What’s

Virtual Motion Capture Protocol (VMCProcotol, OSC/VMC Protocol) is avatar motion communication protocol for virtual motion capture.

You can easily move your avatar by using an easy-to-use library without implementing the handling of VR devices.

You can send and receive motions to and from various applications. .

It is a simple implementation using Open Sound Control and VRM, and can communicate with various environments such as Windows, Mac, Linux, and iOS on machine internal or local network.

Library/Asset

EVMC4U - Unity
VMC4UE - Unreal Engine with VRM4U
VRM4U - Unreal Engine
VMC4B Blender addon for VMCProtocol - Blender
Godot XR VMC Tracker - Godot Engine 4.3 with Godot VRM Importer. video

or you can implement protocol your self.

Logo

VMC Protocol-enabled applications can use the following logos.

logo
larger logo

Sample

Sample implementation

[Combinations(Combinations)

Application Combinations

Licence

MIT Licence

Information included

Basic information

VR model created by VRM standard

Bone information
BlendShape information

Advanced information(optional)

Camera control
Light control
Keyboard input
MIDI Note / CC input
Tracker position
VRM dynamic loading
Calibration control
Configuration
Gaze control

it is not necessary to correspond to all of this information, and you can use only the information you want to use.

Glossary

Server - OSC Server (Receiver)
Client - OSC Client (Sender)

These terms cause confusion about the actual role. So, The VMC protocol defines the following specific terms.

Marionette - Receive motion and draw screen. (Required)
It works server for Performer, commonly port 39539.
(Eg: EVMC4U, VMC4UE)
Performer - Process motion and IK. Send all bones and more info to Marionette. (Required)
It works client to Marionette, commonly send to 39539.
And It works server for Assistant(optional), commonly port 39540.
(Eg: Virtual Motion Capture, Waidayo, VSeeFace, MocapForAll, TDPT)
Assistant - Send some bones, facial expressions, etc to Performer. (optional) It works client to Performer, commonly send to 39540.
(Eg: Waidayo, Sknuckle, Simple Motion Tracker, Uni-studio)

flow layer

Communication format

Open Sound Control(OSC) over UDP/IP
Use appropriate osc type.
Use UTF-8. (Data includes non ascii type)
port numbers commonly use 39539, and 39540. but recommended it can change for user experience.
Packets may be bundled.
The transmission period is undefined. And some messages do not periodically.
The recipient should discard unnecessary messages. You don’t have to process every message.
Which message to send or receive depends on both implementations.
Unknown addresses and too many arguments should be ignored.
If you detect an argument that has too few arguments or an argument of a different type than defined as an extended specification, it must an ignored.

See here for PerfectSync used for advanced facial expression tracking

OSC Debugging

Recommended tools
VMCProtocolMonitor

OSCDataMonitor(Github)
OSCDataMonitor(Download)

Sample

Basic spec
/Address (Type){Value}  

Advanced spec with version
/Address (Type){Value} (Type){Value}  

Marionette(Motion receiver application)

Performer → Marionette specifications.

Available

/VMC/Ext/OK (int){loaded}  
  
V2.5  
/VMC/Ext/OK (int){loaded} (int){calibration state} (int){calibration mode}  
  
V2.7  
/VMC/Ext/OK (int){loaded} (int){calibration state} (int){calibration mode} (int){tracking status}  

loaded: 0=not loaded、1=loaded

calibration state

Uncalibrated = 0
WaitingForCalibrating = 1
Calibrating = 2
Calibrated = 3

calibration mode

Normal = 0
MR Normal = 1
MR Floor fix = 2

tracking status

OK=1
Bad=0

V2.7 spec is not implemented in Virtual motion capture

Relative time

/VMC/Ext/T (float){time}

Current relative time of the sender.
Mainly used to check if communication is possible.

Root Transform

v2.0
/VMC/Ext/Root/Pos (string){name} (float){p.x} (float){p.y} (float){p.z} (float){q.x} (float){q.y} (float){q.z} (float){q.w}  

v2.1
/VMC/Ext/Root/Pos (string){name} (float){p.x} (float){p.y} (float){p.z} (float){q.x} (float){q.y} (float){q.z} (float){q.w} (float){s.x} (float){s.y} (float){s.z} (float){o.x} (float){o.y} (float){o.z}  

p=Position
q=Quaternion
s=MR Scale
o=MR Offset

Model root absolute position.
name is “root”。

It is recommended to treat it as a Loal posture on the receiving side.

From v2.1, a scale for MR synthesis has been added. By using this, the position and size of the avatar can be adjusted to the actual body size.

Bone Transform

/VMC/Ext/Bone/Pos (string){name} (float){p.x} (float){p.y} (float){p.z} (float){q.x} (float){q.y} (float){q.z} (float){q.w}  

name is HumanBodyBones type name(UnityEngine).
p=Position
q=Quaternion

All HumanBodyBones will be send. (Include eye bone and finger bones)

Notice regarding VRM1
In VRM1, there are normalized bone poses controlled by ControlRig and original bone poses.
Depending on the state of ControlRig, the pose information obtained using the same animator.GetBoneTransform may differ.

The recommended approach as VMCProtocol is to use non-normalized (original) bone information without ControlRig applied.
(This is the pose obtained with instance.Humanoid.GetBoneTransform)

While it is not prohibited to send normalized bones (instance.Runtime.ControlRig.GetBoneTransform), it is not recommended.
If you choose to do so, handle it as an option setting that is disabled by default.

VRM BlendShapeProxyValue

/VMC/Ext/Blend/Val (string){name} (float){value}  
/VMC/Ext/Blend/Apply

BlendShapeProxy value in VRM model. After all have been sent, apply will be sent.

Facial expressions and lip sync are sent this.

Note that due to changes in the UniVRM specification, it is Case Sensitive.
In permissive applications (including those using EVMC4U), case sensitivity is ignored, mainly to maintain compatibility, but otherwise it does not work properly.

See here for PerfectSync used for advanced facial expression tracking

https://docs.unity3d.com/ja/Packages/com.unity.xr.arkit@5.1/api/UnityEngine.XR.ARKit.ARKitBlendShapeLocation.html

VRM0 vs VRM1 Incompatibility Warning

Existing VMCProtcol compliant applications use VRM0.
VRM0 and VRM1 have different preset Expressions (VRM0.x : BlendShape).

When using a VRM1-based VRM SDK, VRM0 models are also converted to VRM1 format during automatic migration.

Please refer to the VRM official website for changes.

To maintain compatibility with existing VMCProtocol applications that use the VRM0 format,

Senders using VRM1 system must implement transmission in VRM0 format. However, it is recommended to prepare transmission in VRM1 format as an option.
Recipients using VRM1 system should convert to VRM1 format and process when receiving in VRM0 format.

VRM0 Preset BlendShape	VRM1 Preset Expressions
Joy	happy
Angry	angry
Sorrow	sad
Fun	relaxed
A	aa
I	ih
U	ou
E	ee
O	oh
Blink_L	blinkLeft
Blink_R	blinkRight

Camrea Transform&FOV

V2.1
/VMC/Ext/Cam (string){name} (float){p.x} (float){p.y} (float){p.z} (float){q.x} (float){q.y} (float){q.z} (float){q.w} (float){fov} 

p=Position
q=Quaternion
fov=FOV

Controller Input

V2.1
/VMC/Ext/Con (int){active} (string){name} (int){IsLeft} (int){IsTouch} (int){IsAxis} (float){Axis.x} (float){Axis.y} (float){Axis.z} 

Controller button and axis. (Its dependent to sender applications.)
active 1=press, 0=release, 2=change Axis.

【Event send】keyboard Input

V2.1
/VMC/Ext/Key (int){active} (string){name} (int){keycode}

Keyboard input. (Its dependent to sender applications.)
active 1=press, 0=release.

【Event send】MIDI Note Input

V2.2
/VMC/Ext/Midi/Note (int){active} (int){channel} (int){note} (float){velocity}

MIDI note in.
active 1=press, 0=release.

【Event send】MIDI CC Value Input

V2.2
/VMC/Ext/Midi/CC/Val (int){knob} (float){value}

MIDI CC value.

【Event send】MIDI CC Button Input

V2.2
/VMC/Ext/Midi/CC/Bit (int){knob} (int){active}

MIDI CC buttons.
active 1=press, 0=release.

Device Transform

V2.2
/VMC/Ext/Hmd/Pos (string){serial} (float){p.x} (float){p.y} (float){p.z} (float){q.x} (float){q.y} (float){q.z} (float){q.w}  
/VMC/Ext/Con/Pos (string){serial} (float){p.x} (float){p.y} (float){p.z} (float){q.x} (float){q.y} (float){q.z} (float){q.w}  
/VMC/Ext/Tra/Pos (string){serial} (float){p.x} (float){p.y} (float){p.z} (float){q.x} (float){q.y} (float){q.z} (float){q.w}  

V2.3
/VMC/Ext/Hmd/Pos/Local (string){serial} (float){p.x} (float){p.y} (float){p.z} (float){q.x} (float){q.y} (float){q.z} (float){q.w}  
/VMC/Ext/Con/Pos/Local (string){serial} (float){p.x} (float){p.y} (float){p.z} (float){q.x} (float){q.y} (float){q.z} (float){q.w}  
/VMC/Ext/Tra/Pos/Local (string){serial} (float){p.x} (float){p.y} (float){p.z} (float){q.x} (float){q.y} (float){q.z} (float){q.w}  

Tracker device transform.

Pos = avatar scale.
Pos/Local = device raw scale.
serial = OpenVR Serial No.
p=Position
q=Quaternion

【low frequency】Receive enable

v2.4
/VMC/Ext/Rcv (int){enable:0 or 1} (int){port:0～65535}  
  
v2.7
/VMC/Ext/Rcv (int){enable:0 or 1} (int){port:0～65535} (string){IP Address}  

VMC side receive function is enabled or not. 1=enable, 0=disable.
V2.7 spec is not implemented in Virtual motion capture

【low frequency】DirectionalLight transform & color

V2.4
/VMC/Ext/Light (string){name} (float){p.x} (float){p.y} (float){p.z} (float){q.x} (float){q.y} (float){q.z} (float){q.w} (float){color.red} (float){color.green} (float){color.blue} (float){color.alpha} 

VMC DirectionalLight position and color.
p=Position
q=Quaternion
color=color

【low frequency】Local VRM information

V2.4
/VMC/Ext/VRM (string){path} (string){title}  
  
V2.7
/VMC/Ext/VRM (string){path} (string){title} (string){Hash} 

VMC loaded local vrm file info.
path = local file path.

Difference detection is recommended.

Note: The user needs already agreed to the VRM license.

V2.7 spec is not implemented in Virtual motion capture

【low frequency】Remote VRM information

V3.0
/VMC/Ext/Remote (string){service} (string){json} 

VMC loaded online service info.

service = service name(lower case).
json = service info.

Note: The user needs already agreed to the VRM license.

Service example 
/VMC/Ext/Remote vroidhub {"characterModelId":"123456789456"}
/VMC/Ext/Remote dmmvrconnect {"user_id":"123456789456", "avatar_id":"123456789456"}

【low frequency】Option string

V2.4
/VMC/Ext/Opt (string){option} 

General-purpose setting character string (recipient arbitrary definition)

【low frequency】background color

V2.4
/VMC/Ext/Setting/Color (float){r} (float){g} (float){b} (float){a} 

【low frequency】Window attribute

V2.4
/VMC/Ext/Setting/Win (int){IsTopMost} (int){IsTransparent} (int){WindowClickThrough} (int){HideBorder} 

1=true,0=false

【low frequency】Loaded setting path

V2.5
/VMC/Ext/Config (string){path} 

VMC Setting(Profile) path.

Thru info

V2.6
/VMC/Thru/xxxxxxxxx/xxxxxxxxx (string){arg1} 
/VMC/Thru/xxxxxxxxx/xxxxxxxxx (string){arg1} (float){arg2} 
/VMC/Thru/xxxxxxxxx/xxxxxxxxx (string){arg1} (int){arg2} 

xxxxxxxxx is any name.
vendor specific.
performer must through out from assistant to marionette.

Performer(Motion sender application)

Marionette → Performer or
Assistant → Performer specifications.

Virtual Device Transform

V2.3
/VMC/Ext/Hmd/Pos (string){serial} (float){p.x} (float){p.y} (float){p.z} (float){q.x} (float){q.y} (float){q.z} (float){q.w}  
/VMC/Ext/Con/Pos (string){serial} (float){p.x} (float){p.y} (float){p.z} (float){q.x} (float){q.y} (float){q.z} (float){q.w}  
/VMC/Ext/Tra/Pos (string){serial} (float){p.x} (float){p.y} (float){p.z} (float){q.x} (float){q.y} (float){q.z} (float){q.w}  

Virtual device transform.

Pos = avatar scale.
Pos/Local = device raw scale.
serial = OpenVR Serial No.
p=Position
q=Quaternion

Frame Period

V2.3
/VMC/Ext/Set/Period (int){Status} (int){Root} (int){Bone} (int){BlendShape} (int){Camera} (int){Devices} 

set send period. value = 1/x Frame.

Virtual MIDI CC Value Input

V2.3
/VMC/Ext/Midi/CC/Val (int){knob} (float){value}

Virtual Camrea Transform&FOV

V2.3
/VMC/Ext/Cam (string){Camera} (float){p.x} (float){p.y} (float){p.z} (float){q.x} (float){q.y} (float){q.z} (float){q.w} (float){fov} 

VRM BlendShapeProxyValue

V2.3
/VMC/Ext/Blend/Val (string){name} (float){value}  
/VMC/Ext/Blend/Apply

See here for PerfectSync used for advanced facial expression tracking

https://docs.unity3d.com/ja/Packages/com.unity.xr.arkit@5.1/api/UnityEngine.XR.ARKit.ARKitBlendShapeLocation.html

VRM0 vs VRM1 Incompatibility Warning

Existing VMCProtcol compliant applications use VRM0.
VRM0 and VRM1 have different preset Expressions (VRM0.x : BlendShape).

When using a VRM1-based VRM SDK, VRM0 models are also converted to VRM1 format during automatic migration.

Please refer to the VRM official website for changes.

To maintain compatibility with existing VMCProtocol applications that use the VRM0 format,

Senders using VRM1 system must implement transmission in VRM0 format. However, it is recommended to prepare transmission in VRM1 format as an option.
Recipients using VRM1 system should convert to VRM1 format and process when receiving in VRM0 format.

VRM0 Preset BlendShape	VRM1 Preset Expressions
Joy	happy
Angry	angry
Sorrow	sad
Fun	relaxed
A	aa
I	ih
U	ou
E	ee
O	oh
Blink_L	blinkLeft
Blink_R	blinkRight

Eye Tracking Target Position

V2.3
V2.8 (Disruptive change)
/VMC/Ext/Set/Eye (int){enable} (float){p.x} (float){p.y} (float){p.z}

Eye tracking target object position.
V2.8~: Head relative position.
V2.3~V2.7: absolute position.

【Event send】Information send request

V2.4
/VMC/Ext/Set/Req 

Request immediate transmission.

【Event send】Response string

V2.4
/VMC/Ext/Set/Res (string){Response} 

General-purpose string (sender arbitrary definition)

【Event send】calibration/calibration ready request

V2.5
/VMC/Ext/Set/Calib/Ready  
/VMC/Ext/Set/Calib/Exec (int){mode}   

Ready: Request calibration ready Exec: Request calibration execute (0=Normal,1=MR Normal,2=MR floor fix)

Please allow enough time between Ready and Exec.

【Event send】Request load setting file

V2.5
/VMC/Ext/Set/Config (string){Path} 

Thru info

V2.6
/VMC/Thru/xxxxxxxxx/xxxxxxxxx (string){arg1} 
/VMC/Thru/xxxxxxxxx/xxxxxxxxx (string){arg1} (float){arg2} 
/VMC/Thru/xxxxxxxxx/xxxxxxxxx (string){arg1} (int){arg2} 

xxxxxxxxx is any name.
vendor specific.
performer must through out from assistant to marionette.

DirectionalLight transform & color

V2.9
/VMC/Ext/Light (string){name} (float){p.x} (float){p.y} (float){p.z} (float){q.x} (float){q.y} (float){q.z} (float){q.w} (float){color.red} (float){color.green} (float){color.blue} (float){color.alpha} 

VMC DirectionalLight position and color.
p=Position
q=Quaternion
color=color

【Event send】Call Shortcut

V3.1
/VMC/Ext/Set/Shortcut (string){shortcut}

Call VMC Shortcut

example

/VMC/Ext/Set/Shortcut Functions.FreeCamera
/VMC/Ext/Set/Shortcut Functions.ColorGreen
/VMC/Ext/Set/Shortcut Functions.ShowCalibrationWindow

VMC Protocol specification

What’s

Library/Asset

Logo

Sample

[Combinations(Combinations)

Licence

Information included

Glossary

Communication format

OSC Debugging

Sample

Marionette(Motion receiver application)

Available

Relative time

Root Transform

Bone Transform

VRM BlendShapeProxyValue

Camrea Transform&FOV

Controller Input

【Event send】keyboard Input

【Event send】MIDI Note Input

【Event send】MIDI CC Value Input

【Event send】MIDI CC Button Input

Device Transform

【low frequency】Receive enable

【low frequency】DirectionalLight transform & color

【low frequency】Local VRM information

【low frequency】Remote VRM information

【low frequency】Option string

【low frequency】background color

【low frequency】Window attribute

【low frequency】Loaded setting path

Thru info

Performer(Motion sender application)

Virtual Device Transform

Frame Period

Virtual MIDI CC Value Input

Virtual Camrea Transform&FOV

VRM BlendShapeProxyValue

Eye Tracking Target Position

【Event send】Information send request

【Event send】Response string

【Event send】calibration/calibration ready request

【Event send】Request load setting file

Thru info

DirectionalLight transform & color

【Event send】Call Shortcut