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AJA Video Implementation

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

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

  • 4K or UHDTV modes will map all four links as output, starting with SDI 1 to 4.

HDMI Support

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.

I/O Mode Behaviour

Video IO/Monitoring Preferences / VTR Layoff / VTR Capture UI


In the Video IO/Monitoring preferences page, VTR Layoff UI and VTR Capture UI :

  • 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.

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


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

  • Whether the format is supported at all and, if not, why.
  • 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.

12 Bit Mode

For application version 2015.2 and later, RGB444 12-bit colour can now be sent via 3G SDI and is no longer limited to dual-link 1.5G.

This enables 12 bit in stereo and Quad-SDI scenarios as well as mono over a single cable.

3G Level A

In 2016.1 and earlier application versions, 3G level A can be used only for YUV422 1080/2160p video at high framerates (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 framerates (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.