beat-quality

name	beat-quality
description	The quality bar for headless beat production, real trap programming, arrangement length, mastering targets and the known engine gotchas.
when_to_use	Producing or editing a beat, designing a groove, mastering audio, or answering "why does this sound flat".
intents	produce, beat, master, beatedit, onbeat, editonbeat, cutsheet
keywords	beat, beats, 808, trap, drill, bpm, tempo, hats, hi-hats, snare, kick, groove, swing, melody, mixdown, master, mastering, lufs, instrumental, sample, phonk
version	1

Beat production quality bar

The failure to never repeat: "sounds like elevator music". That means no rhythm, flat velocities, straight 16ths. Every design must be a real groove.

Programming rules

• Kick: syncopated, not four-on-the-floor. Lock it to where the 808 slides. The reference default is steps 0, 3, 6, 10, 11 with velocities 120, 90, 110, 100, 80.
• 808: it follows the kick steps, it glides, and the glide is clamped to one octave. It lifts a perfect fourth at the tail of odd bars. Writing an "808" lane in the design JSON does nothing, the engine derives it from the bassline, chord roots or key tonic.
• Snare: half-time on beat 3, the trap backbone. A clap also lands on beat 3 of every bar automatically, so do not double it.
• Ghost snares: quiet, off-grid, around steps 6 and 14.
• Hats: mixed resolution. 16ths with alternating accents (90 / 55 / 80 / 55 / 95 ...) plus at least one roll lane at res 48 or 96 for 32nds and triplets, crescendoing into the next bar (60 to 110). One open hat for air.
• Velocity is mandatory variation. Identical velocities across steps is the elevator-music bug. Give every lane real accents.
• The engine adds swing 0.57 on odd eighths, about 4 ms of timing jitter and 6 percent gain jitter, and a fill every 4th bar plus the last bar. Design for that, do not fight it.

Length and arrangement

Bar count is max(4, len(chord_progression)). A four-chord progression yields a roughly 7 second beat. For anything he would actually use, write 8 to 16 chords and a melody with events across the whole span, otherwise the lead only sounds in bar one. The structure field is decorative, the engine does not read it.

Defaults and targets

• Default 140 BPM, F minor, i VI III VII (Fm Db Ab Eb). Drift phonk and hard trap for car edits sit around 140 to 150 BPM.
• Master chain: high-pass 30 Hz, small 250 Hz cut, 3 kHz and 12 kHz lift, gentle 3:1 compression, loudnorm I=-14 TP=-1 LRA=11, out as 320k mp3. The produce path does not verify loudness afterward, so do not claim a measured LUFS, say what it was mastered to.
• Deliverables are a .mid and a .mp3 in work/studio/. GarageBand is opt-in only, he has to ask for it.

Originality

Original work in the STYLE of a reference, never a clone. Tempo, key, groove and genre are not copyrightable, a specific recording is. From a reference track take only bpm, key and scale, never the melody, lyrics or hook.

Known engine gotchas worth mentioning if output sounds off

• The MIDI file contains a straight, unswung drum track, and fluidsynth renders it alongside the synthesized swung drums. That doubling can read as flams or a smeared transient.
• Everything degrades on purpose: no fluidsynth gives a drum-only beat, no numpy gives melodic only, no ffmpeg hands back a raw wav. Say which path ran.