Important: Applies to Duo 2 and Quad 2 card. Some other card models (newer than Duo 2/Quad 2) might have the same architecture, but anything older than Duo 2/Quad 2 will not work as described below.

In this document we will be using the Decklink Quad 2 as an example, meaning we will describe having 8 configurable devices.

Our examples shows usage together with CasparCG. However, the device-mapping will work similarly with software like vMix and OBS.

Tip: The Ref input connector (used for Genlock or Tri-level) will always be located closest to the motherboard. In most PC tower cabinets that means that the card itself is mounted upside-down, which also means that you can locate the SDI ports left-to-right, starting with Ref, or bottom-up for rack-mounted cabinets (without PCI raisers).

The biggest source of confusion comes from the relation between the physical SDI I/O ports and the inputs and outputs exposed to the software that will be using it. The confusion comes from the card's flexibility to operate in multiple modes. Start by considering that all SDI I/O can be switched from inputs to outputs, which makes it a challenge to draw wire diagrams without having a plan for how the card will be used in a specific setup.

The software interfaces with the card through an abstraction named a Device. Configuring the card through the Desktop Video Software (found in the Windows Control Panel) decides how many devices it exposes, how they work, and if they are used as inputs or not.

The Quad 2 card has 8 devices, but only if they all are configured as "Single connector". Each of the 8 single-connector devices can be used by the software as either an input, or an output.

The software addresses the device, and it is important to understand how the devices map to the physical SDI I/O. As the software will read the devices in their order, please observe how the physical SDI ordering is interleaved: SDI 1, 2, 3, 4, 5, 6, 7, 8 appears as devices 1, 5, 2, 6, 3, 7, 4, 8.

The illustration below shows how SDI 1 appears as device 1 to the software, but SDI 2 appears as device 5.

The 8 devices actually consist of 4 pairs of 2 devices. The pairs are devices 1+5, 2+6, 3+7, 4+8. Looking at it as physical SDI I/O, this actually means SDI 1+2, 3+4, 5+6 and 7+8 due to the interleaved layout of the devices.

Each of the devices 1, 2, 3, 4 can be set as "Dual-Connnector". Doing this consumes the associated devices (5, 6, 7, 8), which will disappear from the system, effectively stops the connectors being exposed in the software.

Any device can be configured to be an output. A CasparCG channel can have multiple Decklink consumers, and they will all show the same content. The channel's video-mode will be set as the format of the Decklink device by CasparCG.

<channel>
    <video-mode>1080i5000</video-mode>
        <consumers>
            <decklink>
                <device>2</device>
        </decklink>
    </consumers>
</channel>

In this example we'll assume this is the first channel tag in the config, which makes this channel 1 for CasparCG. Adding device 2 as a consumer means the channel will play on SDI 3, given that device 2 is set up with a single-connector in the first place.

Note: Consumers can also be added runtime through the AMCP ADD command.

Important: As you will see with Key+fill outputs, device 2 will actually output on SDI 4 when in a dual-connector mode, and SDI 3 will then show the key-signal.

Any device that's not already being used as a consumer can be added as an input, also known as a producer.

Example AMCP command:

PLAY 1-10 DECKLINK DEVICE 5 FORMAT 1080I5000

In this example we will play device 5 as an input on CasparCG channel 1, layer 10. For this to work, please make sure that:

• Device 1 is set as a single-connector ("SDI 1") and not a dual-connector ("SDI 1 & SDI 2"). Only then device 5 is actually available to the software.
• Device 5 is not already being used as an output (consumer) by any software.
• Your input is connected to SDI 2.

Note: FORMAT is optional in the PLAY-command, but can be used to play inputs of other video-formats that the channel is currently running on. For example FORMAT 720p5000 on a channel with <video-mode>1080i5000</video-mode>. For more information, see the AMCP PLAY command.

Note: @todo: Add documentation on default producers in config once merged: PR 1315

Similar to a single SDI output, you can only address a single device in the consumer of a channel. Since CasparCG always operate with RGBA internally, you don't have to explicitly state that you want to produce a key+fill output. By setting the device as a dual-connector, it will work without any changes to the CasparCG config:

<channel>
    <video-mode>1080i5000</video-mode>
        <consumers>
            <decklink>
                <device>2</device>
        </decklink>
    </consumers>
</channel>

Note: In this example we have to make sure that device 2 is set as a dual-connector ("SDI 3 & SDI 4"). This will give key on SDI 3 and fill on SDI 4.

Instead of outputing a key+fill pair to use for keying in a separate vision mixer, the Quad 2 has the ability to do they keying internally.

<channel>
    <video-mode>1080i5000</video-mode>
        <consumers>
            <decklink>
                <device>2</device>
                 <keyer>internal</keyer>
        </decklink>
    </consumers>
</channel>

In this example, with the property <keyer>internal</keyer> we set device 2 to expect a "clean" SDI input on SDI 3 and anything playing on the CasparCG channel will be keyed/superimposed on top of this signal to come out "dirty" on SDI 4. Again, we have to make sure that device 2 is set as a dual-connector ("SDI 3 & SDI 4").

• All content (graphics, video and audio) will be added/keyed to the signal passing through.
• Throughput latency for the signal will only be 1 frame.
• The original content can still be captured by software, using device 2 as an input.
• The throughput signal can not be manipulated, only added to. To do DVE effects you need to capture the input to software, which adds latency accordingly (input + software + output). This also adds CPU/GPU load as the video will be processed by the software.
• Keying with the internal keyer is a "cheap" operation, as the CPU/GPU only has to produce the content that goes on top, and the keying is offloaded to be done by the Decklink hardware.

Finally, an illustration showing that all modes can be combined. The only limitation to keep in mind is that "dual devices" are limited to 1, 2, 3 and 4, and all "dual devices" consumes their respective device to pair with.

In this config CasparCG would use devices 1, 3, 4, 6 as outputs, and consume devices 2 and 8 as inputs.