Short-Form Vertical Video (Hyperframes)

Short-form = 1080x1920 vertical, 10–30s, talking-head face + motion-graphic scene overlays + karaoke captions. Everything in this skill is distilled from the May Shorts 19 iteration autopsy (v1 → v4) and should be applied on every new short.

Always invoke /hyperframes first. This skill sits on top of it — it does not replace the framework rules (data-* attributes, window.__timelines, composition structure). Those are non-negotiable regardless of the format.

When this skill fires

• "Make a short-form video", "TikTok post", "Reels", "Shorts", "vertical video"
• Any build starting from a talking-head recording + script/transcript intended for social
• Retiming, recutting, or re-syncing an existing short
• Adding karaoke captions synced to a voiceover

Creator-reference mode

If the user names a creator reference for this build — "build this like @handle", "use @handle's style", "blend @h1 + @h2" — before brainstorming scenes, read the matching style fingerprint(s):

1. _reference/creator-library/<handle>/style-distilled.md if it exists (auto-written at ≥3 analyses).
2. Otherwise read each of _reference/creator-library/<handle>/videos/*/analysis.md directly.

Apply their signature moves (hook structure, caption style, pacing cadence, transition rotation, scene archetypes, face treatment) on top of the May Shorts 19 playbook below. The creator fingerprint overrides MOTION_PHILOSOPHY.md defaults for these dimensions, but stays subordinate to PREFERENCES.md — if a creator's signature move conflicts with a captured preference, the preference wins.

If the named handle doesn't have a folder in _reference/creator-library/, stop and tell the user it hasn't been studied yet. Suggest /study-creator <url> on 1–3 of their videos before the build.

The playbook (high-level)

1. Audio is source of truth. Edit audio FIRST (cut retakes, pauses). Save as <name>-edit.mp4. Measure exact duration with ffprobe — this is the composition's data-duration.
2. Transcribe the edited audio with npx hyperframes transcribe <edit>.mp4 --model small.en --json, or if retiming an existing build with a shift() function in captions, keep the existing captions and just shift scene starts.
3. Author scene boundaries in edited-time — NEVER mix original-time and edited-time anchors in the same file. See "Audio-sync protocol" below.
4. Build the composition scaffold (4 layers: ambient-bg, seam-treatment, captions, face) — see "Composition scaffold" below.
5. Author scenes with LOCAL offsets relative to each scene's data-start. Each scene is its own sub-composition under compositions/scene<N>-<label>.html.
6. Lint → draft render → word-exact frame verification → final render. This is the verification gate. Never skip step 3 (frame verification).

Composition scaffold (the 4 always-on layers)

Every short-form vertical has these four sub-compositions under compositions/, loaded on shared tracks:

index.html (root, 1080x1920, data-composition-id="main")
├── ambient-bg.html        track-index="3" — radial gradient + drift grid + particles + vignette
├── face-wrapper + <video> track-index="0" — talking head (see face-mode choreography)
├── seam-treatment.html    track-index="5" — feathers y=960 edge (bottom-half scenes only)
├── scene1-<label>.html    track-index="1" — scene overlays (back-to-back, no gaps)
├── scene2-<label>.html    track-index="1"
├── …
└── captions.html          track-index="2" — karaoke captions, word-synced

• data-duration is identical across root, ambient-bg, seam-treatment, face-video, face-audio, captions. Only scene overlays change over time.
• <audio> for the face is a SEPARATE element (mixer needs it), never use the video's own audio track.
• class="clip" goes on timed divs — NEVER on <video> or <audio>.

Face-mode choreography (the signature move of short-form)

The face lives in a wrapper div sized at the source's native landscape (1920x1080). GSAP animates the WRAPPER (never the video element — animating <video> dimensions freezes frames).

Two modes:

const BOTTOM     = { x: 0,       y: 1136, scale: 0.5625 }; // bottom-half, full landscape visible
const FULLSCREEN = { x: -1166.5, y: 0,    scale: 1.7778 }; // cropped-cover, fills 1080x1920
const MODE_DUR = 0.32;

BOTTOM renders the 1920x1080 source at 1080x607.5 centered in the bottom 960px. FULLSCREEN crops horizontally to fill the portrait frame.

Transition 0.15s BEFORE the new scene's content lands, using ease: "expo.inOut":

[
  { t: <scene-4-start>, mode: FULLSCREEN },
  { t: <scene-5-start>, mode: BOTTOM },
  …
].forEach(({ t, mode }) => {
  mainTl.to("#face-wrapper", { ...mode, duration: MODE_DUR, ease: "expo.inOut" }, t - 0.15);
});

A face that snaps modes instantly is the single most jarring frame in a vertical video. Always interpolate.

Face grading (every short, no exceptions)

#face-video {
  filter: contrast(1.08) saturate(1.08) brightness(0.97);
}

Plus a subtle 1.00 → 1.025 Ken Burns zoom over the full duration (ease: "none") and a side-vignette ::after pseudo-element so the face sinks into the surrounding navy instead of butting against a razor edge.

Seam treatment (required for bottom-half scenes)

A navy→transparent gradient band (60–100px) at y=960 plus a 2px accent scan line with soft glow. Draw it AFTER the face so it sits on top; full-screen scenes will cover it when they take over. Razor-sharp y=960 cuts are the #2 tell for AI-edited content (after background flatness).

Audio-sync protocol (DO NOT skip)

Problem: if audio is edited (retakes/pauses removed), timestamps in the source transcript no longer match the edited video. Scene starts authored in original-time will fire late.

The rule: ALL timing lives in edited-time. Never mix.

Verification procedure for any short-form retime:

1. Measure both audio files:

   ffprobe -v error -show_entries format=duration -of csv=p=0 assets/original.mp4
   ffprobe -v error -show_entries format=duration -of csv=p=0 assets/<name>-edit.mp4

   Difference = total cut time.
2. If using a shift() function in captions.html to map transcript words, treat that as the source of truth. The map shift(originalTime) = editedTime applies to EVERY scene data-start too.
3. Scene internal offsets (inside compositions/sceneN.html) are LOCAL relative to the scene's data-start. If a scene's parent data-start is correct in edited-time, internal offsets stay correct WITHOUT modification — UNLESS a scene straddles a cut, in which case both the parent duration AND internal offsets shift.
4. Face-mode transition array times MUST use edited-time. They are NOT automatically shifted.

Plan format for retimes (use this table structure every time):

Then the face-mode array, then any internal-offset changes, then frame-verification list.

Scene authoring

One scene = one sub-composition file. Scenes sit on the same data-track-index back-to-back (no gaps). Inside each scene:

• data-duration matches the parent's slot exactly
• All GSAP anchors are LOCAL (0-based from scene start)
• Use tl.set({}, {}, <data-duration>) to pad the timeline so GSAP tl.duration() matches data-duration

Scene pacing rules (from the 10 principles)

• No dead frames. Every 100ms has ≥1 animating element. Offset first entrance 0.1–0.3s, not t=0.
• Payoff ≥ 1s hold. The "big reveal" of the scene (stamp, number lock, punchline) must have ≥1s on screen, ideally 1.5s. Budget scenes by reveal time, not total time.
• Motion through full duration. If entrance anims all land by local 2s on a 4s scene, add secondary motion: underline sweeps, checkmark pops, ambient drift on cards, small oscillating glows on pills. Dead pacing = swipe-away.
• Vary eases. At least 3 different eases per scene across entrances.
• One jaw-dropper per 5s of runtime. Typography slam, glitch/chromatic reveal, whip-pan, audio-sync slam. Without these, the video reads as "labeled talking head" — correct but forgettable.

Captions (karaoke style)

• Montserrat 900, 46–58px (for 1080 width), 100% white base
• Active word: scale-1.08 pop + color change to your brand accent (var(--brand-accent))
• Stroke via layered text-shadow, NEVER -webkit-text-stroke (renders inconsistently in Chromium render)
• Drop the rgba background pill — let the stroke hold readability. Captions should feel like graffiti on the frame, not a subtitle track.
• For retimes, use a shift() function inside captions.html to map transcript word timestamps → edited-time. This keeps the transcript JSON untouched and makes retimes mechanical.

See references/captions.md under /hyperframes for the full karaoke implementation. TL;DR: per-word <span> elements with data-word-start, GSAP tweens scoped to each span, tight 0.08–0.12s pop durations.

Ambient background (never ship flat navy)

Minimum viable background stack:

1. Radial gradient base (center lighter than edges by 15–20%)
2. Animated noise/grain overlay at 8–12% opacity
3. 4–8 drifting particle dots or grid traces
4. Subtle vignette

A flat dark fill alone is a placeholder, not a design. For a techy/control-room aesthetic, build a layered background stack: HUD grid masked to a vignette + circuit traces + pulse nodes + a scan beam + a telemetry ticker + corner mono labels.

Audio reactivity

• Headlines pulse 3–6% on beat. Backgrounds can go 10–30% on bass.
• Text reactivity kept subtle (3–6%) so captions stay readable; backgrounds can push harder.
• Use a SEEDED offline analyser (pre-compute the audio feature track) so renders are deterministic. Do NOT use AnalyserNode in the render path — Math.random() and real-time audio nodes break determinism.

Transitions

• Rotate flavors. No two consecutive transitions the same type. Six hard cuts in a row is the #1 tell for AI editing.
• Face-mode transitions (BOTTOM ↔ FULLSCREEN) double as scene transitions when the mode changes between scenes.
• For pure overlay scene-to-scene, install from registry: push-up, flash-through-white, sdf-iris, or the full shader-transitions pack. npx hyperframes catalog --type block to browse.

The verification gate (mandatory — DO NOT ship without)

Lint passing ≠ design working. Never report a short-form render done until you have extracted frames at word-exact timestamps and READ every PNG.

Step 1 — draft render

cd video-projects/<slug>
npx hyperframes lint
npx hyperframes render --quality draft --output renders/<slug>-vN-draft.mp4

Step 2 — word-exact frame extraction

Pick 8–15 timestamps that each correspond to a SPOKEN WORD where a specific visual should be on-screen. Not round numbers. Not mid-scene. The exact word.

mkdir -p renders/frames-vN
for pair in "<t>:<label>" "<t>:<label>" ...; do
  t="${pair%%:*}"; label="${pair##*:}"
  ffmpeg -y -ss "$t" -i renders/<slug>-vN-draft.mp4 \
    -frames:v 1 -q:v 2 "renders/frames-vN/t${t}-${label}.png"
done

Step 3 — Read every PNG

Call Read on every PNG so the image loads into context. Do NOT just list filenames. For each frame confirm:

• The expected visual is on-screen at the expected moment (not 1s late, not early)
• Speaker's face is not cropped in any bottom-half scene
• Full-screen vs bottom-half face mode is correct for that scene
• Captions are on-brand, readable, not overflowing
• No blank frames, no unintentional overlap, no text-off-canvas

Step 4 — if anything fails, fix + re-verify. Never ship broken.

Step 5 — final render

npx hyperframes render --quality standard --output renders/<slug>-vN.mp4

Spot-check 3–4 frames from the final render (same timestamps, different folder frames-vN-final/) to confirm the standard-quality encode didn't change anything.

The 10 rules (quality checklist — run BEFORE first draft)

Every short-form build. Run this list during authoring, not after.

1. No dead frames. Every 100ms has an animating element.
2. Scene payoff ≥ 1s hold. Budget by reveal time, not total time.
3. Face is a character. Grade + Ken Burns + side vignette.
4. No hard seams. Feather y=960 with gradient + scan line.
5. One jaw-dropper per 5s. Typography slam, glitch, whip-pan, audio slam.
6. Audio reactivity non-negotiable. 3–6% text, 10–30% background.
7. Rotate transition flavors. No two consecutive the same.
8. Captions pop, don't politely label. Stroke not pill. Scale + color on active word.
9. Motion through full scene duration. Secondary motion if entrances land early.
10. Background is a layer, not a color. Radial + noise + particles + vignette minimum.
11. Slam/stamp overlays land AFTER target text is fully visible. Reveal logic > word-sync. Stamp t ≥ target-visible t + 0.10–0.25s. Otherwise the punchline lands before the setup.

Project structure (every short-form project)

video-projects/<slug>/
├── hyperframes.json
├── meta.json                    (id, name, dimensions 1080x1920, fps 30)
├── index.html                   (root composition, the 4-layer scaffold)
├── compositions/
│   ├── ambient-bg.html
│   ├── seam-treatment.html
│   ├── captions.html            (with shift() function if retiming)
│   ├── scene1-<label>.html
│   ├── scene2-<label>.html
│   └── ...
├── assets/
│   ├── <name>.mp4               (original recording)
│   ├── <name>-edit.mp4          (edited — cuts removed — this is what the comp uses)
│   ├── transcript.json          (whisper output)
│   └── brand assets (logo, brand-tokens.css, background music)
└── renders/
    ├── <slug>-v1-draft.mp4
    ├── frames-v1/
    ├── <slug>-v1.mp4
    └── ...

Retime protocol (when audio is re-edited or timestamps drift)

1. Measure old and new edited audio durations with ffprobe. Delta = total cut time.
2. Identify cut window(s): which seconds were removed, from where.
3. Write the Plan table: every scene data-start, data-duration, every face-mode transition t, any scene whose internal offsets straddle a cut.
4. For each scene that straddles a cut, both its parent duration AND its internal offsets change. Scenes entirely on one side of the cut just need parent data-start shifted.
5. Lint → draft render → word-exact frame verify → final render. No shortcuts.

What NOT to do in short-form

• Don't animate <video> element dimensions — freezes frames. Animate wrapper div.
• Don't use repeat: -1 on any timeline — breaks the capture engine. Finite counts only.
• Don't use Math.random() or Date.now() — breaks determinism. Seeded PRNG if pseudo-random needed.
• Don't use <br> inside captions — natural wrapping + <br> produces extra unwanted breaks.
• Don't skip the frame verification gate. Lint exit code is not visual truth.
• Don't author in original-time if the audio is edited. Edited-time or nothing.
• Don't leave background: #07121c flat. Layer it.
• Don't hard-cut between scenes. Rotate transition flavors.
• Don't polite-caption. Pop them.
• Don't let the face sit still. Grade + Ken Burns always.

Face-mode & scene lessons

Distilled from four concrete problems early short-form renders ran into and what fixed them. Apply these on every new short.

1. Slam/stamp timing — reveal logic beats word-sync

A SLAM/STAMP overlay (KILLED, DEAD, STOP, etc.) lands AFTER its target text is fully visible, not during the spoken word. In one early build, two products were pitched as opponents — the KILLED stamp fired at local 0.46s while the second product's name didn't appear until 0.66s, so viewers saw "X … KILLED" with no visible target. The joke collapsed.

Rule: stamp_t ≥ target-text-visible_t + 0.10–0.25s. The "visible" timestamp is the END of the target's entrance animation, not its start. Word-sync is a guideline; visual reveal order is the constraint.

2. BOTTOM face-mode scale — don't ship the default

Default BOTTOM = { x: 0, y: 1136, scale: 0.5625 } (exact horizontal fit for a 1920×1080 source) leaves empty studio background flanking the speaker if they occupy <70% of the source frame. This is a common starting default — and it leaves visible dead space left and right of the speaker in every BOTTOM scene when the source framing isn't tight.

Rule: prefer BOTTOM = { x: -180, y: 1110, scale: 0.75 } — crops 180px each side, bottom-anchors to y=1920. Preview ONE frame of BOTTOM mode against the actual source video before committing the constant. If the source speaker is tight-framed already, scale 0.65 may be enough; if the source is wide studio framing, push to scale 0.80 and re-tune x.

Always keep HIDDEN's x, y, scale identical to BOTTOM — they only differ in opacity — so the opacity-fade scenes don't drift geometrically mid-fade.

3. Face-mode transitions — three things at once, not one

When the face changes mode between adjacent scenes, a bare 0.15s pre-roll + 0.32s duration expo.inOut on just the face wrapper reads as rigid — the outgoing scene's panels are still fully opaque behind the morphing face, so the eye sees two things fighting instead of a crossfade.

Rule: for any "hero" scene-to-scene face-mode change (especially BOTTOM ↔ FULLSCREEN), do all three:

1. Extend that specific transition's duration to 0.45–0.55s (not the default 0.32s)
2. Start it 0.25–0.30s before the new scene's data-start (not the default 0.15s)
3. Fade + blur the outgoing scene's panel wrapper to opacity: 0, filter: blur(6px) over 0.20–0.25s, starting 0.25s before scene end

Implementation-wise, promote the face-mode transition array to per-entry dur so one transition can be longer than the others:

[ { t: 2.06, mode: FULLSCREEN, dur: 0.50 }, { t: 3.71, mode: HIDDEN, dur: 0.32 }, ... ]
  .forEach(({ t, mode, dur }) => mainTl.to("#face-wrapper", { ...mode, duration: dur, ease: "expo.inOut" }, t));

Three simultaneous changes = "a real editor edited this." Any one alone = rigid.

4. Data-feel scenes beat decoration scenes mid-video

For scenes 3–5 of a 15–20s short (the "middle grind" where attention drops the hardest), lean on visuals that read as information — bar races, stat grids with counting numbers, heatmaps, sparklines, flowcharts, dashboard chrome with telemetry ticking, pain-point grids that flash red in sequence. One early build's scene 4 was a radar-rings + terminal-chip + sparks combo — functional but decorative, and it read as "bland." Replacing it with a 3×3 pain-point grid lighting up red-orange in sequence + a sparkline stroke-drawing with a YOU-ARE-HERE marker + the payoff slam — same time budget — landed much harder.

Rule: pure typography-plus-icon scenes feel like slides. Data-feel scenes feel like evidence. When a middle scene feels bland, replace the decoration with something that reads as information: a small number ticking up, a bar filling, a chart stroking in, a grid flashing in sequence.

Reference compositions

This workspace doesn't ship bundled example videos. Build your own reference library instead: run /study-creator <url> on a few short-form videos whose editing you admire, and this skill will read each creator's _reference/creator-library/<handle>/style-distilled.md when you say "build this like @handle." Your /setup step already seeds this with the reels you pasted.

Related skills (invoke in addition)

• /hyperframes — framework rules (always first)
• /hyperframes-cli — CLI commands (init, lint, preview, render)
• /gsap — animation library reference
• /hyperframes-registry — installing transition blocks
• /study-creator — study a reference creator so you can later "build this like @handle"