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Using Aximmetry with an External Keyer

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Introduction

Aximmetry comes with its built-in chroma keyer, the ADVANCED B keyer, which is highly appreciated in the industry. However, some of our users might use external keyers. In this article, we will describe how to use Aximmetry with an external keyer.

Workflow

Your workflow will be different depending on using a tracked or a virtual(trackless) camera.

Virtual Camera (trackless cameras)

Preparation

In this case, you feed the studio camera's image to the external keyer, which will produce two outputs:

  • fill
  • matte

Please note that the names of these outputs can vary with each hardware/software you use.

In Aximmetry

Set up your matte and color inputs in the startup configuration. These are usually SDI but can be NDI as well.
Note: It is very important to set these up properly, and not to swap them.

Place a virtual camera compound in your project, depending on the type of scene you are using.

For example:
[Common_Studio]:Compounds\VirtualCam\VirtualCam_A-B_Preview_3-Cam.xcomp

Connect the compound to your scene. If you are unfamiliar with these connections, please refer to this<setting up virtual camera> document.

Navigate to the BILLBOARDS tab.

Select the KEYER panel

Select EXTERNAL KEYER in KEYER TYPE

After selecting the EXTERNAL KEYER type, you will see, that the KEYER panel's attributes have changed, and you can select the Matte Device, which you have defined in the startup configuration.

To select the fill,

Select the INPUT panel

In the Pin Values window, you will find the line, Input Device. if the EXTERNAL KEYER type is selected, Aximmetry handles the Input Device input as fill.

Select the fill input which you have defined in the Startup Configuration.

Limited Functionality Alternative

Connect your studio camera to the external keyer.
Connect Aximmetry's output to the external keyer.

In this case, you can use Aximmetry to simply render the background to your composite, which is put together in the external keyer.
For this, Aximmetry does not need any inputs, only outputs the scene, which will provide the background.
Note: This gives very limited functionality to your workflow.

Limitations:

No, or very limited virtual camera movement, since there is no engine to match the camera's image to the transformation of the virtual set/background.

Tracked Camera

Potentially, there are two ways to set up your system with an external keyer if you are using a tracked camera.

External Keyer first

Preparation

You feed the studio camera's image to the external keyer, which will produce two outputs:

  • fill
  • matte

At the same time, the tracking system is connected to Aximmetry.

In Aximmetry

Place a tracked cam compound in your project, depending on the type of scene you are using.

example:
[Common_Studio]:Compounds\TrackedCam_Unreal\TrackedCam_Unreal_Prev_3-Cam_3-Billboard.xcomp

You can set up the fill and the matte exactly the same way as with the virtual camera.

You can find more details on how to set up camera tracking in this article<setting up tracked cameras>.

Aximmetry composites the rendered background with the external keyer's inputs to produce the final output (composite).
This way you can add virtual camera movements and it is relatively straightforward to adjust the delays between different devices.

Aximmetry first

Preparation

The tracking system is connected to Aximmetry.
Aximmetry renders the moving background based on the tracking data and outputs it.
This moving background is fed into the external keyer.
The studio camera's image is also fed into the external keyer.
The external keyer keys the camera's image and then composites it with the moving background which is coming from Aximmetry and outputs the final composite.

In Aximmetry

Place the tracked cam compound in your project depending on the type of scene you are using.

example:
[Common_Studio]:Compounds\TrackedCam_Unreal\TrackedCam_Unreal_Prev_3-Cam_3-Billboard.xcomp

Set up the tracking as previously discussed in the article<setting up tracked cameras>.. There is no need to set up any camera inputs.

Aximmetry outputs the moving background which can be connected to the external keyer.

Additional information

Note: In this case, you will have to manage the delay between the studio camera's image and Aximmetry's output. There are different ways to do this:

  • You might be able to adjust input delays with your external keyer.
  • If you use professional broadcast equipment, you can use it to add delay to the camera's image.
  • You can use another machine running with a different Aximmetry to add delay to the signal. (This solution is the easiest, which will give you a very good result, but not an absolute guarantee for perfect synchronization for every frame).
Note: With this setup, you can not add any virtual camera movements.

Additional Notes

Fill is also called Color.
Matte is also called Alpha.

Some keyers will output an inverted matte. It is recommended that you turn this off in the external keyer settings to get the proper composite in Aximmetry.


Example of an inverted matte.

You can also counteract this inside Aximmetry:

In case of a virtual cam compound, navigate to the BILLBOARDS tab.

In case of a tracked cam compound, navigate to the INPUTS tab.

Select the KEYER panel.

In the pin values, you can turn the Invert Matte On

Premultiply

Some keyers will output a premultiplied fill. It is recommended that you turn this off in the external keyer settings to get the proper composite in Aximmetry.


The image will look like this if the premultiply setting is incorrect.


The image will look like this if the premultiply setting is correct.

You can also counteract this inside Aximmetry in a similar way as above, but instead of the Invert Matte, you can turn the Premul Fill Off.

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