explainer-video

Explainer Video

Turn one message into a paced, narrated 30–90s short. Run the full pipeline: script → storyboard → scene build → narration/caption sync → edit → polish, with a consistent style system throughout.

When to use

• Produce a 30–90s product, how-it-works, onboarding, or concept video.
• Go from a raw idea or feature to a script, storyboard, and assembled piece.
• Sync narration to visuals and add captions for muted playback.

Story structure (decide this first)

An explainer is an argument, not a feature tour. Before any pipeline step, lock the narrative so every later choice serves it.

• One core idea. A single sentence the viewer should be able to repeat afterward. If you can't state it in one line, the video has no spine — cut scope until you can. Everything that doesn't serve that idea gets dropped, not shrunk.
• Script-first. The VO is the spine; visuals illustrate the line being spoken, never lead it. Write and time the words before you storyboard or animate — it is far cheaper to cut a sentence than a built scene.
• Earn the "how" with stakes. Don't jump from problem to mechanism. Make the viewer feel the cost of the problem first; that tension is what makes them watch the solution.

The explainer story arc — a beat per stage, in order:

(The Script formula table below maps these stages to runtime shares and word budgets — this section is the why and order; that one is the how long.)

Pick one analogy and ride it

Abstract mechanisms land when mapped to something the viewer already knows. Choose a single metaphor and keep it consistent across scenes — switching analogies mid-video resets comprehension.

• Pick a metaphor from the viewer's world (a queue, a thermostat, an assembly line), not the engineering domain.
• One metaphor per video; reuse it for both the visual grammar and the VO wording.
• Test it: if the analogy needs its own explanation, it's the wrong one.

Pacing per beat

Pace tracks tension. Move quickly through Problem/Stakes to reach the value; slow down on the "how" so each step lands; let the payoff breathe.

The pipeline

1. Script — one core message. Structure: problem → solution → how → payoff. Write tight voiceover (VO); time it at ~2.3 words/second (≈140 wpm). A 60s video is ~138 words.
2. Storyboard — one idea per scene. Sketch each frame plus its transition; map each VO line to a visual.
3. Build scenes — animate diagrams/data, kinetic text/keywords, and backgrounds (techniques inlined below).
4. Narration & captions — record/generate VO, align scene cuts to VO beats, burn in captions (most plays are muted).
5. Edit — cut to the narration, hold each idea long enough to land, remove any scene that doesn't advance the message.
6. Polish — color pass, consistent easing, audio mix, end card.

Script formula

Write VO first, in spoken language (contractions, short sentences). Read it aloud and time it before building anything.

VO timing math

• Pace: ~2.3 words/sec (140 wpm) for clear, friendly narration; slow technical lines to ~2.0.
• Estimate scene length from its VO line: seconds = words / 2.3, then add ~0.4s breathing room.
• A scene with no VO (pure visual beat) still needs ≥1.0s to register.

Scene-build techniques (inlined)

Diagram / data reveal (progressive disclosure: nodes → edges → labels):

import gsap from "gsap";
gsap.set(".edge", { strokeDasharray: 1, strokeDashoffset: 1 });
gsap.timeline()
  .from(".node", { opacity: 0, scale: .85, transformOrigin: "center",
                   duration: .45, stagger: .3, ease: "back.out(1.5)" })
  .to(".edge",  { strokeDashoffset: 0, duration: .5, stagger: .3 }, "-=0.6");

Kinetic keyword (word pops in on the stressed syllable):

.kw { display:inline-block; opacity:0; transform:translateY(18px); }
.kw.in { opacity:1; transform:none; transition:all .4s cubic-bezier(.22,1,.36,1); }

Count-up stat:

function countUp(el, to, dur=1200){ const t0=performance.now(); (function f(n){
  const k=Math.min(1,(n-t0)/dur), e=1-Math.pow(1-k,3);
  el.textContent=Math.round(to*e).toLocaleString(); if(k<1)requestAnimationFrame(f);})(t0); }

Render the assembled piece with Remotion (data-driven, deterministic) or After Effects.

Caption sync

Captions are mandatory — assume muted autoplay. Use a .srt/.vtt cue list keyed to the VO. Keep ≤2 lines, ≤42 chars/line, on-screen ≥1.0s, gone before the next line starts.

1
00:00:00,300 --> 00:00:02,600
Managing releases by hand is slow.

2
00:00:02,800 --> 00:00:05,400
Shipfast automates the whole pipeline.

In Remotion, drive captions from the same timing array used for scene cuts so they never drift.

Style-system consistency

Lock one type scale, one color grammar (color = meaning, never reassigned), and one easing curve before building scene 2. Reuse the same enter/exit transitions across scenes so the piece feels like one object, not a montage of experiments. Visuals must illustrate the VO line currently spoken — show, don't decorate.

Output checklist

• Single clear message; every scene advances it.
• VO timed (~2.3 w/s); scene lengths derived from VO.
• Storyboard maps each VO line to a visual.
• Captions burned/available; ≤2 lines, readable.
• Consistent type/color/motion system across all scenes.
• End card with one clear CTA.

Deliver & verify (rendered stills → MP4)

Packaged helper (scripts/): tile your stills with scripts/contact-sheet.sh sheet.png f-hook.png f-mid.png f-end.png, then assert the encode with scripts/probe-mp4.sh out.mp4 [WxH] [fps]. See scripts/README.md.

The assembled explainer is a Remotion composition — frame-deterministic, so any exact frame renders headlessly with no seek harness. Use this tier when the deliverable is an MP4/GIF that carries baked narration and burned captions; for a single web scene, deliver standalone HTML instead.

Output contract:

• A Remotion project with the composition registered (<Composition> + zod schema + defaultProps), all motion frame-driven (no timers / Date.now() / Math.random()).
• Deliverable = the rendered out/*.mp4 (plus the project, so VO/script/data can be re-rendered).
• Narration via <Audio src={staticFile()}>; VO/scene timing baked into props (no realtime audio at render). Captions driven from that same timing array so they never drift.
• Duration data-dependent? compute it in calculateMetadata, not by hand.

Verify loop — render stills → inspect → encode. Render single frames first (cheap, no encode), inspect them, encode only once the frames are right.

# Frame-exact stills at start / mid / end — render with the SHIPPED props, not just defaults
npx remotion still Explainer out/f-start.png --frame=0   --props='{...}'
npx remotion still Explainer out/f-mid.png   --frame=N   --props='{...}'
npx remotion still Explainer out/f-end.png   --frame=L   --props='{...}'   # L = durationInFrames - 1

# Inspect: script→storyboard→scene maps onto frames — sample a frame inside EACH scene's hold,
# confirm narration line and caption are synced to the visual at that frame, no text overflow / off-canvas.

# Only after the stills check out, encode:
npx remotion render Explainer out/explainer.mp4 --props='{...}'

• npx remotion compositions reads durationInFrames/fps to pick the end frame and per-scene hold frames.
• README demo GIF for free: npx remotion render Explainer out/demo.gif --codec=gif.

Before you finish:

1. npx remotion still renders cleanly at frame 0, a frame inside each scene's hold, and last — no errors, no missing assets/fonts.
2. At every sampled scene frame, the caption and the spoken VO line match the visual on screen (no drift).
3. Captions are inside safe areas, ≤2 lines, readable; text is exact and not clipped.
4. Frame-driven only — no Date.now() / Math.random() / timers; the shipped props render correctly (not just defaultProps).
5. Full MP4 encoded and plays with narration; (optional) GIF rendered for the README.

Reference files

• references/script-to-screen-workflow.md — full pipeline detail: the problem→solution→how→payoff script formula with a worked example and word budget, VO timing tables, a fill-in storyboard template with timecodes, a per-scene build checklist, caption authoring guidance (VTT/SRT), and a style-system spec sheet for cross-scene consistency.