ambience-and-sound-for-stills

A pause in a narrated film must sound like a place, not a dropout. A photograph gets a sound only when something visible would make one, placed further away than the narrator. OpenDubStage tool: opendubstage foley (opendubstage.foley: plan, check, Rules, levels, prompts.lint, post.ERA_EQ, post.ROOMS).

1. Beds: never dead air

2. Layers and levels (relative to dialogue)

Nothing in the effects stem ever reaches dialogue level (levels.MAX_OFFSET_LU = −2). Distance is the dial: the narrator is present; the photograph is a memory; a sound that comes across nearer than the narrator is wrong (Heywood, TSNGO: distance, not level, keeps a long film from becoming monotonous). Murch's two-and-a-half layers: dialogue + bed leaves half a layer for spots and music together.

3. Density and timing (foley.Rules defaults)

Natural density is low: measured on a large set of captioned photographs, roughly one spot-worthy object per 5–6 stills. Do not invent sounds for most pictures.

4. When not to add sound

• Portraits, close-ups, posed pictures, smiles (a face ≥ 3 % of the frame counts as a portrait).
• Details and documents: cake, rings, dress, letters, maps, certificates.
• Technically weak pictures (blurry, dark, overexposed): the picture is already asking for forgiveness.
• Objects that make no sound: a lantern does not tick; a padlock being clicked shut does, only if the hand is in the picture.
• Anything with real sync sound (speeches, performances, interviews on camera): the camera already heard it (Apollo 11 left the EVA audio alone).
• 360° spheres and wide empty landscapes: bed plus one slow directional wind texture, no spots (Fire of Love: "winds give it a sense of direction").
• Inside a key line, and inside a designed silence.

5. Avoiding the cartoon feel

1. One action, one material, one place, one distance per prompt; tail "no music, no voices" (Spiegel: a Panzer "in snow", "on wet road", "on dry road").
2. Lint (foley.prompts.lint) rejects whooshes, swooshes, risers, swells, braams, impact hits, stingers, comedic sounds, music, intelligible speech, "epic" or "cinematic" scale.
3. Match the era and the mic (post.ERA_EQ): highpass=f=80,lowpass=f=9000,equalizer=f=3500:t=q:w=1.2:g=-3, 30 ms fades, then loudness-normalise to the layer table. Libraries and generators "sound too modern" (TSNGO; Burns' team); Albrechtsen records foley "badly" on purpose to match rough production sound.
4. Worldize (post.ROOMS): a short room matched to the bed: trees / open land (early reflections only, ~0.4 s), street, small room (~0.5 s), hall (~1.1 s). The narrator's own room is never applied to the photograph's sounds.
5. Prefer textures to hits: laughter as a distant group, not a sitcom laugh; a few steps on pine needles, not a march; one glass at a table, not a toast cascade.
6. Keep source artefacts: handling noise, the maker's breath, interjections are texture (Cameraperson, Fire of Love).
7. Witness test: play a viewer five stills with and without the effects. If they cannot say which is which but prefer "with", the level is right; if they can point at the effect, lower it 3 dB or remove it (Burns' veterans: "Yes, that's the way it was").
8. Invent only from evidence, then age it (Apollo 11's 1202 alarm built from the NASA spec and dirtied).
9. Textures and beds: loop=true, 22–30 s, low prompt influence (0.3) for natural variation; spots 1–3 s at higher influence (0.6); three variants each; keep a manifest with prompt, parameters and date so generation is reproducible.

Prompt template and keyword → class map: references/prompts-and-classes.md.

6. Workflow with opendubstage foley

opendubstage foley analyze SEQUENCE.json [--vision]           # scene analysis per still (keywords, or Apple Vision labels)
opendubstage foley plan SEQUENCE.json -o cuesheet.json [--vision]   # analysis -> cue sheet under the rules; rejected candidates are listed in "decisions"
opendubstage foley check SEQUENCE.json cuesheet.json          # re-verify a (hand-edited) cue sheet; exit 1 on any violation
opendubstage foley generate SEQUENCE.json cuesheet.json --backend library|woosh -o fx
opendubstage foley render cuesheet.json -o stems               # per-layer stems with ffmpeg

plan always passes check (property-based tests assert it). Hand edits go through check. Resolution order when choosing a cue: the picture's moment type wins (speeches, performances, portraits → none); then the no-sound classes; then the first matching spot; then texture; the bed from the scene's median time of day and the majority bed selector among its pictures.

7. Verify