chord-synth

Generate chord progression WAV files. Zero dependencies, pure Node.js synthesis.

When to activate

• User asks about chord progression generation
• User needs help to produce WAV files of chords
• User wants to create music, beats, loops, or backing tracks
• User mentions "arpeggio", "synthesizer", "BPM", or "chord progression"
• User asks to render, generate, or export audio files
• User needs background music or a soundtrack

Quick Start

# Install once (if not already available)
npm install -g chord-synth

# Generate a WAV file
chord-synth --preset "C G Am F" --bpm 120 --output song.wav

# Custom jazz with slash chords
chord-synth --preset "Dm9 | G7/B | Cmaj7 | Am7/E" --instrument piano --drums bossanova --output jazz.wav

# Named preset transposed to key of G
chord-synth --preset "I-V-vi-IV (Pop)" --transpose 7 --output pop_in_G.wav

# Batch render from JSON file
chord-synth --batch render_jobs.json --output ./wavs/

# Discover all options (JSON)
chord-synth --schema
chord-synth --list

Node.js Module Usage

When writing scripts or inline code to generate audio:

const { renderJob, PRESETS, SCHEMA } = require('chord-synth');
const fs = require('fs');

// Render with a named preset
const wav = renderJob({ preset: "I-V-vi-IV (Pop)", bpm: 120, instrument: "piano" });
fs.writeFileSync('output.wav', wav);

// Render with custom chords — slash chords set bass note
const wav2 = renderJob({
  preset: "Dm9 | G7/B | Cmaj7 | Am7/E",
  bpm: 95,
  instrument: "guitar",
  pattern: 17,       // Alberti Bass
  drumPattern: "bossanova",
  swing: 0.66,
  enablePad: true,
  reverbMix: 0.25
});
fs.writeFileSync('bossa.wav', wav2);

CLI Usage

# Single render
chord-synth --preset "Am F C G" --bpm 100 --instrument violin --output sad.wav

# Named preset with transpose
chord-synth --preset "ii-V-I (Jazz)" --transpose 5 --bpm 140 --output jazz_F.wav

# Full JSON input
chord-synth --json '{"preset":"Dm7 | G7 | Cmaj7","bpm":110,"pattern":18,"drumPattern":"swing"}' --output swing.wav

# Batch render from file
chord-synth --batch jobs.json --output ./output_dir/

# Validate batch without rendering
chord-synth --batch jobs.json --dry-run

Batch Jobs Format

Create a JSON file with an array of job objects for --batch:

[
  {
    "name": "pop_piano",
    "preset": "I-V-vi-IV (Pop)",
    "bpm": 120,
    "instrument": "piano",
    "pattern": 1
  },
  {
    "name": "jazz_guitar",
    "preset": "ii-V-I (Jazz)",
    "bpm": 140,
    "instrument": "guitar",
    "pattern": 17,
    "swing": 0.66,
    "drumPattern": "swing"
  }
]

Parameters

Named Presets (28)

Use exact name string as preset value:

Pop/Rock: I-V-vi-IV (Pop), I-vi-IV-V (50s), vi-IV-I-V (Sad), I-IV-V-IV (Rock), I-V-vi-iii-IV (Canon) Jazz: ii-V-I (Jazz), I-vi-ii-V (Jazz Turnaround), iii-vi-ii-V (Coltrane), Autumn Leaves, So What, Steely Dan Neo-Soul/R&B: Neo-Soul I, Neo-Soul II, R&B Smooth Blues: 12-Bar Blues, Minor Blues Latin: Bossa Nova, Girl from Ipanema Modal: Dorian Vamp, Lydian Float, Ambient Pads EDM: EDM Anthem, Trance, House Classic: Pachelbel Canon, Andalusian Cadence, Royal Road (JP), Gospel

Arp Patterns (22)

Other patterns: 4=Down-Up, 5=Up-Down (No Repeat), 6=Down-Up (No Repeat), 8=Random Walk, 9=Outside-In, 10=Inside-Out, 11=Pinky-Thumb, 12=Thumb-Pinky, 14=1-5-3-5, 16=1-3-5-8-5-3, 19=Broken 3rds

Chord Notation

Custom chord strings support: roots (C, C#, Db, D…B), qualities (m, 7, maj7, m7, dim, aug, sus2, sus4, 9, m9, maj9, 7b5, m7b5), slash bass (Am/E, G7/B), separators (space or | with optional whitespace).

Examples: "Dm9 | G7/B | Cmaj7 | Am7/E", "C G Am F", "F#m7 B7 Emaj7"

Output Format

WAV PCM 16-bit mono 44100 Hz. Typical file size: ~1.4 MB for 2 loops at 120 BPM with 4-chord progression.

Recommended Combos

For jazz: pattern 17 (Alberti) or 18 (Stride), swing 0.66, drumPattern "swing" For latin: drumPattern "bossanova", swing 0.58, pattern 1 (Up) For ambient: pattern 0 (Block), rate "1/1", enableDrums false, reverbMix 0.4 For EDM: pattern 1 (Up), rate "1/16", enablePad true, drumPattern "16beat"