Transition Bass Pulse S09

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# CES style instruction — S09 Transition Bass Pulse

You are an experienced motion designer and video editor working in Claude Code. Apply the **S09 Transition Bass Pulse** technique to the supplied footage as specified below.

**B. Project configuration:** 1080×1920, 9:16, 30 fps · Source video: not provided — ask the user for the path before starting · Video language (on-screen text & captions): English

**Sound** — A brief low-frequency accent — a 40–60 Hz pulse with a fast decay — lands on a chapter or section transition. It gives the change a physical 'gear shift' without the brightness of an impact, and on headphones or good speakers it is felt as much as heard. A self-generated sine pulse is an acceptable source when no licensed sample is supplied.

### S09 Transition Bass Pulse

- **When:** ≈ 00:15.00 (0.60 s) (≈ derived — adjust to the nearest natural beat in the footage)
- **Layer / track:** A2+ (under the original voice on A1)
- **What it does:** A single short sub-bass thump marks a chapter change, felt more than heard, with the music briefly ducking around it.
- **Parameters:** Pulse source: Supplied sub-bass sample; Sub-bass sample: (not set); Pulse frequency (Hz): 50; Level: -14 dB; Decay (ms): 600; Sync offset: 0 frames
- **Steps:**
  1. ASSET REQUEST: no sound effect was supplied. Ask the user for a licensed or self-made file (asset kind "sound-effects") and list it under missing assets. Never download copyrighted audio. Until it arrives: switch Pulse source to "Generate a sine pulse locally", or leave the transition without a pulse.
  2. Place the pulse at 00:15.00 on the chapter transition frame exactly. The pulse's attack must be under 10ms.
  3. Level: peak -14 dBFS. Low-pass at 125 Hz so it carries no midrange, keep it mono, and duck the music bed by 4 dB for 600ms around it so low ends do not stack.
  4. Phone-speaker check: small speakers cannot reproduce 50 Hz — add a faint 2nd harmonic (100 Hz, -12 dB relative) or a soft transient click so the accent is still perceptible.
  5. Preserve the original voice: no pitch, timbre or EQ changes to dialogue; only the supporting layers are processed. Master bus: dialogue at -16 to -14 LUFS integrated for social delivery, true peak ≤ -1 dBTP (ffmpeg loudnorm=I=-14:TP=-1:LRA=11, two-pass), and check the result with ebur128.
- **Assets:** Source video (⚠ MISSING) · optional: Sound effects, Music track
- **Fallback:** No sample supplied: generate a simple sine pulse locally (self-made audio is acceptable), or skip the accent. Never download a branded or copyrighted sub-drop.

**G. Asset integrity and restrictions:**
- Do not create or present invented testimonials, comments, quotes, reviews or endorsements.
- Do not fabricate numbers, metrics, charts or results. Data visualisations use only the supplied data.
- Do not create fake screenshots or UI and present them as real. Illustrative graphics must be clearly illustrative.
- Do not attempt unsupported 3D reconstructions or perfect subject separation without a mask; use the documented 2D fallbacks instead.

**I. Quality verification:**
- Check output dimensions and aspect ratio with ffprobe — they must match the configuration exactly.
- Check the output frame rate and that the duration is within ±0.5 s of the target.
- Check audio/video synchronisation at the start, middle and end (lip-sync and SFX hits within 1 frame).
- Inspect frames at every beat boundary for text clipping, overflow and safe-zone violations.
- Confirm the output file exists and plays — never claim a render is complete without an actual output file.
- Report any missing asset or unimplemented effect explicitly.