This section describes the AJA Video implementation in more detail.

Note that "DVIO" refers to the Digital Vision Video Library used by Nucoda and Phoenix to interface to video I/O boards like AJA and DVS.

Mapping of Signals to SDI Ports - Kona 3G and Kona 4

The SDI I/O is mapped as labelled on the Kona 3G, Kona 4, AJA Breakout Box and cables.

  • 4K or UHD modes will map all four links as output, using SDI 1 to 4.


If the AJA video I/O card supports HDMI output using the selected format, video will automatically be output over HDMI in addition to SDI.

The DVIO AJA component will detect the capabilities of the downstream receiver attached to the HDMI port and configure the output accordingly, updating if the receiver changes while running. Specifically :

  • HDMI output will be set to 10 bits/component if the receiver supports that, otherwise 8 bits/component.
  • The protocol sent via the HDMI port will be switched between HDMI and DVI to match the receiver's expectations.
  • The HDMI output is always set to RGB, which all HDMI implementations are required to support (regardless of the receiver's support for YUV).
  • No option is provided to enable YUV over HDMI.

  • The Kona 3G supports 4K video (3840/4096x2160) over SDI but not HDMI. HDMI output is disabled while a 4K video format is selected, resulting in a green display on the attached HDMI receiver. 
  • Normal HDMI display will resume when a non-4K video format is selected.

  • The Kona 4 supports 4K over HDMI
    • From 2018.2, HDMI is always UHD/4K in 2Si Mode - in Quadrant mode HDMI is always HD (change from 2015.2)
    • 2017.1, HDR output over HDMI (as defined by the HDMI 2.0a spec) is supported. Kona 4 Only (monitoring and IO Preferences - page 2 and setup menu)
    • 2015.2, there is an option to downscale 4K to 2K for output via HDMI. This is for users with HDMI displays that do not support 4K. Kona 4 Only

  • Stereo over HDMI is not supported (left eye output only)
  • 2019.2 - Dolby Vision Tunneling via HDMI (HD only) - Kona 4 set to Quadrant Mode to allow 12 Bit RGB444

UHD and 4K

UHD and 4K modes are output over all four SDI ports as quad segments or using 2Si

Changes from Release 2018.2


There are now two transport modes for UHD/4K, this specifies how the signal is output from the Kona 4

  • 2Si -Signal Interleaved
    • For RGB444 10-Bit - all four SDI ports are used (RGB444 12 bit is not supported in 2Si)
    • For YUV422 10-Bit - only SDI Ports 3 and 4 are used as outputs
    • HDMI in 2Si mapping is always in UHD/4K
  • Quadrant Mode
    • Supports all UHD/4K modes using all four SDI Ports (there are frame rate restrictions)
    • RGB444 12-Bit is supported
    • HDMI in Quadrant mode will always be HD

12 Bit Modes - Required for Dolby Vision eCMU

  • 2018.2 - RGB 12-bit output is available only in Quadrant transport mode - not 2Si - Kona 4 / Kona 5
  • 2017.1 - RGB 12-bit output is available via 3G level A as well as B-DL. Kona 4 Only
  • 2015.2 - RGB 12-bit output is available via 3G level B-DL as well as dual-link and is thus supported for stereo and 4K content.
  • 2015.1 - as 2014.2
  • 2014.2 - Support 12 bit output in dual-link mode and it is not available for 4K or stereo.


3G Level A
In 2016.1 and earlier application versions, 3G level A can be used only for YUV422 1080/2160p video at high frame rates (greater than 30 fps).

In version 2017.1, 3G level A can also be used for RGB444 (10 or 12-bit) 1080/2160p video at normal frame rates (less than or equal to 30 fps). Kona 4 Only


Kona 3G does not support 3G level A for RGB444 video.

SD and 720p standards support YUV422 10-bit colour only.

IO Mode Behaviour

Video IO/Monitoring Preferences / VTR Layoff / VTR Capture UI andSetup menu in the GUI


  • Phys Links - The number of physical links (i.e. cables) connecting outputs or inputs (as relevant to use case) of the video I/O card to the remote SDI device. The user must set this to reflect the connections they have made to a monitor or VTR.

  • Max Data Rate - The maximum data rate that the remote SDI device can receive or will send and, if 3G, which levels of 3G are supported. The user must set this to reflect the capabilities of the remote device when performing video output or the output expected from the remote device when performing video input.

  • SDI Colour - The colour encoding that the user would like sent over SDI.  While our application will deliver this colour encoding whenever possible, it cannot be guaranteed to be delivered in all cases and the application may choose to fall back to a colour encoding compatible with the other parameters and the video format in use.

When monitoring a stereo project, the application will deliver stereo video whenever possible. However, it cannot be guaranteed to be delivered in all cases and the application may choose to fall back to mono.

If only one of the desired settings colour encoding and stereo can be achieved, the colour encoding will be preferred and output will fall back to mono.

UI Notification
The application informs the user of the actual SDI configuration in use. For VTR Layoff and Capture, this is displayed in the relevant UI. For monitoring, it is displayed in the main project editor display.

Coloured text is used to indicate general status :

  • Red indicates that the required video format is not supported at all with the current number of physical links and maximum data rate.
  • Yellow indicates that the required video format is supported but with a fall-back colour encoding or, for stereo monitoring only, fall-back to mono output.
  • White indicates that the video format is fully supported.
  • there is also a Sync indicator that will show if the sync is valid and locked

The Video IO/Monitoring Preference and Setup Monitoring page has a button "...View SDI Format Support" :


This opens a dialog that displays, for the current Physical Links, Max Data Rate and SDI Colour settings and each video format available:

  • Whether the format is supported at all .
  • What kind of SDI link will be used for this format.
  • What colour encoding will be used for this format and, if it is not the one desired by the user, why.
  • Whether stereo will be available for this format and, if not, why.

This should help gauge SDI output support for the selected settings and enable experimentation.