Live Streaming in Unreal Engine 5

Software Setup

Users have the option to either stream real-time data or playback data.  If you are using Axis Studio, you can do both at once.   

Go to the Axis Studio and navigate to Settings → BVH Broadcasting → BVH Capture. For real-time capture data enable BVH - CAPTURE and for playback data enable BVH - EDIT. 

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Skeleton

Your target character rest pose will determine which skeleton to choose. 

  • Axis Studio - Thumb Open if you are broadcasting to a character in T-Pose.
  • Unreal Engine skeleton if you are broadcasting to an Unreal character in A - pose
  • Metahuman - For direct support to your metahuman character

Plugin Setup

In order to establish a connection in our Neuron Live link plugin, Axis software data must be active and properly setup prior to proceeding to the next step.

In your UE Editor, go to Windows >Virtual Production>Live link. Click Source --> Axis Neuron Live to view the following window options. Neuron Live Link supports UDP or TCP protocol to receive mocap data. Data from Axis Studio data should appear under Subject Name which will indicate the connection was successful. The subject name will match the name of the character in Axis Studio.

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  1. UDP: Update the local address number to match Axis Studio and make sure the port numbers match
  2. TCP: Deselect Is UDP so that the Live Link plugin can capture TCP data. Update the Remote Address to match Axis studio.

Retargeting Data

Next, you can either use the Noitom Robot skeleton that comes with the plugin, the UE4 Mannequin, or import your own FBX character.

  • Import a character into the content browser.
  • If you are importing a character:
    • Make sure Skeletal Mesh is enabled
    • Under Skeleton select none
    • Enable Use T0 as Reference Pose and Import Morph Targetsmceclip5.png
  • The import should create a few assets needed for real-time streaming:
    • Skeletal Mesh - Magenta Color
    • Skeleton - Blue Colormceclip6.png

Animation Blueprint for live sessions 

Create an Anim Blueprint to tell our character to use the Live Link data. 

  • Right click the Skeleton or Skeletal Mesh
  • Select Create --> Anim Blueprint 
  • Open the Animation Blueprint

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  • In the blueprint space, create a Live Link Pose node and connect the out pin to the Output Pose input pin
    • Type in the subject  name under Live Link Subject Name  

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Select the Live Link Pose node and in the Details panel, select a Retarget Asset.  Depending on what type of character you are using, different remaps will be needed

  • Live Link Remap Asset is Unreal’s base class.  Do not use this one with Axis
  • The Manual Remap Asset is a custom character remap.  You will need to open the GetRemappedboneName Function to modify it
  • The Mixamo OLD Live link Remap works with Mixamo characters with “Mixamorig” Prefix
  • The Neuron Remap drives characters with the Perception Neuron and Perception Neuron Pro Rigs
  • The Studio Remap drives Characters with the Studio Skeleton and Mixamo Rigs without the “Mixamorig” prefix
  • UE Mannequin Live Link Remap Asset drives CC3 characters and may work for other 3rd party characters

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  • After choosing a remap asset make sure to compile and save

Corrective T-Pose

This step is not necessary if you are using the UE4 Mannequin or another UE4 character in A-pose.  Make sure to select the Unreal preset in Axis Studio instead.

If your character is not in a T-pose, correct it following these steps, otherwise.  Some software have their characters in A pose by default, but T-pose is necessary to retarget data from the Axis Studio skeleton.

  • Open the character skeleton that needs correction
  • Use the skeleton tree to select the joints that need correcting to more closely match the Axis Skeleton
  • Make sure to look at the T-pose from the front, top, and side to make sure it looks correct

  • Once the desired pose is achieved, create an Animation Asset with the current pose
  • Name the Animation Asset something memorable and save it in the same folder as the mesh and skeleton
  • Add the corrective pose animation to the character's Anim Blueprint
  • Connect it’s output to the input of Live Link Pose
  • Compile and save. This will update your Anim Blueprint

Create Actor Blueprint Class for live sessions

Next, we are going to create an Actor Blueprint Class  

  • Right click on the Content Browser and select Blueprint Class

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  • Select Actor and open the blueprint

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  • Click Add Component --> Live Link Skeletal Animation Component and Skeletal Mesh component

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  • Select the Skeletal Mesh component
    • In the Details panel, choose your character’s Skeletal Mesh under Animation --> Mesh

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  • Now, just drag the Actor class into the scene

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