| name | viz-frame-audit |
| description | Trigger when: (1) the user mentions "noise", "slop", "frame audit", "video
review", "letter spacing", "padding intrusion", "frame extract", "naive
arrow", or Korean equivalents (노이즈, slop, 프레임 검수, 글자 깨짐), or
(2) after rendering a new or modified Manim scene, or (3) the user asks to
review an mp4 in `media/videos/` or `~/Downloads/`.
Post-render audit workflow for Manim 1080p60 videos. Extracts keyframes via
ffmpeg, inspects them through Claude Code's Read tool, and classifies any
defects into four standing categories (naive arrow / padding intrusion /
glyph kerning drift / frame-order error). Catalogues 12+ verified incidents
across the four GEODE scenes so each is caught the first time, not
rediscovered. The companion authoring skill is [[manim-scene-craft]].
|
| when_to_use | Use AFTER a render (or a re-render after a fix) to verify the four defect
categories. Skip when only running the layout ratchet `--static-check` is
needed.
|
| user-invocable | false |
Viz Frame Audit
The four categories
Videos are inspected against the four standing defect categories below. The
catalogue of verified incidents per category lives in
references/defect-catalogue.md.
| # | Category | Definition | Detection signal |
|---|
| 1 | Naive arrow | Head too small, head colour mismatch with body, label crossing the dashed line | head_size ≤ 0.24, head_color ≠ body color with near-vertical arrow + label at UP * 0.25 |
| 2 | Padding intrusion | Text or box within 0.1 of another box edge, or crossing the canvas edge | Box height < content height, row labels at LEFT * 6.0+, 7+ outline lines in a small box |
| 3 | Glyph kerning drift | Helvetica Neue + Pango misreads specific glyph pairs ("GE ODE", "g eneration", "fit ness", "cr itic") | Spurious space inside a word, more pronounced at smaller font_size |
| 4 | Frame-order error | Empty / half-empty transition frame, content not accumulating, line endpoint missing the last dot | _clear_section + _set_section_title called separately, LaggedStart then separate Create(connectors) |
Workflow
- Decide timestamps — 7-10 per video, one per major bit, avoiding the
transition zones (target the middle of each bit's wait phase).
- Extract —
ffmpeg -ss <t> -frames:v 1 -update 1 -q:v 2 per timestamp.
- Inspect — Read each
.png through Claude Code's Read tool so the
model sees the actual frame; Bash(cat / tail) will NOT show the image.
- Classify — for every finding, assign one of the four category numbers.
- Report — present a
Bit X — symptom one-liner table to the user;
never auto-apply fixes (the user judges whether a layout choice is
intentional).
- Fix → re-render → re-extract → re-Read the same timestamps. Compare
before/after; check for collateral regressions in adjacent bits.
Workflow details in rules/audit-workflow.md and
rules/reporting.md.
File map
Quick reference — extract + inspect
mkdir -p /tmp/<name>_audit && rm -f /tmp/<name>_audit/*.png
for t in 2.5 6.5 10.5 14.5 18.5 24.0 28.0; do
ffmpeg -hide_banner -loglevel error -ss $t \
-i media/videos/<scene>/1080p60/<Name>-EN.mp4 \
-frames:v 1 -update 1 -q:v 2 /tmp/<name>_audit/EN_${t}s.png -y
done
Then Read each .png in Claude Code. KO is audited separately because
Korean text width differs from English — typographic and padding defects
do not transfer 1:1.
Standing line of defence
The verify_hero_layout.py ratchet (covered in
[[manim-scene-craft]]'s rules/layout-ratchet.md) catches text-vs-container
geometry overflow at compile time. This skill's job is everything the
geometric ratchet cannot see: arrow / label spatial relationships,
typography drift inside the box, and animation timing. Steps 2 and 3
(uharfbuzz, pixelmatch) extend the compile-time ratchet so the model spends
less time inspecting frames manually — see rules/typography-drift-gate.md
and rules/pixel-ratchet.md.
