Random Cadence Chord Progression Generator

Description

Sample supplied reviewed progression templates into target keys with delegated spelling-aware transposition and elementary cadence labels.

A musical fixture expresses pitch or timing through explicit numeric conventions such as MIDI numbers, semitone intervals, beats, and durations. A reproducible symbolic sequence is separate from a performed sound or a judgment of musical quality.

Sample supplied reviewed progression templates into target keys with delegated spelling-aware transposition and elementary cadence labels.

When to use this tool

Use this generator to create reproducible cadence chord progression cases from the supplied model or bank. Inspect the returned evidence before using cases in a test or exercise.

How to use the tool and how it works

Supply templates, targetKeys, count in the field shapes below. Set seed when you need an explicit replay.
Run the tool and correct any input error. For generated controls, distinguish a successful fixture containing an invalid case from failure to generate the fixture.
Read exercises. Use the conventions below. Keep answer-bearing fields separate when presenting an exercise.

Preflight every supplied template/key combination. Compute signed diatonic-letter and chromatic-semitone shifts, delegate chord-symbol transposition, and classify the last two supplied Roman chords using root-position and soprano flags. Return sampled progressions and all harmonic evidence.^[1]

Delegated operations used for this result: cadence type classifier; transpose chord progression. Their calculation or parsing conventions apply to the corresponding result fields.^{[2, 3]}

Input field	Meaning and units	Accepted input
templates	Templates	Required. Array of Object; no unknown keys.; minimum items 1; maximum items 16.
templates[].id	Literal identifier used independently of display labels.	Required. Text; minimum UTF-16 length 1; maximum UTF-16 length 32.
templates[].sourceKey	Source Key	Required. Text; minimum UTF-16 length 1; maximum UTF-16 length 8.
templates[].chordSymbols	Chord Symbols	Required. Array of Text; minimum UTF-16 length 1; maximum UTF-16 length 32.; minimum items 2; maximum items 16.
templates[].romanChords	Roman Chords	Required. Array of Text; minimum UTF-16 length 1; maximum UTF-16 length 16.; minimum items 2; maximum items 16.
templates[].penultimateRootInBass	Penultimate Root In Bass	Required. Boolean.
templates[].finalTonicRootInBass	Final Tonic Root In Bass	Required. Boolean.
templates[].finalSopranoOnTonic	Final Soprano On Tonic	Required. Boolean.
targetKeys	Target Keys	Required. Array of Text; minimum UTF-16 length 1; maximum UTF-16 length 8.; minimum items 1; maximum items 16.
count	Count	Required. Safe integer; minimum 1; maximum 32.
seed	Optional numeric seed; takes precedence over context randomness. Without either, use the fixed tool.io default seed.	Optional. Safe integer.

Output field	Interpretation	Returned shape
exercises	Exercises	Required. Array of Object; no unknown keys.; minimum items 1; maximum items 32.
exercises[].templateId	Template Id	Required. Text; minimum UTF-16 length 1; maximum UTF-16 length 32.
exercises[].sourceKey	Source Key	Required. Text; minimum UTF-16 length 1; maximum UTF-16 length 32.
exercises[].targetKey	Target Key	Required. Text; minimum UTF-16 length 1; maximum UTF-16 length 32.
exercises[].originalChordSymbols	Original Chord Symbols	Required. Array of Text; minimum UTF-16 length 1; maximum UTF-16 length 32.; minimum items 2; maximum items 16.
exercises[].transposedChordSymbols	Transposed Chord Symbols	Required. Array of Text; minimum UTF-16 length 1; maximum UTF-16 length 32.; minimum items 2; maximum items 16.
exercises[].romanChords	Roman Chords	Required. Array of Text; minimum UTF-16 length 1; maximum UTF-16 length 32.; minimum items 2; maximum items 16.
exercises[].signedDiatonicSteps	Signed Diatonic Steps	Required. Safe integer.
exercises[].signedChromaticSemitones	Signed Chromatic Semitones	Required. Safe integer.
exercises[].cadenceLabel	Cadence Label	Required. Text.
exercises[].recognizedFunctionalCadence	Recognized Functional Cadence	Required. Boolean.
randomness	Replay source and normalized 32-bit seed, or null seed for an advancing context source.	Required. Object; no unknown keys.
randomness.seed	Optional safe-integer replay seed; normalization and precedence are explained below.	Required. Safe integer. or Null.
randomness.source	Source	Required. Text; one of "context", "seed".

An explicit safe-integer seed takes precedence over injected context randomness and is normalized to an unsigned 32-bit integer. With no seed and no context source, replay uses the fixed tool.io default seed. A context source must return finite values from zero inclusive to one exclusive; its advancing state must be retained separately. randomness records the source and normalized seed, or null for context. These generators are not cryptographic random sources.

json

{
  "input": {
    "templates": [
      {
        "id": "authentic",
        "sourceKey": "C",
        "chordSymbols": [
          "C",
          "F",
          "G7",
          "C"
        ],
        "romanChords": [
          "I",
          "IV",
          "V7",
          "I"
        ],
        "penultimateRootInBass": true,
        "finalTonicRootInBass": true,
        "finalSopranoOnTonic": true
      }
    ],
    "targetKeys": [
      "D",
      "Bb"
    ],
    "count": 2,
    "seed": 42
  },
  "output": {
    "exercises": [
      {
        "templateId": "authentic",
        "sourceKey": "C",
        "targetKey": "D",
        "originalChordSymbols": [
          "C",
          "F",
          "G7",
          "C"
        ],
        "romanChords": [
          "I",
          "IV",
          "V7",
          "I"
        ],
        "signedDiatonicSteps": 1,
        "signedChromaticSemitones": 2,
        "transposedChordSymbols": [
          "D",
          "G",
          "A7",
          "D"
        ],
        "cadenceLabel": "perfect-authentic",
        "recognizedFunctionalCadence": true
      },
      {
        "templateId": "authentic",
        "sourceKey": "C",
        "targetKey": "Bb",
        "originalChordSymbols": [
          "C",
          "F",
          "G7",
          "C"
        ],
        "romanChords": [
          "I",
          "IV",
          "V7",
          "I"
        ],
        "signedDiatonicSteps": 6,
        "signedChromaticSemitones": 10,
        "transposedChordSymbols": [
          "Bb",
          "Eb",
          "F7",
          "Bb"
        ],
        "cadenceLabel": "perfect-authentic",
        "recognizedFunctionalCadence": true
      }
    ],
    "randomness": {
      "seed": 42,
      "source": "seed"
    }
  }
}

Limitations and assumptions

Chord-symbol and Roman-label arrays must align. Template labels and supported harmonic parsing determine the result; this does not synthesize sound, judge voice leading, or establish stylistic musical quality.
A replay requires the same complete input and implementation. The stated sampling convention applies within its eligible space. A finite draw does not exhaust all possible outputs; repeats remain possible unless a distinct-selection rule is explicit.
The field tables state structural bounds; cross-field constraints and bounded search or output budgets also apply. Unknown keys are rejected where the object contract disallows them. Input errors are distinct from null fields and deliberate invalid controls in a successful output.

Alternative or Complementary methods

For a supplied example, inspect the returned construction or delegated check directly. To evaluate a consumer, also test cases chosen for its own boundaries; a generated finite corpus does not establish exhaustive coverage.

References

Tool behavior and example: Random Cadence Chord Progression Generator — tool.io
Calculation or validation: music/cadence-type-classifier — tool.io
Calculation or validation: music/transpose-chord-progression — tool.io

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