Render Vo Anchored Motion Listicle Agent Skill

render-vo-anchored-motion-listicle

Assemble an expert/educator motion-graphic listicle ad from a config: an authoritative spoken

voiceover carries a numbered listicle (hook + N points + CTA) and every visual beat is anchored to

the VO's word-level timestamps. Each beat is a web-animated hyperframe (an HTML page + the Web

Animations API driven by window.renderAt(t)) rendered to video frame-by-frame with Playwright, all

in ONE branded design system (alternating background tiles, big hero numerals, body type, decorative

SVG accents, glass-pill callouts). Periodic color-graded B-roll windows give visual breath, and

captions burn only on the B-roll windows. The shipped master is pure motion-graphic + VO — there

is NO lipsync (the still expert headshot is kept only for a future lipsync variant). This capability

is the FREE, deterministic assembly — the Playwright beat render, the ffmpeg concat, the

window-masked caption burn, the VO+music mix, and the final composite.

scripts/config.example.json is the worked example (Everself "doctor-educator" listicle, ~66s

1080×1920 9:16 at 25fps); scripts/PIPELINE.md maps every config block to its source step and

scripts/README.md documents the free assembly.

Run

This is the FREE, deterministic assembly stage — it spends nothing. The paid inputs are separate

capabilities — the spoken VO (create-vo-elevenlabs, a cloned or cast expert voice, eleven_v3 +

atempo) whose word-level timestamps (Groq whisper-large-v3 word-level) set the timeline; the low

music bed (create-music-elevenlabs); and the stock B-roll (media-proxy, trimmed + color-graded).

Given the VO + words-flat.json + the N authored hyperframe beats + the color-graded B-roll windows +

the brand wordmark SVG, render-vo-anchored-motion-listicle renders each beat frame-by-frame via

Playwright (all beats at fps 25), concats the beats + B-roll, burns the window-masked captions, mixes

the VO under the low music bed, and composites → the master. Re-cuts reuse the existing VO / beats /

B-roll and cost $0.

Contract (the free assembly)

• The spoken VO carries the listicle — it sets the timeline. The cloned/cast expert VO is the

spine; Whisper-transcribe it to word-level timestamps and anchor every beat reveal to those word

times. There is no on-camera human and NO lipsync in the shipped master.

• Beats are web-animated hyperframes, rendered deterministically. Each beat is an HTML page + the

Web Animations API driven by window.renderAt(t); Playwright screenshots it frame-by-frame and

ffmpeg encodes it. This is NOT i2v — it is deterministic web motion graphics.

• ALL beats share the same fps (25). A mismatched-fps beat stutters at the concat seam. Render

every beat and every B-roll window at fps 25.

• ONE design system across every beat. A single _shared.css (palette + type + alternating

tiles + accents + glass-pill) so N beats read as one designed reel; alternate only the background

tile, keep numerals / body / accents / pills consistent.

• Periodic color-graded B-roll windows for breath. Trim + color-grade each stock/brand clip to

the palette (fps 25). These windows are the ONLY captioned windows.

• Captions ONLY on the B-roll windows. On the motion-graphic beats the on-screen type IS the

caption — burning Whisper captions there double-stacks text. Build the caption ASS from the VO word

timings, kept only inside the B-roll windows, 2-word chunks, closing a cue on any >0.4s word gap.

The ASS Format: header MUST carry a Name field — without it the leading-comma bug eats the

first field and captions silently drop. If the host ffmpeg lacks libass, render the cues as timed

PIL PNG overlays (ffmpeg overlay=…:enable='between(t,st,en)') at the same placement.

• Low music bed under the VO. The VO is the spine; the ElevenLabs Music bed sits ~0.18 vol under

it. No ducking needed at that level.

• Never AI-render the brand lockup. The CTA / end beat composites the brand's real wordmark,

never text-in-diffusion.

• FFmpeg composite, deterministic, FREE. Render each beat via Playwright, concat the beats +

B-roll (ffmpeg demuxer), burn the window-masked caption ASS, mix the VO under the music bed,

loudnorm I=-14 → a 1080×1920 25fps h264 crf18 + aac 192k master. No paid calls, no keys.