Computer hardware question (Decklink SDI 4k related)

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Alexander Kinov

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Computer hardware question (Decklink SDI 4k related)

PostSun Dec 17, 2017 1:03 pm

Hi all,
I need to solve a problem with our broadcasting system, but I need to find something before doing anything. I can't make short description (for search or title), so I will give detailed description and I hope someone can advice me.

Thanks in advance!

I'm talking about PC workstation used for playing videos for broadcasting. The computer is equipped with Nvidia GeFOrce videocard and BMD Decklink SDI 4k.

A computer monitor is plugged into one of the outputs of the NVidia. It's used so we can view windows desktop and operate with menus, software, etc.
The BMD device is plugged into BMD video switcher and then the signal is sent for broadcasting.

Imagine the basic situation. You have only one videocard, with 2 or more ouptuts. You have 2 monitors plugged into it. Monitor 1 (for example) is used to see windows desktop, menus, software. Monitor 2 is secondary. You can play video from some software and set it to show on monitor 2. Then you unplug monitor 1. Monitor 2 still shows the video, but now it also shows menus, desktop, etc.

Now imagine my situation. The videos (played by professional software) are sent through the BMD. What will happen if I unplug the computer monitor from the NVidia card? Will the signal sent from the DeckLink start showing windows desktop and software or it will keep showing only the video?

We need to change few cables in our system and rearrange the working place. We need to unplug the computer monitor for few minutes. However, we can't stop the broadcast and we can't afford to make mistakes or make experiments while this computer is playing videos for broadcasting. That's why I need to know what will happen.

Thanks!
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Dave Johnstone

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  • Location: Adelaide

Re: Computer hardware question (Decklink SDI 4k related)

PostSun Dec 17, 2017 2:03 pm

The Blackmagic card is not seen as a graphics card by the OS, the desktop will never be shown on its output without some custom driver. As long as your OS and playout software is happy to continue headless then I don't see any reason why your playout will stop.

How urgent is this? I can play a video on one of my dev system (Linux with HD Extreme 3D) tomorrow and, while playing, unplug the UI monitor to see what happens.

Regards,

Dave.
Freelance Television Broadcast Engineer
and Software Programmer.
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Alexander Kinov

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  • Location: Varna, Bulgaria

Re: Computer hardware question (Decklink SDI 4k related)

PostSun Dec 17, 2017 2:25 pm

If the OS doesn't recognize the Deckling as graphic card, everything should be fine.
In fact, I checked the device manager - the only Display adapter is the NVidia. The BMD is visible under Sound, Video and Game controllers.
The video playing software has settings about the the video output - it shows the Decklink or the TVout (decklink selected).
After reading your answer, I actually tried something. We're broadcasting live at the moment (the playout is not used for the moment), so I tried unplugging the monitor for few seconds. Nothing happened. The video output of the Deckling gives black screen (it has to be black, since playout is not working at the moment. Then plugged the monitor again and everything looks ok. I tried starting Playout - it works fine.

Still, I didn't want to risk unplugging the monitor for more than few seconds, so I'll be thankful if you can make test for few minutes. Thanks!

edit: I tried something else just now. We're still broadcasting live from different source. I started the playout, then unplugged the monitor. The playout kept playing (through the Deckling) as always. Then I plugged the monitor again. Everything looks fine.
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Dave Johnstone

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  • Location: Adelaide

Re: Computer hardware question (Decklink SDI 4k related)

PostMon Dec 18, 2017 12:48 am

Just tried this on my test system, playing out a 60 min clip. Unplugged the UI monitor, plugged it back in then unplugged again - as expected, no effect was seen on the SDI output. Left the monitor unplugged for 30 mins or so, no problems observed.

Regards,

Dave.
Freelance Television Broadcast Engineer
and Software Programmer.
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Alexander Kinov

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  • Joined: Tue Nov 07, 2017 7:05 pm
  • Location: Varna, Bulgaria

Re: Computer hardware question (Decklink SDI 4k related)

PostFri Dec 22, 2017 10:18 am

Thank you very much for the help!

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