VRMA Studio

A desktop editor for VRM Animation (.vrma) files with a familiar video-editor workflow.

Open a .vrma file, watch it play on a VRM avatar instantly, cut and trim it on a timeline, and export a spec-compliant .vrma — no Blender, no Unity, and no rigging knowledge required.

Who is this for?

Editing a VRM animation today usually means importing it into Blender through a fragile add-on, even for a simple cut. VRMA Studio is built for the people who just need the edit:

• VTubers and virtual-assistant developers working with VRM avatars
• Indie game developers using VRM/VRMA pipelines (Three.js, Godot, RPG Developer Bakin)
• Motion-capture users (XR Animator, VRM Posing Desktop) who need post-editing
• Anyone who has never opened Blender and would like to keep it that way

Features

• Instant preview — load a .vrm model and a .vrma animation and it plays immediately in a 3D viewport with orbit controls
• Timeline editing — trim clip edges, split at the playhead, razor-cut, and ripple-trim, with magnetic snapping to frames, edit points, and the playhead
• Frame-accurate transport — timecode readout, frame stepping, edit-point navigation, loop playback, and full keyboard control
• Undo / redo for every edit
• Validation on import and export — problems are reported in plain language, never as raw stack traces
• Round-trip safety — an unedited import → export produces a functionally identical animation, guaranteed by the test suite

Roadmap

• Merging multiple animations with optional crossfade blending
• Per-clip speed adjustment and reverse
• Independent lanes for body, expressions, and look-at
• Auto-repair for malformed VRMA files

Download

Grab the latest Windows installer (.exe) from the Releases page and run it.

Keyboard shortcuts

Key	Action
Space	Play / pause
V / C	Selection tool / razor tool
S	Split clip at playhead
Q / W	Ripple-trim clip head / tail to playhead
← / →	Step one frame (Shift steps one second)
↑ / ↓	Jump to previous / next edit point
Home / End	Go to start / end
+ / -	Zoom timeline in / out
Del	Delete selected clip
Ctrl+Z / Ctrl+Y	Undo / redo
Ctrl+E	Export
Esc	Deselect / close dialog

How it works

A .vrma file is a glTF binary (.glb) carrying the VRMC_vrm_animation extension, which maps animation channels onto VRM humanoid bones so a single animation retargets across any VRM model. VRMA Studio parses that container into an internal document model, performs all edits there, and regenerates a valid .glb from scratch on export — buffers, accessors, and extension data included. Details and spec deviations are documented in docs/format-notes.md.

Development

Prerequisites: Node.js 20+ and, for the desktop shell, Rust.

npm install
npm run dev          # web preview in the browser (no Rust needed)
npm run tauri dev    # desktop app with hot reload

npm test             # regenerates test fixtures, runs the Vitest suite
npm run typecheck    # strict TypeScript check
npm run tauri build  # production build + Windows installers

Project layout

Path	Purpose
src/core/	Pure TypeScript VRMA engine — parser, writer, validator, edit operations. No UI dependencies; fully unit-tested. Binary buffer math lives in src/core/vrma/glb.ts.
src/viewport/	Three.js scene, VRM playback, transport bar
src/timeline/	Timeline UI — ruler, clips, tools, snapping
src/panels/	Project panel, properties panel, export dialog
src/app/	App shell, Zustand store, keyboard shortcuts
src-tauri/	Tauri (Rust) desktop shell
tests/	Vitest suites and generated .vrma fixtures

Releasing

Pushing a tag that starts with v (for example v0.1.0) triggers the release workflow, which builds the Windows installers and attaches them to a draft GitHub Release — review the draft, then publish it.

Built with

Tauri · React · TypeScript · Three.js · @pixiv/three-vrm · Zustand · Tailwind CSS · Vitest

Acknowledgements

• The VRM Consortium for the VRM and VRM Animation specifications
• pixiv for three-vrm and three-vrm-animation