SDI output

Silverstack XT and Silverstack Lab feature 4K SDI output, enabling high-quality playback of ingested clips for QC on an SDI broadcast monitor. The currently selected clip in the player is mirrored to the SDI output, displaying the image in full-screen with 10-bit color depth and chroma subsampling of 4:2:2.

Supported devices#

To enable the SDI output, you need one of the following devices:

UHD (12G Signal) support

AJA T-TAP pro
AJA KONA series (12G)
Blackmagic Design Decklink Cards (12G)

HD (3G Signal) support

AJA Io series
Blackmagic Design Ultrastudio Products
Blackmagic Design Mini Monitor
Blackmagic Design Decklink Cards (3G)

Attach the according interface to your Mac (Thunderbolt or PCIe) and connect the SDI output of the device to the selected destination.

Drivers#

To use the supported devices, you must install all necessary drivers and software provided by the manufacturer:

For Blackmagic Design devices, this means installing the “Desktop Video” software, available in their support section.
For AJA devices, you’ll need the “AJA Desktop Software”, which can also be downloaded from their support area.

External video settings#

As soon as the SDI device is connected, Silverstack requests permission to use it as an external video device. In case you decide to activate the SDI playback later, you can enable it through “Settings > External Video”. You can disable the feature from the same menu in case another application demands its use. If you have multiple output devices attached, you can select which one to use by choosing it in the drop down menu:

Level: Switch between Legal and Full Range
RGB-YCbCr Conversion: Choose the color space Rec. 709 or Rec. 2020 for the outgoing signal.
Video Format:
- Try to Match Clip: This setting will try to match the output format of the SDI to the settings of the clips. Silverstack will try to keep the frame rate and fall back to HD if the resolution is not supported. If the frame rate is not supported it will fall back to 1080p24.
- Fixed : This setting will let you choose the output format manually.

Additionally, you can choose to release a Blackmagic device when Silverstack is in background by enabling the checkbox “Release Blackmagic device when Silverstack is in background”.

You can ignore AJA devices via the checkbox: Don’t use AJA devices

Note: Please be aware that the support of SDI formats depends on the compatibility of the attached hardware device that the implementation in Silverstack is based on.

The SDI indicator#

Once you enable external video output in the settings, a small indicator in the Silverstack media player header bar will display the current status of the SDI output.

Playback modes#

You can choose between two playback modes via the main menu > Playback:

Absolute Time Playback: Tries to play back footage in sync with audio. Silverstack XT will skip frames to stay in sync with audio when video processing or I/O is too slow.
Every Frame Playback: Aims to play back every frame accurately which leads to losing audio. Silverstack XT will play back frame-accurately even if that leads to non-realtime playback.

Image processing#

There are several options for displaying clips via the SDI device, which can be adjusted in the “External Video Out” window:

Visual Controls checkboxes
Allow you to reflect the current Image Analyses settings (False Color and Exposure Range) and framelines on the SDI device.

Orientation dropdown menu
Rotates the output. This setting needs to be used if your SDI display is oriented vertically.

Scaling and Position
“Scale to Fit” scales the image to fit into the output resolution, the full image is shown on the SDI display. “1:1 Pixels” does not scale but might show only parts of the image – in that case use the “Position” sliders to navigate.