JSON Schema · Draft 2020-12
PMF Schema 1.0
Validate
npx ajv-cli validate -s schema/pmf-1.0.schema.json -d your-file.pmf
Root object
Top-level object. Five fields are required; all others are optional and engine-defined.
required:
pmf_version
engine
summary
identity
render_key
pmf_version
string
required
const "1.0"
PMF format version. Must be exactly
"1.0" for this schema.engine
string
required
Name of the generating engine (e.g.
"synthwave_engine").engine_version
string
optional
Semver of the engine that wrote this file.
summary
string
required
maxLength 500
Engine-generated natural language description. Under 80 words. An LLM reads this first.
identity object
Who this composition is and what it sounds like. Four fields are required.
required:
seedbpmkeybars
seed
integerrequired≥ 0
The seed that produced this composition.
mood
stringoptional
Mood preset name (engine-defined, e.g.
"NightDrive").bpm
numberrequired20 – 400
Tempo in beats per minute.
bpm_label
stringoptional
Human label for the tempo (e.g.
"mid-tempo", "driving").key
stringrequired
Key name in standard notation (e.g.
"A minor", "F# minor", "C major").key_type
stringoptional
Scale type:
"natural_minor", "harmonic_minor", "major", "pentatonic", etc.key_shift_semitones
integeroptional−24 – 24
Semitone offset from the engine's reference key.
bars
integerrequired≥ 1
Number of bars in the loop.
time_signature
stringoptional
Time signature. Default:
"4/4".render_key object
Exact rendering context. Together with identity.seed, these fields are the minimum needed to reproduce byte-identical output from a compatible engine version.
required:
sample_ratebarsstem_formatloop_modeengine_version_major
sample_rate
integerrequired8000 – 192000
Audio sample rate in Hz.
bars
integerrequired≥ 1
Bar count for this render. Must match
identity.bars.stem_format
stringrequired
Channel layout:
"mono", "stereo", or engine-defined variant.loop_mode
stringrequiredenum
Whether the composition was rendered as a seamless loop. Allowed values:
"looped" or "finite".engine_version_major
integerrequired≥ 0
Major semver component of the engine. Determinism is stable within a major version.
palette_pack_version
integeroptional≥ 0
Version of the palette pack used, if the engine supports swappable packs.
harmony object · optional
Harmonic structure of the composition. All fields optional.
progression
string[]optional
Chord names in order (e.g.
["Am", "F", "C", "G"]).progression_degrees
string[]optional
Scale degrees for each chord (e.g.
["i", "VI", "III", "VII"]).progression_label
stringoptional
Human description of the progression character (e.g.
"classic minor turnaround").key_root_midi
integeroptional0 – 127
MIDI note number of the key root (A4 = 69).
bass_pattern
integer[]optional−24 – 24 each
Per-beat interval offsets from chord root in semitones.
bass_pattern_label
stringoptional
Human description (e.g.
"root-root-fifth-root").arp_pattern
stringoptional
Arp pattern name (engine-defined).
arp_pattern_label
stringoptional
Human description of the arp movement.
arp_bar_order
integer[]optional
Which arp pattern index plays each bar.
melody object · optional
Named melodic motifs. Keys are motif identifiers ("motif_a", "motif_b", or any name). Each value is a motif object — abc is the only required field.
abc
stringrequired
Motif body in ABC notation. No headers — key context comes from
identity.key. Example: "A2 c B A4".intervals_semitones
integer[]optional
Interval steps in semitones. Allows LLM reasoning without ABC parsing.
rhythm
stringoptional
Human-readable rhythm description (e.g.
"half quarter quarter whole").label
stringoptional
Human description of the motif's musical character.
active_bars
integer[]optional
Bar indices where this motif plays.
arrangement object · optional
How the composition unfolds bar by bar. All fields optional.
template
stringoptional
Arrangement template name (engine-defined).
sections
object[]optional
Array of section objects. Each has:
name (string, required), bars ([start, end] inclusive, required), stems_active (string[], optional).melody_on_bars
integer[]optional
Bar indices where melody plays.
bar_gains
objectoptional
Per-stem gain arrays. Keys are stem names, values are float arrays (one per bar). Range:
0.0–2.0. Semantics: 0.0 = silent, 1.0 = full, >1.0 = boosted.voices object · optional
Engine-defined. Per-voice synthesis parameters. Keys are voice names (e.g.
"kick", "pad", "lead"). PMF specifies no fixed property schema — only the convention that semantic labels accompany raw numeric values where available. Validators accept any object.
fx object · optional
Engine-defined. Post-processing chain parameters. Common sub-keys in practice:
reverb, delay, sidechain, limiter. Content and schema are engine-specific. Validators accept any object.
mix object · optional
Engine-defined. Master mix parameters: stem volume presets, tween timing, reactive control tables. Content and schema are engine-specific. Validators accept any object.
extensions object · optional
Engine-specific extensions under namespaced keys. Each key should match the engine name to avoid collisions (e.g. "synthwave_engine"). Each value is a free-form object.
Use
extensions for engine-specific data that doesn't belong in voices, fx, or mix. Do not duplicate core fields here. See docs/extensions.md for the full policy.
Raw Schema
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