User Manual

Hot Keys

Key	Action
P	Play
R	Rewind
L	Loop
[	Set Range Start
]	Set Range End

Audio Player and Recorder

Allows you to load custom audio and serves as the primary playback mechanism for Audio2Face.

Option	Effect
Audio source Directory	Browse to a folder destination to load all of the audio files within that folder into the “track” menu.
Track	Allows you to select which audio track you would like to playback from your specified library location. Only .wav files are supported currently.
Range	The first box allows you to clip (trim) an audio file to set a desired start time. The second box allows you to clip the audio to specify the end point.
Timeline/AudioWaveForm	A visually descriptive timeline of the audio track - Use mouse to scrub back and forth.
Play Controls	Play - Return to Head - Loop playback and Record.
Recording	Pressing the record button (red Dot) in the play controls panel will reveal the recording tools and live mode for audio2face.
Mute	stops the audio stream to A2F.
Rec	Click to record a new Wav audio file
Live	Click to enable live mode - A2F driven by real time voice data input.
New	Creates a new .wav file to record - enter desired name in the panel to the right. Auto increments names when new tracks created with the same name.
Save	Allows you to save your audio recording as a .wav file.

Attached Meshes

Allows the selection of the desired source training asset.

• Nvidia’s Audio2Face asset loads by default.

• This feature will allow you to assign custom meshes for custom A2F neural networks (NN). (coming soon)

Network

Option	Effect
Network Name	Select which Neural Network you want to use.
Processing Time	Displays the latency of the selected Network.

Pre Processing

Allows the adjustment of key variables that influence the animation result.

Option	Effect
Prediction Delay	Allows the user to tweak the alignment of the audio input and animation output.
Input Strength	Adjusts the audio volume - allowing the user to influence the range of motion of the animation resolve. Can be muted for a subtle performance or amplified for larger/louder performances.

Post Processing

Allows the user to independently control smoothness and strength of the motions on upper and lower face.

Option	Effect
Upper and Lower Face Smoothing	Smooths the motions on the upper and lower regions of the face.
Upper and Lower Face Strength	Allows the user to determine the amplification of the motion on the upper and lower regions of the face.
Face Mask Level	Allows the user to determine the boundary of the upper and lower region of the face. (in the axis of the height)
Face Mask Softness	Allows the user to determine how smoothly the upper and lower face regions blend on the boundary.

Emotion

Allows the user to select a specific face shape from animation training sources to impose on the default face - allowing the user more control to inject specific emotional expressions onto the performance.

Option	Effect
Source Shot	Selects the animation clip.
Source Frame	Selects the specific frame from the animation source to use as shape of influence.

Multiple instances of Audio2Face

You can create multiple instances of Audio2face to run multiple characters in the same stage / scene.

Option	Effect
A2F Pipeline	Adds a connected set of A2F modules.
Male Head	Adds another Default head asset to the scene.
Audio Player	Creates a new Audio Player.
A2F Instance	Creates a new instance of the Audio2Face Network.

OmniGraph Editor

Each Audio2Face instance, audio player and target geometries relationship can be changed in Omnigraph to allow flexible arrangements of which Audio player is connected to which character / instance of audio2face.

Streaming Audio Player

Streaming Audio Player allows streaming audio data from external sources and applications via gRPC protocol. The player supports audio buffering. Playback starts automatically.

• To test Streaming Audio Player you can open corresponding demo scene in the image below.

• Menu -> Audio2Face -> Open Demo Scene -> Streaming Audio Scene.

• Or create a player manually

• In the Audio2Face panel click “+ Audio Player” -> “+ Streaming Audio Player”.

• Or, alternatively, Menu -> Audio2Face -> “+ Audio Player” -> “+ Streaming Audio Player.

• Once the player is created, you need to connect it to the Audio2Face Core instance in Omni Graph Editor (connect corresponding “time” attributes).

• Use the Prim Path of the created player as one of the parameters for the gRPC request, when passing audio data to the player from an external source.

• To send the audio data to the player you need to implement your own logic (client), which pushes gRPC requests to the Streaming Audio Player server.

• Example of such client implemented in Python is provided in “test_client_py”, which is located in A2F directory.

• AUDIO2FACE_ROOT_PATH/exts/omni.audio2face.player/omni/audio2face/player/scripts/streaming_server/test_client.py

• The script provides detailed description of the protocol and parameters (see comments) and also serves as a simple demo client, which takes input WAV audio file and emulates an audio stream by splitting it into chunks and passing it to the Audio Player.

• To test the script: - Launch Audio2Face App and open the Streaming Audio Scene (or create a player manually) - Run the test_client.py script: - python test_client.py <PATH_TO_WAV> <INSTANCE_NAME> - PATH_TO_WAV: provide a path to any WAV audio file with speech - INSTANCE_NAME: Streaming Player Prim Path (see above)

• Required pip packages to be installed. - grpcio - numpy - soundfile - google - protobuf

Character Transfer - Retargeting Pipeline

The Mesh Retargeting tool is available on the Character Transfer Tool tab.

The status message at the bottom of the widget informs the user if there are any steps missing to execute the retargeting successfully.

You can access sample assets used in the online tutorials for the character transfer process in the following locations.

• Omniverse mount: \Nvidia\Assets\Audio2Face\Samples\

• \<Audio2Face Install Directory>\assets\

Note

Hidden directories are currently not visible in content browser / the app’s file browser - will be fixed in upcoming version)

Meshes

In this panel, users can select the meshes to use in the character transfer process.

Option	Effect
Driver A2F Mesh	Selects the character mesh that will be driven by A2F. It should be in neutral closed mouth expression. This mesh is not used for picking correspondence points. (On mark retarget example, this would be /World/charTransfer/mark)
Target Mesh	Selects which character head to retarget onto.

After the target mesh is assigned the “openMouthA2Fmouth” field will appear.

Option	Effect
OpenMouth A2F Mesh	Selects the character mesh that share the same topology as the Driver A2F Mesh, but in Open mouth expression. (On mark retarget example, this would be /World/charTransfer/mark_openMouth)

Mesh Fitting - Correspondence

This is the authoring panel for the correspondence points. This panel remains minimized until the meshes are correctly assigned in the Meshes panel.

Option	Effect
Correspondence visibility	Visibility switch for the points and lines correspondence viewport draw.
Preset	Load and save correspondence setups for custom characters and preloaded presets.
Display Size	Controls the draw size of the correspondence points.
Correspondence list	This widget shows the authored correspondences. Users can select the correspondence pair from the list by clicking it. Shift key or Ctrl can be used in combination with the mouse click to do multiple selections.
Add Mode	Enter Add Mode. In this mode, the user can pick the correspondence points between the meshes.
Edit Mode	Enter Edit Mode. In this mode, the user can reposition the existing correspondence points by clicking and dragging the point to a new position on the mesh.
Delete Mode	This will delete selected correspondence points on the list.
Fitting Iterations	Shape Fitting number of iterations. Can be more accurate with a higher number but also takes longer to execute. 3 is a good starting point and is used on all our example characters.
Fitting Stiffness	Shape Fitting stiffness to try keep its original contour. 100 is a good starting point and is used on all our example characters.
Begin Mesh Fitting	Execute the retarget operations when clicked.

Post Wrap

Post wrap panel shows the available fitted mesh for the post wrap process. The Smooth Level and and Begin Post Wrap button will be hidden if not Fitted Mesh is selected from the drop down.

Option	Effect
Fitted Mesh	Fitted mesh is assigned in this field. Mesh created from Mesh Fitting process above will be automatically selected when the Mesh Fitting process finishes.
Smooth Level	Smoothing level on the target mesh. Low number preserves the original details of the A2F mesh, high number smooths out the details and possible artifacts - Recommended to start low and increase as needed.
Begin Post Wrap	Start Post Wrap process as part of retarget. This process applies multiple deformers that are chained to make the live connection between a2f mesh and the target mesh.

Tools

Option	Effect
Male Template	Adds A2F neutral “mark” head and “mark_openMouth” meshes to the stage. Both necessary for the character transfer pipeline.
Delete setup	Removes all Character Transfer related nodes and connections as well as reset the meshes to a2f neutral state.
Delete Correspondence	Deletes all user created correspondence points assigned to the meshes.
Wrap UI	Opens Wrap UI which offers additional options for the wrapping process.

Wrap UI

Wrap UI provides some options for users to use one driver mesh to drive one or more secondary meshes. For example, the face mesh is used as a driver for the eyebrows and moustache meshes. This UI execution uses the scene selection information to know which meshes to execute on. The first selected mesh would be the driver to drive one or more of the following selected meshes.

Option	Effect
Use Max Distance	Toggle for considering Max Distance field below to set the weights of the deformer. When enabled, any driven points further than the Max Distance to the driver mesh will have 0 weight, hence not affected by the Wrap deformer.
Max Distance	The cutoff distance of each driven point to the driver mesh surface. This field is disabled until the Use Max Distance checkbox above is enabled.
Face Tangent Space	Use face tangent space to store and apply the offset vector of each point to the surface. When disabled, the offset vector would be applied in the object space of the driven mesh.

When the tool detects the intended driven mesh already has an incoming connection, a popup would appear for each mesh to let the user decide the next action.

Option	Effect
Skip	Leave the specified mesh be. No new Wrap deformer would be created for this particular mesh.
Replace	Delete the upstream node of the mesh, and replace it with the new created Wrap deformer.
Add	Add new Wrap deformer and connect it to the mesh. The previous upstream node will be disconnected from the driven mesh but not deleted.

BlendShape Generation

The Blendshape Generation tool allows the user to generate a set of blendshapes from a custom neutral mesh. Run your mesh through the character Transfer process, select your mesh then click “Blendshape Transfer”. A full set of shapes will be generated and available for export as USD for use in any DCC application.

Option	Effect
BlendShape Transfer	Runs the process to generate a set of Blendshapes for a target Head mesh.
Export as USD	Exports the blendshapes as USD for use in other applications.

Data Conversion tab

This tab provides all of the export and format functionality

Common Settings

Option	Effect
Export Directory	Select a destination for the point cache export.
File Name	Specify the filename of the exported cache.
Playback FPS	Select the Frames per second you would like the cache to be exported at.

Geometry cache

Option	Effect
Export Filter	Select the mesh filter to select the meshes within the stage from which you want to export the animation cache for. (only exports the animation data - does not export the source mesh.)
Export as	You have the choice of a USD point cache export or a Maya point cache export.

Additional Export Notes

1. When exporting a custom mesh used in the character transfer process. Be sure to select the mesh in the stage that is labelled with “_result”.

2. When exporting a Maya cache, you can import the source mark head to Maya to assign the cache too. A mark asset (male_head_model_hi_published.mb) can be found in your install directory /audio2face/assets/

Blendshape Conversion

Allows the user to convert the output a2f animation into a blendshape-driven animation

Option	Effect
Input anim mesh	The mesh you want to convert into a blendshape animation. It is usually the mesh from the A2F pipeline.
Blendshape mesh	The neutral mesh with blendshape prims and this should be based on the usdSkel schema.
Set up blendshape solve	Setting up an interactive blendshape solve pipeline in the stage.

Export as json	Export the resulting blendshape weight values as .json file.
Export as USD SkelAnimation	Export the resulting blendshape weight values as .usd in the SkelAnimation prim.
Additional notes	When exporting animation, you will use the information in “common settings” for the file path and the playback fps.
MetaHuman	Now supports Unreal Engine’s MetaHuman via the Omniverse Unreal Engine Connector version 103.1. The exporter creates custom “animation curves” that are imported as an animation sequence to align with the Metahuman skeleton.
Two arrays
custom:mh_curveNames	This token array contains the names of the control curves, like CTRL_expressions_eyeLookUpR.
custom:mh_curveValues	this float array contains the time sampled curve value data.

Pose & pose option table

Option	Effect
Pose	Name of the blendshape poses.
Use	whether we want to include or exclude the pose in the blendshape solve.
Cancel pair	tagging 2 poses that cancel each other. They cannot be used together at a frame, only one of them can get a non-zero weight.
Symmetry	tagging 2 poses that are symmetric. They try to have the same weights during the blendshape conversion.
Select All, Selection options	(Right mouse click menu): Handy pose selection options.

Toggle use	Toggle the selected “use” checkboxes in the table.
Tag/untag cancel pair	Tag/untag the selected 2 poses as a cancel pair.
Tag/untag symmetry pair	Tag/untag the selected 2 poses as a symmetry pair.
Weight regularization	Stronger value prevents the solve to compute strong weight values. Weight regularization.
Temporal smoothing	Stronger value prevents pops between consecutive frames. Temporal weight regularization.
Weight Sparsity	Stronger value generates sparse blendshape weights, which is preferable for animator’s edit. L1 weight regularization.
Symmetric Pose	Stronger value makes the symmetry poses to have more similar weight values.
Load preset	Load preset blendshape options from a .json file.
Save preset	Save blendshape options as preset in a .json file.