Input animation binary file format specification

Overall structure

The input animation binary file begins with a 64 bit integer magic number. The value of this number in hexadecimal notation is 0x6a8faf6e0f9e42c6 and can be used to identify valid input animation files.

The next eight bytes are two Int32 values declaring the major and minor version number of the file.

The rest of the file is taken up by animation data, which may change between version numbers.

Section	Type
Magic Number	Int64
Major Version Number	Int32
Minor Version Number	Int32
Animation Data	see version section

Version 1.1

The input animation data consists of three boolean values that indicate whether the animation contains Camera, Hand, and Eye Gaze data, followed by a sequence of animation curves. The curves present depends on the values of these booleans. Each curve can have a different number of keyframes.

Section	Type	Notes
Has Camera Pose	[Boolean]
Has Hand Data	[Boolean]
Has Eye Gaze	[Boolean]
Camera	Pose Curves	Only if Has Camera Pose is true
Hand Tracked Left	Boolean Curve	Only if Has Hand Data is true
Hand Tracked Right	Boolean Curve	Only if Has Hand Data is true
Hand Pinching Left	Boolean Curve	Only if Has Hand Data is true
Hand Pinching Right	Boolean Curve	Only if Has Hand Data is true
Hand Joints Left	Joint Pose Curves	Only if Has Hand Data is true
Hand Joints Right	Joint Pose Curves	Only if Has Hand Data is true
Eye Gaze	Ray Curves	Only if Has Eye Gaze is true

Version 1.0

The input animation data consists of a sequence of animation curves. The number and meaning of animation curves is fixed, but each curve can have a different number of keyframes.

Section	Type
Camera	Pose Curves
Hand Tracked Left	Boolean Curve
Hand Tracked Right	Boolean Curve
Hand Pinching Left	Boolean Curve
Hand Pinching Right	Boolean Curve
Hand Joints Left	Joint Pose Curves
Hand Joints Right	Joint Pose Curves

Joint pose curves

For each hand a sequence of joint animation curves is stored. The number of joints is fixed, and a set of pose curves is stored for each joint.

Section	Type
None	Pose Curves
Wrist	Pose Curves
Palm	Pose Curves
ThumbMetacarpalJoint	Pose Curves
ThumbProximalJoint	Pose Curves
ThumbDistalJoint	Pose Curves
ThumbTip	Pose Curves
IndexMetacarpal	Pose Curves
IndexKnuckle	Pose Curves
IndexMiddleJoint	Pose Curves
IndexDistalJoint	Pose Curves
IndexTip	Pose Curves
MiddleMetacarpal	Pose Curves
MiddleKnuckle	Pose Curves
MiddleMiddleJoint	Pose Curves
MiddleDistalJoint	Pose Curves
MiddleTip	Pose Curves
RingMetacarpal	Pose Curves
RingKnuckle	Pose Curves
RingMiddleJoint	Pose Curves
RingDistalJoint	Pose Curves
RingTip	Pose Curves
PinkyMetacarpal	Pose Curves
PinkyKnuckle	Pose Curves
PinkyMiddleJoint	Pose Curves
PinkyDistalJoint	Pose Curves
PinkyTip	Pose Curves

Pose curves

Pose curves are a sequence of 3 animation curves for the position vector, followed by 4 animation curves for the rotation quaternion.

Section	Type
Position X	Float Curve
Position Y	Float Curve
Position Z	Float Curve
Rotation X	Float Curve
Rotation Y	Float Curve
Rotation Z	Float Curve
Rotation W	Float Curve

Ray curves

Ray curves are a sequence of 3 animation curves for the origin vector, followed by 3 animation curves for the direction vector.

Section	Type
Origin X	Float Curve
Origin Y	Float Curve
Origin Z	Float Curve
Direction X	Float Curve
Direction Y	Float Curve
Direction Z	Float Curve

Float curve

Floating point curves are fully fledged Bézier curves with a variable number of keyframes. Each keyframe stores a time and a curve value, as well as tangents and weights on the left and right side of each keyframe.

Section	Type
Pre-Wrap Mode	Int32, Wrap Mode
Post-Wrap Mode	Int32, Wrap Mode
Number of keyframes	Int32
Keyframes	Float Keyframe

Float keyframe

A float keyframe stores tangent and weight values alongside the basic time and value.

Section	Type	Notes
Time	Float32
Value	Float32
InTangent	Float32	Version 1.0 only
OutTangent	Float32	Version 1.0 only
InWeight	Float32	Version 1.0 only
OutWeight	Float32	Version 1.0 only
WeightedMode	Int32, Weighted Mode	Version 1.0 only

Boolean curve

Boolean curves are simple sequences of on/off values. On every keyframe the value of the curve flips immediately.

Section	Type
Pre-Wrap Mode	Int32, Wrap Mode
Post-Wrap Mode	Int32, Wrap Mode
Number of keyframes	Int32
Keyframes	Boolean Keyframe

Boolean keyframe

A boolean keyframe only stores a time and value.

Section	Type
Time	Float32
Value	Float32

Wrap mode

The semantics of Pre- and Post-Wrap modes follow the Unity WrapMode definition. They are a combination of the following bits:

Value	Meaning
0	Default: Reads the default repeat mode set higher up.
1	Once: When time reaches the end of the animation clip, the clip will automatically stop playing and time will be reset to beginning of the clip.
2	Loop: When time reaches the end of the animation clip, time will continue at the beginning.
4	PingPong: When time reaches the end of the animation clip, time will ping pong back between beginning and end.
8	ClampForever: Plays back the animation. When it reaches the end, it will keep playing the last frame and never stop playing.

Weighted mode

The semantics of the Weighted mode follow the Unity WeightedMode definition.

Value	Meaning
0	None: Exclude both inWeight or outWeight when calculating curve segments.
1	In: Include inWeight when calculating the previous curve segment.
2	Out: Include outWeight when calculating the next curve segment.
3	Both: Include inWeight and outWeight when calculating curve segments.