render-song-mv

Assemble a song-driven music-video ad from a config: a purpose-written, sung song is the entire narration (no separate voiceover), and every visual beat is timed to the lyrics. The delivered song sets the timeline; N tableaux (one keyframe → one image-to-video clip per lyric beat, all in a single look pack) are cut to their lyric windows and hard-concatenated on the beat, captions are built from the song's OWN word timings with the hook line landing on the chorus drop, and the spot closes on a PIL brand end card. It reads like a tiny animated music video, not a demo. scripts/config.example.json is the worked example (Loóna "Fall In Love With Sleep Again", 28s paper-craft 9:16); scripts/PIPELINE.md maps every config block to its step and scripts/README.md documents the free assembly.

Run

This is the FREE, deterministic assembly stage — it spends nothing. The three paid inputs are separate capabilities: the sung song (create-music-elevenlabs, music_v1, force_instrumental FALSE — the lyrics ARE the script, returns mp3 + words.json), one keyframe per tableau (create-image-fal), and one Kling 3.0 i2v clip per tableau (create-video-fal). Given the delivered song + words.json + one clip per beat, render-song-mv cuts each clip to its lyric window, hard-concats on the beat, builds the lyric-synced captions, composites the PIL end card, and muxes → the master. Re-cuts reuse the existing song / keyframes / clips and cost $0.

Contract (the free assembly)

• The sung song carries the narration — no separate VO. The generated ElevenLabs track IS the bed and the script (force_instrumental false); do not add a spoken voiceover or a second music bed.
• Plan the timeline AROUND the delivered song. The song is generated first and reshapes/ overshoots length; snap every tableau boundary to the lyric-phrase edges in the returned word timings (timeline.json) — never trim the song to a pre-planned grid.
• Captions from the song's OWN word timings, not Whisper (script-window). Chunk audio/words.json (~3 words at lyric boundaries); accent words get the warm-glow color. Whisper on sung audio returns "🎵 Music Playing 🎵", so it can't caption lyrics.
• Land the hook on the chorus drop. Exactly ONE hero tableau (is_hook) is timed so the payoff word (song.hook_word) sits on the chorus drop; accent that word in the captions.
• One look pack for consistency. A single style_opener + negative_tail + palette drives every keyframe so N beats read as one film; no morph within a clip.
• Hard cuts on the beat. Cut each clip to its lyric window and hard-concat — no dissolves (one optional match-cut into the hero reveal).
• PIL end card from the real app icon — never AI-render brand text. The lockup is composited deterministically (brand gradient + circular app icon + wordmark + tagline + CTA) from the brand's real asset; a diffusion model garbles a wordmark.
• FFmpeg composite, deterministic, FREE. Burn the caption ASS, overlay the end-card PNG on the final window, mux the song, boost the climax beat, loudnorm to −14 LUFS → 1080×1920 h264+aac. No paid calls, no keys.