OSC Face Tracking

External applications can send face tracking data directly to VRChat's Face Tracking system using OSC. The input uses the Unified Expressions tracking keys established by VRCFaceTracking (VRCFT).

Enable OSC in VRChat and use an avatar configured for Face Tracking with Use All Tracking Keys enabled. The avatar's Blendshapes Sets and Parameter Behaviors determine how the incoming values affect its appearance.

Message format

Field	Value
Address	/tracking/face/v1
Arguments	One OSC blob (type tag b; OSC type-tag string ,b).
Blob payload size	Exactly 102 bytes.
Byte order	One unsigned byte per tracking key, in the order below.
Value range	0 to 255. VRChat decodes each byte as byte / 255.0 to produce a tracking strength from 0 to 1.

Send the complete 102-byte payload in every message. Set any key your tracking source does not provide to 0. Preserve its position in the payload; do not omit unsupported keys. VRChat ignores messages with the wrong number of arguments or the wrong blob payload size.

Use your OSC library's blob argument type to send the byte array. The 102 bytes are the blob's data payload, excluding the OSC blob length field and alignment padding. Voice and Viseme_* are inputs supplied by VRChat and are not part of this payload.

For example, a payload with byte 36 set to 255 and all other bytes set to 0 sends JawOpen = 1 with all other tracking keys at 0.

Tracking key order

Indices are zero-based. These names are also the tracking key names used in Blendshapes Sets and Parameter Behaviors, including the Expression field in Custom mode.

Index	Tracking key
0	EyeLookOutRight
1	EyeLookInRight
2	EyeLookUpRight
3	EyeLookDownRight
4	EyeLookOutLeft
5	EyeLookInLeft
6	EyeLookUpLeft
7	EyeLookDownLeft
8	EyeClosedRight
9	EyeClosedLeft
10	EyeDilationRight
11	EyeDilationLeft
12	EyeConstrictRight
13	EyeConstrictLeft
14	EyeSquintRight
15	EyeSquintLeft
16	EyeWideRight
17	EyeWideLeft
18	BrowPinchRight
19	BrowPinchLeft
20	BrowLowererRight
21	BrowLowererLeft
22	BrowInnerUpRight
23	BrowInnerUpLeft
24	BrowOuterUpRight
25	BrowOuterUpLeft
26	NasalDilationRight
27	NasalDilationLeft
28	NasalConstrictRight
29	NasalConstrictLeft
30	CheekSquintRight
31	CheekSquintLeft
32	CheekPuffRight
33	CheekPuffLeft
34	CheekSuckRight
35	CheekSuckLeft
36	JawOpen
37	JawRight
38	JawLeft
39	JawForward
40	JawBackward
41	JawClench
42	JawMandibleRaise
43	MouthClosed
44	LipSuckUpperRight
45	LipSuckUpperLeft
46	LipSuckLowerRight
47	LipSuckLowerLeft
48	LipSuckCornerRight
49	LipSuckCornerLeft
50	LipFunnelUpperRight
51	LipFunnelUpperLeft
52	LipFunnelLowerRight
53	LipFunnelLowerLeft
54	LipPuckerUpperRight
55	LipPuckerUpperLeft
56	LipPuckerLowerRight
57	LipPuckerLowerLeft
58	MouthUpperUpRight
59	MouthUpperUpLeft
60	MouthUpperDeepenRight
61	MouthUpperDeepenLeft
62	NoseSneerRight
63	NoseSneerLeft
64	MouthLowerDownRight
65	MouthLowerDownLeft
66	MouthUpperRight
67	MouthUpperLeft
68	MouthLowerRight
69	MouthLowerLeft
70	MouthCornerPullRight
71	MouthCornerPullLeft
72	MouthCornerSlantRight
73	MouthCornerSlantLeft
74	MouthFrownRight
75	MouthFrownLeft
76	MouthStretchRight
77	MouthStretchLeft
78	MouthDimpleRight
79	MouthDimpleLeft
80	MouthRaiserUpper
81	MouthRaiserLower
82	MouthPressRight
83	MouthPressLeft
84	MouthTightenerRight
85	MouthTightenerLeft
86	TongueOut
87	TongueUp
88	TongueDown
89	TongueRight
90	TongueLeft
91	TongueRoll
92	TongueBendDown
93	TongueCurlUp
94	TongueSquish
95	TongueFlat
96	TongueTwistRight
97	TongueTwistLeft
98	SoftPalateClose
99	ThroatSwallow
100	NeckFlexRight
101	NeckFlexLeft

Synchronization

VRChat synchronizes received face tracking data to remote viewers through its native face tracking synchronization. You do not need to send each key through a custom synced avatar parameter. See Networking and synced parameters for fidelity considerations and when to use a synced parameter instead.