Configuring Duo 2 and 1 video output on ATEM

ArthurdeChaurand · September 29, 2025, 10:18am

Hello guys !

As many of you advised me, i bought a Blackmagic Duo 2 card for my Atem Television Studio Pro HD. But, unfortunately, i encounter some logs issues when i start my CasparCG server.

Here my config file:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <paths>
    <media-path>/home/casparcg/Documents/media/</media-path>
    <log-path>/home/casparcg/Documents/log/</log-path>
    <data-path>/home/casparcg/Documents/data/</data-path>
    <template-path>/home/casparcg/Documents/template/</template-path>
  </paths>

   <channels>
      <channel>
        <video-mode>1080p5994</video-mode>
        <straight-alpha-output>true</straight-alpha-output>
          <consumers>
            <decklink>
              <device>1</device>
                <embedded-audio>true</embedded-audio>
                <latency>low</latency>
                <keyer>external</keyer>
                <key-only>false</key-only>
                <buffer-depth>3</buffer-depth>
            </decklink>
          </consumers>
      </channel>

      <channel>
        <video-mode>1080p5994</video-mode>
        <straight-alpha-output>true</straight-alpha-output>
          <consumers>
            <decklink>
              <device>2</device>
                <embedded-audio>true</embedded-audio>
                <latency>low</latency>
                <keyer>external</keyer>
                <key-only>false</key-only>
                <buffer-depth>3</buffer-depth>
            </decklink>
          </consumers>
      </channel>
  </channels>

  <controllers>
    <tcp>
      <port>5250</port>
      <protocol>AMCP</protocol>
    </tcp>
  </controllers>

  <osc>
    <predefined-clients>
      <predefined-client>
        <address>127.0.0.1</address>
        <port>6251</port>
      </predefined-client>
    </predefined-clients>
  </osc>
</configuration>

My Blackmagic Desktop Video Setup :

All of my channels are setup in 1080p59.94 too

My cable behind the card :

Green = fill
Red = video
Blue = key

Am i correct here ?

I am running on a Ubundu

My error log from CasparCG Server 2.4.3 Stable version :

[2025-09-29 12:07:39.899] [info]    ############################################################################
[2025-09-29 12:07:39.899] [info]    CasparCG Server is distributed by the Swedish Broadcasting Corporation (SVT)
[2025-09-29 12:07:39.899] [info]    under the GNU General Public License GPLv3 or higher.
[2025-09-29 12:07:39.899] [info]    Please see LICENSE.TXT for details.
[2025-09-29 12:07:39.899] [info]    http://www.casparcg.com/
[2025-09-29 12:07:39.899] [info]    ############################################################################
[2025-09-29 12:07:39.899] [info]    Starting CasparCG Video and Graphics Playout Server 2.4.3 N/A Stable
[2025-09-29 12:07:39.900] [info]    "/usr/share/casparcg-server-2.4/casparcg.config":
[2025-09-29 12:07:39.900] [info]    -----------------------------------------
[2025-09-29 12:07:39.900] [info]    <?xml version="1.0" encoding="utf-8"?>
[2025-09-29 12:07:39.900] [info]    <configuration>
[2025-09-29 12:07:39.900] [info]       <paths>
[2025-09-29 12:07:39.900] [info]          <media-path>/home/casparcg/Documents/media/</media-path>
[2025-09-29 12:07:39.900] [info]          <log-path>/home/casparcg/Documents/log/</log-path>
[2025-09-29 12:07:39.900] [info]          <data-path>/home/casparcg/Documents/data/</data-path>
[2025-09-29 12:07:39.900] [info]          <template-path>/home/casparcg/Documents/template/</template-path>
[2025-09-29 12:07:39.900] [info]       </paths>
[2025-09-29 12:07:39.900] [info]       <channels>
[2025-09-29 12:07:39.900] [info]          <channel>
[2025-09-29 12:07:39.900] [info]             <video-mode>1080p5994</video-mode>
[2025-09-29 12:07:39.900] [info]             <straight-alpha-output>true</straight-alpha-output>
[2025-09-29 12:07:39.900] [info]             <consumers>
[2025-09-29 12:07:39.900] [info]                <decklink>
[2025-09-29 12:07:39.900] [info]                   <device>1</device>
[2025-09-29 12:07:39.900] [info]                   <embedded-audio>true</embedded-audio>
[2025-09-29 12:07:39.900] [info]                   <latency>low</latency>
[2025-09-29 12:07:39.900] [info]                   <keyer>external</keyer>
[2025-09-29 12:07:39.900] [info]                   <key-only>false</key-only>
[2025-09-29 12:07:39.900] [info]                   <buffer-depth>3</buffer-depth>
[2025-09-29 12:07:39.900] [info]                </decklink>
[2025-09-29 12:07:39.900] [info]             </consumers>
[2025-09-29 12:07:39.900] [info]          </channel>
[2025-09-29 12:07:39.900] [info]          <channel>
[2025-09-29 12:07:39.900] [info]             <video-mode>1080p5994</video-mode>
[2025-09-29 12:07:39.900] [info]             <straight-alpha-output>true</straight-alpha-output>
[2025-09-29 12:07:39.900] [info]             <consumers>
[2025-09-29 12:07:39.900] [info]                <decklink>
[2025-09-29 12:07:39.900] [info]                   <device>2</device>
[2025-09-29 12:07:39.900] [info]                   <embedded-audio>true</embedded-audio>
[2025-09-29 12:07:39.900] [info]                   <latency>low</latency>
[2025-09-29 12:07:39.900] [info]                   <keyer>external</keyer>
[2025-09-29 12:07:39.900] [info]                   <key-only>false</key-only>
[2025-09-29 12:07:39.900] [info]                   <buffer-depth>3</buffer-depth>
[2025-09-29 12:07:39.900] [info]                </decklink>
[2025-09-29 12:07:39.900] [info]             </consumers>
[2025-09-29 12:07:39.900] [info]          </channel>
[2025-09-29 12:07:39.900] [info]       </channels>
[2025-09-29 12:07:39.900] [info]       <controllers>
[2025-09-29 12:07:39.900] [info]          <tcp>
[2025-09-29 12:07:39.900] [info]             <port>5250</port>
[2025-09-29 12:07:39.900] [info]             <protocol>AMCP</protocol>
[2025-09-29 12:07:39.900] [info]          </tcp>
[2025-09-29 12:07:39.900] [info]       </controllers>
[2025-09-29 12:07:39.900] [info]       <osc>
[2025-09-29 12:07:39.900] [info]          <predefined-clients>
[2025-09-29 12:07:39.900] [info]             <predefined-client>
[2025-09-29 12:07:39.900] [info]                <address>127.0.0.1</address>
[2025-09-29 12:07:39.900] [info]                <port>6251</port>
[2025-09-29 12:07:39.900] [info]             </predefined-client>
[2025-09-29 12:07:39.900] [info]          </predefined-clients>
[2025-09-29 12:07:39.900] [info]       </osc>
[2025-09-29 12:07:39.900] [info]    </configuration>
[2025-09-29 12:07:39.900] [info]    -----------------------------------------
[2025-09-29 12:07:39.900] [info]    Initialized video modes.
[2025-09-29 12:07:40.303] [info]    Initializing OpenGL Device.
[2025-09-29 12:07:40.331] [info]    Initialized OpenGL 4.5.0 NVIDIA 580.65.06 NVIDIA Corporation
[2025-09-29 12:07:40.376] [info]    Initialized OpenGL Accelerated GPU Image Mixer for channel 1
[2025-09-29 12:07:40.376] [info]    video_channel[1|1080p5994] Successfully Initialized.
[2025-09-29 12:07:40.376] [info]    Initialized OpenGL Accelerated GPU Image Mixer for channel 2
[2025-09-29 12:07:40.376] [info]    video_channel[2|1080p5994] Successfully Initialized.
[2025-09-29 12:07:40.377] [info]    Initialized channels.
[2025-09-29 12:07:40.377] [info]    Initialized command repository.
[2025-09-29 12:07:40.377] [info]    Initialized image module.
[2025-09-29 12:07:40.377] [info]    Initialized ffmpeg module.
[2025-09-29 12:07:40.377] [info]    Initialized oal module.
[2025-09-29 12:07:40.377] [info]    Initialized decklink module.
[2025-09-29 12:07:40.377] [info]    Initialized screen module.
[2025-09-29 12:07:40.377] [info]    Initialized newtek module.
[2025-09-29 12:07:40.377] [info]    Initialized artnet module.
[0929/120740.547004:WARNING:policy_logger.cc(148)] :components/enterprise/browser/controller/chrome_browser_cloud_management_controller.cc(88) Could not create policy manager as CBCM is not enabled.
[2025-09-29 12:07:40.552] [info]    Initialized html module.
[2025-09-29 12:07:40.552] [info]    Initialized modules.
[2025-09-29 12:07:40.563] [info]    Device may not support video-format: 1080p59.94
[2025-09-29 12:07:40.564] [info]    DeckLink Duo 2 [1-1|1080p5994] Enabled embedded-audio.
[2025-09-29 12:07:40.564] [info]    DeckLink Duo 2 [1-1|1080p5994] Enabled low-latency mode.
[2025-09-29 12:07:40.564] [info]    DeckLink Duo 2 [1-1|1080p5994] Enabled external keyer.
[2025-09-29 12:07:40.579] [info]    DeckLink Duo 2 [1-1|1080p5994] Initialized.
[2025-09-29 12:07:40.591] [info]    Device may not support video-format: 1080p59.94
[2025-09-29 12:07:40.591] [info]    DeckLink Duo 2 [2-2|1080p5994] Enabled embedded-audio.
[2025-09-29 12:07:40.591] [info]    DeckLink Duo 2 [2-2|1080p5994] Enabled low-latency mode.
[2025-09-29 12:07:40.591] [error]   DeckLink Duo 2 [2-2|1080p5994] Failed to enable external keyer.
[2025-09-29 12:07:40.611] [info]    DeckLink Duo 2 [2-2|1080p5994] Initialized.
[2025-09-29 12:07:40.611] [info]    Initialized startup producers.
[2025-09-29 12:07:40.611] [info]    Initialized controllers.
[2025-09-29 12:07:40.611] [info]    Initialized osc.
[2025-09-29 12:07:40.621] [info]    DeckLink Duo 2 [1-1|1080p5994] Reference signal: not detected.
[2025-09-29 12:07:40.630] [info]    DeckLink Duo 2 [2-2|1080p5994] Reference signal: not detected.
[0929/120740.715297:WARNING:sandbox_linux.cc(393)] InitializeSandbox() called with multiple threads in process gpu-process.

My objective :

1 key and fill (so 2 output from decklink for my ATEM)
1 vidéo output (as source for my ATEM)

Thank you, again, for your help !
Arthur

ZimeX · September 29, 2025, 11:31am

This is not correct. As you can see in your screenshots channel 2 is on SDI3.

Then key is SDI 1 and fill SDI 2

I also don’t know if <straight-alpha-output> is valid XML for the config.

/Simon

ArthurdeChaurand · September 29, 2025, 11:34am

Hello Simon,

Ok so my config file is not good, right ?

ZimeX · September 29, 2025, 11:36am

Hello,

Your config file is ok. Except <straight-alpha-output>I cannot see where you got from. The log show it is working but this field does not add anything.

Do you not get any output?

ArthurdeChaurand · September 29, 2025, 11:38am

No i have no output, my casparcg server crashing every times at start with this error mentionned above

ZimeX · September 29, 2025, 11:40am

Then it is not clear in the log what causes caspar to crash. How are you starting the server?

How did you install it?

ArthurdeChaurand · September 29, 2025, 11:42am

Via prompt sh:

#!/bin/bash
# --- Chemin vers ton binaire CasparCG ---
gnome-terminal -- bash -c "/usr/bin/casparcg-server-2.4 \
   /usr/share/casparcg-server-2.4/casparcg.config; exec bash"

ZimeX · September 29, 2025, 11:43am

It could be something with CEF. How did you install this?

ArthurdeChaurand · September 29, 2025, 11:46am

Via the Stable Noble amd64.deb in line commands

Julusian · September 29, 2025, 11:48am

Nothing in that log output looks problematic to me

ArthurdeChaurand · September 29, 2025, 12:25pm

Hmmm i don’t understand, i have no input on my ATEM when i start video …

No images, no sound …

didikunz · September 29, 2025, 1:09pm

The numbering of the SDI outputs on these cards is a bit weird. I usually use an SDI monitor to try out each output, to figure out, what it is. Then you have at least the Caspar side correct and can go further with the ATEM configuration.

ArthurdeChaurand · September 29, 2025, 1:12pm

I really don’t have any video output, it’s very strange. I admit I’m a little lost in what I should do…

didikunz · September 29, 2025, 2:55pm

Do you have something, that you can look at an SDI feed somehow? A monitor, maybe with an SDI to HDMI converter or something? So that you can check, if something is coming out of the Decklink card’s outputs?

You can not solve a problem, as long as you don’t know what causes it. For instance it could be a problem with a setting in the ATEM, or somewhere in between. To isolate the problem you should first find out if something is coming out of the Decklink. If that is ok, you try the next device in your chain, until you found the problem and solve it.

ArthurdeChaurand · September 29, 2025, 3:53pm

Ok guys… Ahahah I didn’t sleep at all last night and it seems that it’s playing tricks on me… I had simply put my inputs in the outputs… there you go ahaha ! Well, I just still have to find the right scheme to manage the key and the fill because when I put a video in the program and I turn on CasparCG in DSK1, I have a black screen which comes to superimpose the rest.

andyw · September 30, 2025, 8:03am

There are some hints on Atem DSK config for CasparCG on the Wiki in the vision mixer section here.

didikunz · September 30, 2025, 8:23am

@andyw When I click your link I get an empty page. Maybe it works by copy / paste the link from here https://github.com/CasparCG/help/wiki/Server%3A-Vision-Mixer-Settings

andyw · September 30, 2025, 9:41am

@didikunz Thanks for catching that poor link.

Not sure why that did not work as I used the link icon alonside the Atem element on the page, right clicked and copied the link, pasting that address into the forum link field.

A bit more investigation shows that some click methods open a page to add a new topic to the wiki, but using a right-click takes me to the correct part of the vision mixer info. Quite odd.