updraftSound

UPDRAFT's score, the world's spatial sound, and the one thing that joins the sound to the picture: the scene's Listener entity is put on the film camera every frame, so the whole spatial mix is heard from wherever the cut is.

Registers as the film's sound slice. Nothing here reads wall time — every cue and every gain is a function of the film clock, so two runs of Film.play() make the same sound in the same order at the same frames.

The mix, movement by movement

Measured across a tick sweep, the master RMS peaks at 0.296 on the dome (t=80) and falls to 0.099 in the last shot — the arc is in the numbers, not only in the intent.

The sources

Twenty-six, all spawned under Stage by build(ctx).

Non-spatial — the space the listener is in rather than a thing in it: SndRoom (the still interior), SndPlain (800 m of frozen plain), and four score decks SndScoreI / III / IV / V, none of them looping.

Spatial — heard from wherever the cut is, and several of them move:

• SndFront — the flame front, and it travels. One source that walks from the cracked lamp on Gallery 3 to the apex of the dome, 166 m and fifty-eight seconds later. Its keys are the places the cut looks at, so the fire is heard where it is seen: the shelf run in shot 5, the far wall in shot 7, the Gallery 6 rail in shot 9, Gallery 12 in shot 10.
• SndBody — the burning column below the front, standing on the axis at the middle of everything already alight, so every interior set-up gets its crackle bed from the right height.
• SndRoar — the shaft's roar, climbing the axis with s.heat.
• SndTimber — oak complaining two galleries under the fire, never above it.
• SndChimney — the low half of Movement IV. maxDistance 1200 and a shallow rolloff, because a chimney is a low-frequency thing and carries a kilometre; it is still audible from shot 14's camera.
• SndDoor1..4 — the high half, at the four ground-floor doors. maxDistance 45, so it does not leave the room.
• SndCollapse — cued once at 57.2 and dragged ninety metres down the shaft while it plays, ringing out under the cut that follows it.
• SndDome — cued once at 77.0 at the apex. maxDistance 1400: its decay is still heard 800 m out on the plain in shot 14.
• SndDesk1..6 + SndLamp3 + SndLamp14 — the forty practicals, carried by eight. Inaudible from the slate in shot 2; guttering round the lens when the camera cranes to nine metres in shot 11.
• SndFolio — one folio, twice. The same source is the page lifting in the floor draught on Desk 7 in shot 1 and the same page burning four hundred metres up in shot 15. The rhyme the film is built on, carried in sound.

The bank

Sixteen clips in /source/sounds, generated through services.audio_gen and then baked by this slice: mono-downmixed for the spatial sources, equal-power crossfaded end-to-start so the loops do not tick, and peak-normalised. The room tone came back at a peak of 0.026 and would have been inaudible unbaked.

Reading the mix

M.report() gives one line per live voice — whether it is audible, the gain it reaches the mix at, its distance from the listener, and, when it is silent, the mixer's own reason. audio.observe() is the surface underneath it.

Cueing

A source is started the frame its gain first rises above zero and stopped the frame it returns to zero (ride), so a deck's playhead is a function of the film clock alone. The four things that happen exactly once — the chimney cracking at 21.6, a page skidding the Gallery 14 boards at 15.0, the collapse at 57.2 and the dome at 77.0 — are edge-triggered on the clock crossing their second and re-armed by reset().