⏱ 1 min read

Animation Compression Tool

A Unity editor tool that automatically reduces AnimationClip asset size via RDP compression that converts Stream curves to Constant + missing-binding cleanup

Problem

Character AnimationClip assets are excessively large.

Curves whose values never actually change are also stored as Stream (keyframe-based), which is wasteful
Bone/component-path bindings that vanished when the character rig changed remain in the clips
Manually optimizing hundreds of clips is not realistic

Constraints

Animation quality must not change after compression — if tolerance is exceeded, keep the original automatically
Previously, converting to Linear Tangent caused animations to stutter visibly

Implementation

01
1. RDP keyframe compression
Convert Stream → Constant for curves with no variation or with deltas inside the tolerance.
After compression, validate the actual curve error and automatically retain the original when tolerance is exceeded.
- Unify on SetEditorCurve instead of clip.SetCurve() → prevents YAML format duplication (fixes a bug where the previous approach actually increased size)
- Tangent: Linear → ClampedAuto — resolves the prior stutter issue and allows a more generous error tolerance
- Expanded the Weighted-mode removal scope to all non-Rotation curves
02
2. Missing-binding cleanup
Automatically detect and remove bindings whose bone/component paths no longer exist in the prefab.
- Auto-locate prefabs via the Animation/ → Prefab/ folder mapping
- Handles all curves including Rotation, plus ObjectReference curves (Sprite swap, etc.)
- Built-in safety check for mixing different character folders — must run per Cookie (per character folder) to behave correctly
03
3. Safety-first design
- Risky options like Scale removal and missing-binding cleanup are OFF by default
- "Test Run" button — preview results before actually applying
- Settings are auto-persisted via EditorPrefs (survives window close)

Conclusion

Results

Single clip (CH_MelonSoda_A001_Emotion_Happy_01)

	Before	After	Reduction
File size	468.3 KB	290.9 KB	−37.9%
Stream curves	257	206	−51
Constant curves	263	314	+51

Batch (CH_MelonSoda 50 clips)

	Value
Clips processed	50
Keyframes	565,028 → 231,918 (−333,110)
Bindings	26,891
Removed bindings	7,839

Before / After

Before / After compression

Default (0.0005) compression Before / After

BEFORE

AFTER

Tradeoffs & Future Work

Tradeoffs

Missing-binding cleanup must be run per character folder — running across mixed character folders can cause false positives
The default tolerance (0.0005) suits most characters, but special motions need a separate check

Future Work

A shared editor tool for all characters — a self-service structure the animation team uses directly