# Many Video Outputs



## Ard (Aug 6, 2018)

I'm a Sound Designer by trade, so I'll use audio terminology to describe what I'm looking for.

When I want to patch my Qlab into many different analog speakers. I use an audio interface, (focusrite, MOTU, ect) to get many different channels.

For a personal video project, what is available to patch my Qlab into many different analog televisions? Is there such thing as a "video interface"? It seems every "video interface"-esque product is only 1:1, for one source to one destination. Is there a USB/Firewire/Thunderbolt box that can be patched into multiple RCA destinations? Either conveniently or inconveniently?


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## sk8rsdad (Aug 6, 2018)

Does each analog TV show the same video or different video on each TV? Are they actually TV's with a tuner or composite video monitors?


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## Ard (Aug 6, 2018)

Discrete isolated Signals. Either an RCA line to each TV or, ideally, a handful of "any-channel" RF Modulators chained together.

Where I'm stuck is getting multiple channels of analog video out of a computer. With audio this is super easy but I'm not seeing any options on the video side.


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## dbaxter (Aug 6, 2018)

I fear you're stuck because you're not used to being able to plug additional video cards into your computer like you can on a Windows machine. You might have some success looking into the Matrox line of multiple 'head' video out devices. They do work with OSX.


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## sk8rsdad (Aug 6, 2018)

The typical approach for multiple video streams is a media server. In your case there's the added wrinkle of converting the signal to an analog feed or RF signal. This one is out of my depth. Feeding a media server into multiple RF modulators is likely too expensive for a home project. It would be cheaper to replace the TVs with digital displays. 

If Qlab can send to an IP device then maybe there's a slightly less expensive with an IP-to-analog converter on each TV, but I don't think QLab can do that.

If it were the same signal for each TV then ZeeVee (and others) make devices that can do the RF modulation, but that's not a typical home project unless you've recently won a Powerball draw.


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## Ard (Aug 6, 2018)

dbaxter said:


> I fear you're stuck because you're not used to being able to plug additional video cards into your computer like you can on a Windows machine. You might have some success looking into the Matrox line of multiple 'head' video out devices. They do work with OSX.


Matrox is the right idea, but then I believe I'm capped at three channels per thunderbolt or minidisplay. Curious: If I was running a Windows machine are there options not found in macland that might bring me in the right direction?


sk8rsdad said:


> The typical approach for multiple video streams is a media server. In your case there's the added wrinkle of converting the signal to an analog feed or RF signal. This one is out of my depth. Feeding a media server into multiple RF modulators is likely too expensive for a home project. It would be cheaper to replace the TVs with digital displays.
> 
> If Qlab can send to an IP device then maybe there's a slightly less expensive with an IP-to-analog converter on each TV, but I don't think QLab can do that.
> 
> If it were the same signal for each TV then ZeeVee (and others) make devices that can do the RF modulation, but that's not a typical home project unless you've recently won a Powerball draw.


 I had considered Syphon over IP to a raspberry pi or similiar device that had an analog video output built in, but then I believe I lose the audio, and that could become a overly-complicated setup anyway.


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## RonHebbard (Aug 6, 2018)

Ard said:


> Matrox is the right idea, but then I believe I'm capped at three channels per thunderbolt or minidisplay. Curious: If I was running a Windows machine are there options not found in macland that might bring me in the right direction?
> 
> I had considered Syphon over IP to a raspberry pi or similiar device that had an analog video output built in, but then I believe I lose the audio, and that could become a overly-complicated setup anyway.


Hi @Ard! Let's page @ruinexplorer for you. 
Toodleoo! 
Ron Hebbard


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## ruinexplorer (Aug 6, 2018)

Your easier bet will be sticking with a composite signal. When you say "many", what ballpark number are you looking for? 

I think what I would be looking at is one of the devices for a video wall. These can take a single signal and break it into multiple streams, so that each monitor only receives one section of the overall image. I would use a media server program with an output raster the size of your total display and then fill that with all your video streams. The biggest challenge will be the processing power for all of the clips running at the same time.

I hope this gives you a direction to start.


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## dbaxter (Aug 6, 2018)

Ard said:


> Curious: If I was running a Windows machine are there options not found in macland that might bring me in the right direction?


A Windows machine can easily have as many as 4 video outputs as there are PCI sockets on your mother board. I say 4 as I'm not aware of any video cards with more than 4 outputs. Now you're going to need a hefty CPU to drive that, but the cards themselves will help with the processing. Since you say "analog televisions", I assume you can't use the HDMI or VGA output these cards will have so you'll still need converters to get to a composite video signal (and yet again to get to a Channel 3 signal).
For software, I can't help but mention that Cue Player Premium Plus [disclaimer - my company] will control up to 6 video displays.


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## Chris15 (Aug 8, 2018)

The reason that you don't see multi output video devices in the same way you see audio interfaces is all down to data rates.
Let's call an audio signal of 48 kHz at 16 bits standard. Add in some overheads and that gives us a data rate of around 800 kbps per channel.
For a 1080p60 video signal, you're looking at a data rate just short of 3 Gbps.
So in the same amount of bandwidth as 1 HD video signal we can fit over 3500 audio channels.
When we think about USB 3.0 only having 5Gbps of bandwidth available, the number of uncompressed video channels becomes severely limited.

Now most of the time a PC is not going to send uncompressed video to the output device, it'll rely on the video card's RAM and GPU to do much of the heavy lifting, but there are still several times more bits that need to be sent every second for a video image vs an audio signal and so the physics will always dictate that we are unlikely to see a 6 output USB to video box...


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## Ard (Aug 8, 2018)

ruinexplorer said:


> Your easier bet will be sticking with a composite signal. When you say "many", what ballpark number are you looking for?
> 
> I think what I would be looking at is one of the devices for a video wall. These can take a single signal and break it into multiple streams, so that each monitor only receives one section of the overall image. I would use a media server program with an output raster the size of your total display and then fill that with all your video streams. The biggest challenge will be the processing power for all of the clips running at the same time.
> 
> I hope this gives you a direction to start.



My ballpark would be around 12. Your linked HDMI splitter unit looks like a great upgrade from a triplehead.


Chris15 said:


> The reason that you don't see multi output video devices in the same way you see audio interfaces is all down to data rates.
> Let's call an audio signal of 48 kHz at 16 bits standard. Add in some overheads and that gives us a data rate of around 800 kbps per channel.
> For a 1080p60 video signal, you're looking at a data rate just short of 3 Gbps.
> So in the same amount of bandwidth as 1 HD video signal we can fit over 3500 audio channels.
> ...


Thats it! I was so curious why there wasn't an overtly easy consumer-friendly option. Data rate makes sense. Although for lo-fi situations like mine, I'd be curious how many streams you could fit (but now I'd be surprised if there's any sort of product in the market for that).

At the end of the day, I'm now considering just going for a team of raspberry pis, running independently as opposed to a single Qlab brain, as my situation could operate either way. But I'm super glad to be a bit more informed on video workflow! Thanks everybody.


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## StradivariusBone (Aug 8, 2018)

The Triple/DoubleHead2Go units take a single output display and essentially make a super wide window that can be divided into three monitors. Windows/OSX will see it as a single display, but Matrox has software that divides it into three windows. It works...sort of. I don't know that they have updated the software since High Sierra came out. As of a few months back they had not. I wouldn't recommend buying it before trying it out. I don't think it will be the best solution to your specific problem.


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## jtweigandt (Aug 8, 2018)

I use pi's for kiosk display at our Will Call and for a large projection "slide show"
And since you mentioned my favorite little micro computer.. here's a link to a whole nuther rabbit hole
raspberry pi video wall https://www.raspberrypi.org/blog/video-wall/

https://matthewepler.github.io/2016/01/05/piwall.html


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## ruinexplorer (Aug 8, 2018)

A device like TripleHead2Go will tell the graphics card that the display is twice or three times as wide and then allots the left/center/right portion of that image to separate displays. This works great if you have a need for more higher resolution displays but only one output.

A video wall processor will take your standard display (say 1920x1080), break it into pieces (like the TH2G), upscale each piece to fit the resolution of the display, and display them in the order you have told it. Think about a painter's grid for video. For your application, I would personally use a program like Isadora where I could put six videos on one output and six on a second output. Each of those outputs would go to a 2x3 video wall processor, sending your video where it needs to go. Since each of the displays is low resolution, if your files are all 480i to match, you shouldn't tax your system.

jtweigandt I've looked at that raspberry pi video wall set up and would love to try it some time. Have you tried it?


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## jtweigandt (Aug 9, 2018)

jtweigandt I've looked at that raspberry pi video wall set up and would love to try it some time. Have you tried it?[/QUOTE]

I have not tried it, but have used pis for at least 6 different applications from video kiosk, to rdp terminal, to xray image storage and retrieval ,to the comm backbone for the theater, and love those darned little things. Lotta bang for the buck


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## ruinexplorer (Aug 9, 2018)

Definitely cheaper than the commercial version that I posted. One more thing for my project box.


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## Jay Ashworth (Aug 10, 2018)

One thought that I don't know if anyone quite got to.

If you can put 4k out of your computer, you could then use something like those RPis with the customized omxplayer to pick specific parts out of the 4k, effectively multiplexing all your video panes into it.

Is 720p enough actual end-screen resolution for your use? That could increase how many signals you could mux.


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