Motion design film skill

Motion-design film

You are the director, motion designer, composer and editor of a short film — and every frame of it is rendered by code. The pipeline was battle-tested on real films; each step exists because skipping it once produced a visible defect.

brief ─► story & beat sheet ─┬─► music.py ────────────────┐
                             ├─► tts.py ─► stt_check.py ──┼─► mix.py ──────────┐
                             └─► scenes ─► timeline.js ─► render.mjs ─────────┴─► finalize.sh ─► MP4
                                   ▲
                    optional footage: capture.mjs + clock.js (live site / app / game)

Scripts are in scripts/ (run them from your work folder; they read and write relative to the current directory). The compositor template is assets/comp-template/. One-time setup: npm install in the skill folder, pip install numpy scipy, Chrome and ffmpeg on PATH.

1. Brief: what is the one feeling?

Before any pixels, answer in a sentence each: what is it, who watches (a class of kids, investors, users in a feed, a jury), what should they feel and do after 2 minutes. A film about a calm to-do app should feel calm after the chaos; a game trailer should feel like a ride; a research result should feel like a revelation. Pick the language of the audience.

Collect the raw truth: real names, real numbers, real features, real screenshots or a live URL. Invented numbers in a promo film are a liability — use placeholders the user will replace and say so.

2. Story on a music grid

Write a beat sheet on a 120 BPM grid (bar = 2 s): cuts land on even seconds, accents on half-seconds, the hardest hits on music impacts. The template follows the spine that works for almost anything:

time	beat	purpose
0–8	Hook — a question or tension the viewer feels	stop the scroll
8	Name — logo slam on the first impact	who we are
8–24	Problem → Turn — the messy "before", then it collapses into one point	why it matters
24–40	How — 3 numbered steps with (mock) screens	it's simple
40–56	What — features on the beat, a grid of tiles	it's rich
56–64	Feeling — one calm sentence, a marker highlights the key word	the emotional core
64	Proof — big numbers on the second impact	it's real
64–88	Growth / journey — chart, route, map	it goes somewhere
88–104	People — avatars connect into a network	it's for us
104–112	Pulse — a word per beat	energy peak
112–120	Action — logo, tagline, CTA, URL	what to do now

Adapt freely: a game swaps Problem for a cinematic montage, a research film swaps Features for a chart sequence, a 30-second ad keeps Hook → Name → What → Action. Voiceover: one short line per beat, ≤2.5 words/s (≈200–260 words per 2 minutes), silence around the big hits.

3. Music — scripts/music.py

python3 scripts/music.py → the default 120-s score (A-minor → C-major anthem, impacts at 8/64/112 s). Different length/structure: --print-default-plan > plan.json, edit sections (in bars) and impacts, --plan plan.json. The plan and the beat sheet must agree.

4. Voice — scripts/tts.py → scripts/stt_check.py

export OPENROUTER_API_KEY=…          # or ./.openrouter_key (gitignored)
python3 scripts/tts.py script.json   # vo/NN.mp3 + vo/subs.json, warns about overlaps
python3 scripts/stt_check.py script.json

script.json = model, voice, lines {start, text, spoken} (spoken may carry ElevenLabs v4 audio tags like [excited]). Fix overlaps by moving start, then tts.py --retime. Always run stt_check.py — it is the only reliable way to know nothing was read aloud wrong when nobody in the loop listens. Details, models, voices, key handling: references/voice.md.

5. Scenes — assets/comp-template/ (the heart of it)

Copy the template to comp/. engine.js is a tiny deterministic motion engine (every frame is a pure function of time). timeline.js is the film: edit TEXT, COLORS, CLIPS and times. It already contains a complete 120-s film made only of motion graphics — living gradient backgrounds, kinetic type, notification chaos, a collapse-to-a-point transition, numbered steps with animated skeleton UI, flipping feature tiles, a marker highlight, odometers, a growing chart with a drawn line, a rocket on a route, a network of people with data pulses, a beat-synced word montage and a CTA end card. Render it as is to see the standard you're aiming for.

Read references/motion-design.md before designing scenes: timing, easing, hierarchy, layering, colour, type, transitions, and how to invent new scenes that still feel like one film.

Real visuals make it stronger when they exist:

• a live website/app/game — film it frame-perfectly with scripts/capture.mjs (virtual clock, see references/capture.md; example: examples/capture.example.mjs on examples/live-app-demo/);
• screenshots or photos — drop them into scenes as <img> with slow Ken Burns moves;
• existing clips — put them in footage/ and name them in CLIPS; mock windows, phones and cards play them instead of the skeleton UI.

node scripts/render.mjs sheet 0.5 120 2.5   # contact_sheet.png — LOOK at it, every iteration
node scripts/render.mjs part 24 40          # fast check of one beat
node scripts/render.mjs                     # full film → video_silent.mp4 (~3–5 min for 120 s)

6. Mix and deliver

python3 scripts/mix.py                         # music ducked under voice, -14 LUFS → mix.wav
bash scripts/finalize.sh "Orbit — launch film"  # master + light copy + final_sheet.png

Look at final_sheet.png before handing over: text cut at the edges, two titles fighting, subtitles over giant type, dead seconds where nothing moves, clips frozen on their first frame. Then present the film beat by beat in plain words, give both file paths, and mention what you'd improve and anything that cost money (TTS is a few cents).

Pitfalls

references/troubleshooting.md — symptoms → causes → fixes (white/black frames after a time-lapse, clips frozen on frame 0, wrong server, overlapping voice, fonts, %20 paths…).