Offbeat

How it works01 — 06

01 · Listen

Listening

The music is heard sixty times a second, from the lowest bass to the air above the cymbals.

Analyser: Web Audio, a 2,048-point FFT: 1,024 bins, smoothed at 0.55 from one frame to the next.
Range: −84 to −10 dB. A noise floor is cut off, so the relief rises from black.
Bands: 96 on a logarithmic scale, 30 Hz to 16 kHz, the way the ear hears pitch; each keeps its loudest bin.
Tilt: +3 dB per octave around 250 Hz. Music loses about as much, or the bass would bury the highs.

02 · Order

Silence is drifting dust. Sound sweeps it into a landscape, and lets it go when the music stops.

Depth: A new line every 160 ms comes to the front; 26 lines, about four seconds deep.
Light: Each line is a veil lit from above that hides the ones behind. The tone is continuous, then screened: never a stroke.
Screen: One dot per cell, 6 px apart (7.5 on a wide screen), snapped to the physical pixel. Only their size changes.
Level: Measured against the track itself: it rises in 0.3 s and forgets in 8 s, so a quiet intro already falls into place.
Scrub: The whole track is decoded in the background, 24 kHz, the same analysis: dragging the timeline shows the real song.

03 · Beat

A hard hit knocks the front crest back into chaos for an instant. Counted, the hits become a tempo.

Onsets: Positive spectral flux, the bass weighted 1.6×, above the mean plus 1.7 deviations of the last 1.5 s; one per 180 ms at most.
Peak: Only the strongest, past 2.6 deviations, scatter the crest and get a mark.
Tempo: Every gap between hits over twelve seconds votes, folded into 70–180 BPM.
Shown: Re-read every second, and only once five readings agree within 2 BPM. Never a wrong number.

04 · Crate

Six crates, shuffled anew on every visit: the gems come up often, but any record can fall under your finger.

Source: Audius, under its open music licence: the underground charts and the all-time ones, 300 records a genre.
Weight: Favourites over the square root of plays, so a confidential record can outweigh a hit. One per artist.
Draw: Weighted, without replacement (Efraimidis–Spirakis), the weight flattened again so that chance has its share.
Honest: Reposts don’t count. Past 15 % favourites per play, a record is inflated and never drawn.

05 · Memory

Every sleeve starts faint. What you have heard fills in, dot by dot, and stays.

Fingerprint: 32 moments by 32 bands; each cell keeps the loudest it heard.
Sleeve: Three or four colours seeded by the record, their hue from its mood. Unheard, the same colours, smaller dots.
Print: Once decoded, the whole track as 48 crests stacked face on, beginning at the top, to keep or share.
Kept: In this browser only: record ids and our analysis, nothing from Audius.

06 · Colophon

A lab piece, the night-time sister of a portfolio.

Track: Default track. Credit to come.
Made by: Nicolas Blanc
Type: Tangerine, Instrument Sans, JetBrains Mono
Keys: Space play or pause · ←/→ five seconds · ↑/↓ volume · N next record · P back · K keep it · C the crate · F full screen · ? this page · Esc close
Built with: Web Audio API, three.js (WebGL), Next.js