Video Motion Previs

Video Motion Previs

Use the lightweight video-motion-previs wrapper to operate the real Motion Previs Studio v4 control API. The wrapper reads the app's localhost-only, token-protected discovery descriptor and calls the same allowlisted actions as the upstream MCP bridge.

When to use this skill

Use this skill for reference-video analysis and Motion Previs Studio production packs. Route pure Blender scene scripting to a Blender skill, ComfyUI graph authoring to an AI-video/ComfyUI skill, web animation performance to optimize-web-animations, and general video editing to video-production.

This is not a fully headless renderer. A running Electron app owns MediaPipe, ffmpeg, UI state, analysis, and export. The CLI is the control surface, not a replacement analysis engine.

Instructions

1. Check before installing

From this skill directory:

node scripts/video-motion-previs.mjs check

The JSON result distinguishes:

• a packaged install in /Applications or ~/Applications on macOS;
• a source checkout from MOTION_PREVIS_SOURCE or common local paths;
• a live app with a healthy protocol-v1 control server;
• Node/platform incompatibility and stale discovery files.

Do not reinstall a healthy existing app by default. Motion Previs Studio's generated MediaPipe/model/runtime assets are relatively large, so keep installation idempotent.

2. Install only when needed

node scripts/video-motion-previs.mjs install

Installation policy:

• macOS Apple Silicon: use the inspected official upstream installer and latest arm64 release. Pass --packaged only when replacing a usable source checkout with the packaged app.
• Windows 11 x64: the CLI reports the official latest-release installer URL; installation remains user-visible because the upstream NSIS installer is unsigned and interactive.
• Linux or Intel macOS: use install --source [DIR] to clone the source, run npm ci, and prepare pinned SHA-256-verified runtime assets. Linux still needs explicit ffmpeg/ffprobe runtime overrides or PATH as documented upstream.

The upstream installer removes and replaces an existing Motion Previs Studio v4.app, so never force it without user intent.

Install the wrapper itself on PATH when terminal-wide access is desired:

node scripts/video-motion-previs.mjs link
video-motion-previs check

3. Launch and prove connectivity

video-motion-previs launch
video-motion-previs state
video-motion-previs screenshot /tmp/motion-previs.png

launch reuses a healthy running app, opens the packaged app when available, or starts a prepared source checkout. state is always the first motion command. It confirms loaded media, range, mode, analysis state, settings, last bundle, and Blockout availability.

If the descriptor exists but health fails, quit/relaunch the app. The descriptor is normally:

• macOS/Linux: ~/.config/motion-previs/control.json
• Windows: %APPDATA%\Motion Previs Studio\v4\control.json
• override: MOTION_PREVIS_CONFIG_DIR or MPS_CONFIG_DIR

Never print or persist the bearer token in reports or committed files.

Examples

4. Drive one shot from the CLI

Use explicit commands when human review is needed between stages:

video-motion-previs import-file "/absolute/path/to/shot.mp4"
video-motion-previs set-range 0 3
video-motion-previs set-mode camera_only
video-motion-previs set-settings '{"sampleFps":6,"resolution":"720p"}'
video-motion-previs analyze
video-motion-previs wait --timeout 900
video-motion-previs export
video-motion-previs list-bundle

Use the bounded workflow when all inputs are already approved:

video-motion-previs workflow "/absolute/path/to/shot.mp4" \
  --start 0 --end 3 --mode camera_only --sample-fps 6 --timeout 900

A URL can be used instead of a local path. Motion Previs Studio delegates compatible web-video downloads to yt-dlp:

video-motion-previs workflow "https://example.com/reference-video" \
  --start 2 --end 7 --mode actor_motion

Valid modes are camera_only, actor_motion, object_motion, and full_scene. Settings accepted upstream are sampleFps, maxPeople, smoothing, detectionConfidence, trackingConfidence, and resolution (auto or 720p). Times are seconds.

5. Use raw actions only for advanced automation

video-motion-previs call get_state '{}'
video-motion-previs call send_to_blockout '{"which":"openpose"}'

The upstream v4.1 control surface has 11 allowlisted actions:

get_state, import_file, import_url, set_range, set_mode, set_settings, run_analysis, export_pack, list_bundle, send_to_blockout, and screenshot.

For an MCP client rather than direct CLI control, point it at the upstream zero-dependency bridge:

claude mcp add motion-previs -- node "/ABSOLUTE/PATH/motion-previs-studio/mcp/motion-previs-mcp.mjs"

The app must still be running. The bridge discovers port and token automatically.

Best practices

6. Verify output instead of assuming success

After export, require both the returned bundle path and a successful list-bundle. Depending on selected controls and local model availability, a pack can include reference.mp4, depth/edge/line-art/motion/pose videos, openpose_keypoints.json, camera_motion.json, Blender import scripts, comfyui_manifest.json, prompt/shot-bible files, quality reports, and bundle_manifest.json.

Verification gate:

1. state reports analysis.status: "done" before export.
2. export returns bundlePath and zipPath.
3. list-bundle matches the controls requested; optional layers are not promised unconditionally.
4. Inspect bundle_manifest.json and quality_report.json before downstream generation.
5. Test a short 3–5 second range before processing a long clip.

Troubleshooting

• App is not running: run launch, wait for state, then retry.
• Stale descriptor: fully quit both packaged and source instances, remove only the stale control.json, and relaunch.
• No media loaded: run import-file or import-url before analysis.
• Export says no completed analysis: poll with wait until status is done; do not export while running or after error.
• Pose is weak: shorten the range, improve subject visibility, lower sampling cost for a diagnostic pass, and inspect quality/pose diagnostics.
• Camera solve follows the subject: compare camera_only and full_scene; the solver uses subject-masked background optical flow.
• Depth unavailable: allow the supported CPU/WASM fallback, or export without that optional layer.
• Blockout unavailable: launch Blockout and open its destination project before send-to-blockout.

References

This workflow was checked against upstream v4.1.0 at commit 95e7d0ff1d4cc546f7eb09a74ccbd084988a19bc. The verified surfaces are README.md, package.json, install.sh, mcp/README.md, mcp/motion-previs-mcp.mjs, electron/control.cjs, and src/control/handler.ts. Preserve upstream LICENSE, NOTICE, and third-party attribution when redistributing the app.