# Music Production Calc

Studio arithmetic: tempo grids, song length, tap tempo, key shifts and capo, Camelot mixing, diatonic chords, fretboard notes, pitch-speed and delay tails.

## How to pay

Machine-payable over x402. USDC on: Base (eip155:8453), Solana (solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp), Polygon (eip155:137), Arbitrum One (eip155:42161).
No accounts. No API keys. No signup. The paying wallet is the account.

## Machine-readable

- OpenAPI: https://music-production-calc.x402tookit.com/openapi.json
- x402 manifest: https://music-production-calc.x402tookit.com/.well-known/x402
- Catalog (free): https://music-production-calc.x402tookit.com/catalog
- Health (free): https://music-production-calc.x402tookit.com/health
- Uptime (free): https://music-production-calc.x402tookit.com/uptime

## Endpoints (9)

### GET /camelot-key — $0.02
Camelot wheel code for a musical key and its harmonic-mixing matches; optionally test if two keys mix.
Params: key: string, mixWith?: string
Example: https://music-production-calc.x402tookit.com/camelot-key?key=Am&mixWith=C

### GET /delay-tail — $0.02
Feedback delay decay: dB lost per repeat, repeats to fall 60 dB and total tail time in ms from delay and feedback.
Params: delayMs: number, feedbackPercent: number, decayDb?: number
Example: https://music-production-calc.x402tookit.com/delay-tail?delayMs=500&feedbackPercent=50

### GET /diatonic-chords — $0.02
The 7 triads and 7th chords of a key (major, natural or harmonic minor) with spelled notes and Roman numerals.
Params: key: string, scale?: string
Example: https://music-production-calc.x402tookit.com/diatonic-chords?key=C

### GET /fret-note — $0.02
Note name, MIDI number and Hz at a fret on guitar, bass, ukulele or violin strings, with alternate tunings.
Params: instrument: string, string: integer, fret: integer, tuningOffset?: integer, a4?: number
Example: https://music-production-calc.x402tookit.com/fret-note?instrument=guitar&string=6&fret=5

### GET /key-shift — $0.02
Shift a key by semitones with the right sharp or flat spelling, its relative major or minor, signature and capo shapes.
Params: key: string, semitones: integer, prefer?: string, capo?: integer
Example: https://music-production-calc.x402tookit.com/key-shift?key=Eb&semitones=4

### GET /pitch-speed — $0.02
Convert semitones, cents, speed percent, two frequencies or two BPMs into one varispeed ratio with all equivalents.
Params: semitones?: number, cents?: number, speedPercent?: number, fromHz?: number, toHz?: number, fromBpm?: number, toBpm?: number, bpm?: number, hz?: number
Example: https://music-production-calc.x402tookit.com/pitch-speed?semitones=1&bpm=120&hz=440

### GET /song-length — $0.02
Song length in seconds and m:ss from bars, BPM and time signature, plus bars or BPM needed for a target length.
Params: bars: number, bpm: number, beatsPerBar?: integer, beatUnit?: integer, bpmUnit?: string, targetSeconds?: number
Example: https://music-production-calc.x402tookit.com/song-length?bars=64&bpm=120&beatsPerBar=4&beatUnit=4

### GET /tap-timestamps — $0.02
Tap tempo from tap timestamps in ms: mean and median BPM, interval spread and jitter percent.
Params: taps: string
Example: https://music-production-calc.x402tookit.com/tap-timestamps?taps=0%2C500%2C1010%2C1490%2C2000

### GET /tempo-grid — $0.02
Note values 1/1 to 1/32 (straight, dotted, triplet) at a BPM as ms, LFO Hz, samples and MIDI ticks.
Params: bpm: number, sampleRate?: number, ppq?: integer
Example: https://music-production-calc.x402tookit.com/tempo-grid?bpm=120&sampleRate=44100&ppq=480

## Terms

Music-production arithmetic computed locally from the numbers you give, using equal temperament with A4 = 440 Hz unless stated. Tempo, key and spelling conventions differ between DAWs, publishers and DJ software: the conventions used are stated in each answer. Not engineering, legal or licensing advice.