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Outputs

Blackmagic Decklink cards are add-on PCIe cards that output SDI signal (and, for some models, SMPTE 2110).

Outputting the video signal via Decklink cards is interesting because it is directly compatible with other professional equipment and eliminates the need for converters; it allows for longer cable runs than HDMI / DisplayPort; and most importantly, it supports more video outputs, either via 8-output cards, or by installing multiple cards.

One drawback is that the video formats are restricted to well-known broadcast formats. In particular, 16:10 video is not possible.

Professional ("Quadro") NVidia GPUs are recommended for optimal performance.

Just like a GPU output, a Decklink output captures a zone of the stage, supports deformations, can be mixed with GPU outputs on the same server.

To add one: Edit Media Server window → "Add Output" → "DeckLink SDI"

Multiple Decklink outputs per server (and per card) are supported.

Settings

decklink settings

  • Card ID: which Decklink device outputs the signal. Depending on the configuration in Decklink's control panel, a single physical card can expose between 1 and 8 logical devices.
  • Color depth: SDI is usually 10b, but 8b is supported too.
  • Color standard: sRGB / Rec.709 / Rec.2020 / Rec.2100 HLG (HLG forces 10-bit, embeds HDR metadata)

Synchronization & genlock

Multiple outputs on the same physical card works out of the box, no extra synchronization is required : using an external genlock is possible, but not required.

When using multiple physical cards, you need to provide a genlock signal, otherwise no output will work. This is by design, to avoid situations where customers think that the outputs are synchronized together, but they are not. A warning will be visible in Producer's LOG tab in this case.

Using a Decklink output will make the Decklink card drive the framerate of the mediaserver. This means that any GPU output will not be perfectly synchronized to its screen anymore, and might experience tearing. This is done to ensure that the SDI signal is perfect.

Limitations

  • No embedded SDI audio yet, but you can use Decklink's audio driver instead, which muxes the audio in the SDI.
  • No fractional framerates yet