render-stopmotion-hand-swatch-cycle

Assemble a stop-motion hand-swatch-cycle ad from a config: a fast, tactile product demo where a single hand swipes ONE cosmetic barrel across a cream "skin-patch" test surface, and the shade of the barrel AND the painted swatch stripe changes on every frame while the hand, background, crop, and lighting hold still — cycling the variant family so the viewer self-identifies their match, then a hero-pick payoff and a branded end card. This capability is the FREE, deterministic assembly — the per-plate PNG→mp4 loop encode, the concat-demux, the end-card render, and the music mux.

scripts/config.example.json is the worked example (DIBS Beauty "Pick Your Match", ~16.6s 1080×1920 9:16, ~24 cycle plates + finale beats + a 3s end card); 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 master-anchor plate + the per-shade / motion / finale plates + the end-card hero BG (create-image-gpt-image-fal, gpt-image-2 EDIT mode, each plate anchored to the SAME master-anchor — never chained), and the music track (create-music-elevenlabs, or a brand-supplied mp3). Given the ordered plate PNGs + per-plate holds + the end-card hero BG + the brand logo SVG + the music track, render-stopmotion-hand-swatch-cycle loop-encodes each plate at its hold, concat-demuxes with hard cuts into a silent master, appends the HTML-rendered end card, and muxes the music under it → the master. Re-cuts (re-timed holds, a re-ordered cycle, a swapped end card) reuse the existing plates / track and cost $0.

Contract (the free assembly)

• Still plates, not i2v — held for tuned durations. Each plate is a static PNG loop-encoded (ffmpeg -loop 1 -t <pose_hold_ms>) to 1080×1920 @ 30fps crf18. This is stop-motion — discrete held frames, no camera moves, no character animation. Do not animate the plates.
• Fast stop-motion cadence, HARD cuts. Motion / half-painted plates hold 150–250ms, per-shade plates ~380ms (or ~1000ms for a slower cycle), hero / bookend beats 1100–1800ms; average ~380ms. Concat-demux the plate mp4s in order with hard cuts (ffmpeg -f concat) — NO dissolves. The frame-swap tactility is the whole point; a crossfade erases it.
• Concat-demux, not filter_complex. The plates are silent stills, so the concat demuxer over the ordered plate list is correct and cheapest. (filter_complex is only needed when clips carry mismatched audio — these don't.)
• The music carries it — no VO. A pre-sourced brand instrumental (128–130 BPM works well), volume ≈0.4, fade in/out. Do not add a spoken voiceover or a second bed.
• End card via Playwright HTML from the real logo SVG — never AI-render brand text. A serif tagline + sans subtitle + the real logo SVG composited over a hero product/swatch BG by an HTML template (Chromium headless), rendered to a silent ~3s clip. A diffusion model garbles a wordmark.
• Music plays UNDER the end card with a fade tail — no silent tail. Mux the track over the whole video including the end card, fade over the last ~0.5s so the video ends WITH the music.
• FFmpeg composite, deterministic, FREE. Loop-encode each plate, concat-demux on hard cuts, append the end card, mux the music with a fade tail → a 1080×1920 h264+aac master (~16.6s). No paid calls, no keys (beyond the Playwright/Chromium the end-card render needs).