Live Countdown Split-screen — our demo

One example among many. Don't reuse its story, arc, shots, props or timings.

Demo: Counting Itself Down (自己倒數, 59.5 s) · countdown.mp4 · source in demo/

The last minute of the Artemis II launch (1 April 2026, Launch Complex 39B), in real time from T−32.5 to T+27.0 with no cut in time. Everything on screen is NASA's own launch-day material: the live broadcast and its audio, the Firing Room, a camera on the rocket, a camera on Orion, a drone, two ground cameras, a crew photo and the mission fact sheet. This is an unofficial film; NASA did not make or endorse it.

Story & structure

The story is three hand-overs of control, all heard in the native audio. At T−33 the ground launch sequencer gives the count to the rocket ("GLS, go for ALS" — "Great call-out. The rocket is on its own"); the rocket counts itself down; at T+21 "Houston, now controlling the flight of Integrity". A control strip in the clock header (地面 GLS → 火箭 ALS → 休斯敦 HOUSTON) carries the turns.

Shape: cells rise toward zero, merge, then open again for the consequences. Hook (0–0.5 s): the first spoken call flips the control strip on a single wide shot of the pad while the title package lands. Setup (2.5–13 s): the Firing Room opens beside the pad as a "same window" cell (the people who just handed over can only watch), the crew photo with name tags, then a thrust bar (SLS 15 % over Saturn V) on "the most powerful rocket NASA has ever launched". Development (13–22 s): the planned-vs-heard checklist and the fact sheet; the narrator's only line before zero; a punch-in on the pad on "sound suppression water is flowing"; the rocket's own camera replaces the paper. The count (22.4–32.5 s): a 3×3 grid with the clock in the centre; each spoken number opens one camera out of a "standby" slot; RS-25 start flags the engine camera and ticks "heard −6.0". Zero (32.5 s): nine cells merge into one real-time picture of the pad, the clock inverts. After zero: two hard-cut full screens (drone, Banana Creek), a breath, then three cells: the drone climbing, the camera on the rocket, and a flight-events panel whose second countdown runs to booster separation (T+2:09, expected); the loop's "good roll, pitch" ticks it. "Houston, now controlling…" fills the last control segment and the layout resolves to one cell under the title.

Why it fits the style: the real minute already has a countdown, three spoken hand-overs and a zero; the edit only has to make the second visible. Native moves spent: many into one (signature), clock inversion, control strip, the grid filling on the count, sync badges (including one honest "same window" cell), the planned-vs-heard checklist, a second countdown, event flags, a punch-in on a call, a document by rows.

Layouts

Film time t, mission time M = t − 32.5.

#	t	M	Native call / event	Layout	Note
1	0.0	−32.5	—	1 cell: broadcast, pad wide	title package 0.45–6.8
2	0.40	−32.1	"GLS, go for ALS."	control strip ground → rocket	strong action at 0.4 s
3	2.50	−30.0	"Great call-out. The rocket is on its own."	2: broadcast + Firing Room	"same window" badge
4	5.26	−27.2	"Four brave explorers…"	3: + crew photo	names pop 0.16 s apart
5	7.40	−25.1	"…the most powerful rocket…"	4: + thrust bars under the broadcast	comparison held 4.4 s
6	13.10	−19.4	(gap) narrator: "About ten days: around the Moon, and back."	3: broadcast + checklist + fact sheet	two rows, annotation band
7	16.47	−16.0	"Sound suppression water is flowing."	punch-in on the pad base + event flag	2880-px extraction
8	19.60	−12.9	—	fact sheet → rocket camera (wipe)
9	22.42	−10.1	"Ten,"	3×3 grid: clock centre, checklist, transcript (2 slots), 3 standby slots
10	23.10 / 24.22 / 25.24	−9 / −8 / −7	"nine, eight, seven,"	Orion, drone, Firing Room pop in	one tom each
11	26.46	−6.0	"RS-25 engines lit…"	event flag on the engine camera; checklist "heard −6.0"
12	32.50	0	"…booster ignition."	many into one (0.42 s) → OSB II real-time, flash, clock inverts	music silent 32.25–32.5
13	36.36	+3.9	"The crew of Artemis II, now bound for the Moon."	hard cut: drone full screen
14	39.50	+7.0	"Humanity's next great voyage begins."	hard cut: Banana Creek full screen
15	41.7–42.0	+9.2	(breath)	roar tail only; wind enters (J-cut)
16	42.00	+9.5	narrator: "Next on the clock: booster separation, at two minutes nine."	3: drone + rocket camera + flight events	second countdown −1:59
17	46.40 / 49.78	+13.9 / +17.3	"Good roll, pitch." / "Roger, roll, pitch."	flight events tick
18	51.30	+18.8	—	drone → tracking telescope (wipe)
19	53.78	+21.3	"Houston, now controlling the flight of Integrity…"	control strip rocket → Houston
20	54.0–59.5	+21.5 → +27	the line ends under the card	1: rocket camera full screen + end card	5.5 s

Sync per camera (source second s): broadcast s = M + 46.8; rocket camera s = M + 34.8 (its burned-in timer); Orion s = M + 26.25 (first RS-25 light at T−6.36); drone s = M + 10.4; Banana Creek s = M + 19.0; OSB II s = 3.0 + 2.5·M (slow-motion ×2.5); Firing Room not synced. All in demo/tools/prep.sh.

Score structure

60 BPM, beat = tick = whole second of M (t 0.5, 1.5, …). D minor drone → D major at zero.
0.40 hand-over: timpani D, gran cassa, trombone stabs D/A, tubular bell D5. From 2.5: a bass drum per beat; synth drone (D1/A1, low-pass 140 → 1,300 Hz toward zero). 7.7: horn arpeggio D–F–A as the bars grow. From M −19: off-beat hats. Counts: a tom + timpani A on each spoken number; RS-25: gran cassa, tuba D1 and trombone A2 held. Last 4 s: snare sixteenths; T−3: timpani roll crescendo; silence 32.25–32.5 (music only).
Zero: gran cassa, bass drum, crash, timpani, tuba / trombones / horns in D major, tubular bell; half-time bass drum after; horns move to B3/G2 and A3/C♯4 under the two full screens. Breath 41.7–42.0: only the roar tail, then synthetic wind (J-cut into the rocket camera layout).
42.0 →: contrabass pizzicato ostinato D–D–A–C on the beat, light hats, glockenspiel A5 on each ticked flight event. 53.78: tubular bells A4/D5, horn D4, timpani. End card: D major brass, glockenspiel D6–A5–F♯5.
Mix: the NASA broadcast audio is on top throughout; music ~8–10 dB under it before zero and ~6–7 dB under it after zero (lifted 3.5 dB from ignition on), ducked under speech; the narrator only in gaps of the broadcast. Ticks alternate 1,850 / 1,480 Hz (±15 % pan), louder in the last ten seconds, a soft 1,250 Hz after zero. Pre-master: normalised to −14 LUFS, then a linked look-ahead limiter (5 ms, 150 ms release, ceiling −3.3 dBFS) so the ignition keeps its punch (about 3 dB of reduction). −14.0 LUFS, true peak −1.9 dBFS.
Voice: Kokoro bf_emma, two lines, chosen to sound unlike the broadcast's voices.

Palette & props

Ground #06080A, panels #0B0E11, accent #FF5B1F, speaking / heard #FF3B30, text #F2F5F7 / #7C878D.
Cells: HUD clock 656×184 and transcript 1,208×184 at the bottom; pre-zero big cell 1,240×840 with a 624-wide right column; the 3×3 grid 618×338 per slot (transcript spans two).
Checklist rows: T−33 go for ALS (heard −32.1), T−30 core stage → ALS, T−12 H2 burn-off igniters, T−10 engine start command, T−6.36 RS-25 startup (heard −6.0), T−0 booster ignition (heard +0.2).
Fact sheet rows "10 DAY TEST FLIGHT" and "2 EARTH ORBITS", measured on the page so the window's edges fall in white space; annotation band 28 % of the cell.
Thrust bars: SLS orange at 820 px, Saturn V grey at 820 / 1.15, a dashed orange "+15%" marker.

Title card

Opening package (lower left of the first cell, 0.45–6.8 s): 自己倒數 / COUNTING ITSELF DOWN, then 阿爾忒彌斯二號 · 2026 年 4 月 1 日 · 39B 發射臺 and the English line.

End card (54.0–59.5 s, left-aligned over the rocket camera, the clock and transcript still running): 自己倒數 (Noto Sans SC 700, 112 px) / COUNTING ITSELF DOWN; a thin orange rule; 實時倒計時分屏 LIVE COUNTDOWN SPLIT-SCREEN; LemoLab × Claude Opus 5.5; 素材：NASA · 公有領域 · 非官方作品 / FOOTAGE: NASA · PUBLIC DOMAIN · UNOFFICIAL. The "LemoLab × Claude Opus 5.5" sign-off belongs to this library's demo only; a user's film carries no LemoLab credit and no copy of this card.

Build notes

demo/
  index.html          the page: LAY layouts, camRegion, clock / transcript / checklist / doc / profile / thrust cells,
                      EV (mix events), TEXTS (readcheck), SUBFIT (one-line subtitles)
  tools/prep.sh       the sync table: every camera to frames/<cam>/<film frame>.jpg with one grade
  tools/grab.py       HTTP range excerpt of a NASA original + SOURCES.jsonl entry
  tools/footage.py    search / fetch / record licences (NASA, Commons, Internet Archive) → SOURCES.md
  tools/subs.mjs      cues → audio/cues.json (+ one line per language, ≥ 1.8 s)
  tools/fetch_fonts.py  Barlow, Barlow Condensed, IBM Plex Mono, Noto Sans SC subset (OFL)
  tools/final_asr.py  Whisper on the finished film
  audio/lines.json    narrator (Kokoro)      audio/mix.py   native audio, ticks, foley, score, ducking, pre-master
  FACTS.md · SOURCES.md · SOURCES.jsonl · CREDITS
  raw/ frames/ out/ fonts/ audio/vo/   downloaded or generated, not committed

sh demo/build.sh (library set up with setup.sh deps voice music): fetches the NASA excerpts (~400 MB), fonts, voice model and the vsco2ce / vcsl samples if missing → narrator + speech check → frames (prep.sh) → subtitles + one-line check → readcheck → events → render (1,785 frames, 30 fps) → mix → mux (−14 LUFS, grain 1) → small cut → poster / style frame (t 28.5) → Whisper on the film.

Demo-specific choices and pitfalls: the broadcast excerpt is a stream copy, so its zero (46.8 s) depends on the keyframe it starts on; re-measure after a re-fetch. The rocket camera's burned-in timer gives a frame-exact zero, but the same file's audio runs about 1 s early, so sync it on picture only. The Firing Room reel has no clock: it is labelled "same window" and kept away from the seconds where its content could contradict the clock. "GLS, go for ALS" is heard by Whisper as "go for your left"; it is identified from NASA's countdown list and the commentary that follows (FACTS.md §T). Split the count into two cues: shown as one, its whole Chinese line ("…RS-25 點火") appears four seconds early. Fill the 3×3 grid's empty slots with "standby" frames that each count opens, not black. Put the fact-sheet annotation in a dark band below the paper, not over the page's own type, and keep the paper window a fixed 600 source px wide (scaled to fit, paper white above and below) so every row's text is whole. Don't hold a static pad wide shot for ten seconds; break it with a punch-in on "sound suppression water" (from a 2,880-px extraction, no upscaling).