# Audio candidate pool — rotating pools per altitude (2026-06-26)

Candidate soundtrack/ambience for the **"audio + video" setting**. Following operator
feedback, each altitude now has a **rotating pool** (mirrors the video `Scale.pool`
model — random pick per landing, or pairable per-clip).

## Two audio layers per altitude (operator, 2026-06-26)

The "audio + video" setting layers **two** kinds of audio per altitude:
1. **Ambience / audio track** — the soundscape (waves, reef crackle, chorus, etc.).
   **This is what we're sourcing now.**
2. **Music track** — a separate composed musical layer. **Shipped** (2026-07-01)
   as the Audio-dropdown **"Music"** option: unlike the earlier per-altitude idea,
   it is now **one single ethereal loop played the same at every altitude** (see
   § Music below).

Pools below are the **ambience** layer unless marked `music`. **Distinction (operator):**
the ambience/soundtrack layer is an *environmental, real-world soundscape* (waves, reef,
whale, room-tone hum) — **not composed music**. A musical pad/track, however nice, belongs
in the music layer, even for "atmospheric" altitudes like cosmos/orbit.

**Media is gitignored** (`simulator/sample_media/**/*.{wav,mp3,…}`); this file is the
re-sourceable record. Files: `simulator/sample_media/audio/<altitude>/<name>.<ext>`,
served at `/media/audio/<altitude>/<name>.<ext>`. Review gallery (gitignored):
`simulator/static/review_audio.html` → `/review_audio.html` with the sim running.

## Round-2 feedback applied (operator, session 2026-06-26)

- **abyss** ✓ kept (blue-whale moan) · **coast** ✓ kept (waves + terns)
- **cosmos** ✗ plasma static "hurt my ears" → replaced with 3 NASA **sonifications**
- **orbit** ✗ whistlers "sound like lasers" → replaced with gentle Earth **chorus** (+ wind)
- **reef** ✗ "shouldn't have whales (too deep for a reef)" → whale removed; now crackle + diver
- Operator: *"try all three… rotation of audio like the video, or per-video audio track."*

## Design arc

Descending the dial is one journey: **cosmos & abyss** = vast/dark/sparse siblings;
**coast** = warm human middle; **orbit & reef** = transitional membranes. The science
recordings (NASA/NOAA) keep the "machines reshaping perception" thesis literal.

## Pools

| altitude | id | clip | source | dur | license |
|---|---|---|---|---|---|
| 🌌 cosmos | `cosmos/pillars` | **✓ KEEP** — Pillars of Creation (M16), twinkly sweep | NASA/CXC/SAO — https://chandra.si.edu/sound/m16.html (`sounds/m16_all.mp4`) | 30s | PD (NASA, credit) |
| 🌌 cosmos | `cosmos/music` | 🎵 **music track — TBD** (deferred). Black-hole drone DROPPED (too creepy, not awe-inspiring); Galactic Center dropped earlier | — | — | — |
| 🛰 orbit | `orbit/spaceamb` | **✓ KEEP** — station room-tone hum ("inside the orbiting craft") | Sonicfreak — https://freesound.org/s/174450/ (`cdn.freesound.org/previews/174/174450_746632-hq.mp3`) | 2:31 | CC0 |
| 🛰 (music) | _deferred_ | 🎵 "Frozen Star" warm pad — moved to MUSIC layer (it's music, not ambience) | Kevin MacLeod / incompetech — https://incompetech.com/music/royalty-free/mp3-royaltyfree/Frozen%20Star.mp3 | 3:41 | CC-BY |
| 🐠 reef | `reef/soundscape` | **✓** richer reef (round 4) — 6-layer bake: submerged underwater bed (bubbles/sloosh) + shrimp crackle + fish chorus + toadfish + grouper + damselfish | NOAA SanctSound (FK+GR `*_snappingshrimp_*`, `FK02_01_fishchorus`, `GR01_01_toadfish`, `FK03_01_redgrouper`, `PM05_01_damselfish`) + DCSFX "Underwater [Loop] AMB" https://freesound.org/s/366159/ (`cdn.freesound.org/previews/366/366159_6725579-hq.mp3`); loop-to-60 + amix + dynaudnorm | 60s | PD (NOAA) + CC0 (underwater) |
| 🏖 coast | `coast/waves` | Sea waves + tern calls | BigSoundBank #0267 — https://bigsoundbank.com/sea-waves-and-seagulls-s0267.html (`/UPLOAD/mp3/0267.mp3`) | 57s | CC0 |
| 🕳 abyss | `abyss/whale` | NE Pacific blue-whale "AB call" | NOAA PMEL — https://www.pmel.noaa.gov/acoustics/multimedia/NETS_bluWhale.wav | 13s | PD (NOAA) |

## Music (the Audio-dropdown "Music" option, shipped 2026-07-01)

**One** ethereal ambient loop, played the same at every altitude (altitude-independent —
NOT the per-altitude idea the "cosmos/music" / "Frozen Star" rows above reserved; those
stay as historical candidates). The operator's brief: *ethereal, relaxing — like
innerflo.me.* CC0 (operator's sourcing choice), so attribution is courtesy, not required.

| id | clip | source | dur | license |
|---|---|---|---|---|
| `music/ethereal` | **✓ KEEP** — "Ambient F Sharp Minor Ethereal Choir Pad 1": blurry, paulstretched layered choir — "peaceful, magical, soothing" | deadrobotmusic — https://freesound.org/people/deadrobotmusic/sounds/808032/ (hq preview: `cdn.freesound.org/previews/808/808032_*-hq.mp3`) | 3:38 | CC0 |

Production: `simulator/build_audio_media.py` `SOURCES["music"]` → seamless loudness-normalized
loop at `audio/music/ethereal.loop.mp3`, served `/media/audio/music/ethereal.loop.mp3`
(client fallback: `app.js` `MUSIC_FALLBACK`). Download the sound page's WAV/MP3 to
`simulator/sample_media/audio/music/ethereal.mp3`, then `python simulator/build_audio_media.py`.

## Sourcing rule (learned 2026-06-26)

**Source only from a browsable page the operator can open and whose license is stated.**
The Mixkit clips were pulled by raw CDN asset id (`assets.mixkit.co/.../<id>-preview.mp3`)
with no findable catalog page — operator couldn't see them, so they were removed. Good
hubs: NASA SVS / Chandra, NOAA PMEL/SanctSound (PD), BigSoundBank (CC0), Pixabay
(visible license). Avoid asset-id grabs and ND/NC licenses.

## Open items / next pass

- **orbit** — ✅ SETTLED: `orbit/spaceamb` (Sonicfreak station room-tone hum, CC0). Rejected
  en route: laser whistlers, Earth chorus, plain wind, "Frozen Star" pad (music). A real NASA
  ISS recording (Hadfield "Space Station Noise", SoundCloud) remains the authentic upgrade if
  ever wanted — needs a harder fetch (no yt-dlp; brew install denied).
- **ambience layer COMPLETE** — all 5 picked: cosmos/pillars · orbit/spaceamb · coast/waves ·
  reef/soundscape · abyss/whale. Next is the production pass + wiring (below) and the music layer.
- **reef** — ✅ round-4 6-layer bake (`reef/soundscape`): NOAA PD biological layers + a CC0
  submerged underwater "you're under" bed (DCSFX freesound #366159, hq preview). License clean.
  SanctSound clips: `files/SanctSound_*.mp4` at `https://sanctsound.ioos.us/files/` (extract audio).
- **music layer** — ✅ SHIPPED 2026-07-01 as the Audio-dropdown "Music" option, but as
  ONE altitude-independent ethereal loop (`music/ethereal`, CC0), not the per-altitude
  track once envisioned. See § Music above. (The `cosmos/music` / "Frozen Star" rows are
  now historical per-altitude candidates, not planned work.)
- **Production (after picks):** loop seams, length normalization, cross-altitude crossfade
  (mirror video); cosmos/abyss clips are short → loop.

## Re-download / re-bake

```
A=simulator/sample_media/audio; FF=$(python -c "import imageio_ffmpeg;print(imageio_ffmpeg.get_ffmpeg_exe())")
mkdir -p $A/cosmos $A/orbit $A/reef $A/coast $A/abyss
# NASA sonifications (mp4 -> mp3)
for u in perseus_sonification:blackhole m16_all:pillars galactic_all:galaxy; do
  f=${u%%:*}; o=${u##*:}; curl -fsSL "https://chandra.si.edu/sound/sounds/$f.mp4" -o /tmp/$o.mp4
  "$FF" -y -i /tmp/$o.mp4 -vn -q:a 4 $A/cosmos/$o.mp3; done
curl -fsSL "https://svs.gsfc.nasa.gov/vis/a010000/a011000/a011073/Earthsong-540-MASTER_high.mp4" -o /tmp/es.mp4
"$FF" -y -i /tmp/es.mp4 -vn -q:a 4 $A/orbit/earthsong.mp3
curl -fsSL "https://assets.mixkit.co/active_storage/sfx/1162/1162-preview.mp3" -o $A/orbit/wind.mp3
curl -fsSL "https://www.nhm.ac.uk/content/dam/nhm-www/discover/audio/sound-of-coral-reef.mp3" -o $A/reef/crackle.mp3
curl -fsSL "https://assets.mixkit.co/active_storage/sfx/1242/1242-preview.mp3" -o $A/reef/scuba.mp3
curl -fsSL "https://bigsoundbank.com/UPLOAD/mp3/0267.mp3" -o $A/coast/waves.mp3
curl -fsSL "https://www.pmel.noaa.gov/acoustics/multimedia/NETS_bluWhale.wav" -o $A/abyss/whale.wav
# layered reef
"$FF" -y -i $A/reef/crackle.mp3 -i $A/reef/scuba.mp3 \
  -filter_complex "[1:a]volume=0.55[s];[0:a][s]amix=inputs=2:duration=first,dynaudnorm" -q:a 4 $A/reef/layered.mp3
```