays running simultaneously

Sat Jul 28, 2018 5:47 pm

I’m looking for advice for a project that is running 4 x 17”screens simultaneously with different video footage on each screen.
I intended to use a Pi for each one.

Question
1) How can I sync them all to play the video footage at exactly the same time looping in sync (2 -3 min loop)?

2) I’m looking for a UK supplier of screens who can provide hdmi 15” or 17” screen modules ready to go without any case. No touch screen required. Any recommendations?

3) Can you get square screens?

I would really appreciate any help with any of these questions, thanks

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DougieLawson
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Re: Multiple displays running simultaneously

Sat Jul 28, 2018 5:56 pm

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ghans
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Re: Multiple displays running simultaneously

Sat Jul 28, 2018 7:12 pm

No Raspberry Pi can drive more than 2 screens at 30fps/1080p.
You will need multiple Raspberries. This is a solved problem.

www.piwall.co.uk

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syadnom
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Re: Multiple displays running simultaneously

Sun Jul 29, 2018 1:52 pm

Not sure if you want a single Pi to drive multiple screens or just a way to synchronously play a video of multiple displays.

For the first, I don't think you really can without resorting to USB video which will likely suck...

But the second, the most straight forward solution is to render the video on one Pi and stream it to a multicast address. Then on other Pis, each with their own screen, play the multicast stream with omxplayer. That should be VERY close to synchronous.

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Re: Multiple displays running simultaneously

Sun Jul 29, 2018 3:25 pm

Do people only read the title ?!

He did say one pi per screen....

You could have a copy of the video on each pi, and start each one playing simultaneously via SSH.
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Rudgey
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Re: Multiple displays running simultaneously

Mon Jul 30, 2018 8:34 am

Thanks for the suggestions, very helpful, I have looked at the Pi Wall before which is interesting.

Just to clarify I intend to run 4-5 HD videos 30 or 60 FPS, one video on each Pi for each screen, the problem is as they are of the same footage (each slightly different treatment) and need to sync together.

Ideally as simple as possible! as these will be used in an art installation and will need to be switched on each day at a gallery space.
If setting off the videos to run at exactly the same time is not straightforward I could possibly leave the exhibit running for two weeks and hope none of the Pi’s over heat?

Mike what is SSH ? I’m not much of a programmer

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RaTTuS
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Re: Multiple displays running simultaneously

Mon Jul 30, 2018 8:45 am

4 x (pi +screen) simultaneously is do able - depends on how to want to keep things synced - if they are all linked via ethernet you could arrange for one to start all videos at once and run for x hours with a restart when you see they have drifted
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ghans
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Re: Multiple displays running simultaneously

Mon Jul 30, 2018 8:51 am

I doubt there is any solution out there which is as "turn-key" as PiWall. Some basic computer knowledge will be necessary for that too, mind you.

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Re: Multiple displays running simultaneously

Mon Jul 30, 2018 9:25 am

Rudgey wrote:
Mon Jul 30, 2018 8:34 am
Thanks for the suggestions, very helpful, I have looked at the Pi Wall before which is interesting.

Just to clarify I intend to run 4-5 HD videos 30 or 60 FPS, one video on each Pi for each screen, the problem is as they are of the same footage (each slightly different treatment) and need to sync together.

Ideally as simple as possible! as these will be used in an art installation and will need to be switched on each day at a gallery space.
If setting off the videos to run at exactly the same time is not straightforward I could possibly leave the exhibit running for two weeks and hope none of the Pi’s over heat?

Mike what is SSH ? I’m not much of a programmer
Overheating is NOT an issue. This rumour really needs to go away!
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syadnom
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Re: Multiple displays running simultaneously

Mon Jul 30, 2018 2:41 pm

If you sync the time on the pis via ntp and you script the videos to start at the top of the minute then they should be pretty closely synced.

Ssh isn’t going to sync well, the time it takes for the sessions to connect is somewhat variable and also single threaded so you will have some offset.

Still...there’s the multicast option. Stream each video out from a single source to a different multicast address and have each pi play that. Then the pis don’t handle the timing, they just play the stream as it arrives.

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dividuum
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Re: Multiple displays running simultaneously

Tue Jul 31, 2018 4:42 pm

Rudgey wrote:
Mon Jul 30, 2018 8:34 am
Thanks for the suggestions, very helpful, I have looked at the Pi Wall before which is interesting.
[...]
Mike what is SSH ? I’m not much of a programmer
If you're willing to trade money for convenience, you can look at our info-beamer hosted digital signage solution. It can do what you describe easily, you don't have to program anything and setting things up and managing them is pretty simple. For different videos on different Pis, synced to play at the same time (which then requires all videos having the exact same duration) is pretty easy to do with the HD Player package. Basically you create a playlist for each screen, each having the same total duration. Then you activate "☑ synced playback" and install each on one of the devices. That's all. Updating content can be done by just editing your playlist again. Let me know if you have any questions.
info-beamer hosted - A user and programmer friendly digital signage platform for the Pi: https://info-beamer.com/hosted

Rudgey
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Re: Multiple displays running simultaneously

Sat Aug 04, 2018 7:58 pm

Info Beamer looks interesting, yes I would really like a turn key solution with start and stop times to control the media players. Unfortunately I think your solution David is rather out of my budget as it has more commercial features than I require as a poor Artist.
Also I will not have any internet access at the sites to stream anything, all needs to be self contained.

I wonder if there is any sort of usb media player which can be timed and synced ?

Otherwise I may have to ask my nephew who is a programmer to see if he can write something for me, your suggestions will give him some really helpful directions, thank you.

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dividuum
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Re: Multiple displays running simultaneously

Sat Aug 04, 2018 8:41 pm

Rudgey wrote:
Sat Aug 04, 2018 7:58 pm
Info Beamer looks interesting, yes I would really like a turn key solution with start and stop times to control the media players. Unfortunately I think your solution David is rather out of my budget as it has more commercial features than I require as a poor Artist.
info-beamer is really on the lower end of the price range for professional digital signage. Unless you get the screens and power to run your installation for free, I would guess that info-beamer adds around 30-40% to the total budget of a project like this if it runs for a year. Which seems to be more than affordable and your project is ready to go immediately and won't ever have to think about it again while it is running.
Rudgey wrote:
Sat Aug 04, 2018 7:58 pm
Also I will not have any internet access at the sites to stream anything, all needs to be self contained.
You don't need the bandwidth to stream. A dog slow internet connection (visitor WiFi?) is more than sufficient.
Rudgey wrote:
Sat Aug 04, 2018 7:58 pm
I wonder if there is any sort of usb media player which can be timed and synced ?
No idea, sorry.
info-beamer hosted - A user and programmer friendly digital signage platform for the Pi: https://info-beamer.com/hosted

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