Reference Motion Transfer

Reference Motion Transfer

Use this Skill when the user wants to take the motion from one video and apply it to a different subject — "make my character do this dance", "let the mascot copy these gestures", "repeat this camera move on my product". The motion source is a reference video; the target is a character image, a text description, or both.

Core principle: analyze the motion before writing anything, keep one motion source per run, and spend the model's capacity on motion fidelity — not on a busy scene.

This Skill builds prompts through h3-prompt-writing. Follow its guides exactly: base-en.txt for T2VA / I2VA / FL2VA / L2VA, ref-en.txt for Ref2VA. Field names, section order, labels, and timing notation come from those guides and must not be improvised.

1. Trigger

Use this Skill when the user's request matches any of:

• Transfer a dance, gesture set, or body action from a reference video to a new character
• Make a mascot / product / creature mimic a person's movement
• Replicate a camera movement from a reference clip onto a new scene
• "Same motion, different subject" requests, in any language
• Motion-style transfer where timing and body mechanics matter

Do not use this Skill when:

• The user only wants the look of a video (style/grade transfer with no motion) — that is a style task, not motion transfer
• The user wants to edit, cut, or extend the reference video itself — that is video editing / video continuation, not this Skill
• The request targets a real, identifiable private person without consent — impersonation is prohibited by the H3 Acceptable Use Policy
• There is no reference video, keyframe, or pose image — a pure text choreography request has nothing to transfer from; decline and redirect to the base h3-prompt-writing T2VA
• The sequence needs more than 15 seconds of continuous motion and the user refuses segmentation

2. Intake

Minimum viable intake — confirm all of these before analysis:

1. Motion reference video (required for the Ref2VA route)
   • Best: 4–15 seconds, one clearly visible moving subject, static or simple camera
   • If longer than 15s, ask the user to pick a ≤15s window, or plan segmentation
   • Confirm the user has the right to use it; do not accept private-person footage for impersonation
2. Target subject (required)
   • A reference image of the character/mascot/product, or a precise text description
   • If the body plan differs from the reference subject (e.g. blob mascot vs. human dancer), note it now — it drives feasibility
3. Output format — aspect ratio (16:9 / 9:16 / 1:1 / 4:3 / 3:4 / 21:9) and duration (4–15s; default: match the reference window)
4. Camera policy — static camera (default, recommended) or copy reference camera
5. Scene policy — default to a simple, neutral scene; complex scenes consume motion fidelity
6. Audio policy — silent, SFX-only, or BGM direction; whether to reference the reference video's audio rhythm

If the user has no reference video, route to the fallback modes in Section 7 and say so explicitly — motion fidelity drops significantly.

3. Goal

Deliver one approved video (or one approved segment chain) in which:

• The target subject performs the reference motion recognizably, with matching timing and tempo
• The target's identity stays stable across every frame
• Body mechanics look natural for the target's proportions — no copied anatomy glitches
• Output ratio, duration, camera and audio policy match the intake confirmation

Success is judged by motion fidelity first, identity stability second, everything else third.

4. Analysis

Analyze before writing any prompt. Produce a short analysis block:

Reference video:

• Motion class: full-body dance / upper-body gesture / locomotion / facial performance / camera-only move
• Subject framing: full body / half body / close-up
• Tempo: slow / medium / fast, and whether the rhythm is steady or accent-driven
• Occlusions, props, and interaction with objects or other people
• Camera: static, panning, tracking, orbiting — and how much of the frame the motion occupies

Complexity grade:

• S — slow, single-plane motion, no occlusion (wave, nod, sway, slow walk) → single generation, up to 15s
• M — multi-limb coordinated motion, moderate tempo (dance phrase, jump-and-land) → single generation, ≤10s recommended
• L — spins, fast footwork, acrobatics, heavy occlusion → segment into 2+ clips of ≤8s, or ask the user to simplify

Target subject:

• Body-plan compatibility with the reference subject (humanoid / quadruped / object)
• 3–5 identity anchors that must survive every frame (silhouette, color, signature props)
• Which reference motions are physically implausible for this body — flag them now

Verdict: one paragraph stating the transfer plan is feasible / feasible-with-simplification / not feasible, and why.

5. Planning

Convert the analysis into a production plan:

1. Motion Beat Sheet — segment the reference motion into 1–4 beats with timecodes while watching the reference, e.g. 0.0–2.5s: weight shifts left, both arms rise; 2.5–5.0s: spin .... One beat = one readable action. Never exceed 4 beats per 15s. Beats are an analysis artifact: derive them from what the reference actually shows, never invent them.
2. Duration — match the reference window, clamped to 4–15s. M-grade: ≤10s. L-grade: ≤8s per segment.
3. Aspect ratio — full-body motion: 9:16 or 16:9; upper-body gestures: 1:1 / 3:4 / 9:16; camera-move replication: match the reference ratio. Never let the chosen ratio crop the moving body parts.
4. Camera — default static. Copy the reference camera only when the camera move is the point of the request.
5. Scene — neutral studio / clean backdrop by default. A rich scene is a deliberate trade against motion fidelity; say so when the user asks for one.
6. Segmentation — L-grade or >15s: split at a motion pause, plan tail-frame continuation (Segment A's last frame becomes Segment B's first-frame reference).

6. Intermediate Artifacts

Before generation, keep these artifacts visible to the user:

• Motion Beat Sheet — the timecoded beat list from Section 5
• Target Subject Card — the identity anchors; if the user gave no image, generate one still of the target first and lock it
• Transfer Brief — one short paragraph: what moves (the reference motion), who performs (the target), what stays (timing, tempo), what changes (subject, scene, style), camera & audio policy
• Optional: first/last frame stills when an FL2VA hybrid is planned

Generation starts only after the user confirms the Transfer Brief.

7. H3 Strategy

Choose the generation mode from the available assets, in this priority order:

Segmentation for long/complex motion: run Ref2VA per segment with identical subject definitions; use each segment's approved tail frame as the next segment's <Picture N> first-frame anchor (Ref2VA + keyframe-completion hybrid).

Never mix two reference videos in one generation — one motion source per run.

8. Prompt Construction

All prompts are written through h3-prompt-writing rules. For the primary Ref2VA route:

1. subject_definitions — one <Subject N> for the target (appearance source: <Picture N> or text), one <Subject N> for the motion itself sourced from <Video 1>, e.g. <Subject 2> is the dance routine performed in <Video 1>, including its step sequence, timing, and tempo.
2. summary — prefix [reference generation]; state who performs what, sourced from which labels.
3. retention_analysis — target appearance: fully_preserved; motion: attribute_transfer from the reference performer to the target; camera (when copied): a <Video N> entry with fully_preserved for its camera path and pacing.
4. detailed_description — style sentence(s) first, then [Shot 1] with no timestamp. The reference video is the only source of the motion: never restate specific dance steps or poses. Write the beat structure as timecoded windows that point back to the motion source ("the fox performs <Subject 2> from 0.00 to 7.00 seconds, following its tempo exactly"); describe what the output adds — scene, camera policy, subject placement, sound. 350–500 English words for generation tasks.
5. overall_soundscape / non_diegetic_music — per the audio policy; N/A when unused.
6. Language rules: sections in English; dialogue/lyrics/visible text keep their original language inside <d> or quotation marks.

For fallback modes, follow base-en.txt: I2VA / FL2VA / L2VA open with the exact keyframe-alignment instruction line, then the three core fields in order.

Ready-to-run prompts for every mode, ratio, and duration live in references/prompt-library.md.

9. Generation

• Model: MiniMax H3. Duration = planned window (4–15s), ratio = planned ratio.
• First pass at default resolution (shorter side 768px). Only after the motion is approved, upgrade with H3-Regenerate-2K if 2K is needed.
• generate_audio=true when SFX/BGM are part of the plan; keep the music direction in non_diegetic_music consistent with the reference tempo.
• One generation per planned segment; do not batch-variant the whole chain.
• Change exactly one variable per retry (see Section 11).

10. Review

Check against this list before delivery:

• Motion fidelity — the reference motion is recognizable; every beat from the Beat Sheet appears in order; tempo matches
• Coverage — no beat silently dropped; the final beat lands inside the video duration
• Identity — the target's anchors hold in every frame; no features leak over from the reference performer
• Body integrity — no extra limbs, melting joints, frozen limbs, or sudden costume changes
• Camera policy — static stayed static; copied camera matches the reference path
• Scene discipline — background did not steal detail budget from the moving body
• Audio — matches the agreed policy; music tempo fits the motion

Score each item pass / partial (name the failing beat) / fail. Partial or fail goes to Section 11 with a named cause.

11. Retry Strategy

Fix the cheapest layer first. Never rewrite the whole prompt on failure.

Escalate to the user only after two failed retries of the same layer: offer simplification options (shorter window, fewer beats, simpler motion) instead of a third blind retry.

12. Output

Deliver together:

1. Final video file(s), in segment order when chained
2. The Motion Beat Sheet and Transfer Brief
3. The final prompt text exactly as generated (it is a reusable asset)
4. A settings record: mode, ratio, duration, audio policy, resolution pass
5. Review notes with any accepted caveats (e.g. "beat 3 simplified after retry 2")

Boundaries

This Skill transfers motion, not identity: do not copy the reference performer's face, body, or likeness onto the target, and never use it to make a real private person appear to perform actions they did not perform. For pure style transfer, video editing, or >15s unsegmented requests, route to the appropriate workflow instead of forcing this one.