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/embedded-captions

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by HeyGenheygen-com/hyperframes55k stars
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Add captions or subtitles to an existing single-subject talking-head video without editing the footage. Use for plain verbatim captions, cinematic captions embedded behind the subject, VFX captions, “炸/特效/酷炫字幕,” or a named identity from the 35-style catalog. Route by visual identity, not by backend engine. The quiet `anchor` rail is the default; embed every word only when the user explicitly wants a fully cinematic treatment. The workflow runs locally end to end, including transcription and subject matting; split multi-shot footage before applying it.

Requires /hyperframes

Use this Skill: https://skilld.dev/gh/heygen-com/hyperframes/embedded-captions

This session only. Nothing lands on disk.

referencestypographic-moves.md

≈2.2k tokens on demand. Your agent reads this file only when SKILL.md points to it.

Typographic moves — a palette, not a cage

cinematic-cream template locks DNA only (font-family, motion, color palette defaults). It does NOT enforce slot structure. The agent writes each caption group's typography from scratch via the plan.json css field.

This doc is a palette of tried combinations — pick what fits the scene, invent new ones, skip these if the content demands. These are recommendations, not rules.

Size vs text length — DO THIS BEFORE PICKING SIZE

Bigger is NOT better if the word doesn't fit the frame width. Every time you pick a font-size, sanity-check against word length:

Rough rule for Inter 900 uppercase at -0.03em tracking: max_font_px ≈ frame_width / (longest_word_chars × 0.72)

The 0.72 multiplier is intentionally conservative — it targets the text filling ~90% of the frame width so there's a small side margin. If you want edge-to-edge, drop to 0.65, but you lose a bit of safety margin.

720px portrait:

  • 3-char word (15%): max ~330px (a single big number like "15%")
  • 5-char word (TAKE): max ~200px
  • 7-char word (AUGMENT / QUANTUM / MATTERS): max ~143px
  • 10-char word (CREATIVITY): max ~100px
  • 13-char word (UNPRECEDENTED): max ~77px

1920px landscape:

  • 7-char word: max ~380px
  • 10-char word: max ~267px

For italic/upright 500-700 it's slightly narrower — increase max by ~10%.

If you want the word bigger than it fits:

  • Split into multiple words per group (natural wrap), OR
  • Add explicit <br> between syllables, OR
  • Drop letter-spacing to -0.05em, OR
  • Accept that the matte will cut part of it (Vogue-cover embed effect — only works when the cut area is exactly where the subject is)

Never let the text OVERFLOW the frame edge — that's not cinematic, that's just broken. Use the heuristic.

Sizing discipline (frame-height-relative)

Portrait 9:16 (720×1290) and landscape 16:9 (1920×1080) have very different comfort ranges. Use calc(<pct> * var(--h)) for responsive:

Feel % of frame height Example calc
Whisper / label 4-6% calc(0.05 * var(--h))
Soft opener 6-9% calc(0.07 * var(--h))
Narrative body 9-14% calc(0.11 * var(--h))
Emphasis 14-22% calc(0.18 * var(--h))
Climax / monumental 22-35% calc(0.28 * var(--h))
Title-bigger-than-face 40%+ calc(0.48 * var(--h))

Use absolute px only when a specific scale needs to look identical across frame sizes (rare). Prefer calc + var(--h).

Named moves — pick per group

Italic contemplative opener (memory-wall cap-1 lineage):

font-weight: 600;
font-style: italic;
letter-spacing: -0.01em;
font-size: calc(0.075 * var(--h));

Italic continuation / dreamier continuation (cap-2 lineage):

font-weight: 500;
font-style: italic;
letter-spacing: -0.005em;
font-size: calc(0.065 * var(--h));

Upright pivot / statement (cap-3 lineage — "but suddenly"):

font-weight: 700;
letter-spacing: -0.015em;
font-size: calc(0.07 * var(--h));

Uppercase climax / monumental (cap-4 lineage — "EVERYTHING IS SHARP AGAIN"):

font-weight: 900;
text-transform: uppercase;
letter-spacing: -0.03em;
line-height: 0.95;
font-size: calc(0.18 * var(--h));

Chapter card / full-frame Adam Curtis manifesto:

font-weight: 700;
text-transform: uppercase;
letter-spacing: -0.015em;
line-height: 0.9;
font-size: calc(0.14 * var(--h));

News chyron / broadcast label (small, locked):

font-weight: 500;
letter-spacing: 0.02em;
font-size: calc(0.038 * var(--h));

Tiny side note / caption-on-surface:

font-weight: 400;
font-style: italic;
font-size: calc(0.045 * var(--h));

Vogue-masthead monumental:

font-weight: 900;
text-transform: uppercase;
letter-spacing: -0.04em;
line-height: 0.85;
font-size: calc(0.32 * var(--h));

Narrative arcs (suggestions, not required)

Poem arc — memory-wall canonical: italic opener → italic continuation → upright pivot → uppercase climax. Four steps.

Question-answer arc: italic question small → uppercase answer big. Two steps.

List-of-three arc: three equal-weight narration segments, one climactic uppercase. Four steps.

Single-statement arc: one monumental uppercase held long. One step.

Whisper-hook arc (short-form): tiny italic hook → massive uppercase reveal. Two steps.

The number of groups comes from the content. A 25s Pausch talk has ~8 beats. A 7s TikTok hook has 2-3 beats. Don't force 4 or 5 or 7 — read the transcript and mark breath-groups.

Position + layer vocabulary

Position is where the caption lives in frame. Use:

  • top / left / right / bottom (percentages or px) for anchor
  • transform: translateX/Y for fine offsets
  • text-align: center / left / right for alignment

Layer per group:

  • bg (default) — behind subject. Matte occludes. Cinematic embed. Works on clean zones (sky, walls) OR intentionally crosses subject for the Vogue-masthead effect.
  • fg — on top of subject. Announcement. Use for climax breakthroughs or when bg would be 100% occluded by body.

Tone per group:

  • soft — gentle per-word opacity+y drift (0.45s power2.out). Use for introspective, dreamy, or narrative content.
  • present — snappy per-word opacity+y+scale pop (0.22s power3.out). Use for emphatic or declarative beats.

Anti-patterns the DNA protects against

The DNA defaults prevent most ugly outcomes. But avoid in per-group CSS:

  • Multiple different font-family within one video (DNA is one family)
  • Multiple saturated colors (one accent at most; DNA defaults cream or deep warm)
  • letter-spacing above ±0.05em unless there's a specific reason
  • font-weight 300 or below — too light for screen
  • font-style: italic on emphasis — italic is for lyricism, not stress

When cinematic-cream is wrong

This DNA assumes mid-to-dark backgrounds (luminance 60-180). For:

  • Bright white studios → cinematic-cream's cream + screen washes out, and the DNA is locked (you cannot recolour it) → use Standard mode (opaque rail) instead
  • Documentary formal → Standard mode (documentary-dignified direction; see references/direction-catalog.md §1)
  • Energetic vlog hooks → future kinetic-vlog DNA (not yet shipped)

Example: memory-wall original, expressed in freeform

Same output as the canonical memory-wall.html, but using slot-free plan:

{
  "template": "cinematic-cream",
  "caption_layer": "bg",
  "groups": [
    {
      "id": "cg-0",
      "tone": "soft",
      "in": 0.2,
      "out": 4.85,
      "css": "top: 14%; right: 6%; left: auto; text-align: right; font-size: calc(0.09 * var(--h)); font-weight: 600; font-style: italic; letter-spacing: -0.01em;",
      "words": [
        { "text": "Some", "start": 0.24, "end": 0.44 },
        { "text": "memories", "start": 0.48, "end": 0.82 },
        { "text": "feel", "start": 0.92, "end": 1.14 },
        { "text": "soft", "start": 1.2, "end": 1.64 }
      ]
    },
    {
      "id": "cg-1",
      "tone": "soft",
      "in": 2.55,
      "out": 4.85,
      "css": "top: 26%; right: 10%; left: auto; text-align: right; font-size: calc(0.075 * var(--h)); font-weight: 500; font-style: italic;",
      "words": [
        { "text": "like", "start": 2.66, "end": 2.78 },
        { "text": "old", "start": 2.88, "end": 3.02 },
        { "text": "film", "start": 3.16, "end": 3.46 }
      ]
    },
    {
      "id": "cg-2",
      "tone": "present",
      "in": 4.9,
      "out": 8.04,
      "css": "top: 18%; right: 6%; left: auto; text-align: right; font-size: calc(0.085 * var(--h)); font-weight: 700;",
      "words": [
        { "text": "but", "start": 5.04, "end": 5.18 },
        { "text": "suddenly", "start": 5.24, "end": 5.76 }
      ]
    },
    {
      "id": "cg-3",
      "tone": "present",
      "in": 6.7,
      "out": 8.04,
      "css": "top: 32%; right: 6%; left: auto; text-align: right; font-size: calc(0.11 * var(--h)); font-weight: 900; text-transform: uppercase; letter-spacing: -0.03em; line-height: 0.95;",
      "words": [
        { "text": "everything", "start": 6.82, "end": 7.14 },
        { "text": "is", "start": 7.18, "end": 7.28 },
        { "text": "sharp", "start": 7.32, "end": 7.52 },
        { "text": "again", "start": 7.58, "end": 7.92 }
      ]
    }
  ]
}

Same visual, no slot constraint. Each group owns its typography.

Source: SKILL.md on GitHub

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    The skill is a professional video production tool for embedding cinematic captions into videos. It utilizes industry-standard tools like FFmpeg for audio/video processing, WhisperX for transcription, and Puppeteer for rendering. The skill includes built-in security features such as HTML sanitization of transcript data and Subresource Integrity (SRI) for external scripts.

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    Risk: LOW · No issues

Signed by skilld at 0a5e3c7. This ties the file your Agent reads to that commit on GitHub. It does not review the instructions.

Last checked against GitHub 17 hours ago.

Activeupdated 4 days ago

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