Properties
| Name | Type | Description |
|---|---|---|
| matched | boolean | True when the fingerprint matched a known recording in the AcoustID database. |
| score | number | AcoustID match confidence, 0–1. |
| acoustid | object | AcoustID UUID for the recording group, when known. |
| mbid | object | MusicBrainz Recording ID for the matched recording. |
| isrc | object | ISRC, when resolvable from the matched recording. |
| track_name | object | Track title from the AcoustID/MusicBrainz match. |
| artist_name | object | Artist name(s) from the AcoustID/MusicBrainz match. |
| in_catalog | boolean | True if the matched recording is already in the FreqBlog catalog. When true, `audio_features` is populated. |
| audio_features | object | Full FreqBlog audio features for the matched recording — populated when the MBID resolves to a catalog row, otherwise null. Call `/lookup` separately if you want to trigger an on-demand analysis for u |
| fingerprint_duration_seconds | object | Duration of the fingerprinted audio (seconds), as reported by Chromaprint. |
| analysis | object | Audio features computed directly from the file you uploaded, populated when the recording could not be resolved to a catalog row (unknown fingerprint, or matched but not in the catalog). Set `analyze= |
| features_from | object | Where the returned features came from — `catalog` (a known recording, in `audio_features`) or `upload` (computed from your file, in `analysis`); null when no features were produced. Deliberately expli |
JSON Schema
{
"$schema": "https://json-schema.org/draft/2020-12/schema",
"$id": "https://artifacts.apis.io/freqblog-com/json-schema/freqblog-com-identify-response-schema.json",
"title": "IdentifyResponse",
"x-generated": "2026-10-30",
"x-method": "derived",
"x-generator": "derive-json-schema.py",
"x-source": "openapi/freqblog-com-openapi.json#/components/schemas/IdentifyResponse",
"properties": {
"matched": {
"type": "boolean",
"title": "Matched",
"description": "True when the fingerprint matched a known recording in the AcoustID database."
},
"score": {
"type": "number",
"maximum": 1.0,
"minimum": 0.0,
"title": "Score",
"description": "AcoustID match confidence, 0–1."
},
"acoustid": {
"anyOf": [
{
"type": "string"
},
{
"type": "null"
}
],
"title": "Acoustid",
"description": "AcoustID UUID for the recording group, when known."
},
"mbid": {
"anyOf": [
{
"type": "string"
},
{
"type": "null"
}
],
"title": "Mbid",
"description": "MusicBrainz Recording ID for the matched recording."
},
"isrc": {
"anyOf": [
{
"type": "string"
},
{
"type": "null"
}
],
"title": "Isrc",
"description": "ISRC, when resolvable from the matched recording."
},
"track_name": {
"anyOf": [
{
"type": "string"
},
{
"type": "null"
}
],
"title": "Track Name",
"description": "Track title from the AcoustID/MusicBrainz match."
},
"artist_name": {
"anyOf": [
{
"type": "string"
},
{
"type": "null"
}
],
"title": "Artist Name",
"description": "Artist name(s) from the AcoustID/MusicBrainz match."
},
"in_catalog": {
"type": "boolean",
"title": "In Catalog",
"description": "True if the matched recording is already in the FreqBlog catalog. When true, `audio_features` is populated.",
"default": false
},
"audio_features": {
"anyOf": [
{
"$ref": "#/$defs/TrackLookupResponse"
},
{
"type": "null"
}
],
"description": "Full FreqBlog audio features for the matched recording — populated when the MBID resolves to a catalog row, otherwise null. Call `/lookup` separately if you want to trigger an on-demand analysis for unknown recordings."
},
"fingerprint_duration_seconds": {
"anyOf": [
{
"type": "number"
},
{
"type": "null"
}
],
"title": "Fingerprint Duration Seconds",
"description": "Duration of the fingerprinted audio (seconds), as reported by Chromaprint."
},
"analysis": {
"anyOf": [
{
"$ref": "#/$defs/AudioAnalysisResponse"
},
{
"type": "null"
}
],
"description": "Audio features computed directly from the file you uploaded, populated when the recording could not be resolved to a catalog row (unknown fingerprint, or matched but not in the catalog). Set `analyze=false` to skip this and get identification only."
},
"features_from": {
"anyOf": [
{
"type": "string"
},
{
"type": "null"
}
],
"title": "Features From",
"description": "Where the returned features came from — `catalog` (a known recording, in `audio_features`) or `upload` (computed from your file, in `analysis`); null when no features were produced. Deliberately explicit: catalog values come from our 30-second-preview pipeline and upload values from your full file, so they are not interchangeable and a caller should never have to guess which it got."
}
},
"type": "object",
"required": [
"matched",
"score"
],
"$defs": {
"AudioAnalysisResponse": {
"properties": {
"bpm": {
"type": "number",
"maximum": 300.0,
"minimum": 20.0,
"title": "Bpm",
"description": "Tempo in beats per minute. Same field name/role as `tempo` in Spotify's response shape."
},
"bpm_alt": {
"anyOf": [
{
"type": "number"
},
{
"type": "null"
}
],
"title": "Bpm Alt",
"description": "Half-time corrected alternative BPM (twice the detected `bpm`), when our heuristic is fairly confident the detector locked onto half the beat grid. Only offered for tracks detected at 70-88 BPM; null otherwise. Never replaces `bpm`. Drum & bass is the one exception: a track detected at 108-122 BPM gets 1.5x the detected `bpm` (e.g. 115 -> 172.5), because the detector often reads a 174 BPM break at two-thirds speed."
},
"bpm_confidence": {
"type": "number",
"title": "Bpm Confidence",
"description": "Beat-strength score from Essentia's RhythmExtractor2013. Higher = stronger rhythmic pulse. Range about 0–5.3, catalogue median ~2.9. Values below 1.0 indicate weak or absent rhythm (ambient, spoken word)."
},
"key": {
"type": "string",
"title": "Key",
"description": "Musical key and scale as a human-readable string, e.g. `A-Minor` or `F#-Major`. Combines Spotify's integer `key` + `mode` fields into one readable value."
},
"key_confidence": {
"type": "number",
"maximum": 1.0,
"minimum": 0.0,
"title": "Key Confidence",
"description": "Key detection confidence [0–1]. Below 0.4 indicates atonal, modal, or harmonically ambiguous content."
},
"mode": {
"anyOf": [
{
"type": "integer",
"maximum": 1.0,
"minimum": 0.0
},
{
"type": "null"
}
],
"title": "Mode",
"description": "Musical mode as a Spotify-compatible integer: `0` = minor, `1` = major. Direct drop-in for Spotify's deprecated `mode` field."
},
"key_int": {
"anyOf": [
{
"type": "integer",
"maximum": 11.0,
"minimum": 0.0
},
{
"type": "null"
}
],
"title": "Key Int",
"description": "Pitch-class integer for the key, Spotify-compatible: `0` = C, `1` = C♯/D♭, `2` = D, … `11` = B. `null` when the key is undetected/atonal (Spotify used `-1`)."
},
"camelot": {
"anyOf": [
{
"type": "string"
},
{
"type": "null"
}
],
"title": "Camelot",
"description": "Camelot wheel notation for harmonic mixing, e.g. `8A` (A-Minor) or `5B` (D-Major). Used by DJs to find harmonically compatible tracks. A = minor keys, B = major keys. Numbers 1–12."
},
"open_key": {
"anyOf": [
{
"type": "string"
},
{
"type": "null"
}
],
"title": "Open Key",
"description": "Open Key notation for harmonic mixing, e.g. `1m` (A-Minor) or `1d` (C-Major). Alternative to Camelot — used by Serato DJ and Mixed In Key. d = major (dominant), m = minor. Numbers 1–12."
},
"acousticness": {
"anyOf": [
{
"type": "number",
"maximum": 1.0,
"minimum": 0.0
},
{
"type": "null"
}
],
"title": "Acousticness",
"description": "Acousticness [0–1]. Where the recording has AcousticBrainz features we serve their trained-classifier value. Otherwise, a model that listens to the preview (PANNs embeddings, CC BY 4.0, trained on AcousticBrainz's CC0 labels) as each track is re-analysed since 2026-09-27, most-requested first; tracks not yet reached carry our spectral-flatness estimate rescaled onto the same distribution, which is a sorting signal rather than a verdict on one track."
},
"danceability": {
"anyOf": [
{
"type": "number",
"maximum": 1.0,
"minimum": 0.0
},
{
"type": "null"
}
],
"title": "Danceability",
"description": "How suitable the track is for dancing [0–1], on AcousticBrainz's scale: its own classifier value where the recording has AcousticBrainz features, otherwise a model that listens to the preview (PANNs embeddings, CC BY 4.0, trained on AcousticBrainz's CC0 labels). Rolling out since 2026-09-27, most-requested first; tracks not yet reached carry our earlier tempo/beat-strength estimate. Re-derive thresholds rather than copying them from another service."
},
"instrumentalness": {
"anyOf": [
{
"type": "number",
"maximum": 1.0,
"minimum": 0.0
},
{
"type": "null"
}
],
"title": "Instrumentalness",
"description": "Likelihood the 30-second preview contains no vocals [0–1] (above 0.5 = likely instrumental), from a PANNs-based model trained on the vocal/no-vocal labels of the MUSAN corpus (Snyder et al. 2015, CC BY 4.0). Describes the preview, not the whole track. Null where a track has not been through the model yet."
},
"liveness": {
"anyOf": [
{
"type": "number",
"maximum": 1.0,
"minimum": 0.0
},
{
"type": "null"
}
],
"title": "Liveness",
"description": "Likelihood the track was performed live [0–1]. **Null for tracks from our own audio analysis**: our signal-based estimate was not reliable enough to serve (it read most studio recordings as live), so we return null rather than a misleading value. Populated where an external source supplies it."
},
"speechiness": {
"anyOf": [
{
"type": "number",
"maximum": 1.0,
"minimum": 0.0
},
{
"type": "null"
}
],
"title": "Speechiness",
"description": "Presence of spoken words [0–1] (above ~0.33 = rap or mixed speech, above ~0.66 = mostly spoken). **Null for tracks from our own audio analysis**: our signal-based estimate was not reliable enough to serve, so we return null rather than a misleading value. Populated where an external source supplies it."
},
"valence": {
"anyOf": [
{
"type": "number",
"maximum": 1.0,
"minimum": 0.0
},
{
"type": "null"
}
],
"title": "Valence",
"description": "Musical positiveness [0–1]. High = happy/euphoric, low = sad/dark. Estimated from scale, tempo, brightness and energy — a coarse signal; treat it as a sorting aid rather than a per-track verdict."
},
"mood": {
"anyOf": [
{
"type": "string"
},
{
"type": "null"
}
],
"title": "Mood",
"description": "MIREX-style mood category derived from valence and energy. One of: happy, calm, sad, tense, energetic, melancholic, neutral. Maps the four-quadrant mood model: high valence + high energy = happy; low valence + high energy = tense; etc."
},
"representative_segment_start": {
"anyOf": [
{
"type": "number"
},
{
"type": "null"
}
],
"title": "Representative Segment Start",
"description": "Start time in seconds of the highest-energy 30-second window. Identifies the most sonically representative (e.g. chorus or drop) segment. Useful for sync licensing, preview generation, and waveform thumbnails. 0.0 for tracks ≤ 30 s."
},
"rms_energy": {
"type": "number",
"maximum": 1.0,
"minimum": 0.0,
"title": "Rms Energy",
"description": "Perceptual intensity [0–1] from RMS loudness, on our own scale (loud masters sit near the top of it). Computed over the same 30-second window as BPM and key."
},
"loudness_db": {
"anyOf": [
{
"type": "number"
},
{
"type": "null"
}
],
"title": "Loudness Db",
"description": "Integrated loudness in dBFS (decibels relative to full scale). Same field role as `loudness` in Spotify's response shape. Typical mastered pop/electronic: -10 to -5 dBFS. Quiet/acoustic: -20 to -15."
},
"time_signature": {
"anyOf": [
{
"type": "integer"
},
{
"type": "null"
}
],
"title": "Time Signature",
"description": "Beats per bar. ASSUMED 4 (4/4) for every analysed track, not measured: no meter estimator we have tested beats a constant 4 on a mostly 4/4 catalogue. Same field role as `time_signature` in Spotify's response shape, kept for compatibility; do not filter or branch on it."
},
"mood_vector": {
"anyOf": [
{
"additionalProperties": {
"type": "number"
},
"type": "object"
},
{
"type": "null"
}
],
"title": "Mood Vector",
"description": "Dimensional mood scores [0–1] across five axes: `happy`, `sad`, `aggressive`, `relaxed`, `party`. Populated when an AcousticBrainz high-level match is found; `null` otherwise. Use these for fine-grained mood filtering beyond the single-label `mood` field."
},
"cached": {
"type": "boolean",
"title": "Cached",
"description": "True if this result was served from the server-side cache. Cached responses are < 100 ms. The underlying analysis is identical to a fresh result.",
"default": false
},
"bpm_snapped": {
"anyOf": [
{
"type": "integer"
},
{
"type": "null"
}
],
"title": "Bpm Snapped",
"description": "`bpm` rounded to a whole number — the grid tempo, in the form every DJ tool reports. Traktor, Serato and Rekordbox return clean integers because they derive a BEAT GRID, and a grid has exactly one tempo by construction; our `bpm` is a *measurement* of the audio, so it carries a decimal. For grid-produced music the true tempo is almost certainly the whole number and the decimal is our error — `bpm_confidence` correlates with how close we land to an integer, which is the evidence for that. **Always populated, never null.** Use `bpm` when you want the measurement (beatmatching by ear, where 127.89 vs 128.00 is the point) and `bpm_confidence` to judge how far to trust either.",
"readOnly": true
}
},
"type": "object",
"required": [
"bpm",
"bpm_confidence",
"key",
"key_confidence",
"rms_energy",
"bpm_snapped"
],
"title": "AudioAnalysisResponse"
},
"ExtendedAudioFeatures": {
"properties": {
"gender": {
"anyOf": [
{
"type": "string"
},
{
"type": "null"
}
],
"title": "Gender",
"description": "Always null since 2026-10-02. Was a vocal-gender classification (`male` / `female`) from AcousticBrainz; it was too unreliable on real catalogue tracks to serve. The key is kept so existing parsers don't break."
},
"timbre": {
"anyOf": [
{
"type": "string"
},
{
"type": "null"
}
],
"title": "Timbre",
"description": "Timbral brightness classification: `bright` / `dark`. Bright = strong high-frequency content (cymbals, electric guitar); dark = bass-dominant."
},
"tonal_atonal": {
"anyOf": [
{
"type": "string"
},
{
"type": "null"
}
],
"title": "Tonal Atonal",
"description": "Tonality classification: `tonal` / `atonal`. Tonal = clear key centre; atonal = ambiguous or shifting tonality (typical of avant-garde / drone)."
}
},
"type": "object",
"title": "ExtendedAudioFeatures",
"description": "Higher-level categorical labels from AcousticBrainz. Each value is the\nmost-confident class from a binary classifier — useful for filtering /\nbucketing but not for fine-grained analysis."
},
"TrackLookupResponse": {
"properties": {
"track_name": {
"type": "string",
"title": "Track Name",
"description": "Track name as indexed in the catalogue or from MusicBrainz."
},
"artist_name": {
"type": "string",
"title": "Artist Name",
"description": "Artist name."
},
"album_name": {
"anyOf": [
{
"type": "string"
},
{
"type": "null"
}
],
"title": "Album Name",
"description": "Album or single title. Populated for catalog tracks."
},
"itunes_track_id": {
"type": "string",
"title": "Itunes Track Id",
"description": "iTunes track ID for catalog tracks; 'mb:{mbid}' for AcousticBrainz-sourced tracks. (The former 'fma:' / 'msd:' ids no longer resolve.)"
},
"isrc": {
"anyOf": [
{
"type": "string"
},
{
"type": "null"
}
],
"title": "Isrc",
"description": "International Standard Recording Code. Uniquely identifies this specific master recording."
},
"mbid": {
"anyOf": [
{
"type": "string"
},
{
"type": "null"
}
],
"title": "Mbid",
"description": "MusicBrainz Recording ID (UUID). Cross-reference to the open music encyclopedia."
},
"is_remix": {
"type": "boolean",
"title": "Is Remix",
"description": "True when this recording is a third-party remix/bootleg (not an original mix or same-performance version). Parsed from the title + credit at ingest. Always present; false for originals and fallback-layer tracks.",
"default": false
},
"remixer": {
"anyOf": [
{
"type": "string"
},
{
"type": "null"
}
],
"title": "Remixer",
"description": "The third-party artist credited with the remix, when attributable; null for style-descriptor or unnamed remixes."
},
"mix_name": {
"anyOf": [
{
"type": "string"
},
{
"type": "null"
}
],
"title": "Mix Name",
"description": "Version/mix descriptor for any variant (remix OR version), e.g. 'Extended Mix', 'Alesso Remix'. Null for a plain original."
},
"remix_of_isrc": {
"anyOf": [
{
"type": "string"
},
{
"type": "null"
}
],
"title": "Remix Of Isrc",
"description": "ISRC of the ORIGINAL recording this remix is based on, when the original is in the catalog (matched by base title + artist). Lets you jump from a remix to its source recording. Null for originals, unmatched remixes, and fallback-layer tracks."
},
"release_date": {
"anyOf": [
{
"type": "string"
},
{
"type": "null"
}
],
"title": "Release Date",
"description": "Release date in ISO 8601 format (YYYY-MM-DD), from catalogue metadata. Null for fallback-layer tracks."
},
"duration_ms": {
"anyOf": [
{
"type": "integer"
},
{
"type": "null"
}
],
"title": "Duration Ms",
"description": "Full track duration in milliseconds, from catalogue metadata. Distinct from `duration_seconds` (which is the analysed 30s window)."
},
"explicit": {
"anyOf": [
{
"type": "boolean"
},
{
"type": "null"
}
],
"title": "Explicit",
"description": "True if the track is marked explicit by the source. Null when not reported."
},
"bpm": {
"type": "number",
"maximum": 300.0,
"minimum": 20.0,
"title": "Bpm",
"description": "Tempo in beats per minute."
},
"bpm_alt": {
"anyOf": [
{
"type": "number"
},
{
"type": "null"
}
],
"title": "Bpm Alt",
"description": "Half-time corrected alternative BPM (twice the detected `bpm`), when our heuristic is fairly confident Essentia locked onto half the beat grid. Only offered for tracks detected at 70-88 BPM; null otherwise (drum & bass detected at 108-122 BPM instead gets 1.5x, e.g. 115 -> 172.5: the detector often reads a 174 BPM break at two-thirds speed). **Never** replaces `bpm` — use this when your downstream tooling expects the perceived rather than detected tempo (e.g. pop tracks like 'Blinding Lights' where Essentia returns ~85 but the perceived BPM is ~171)."
},
"bpm_confidence": {
"anyOf": [
{
"type": "number"
},
{
"type": "null"
}
],
"title": "Bpm Confidence",
"description": "Beat-strength score from Essentia RhythmExtractor2013, about 0–5.3 (catalogue median ~2.9). Below ~1.5 the tempo is worth checking by ear: on crowd-tapped electronic tracks our BPM matched a listener's tempo 57% of the time below 1.0 and 99% at 3.5–4. Null for AcousticBrainz-sourced tracks."
},
"key": {
"type": "string",
"title": "Key",
"description": "Musical key and scale, e.g. `C#-Minor`."
},
"key_confidence": {
"anyOf": [
{
"type": "number",
"maximum": 1.0,
"minimum": 0.0
},
{
"type": "null"
}
],
"title": "Key Confidence",
"description": "Key detection confidence [0–1]. Null for AcousticBrainz-sourced tracks."
},
"mode": {
"anyOf": [
{
"type": "integer",
"maximum": 1.0,
"minimum": 0.0
},
{
"type": "null"
}
],
"title": "Mode",
"description": "Spotify-compatible mode integer: 0 = minor, 1 = major."
},
"key_int": {
"anyOf": [
{
"type": "integer",
"maximum": 11.0,
"minimum": 0.0
},
{
"type": "null"
}
],
"title": "Key Int",
"description": "Spotify-compatible pitch-class integer for the key: 0 = C, 1 = C♯/D♭, 2 = D, … 11 = B. `null` when the key is undetected/atonal (the Spotify-shaped `/v1/audio-features/{id}` endpoint reports `-1` in that case, matching Spotify's convention)."
},
"camelot": {
"anyOf": [
{
"type": "string"
},
{
"type": "null"
}
],
"title": "Camelot",
"description": "Camelot wheel notation, e.g. `12A`."
},
"open_key": {
"anyOf": [
{
"type": "string"
},
{
"type": "null"
}
],
"title": "Open Key",
"description": "Open Key notation, e.g. `5m` (C#-Minor). d=major, m=minor."
},
"energy": {
"anyOf": [
{
"type": "number",
"maximum": 1.0,
"minimum": 0.0
},
{
"type": "null"
}
],
"title": "Energy",
"description": "Perceived energy [0–1] of the 30-second preview: a PANNs-based model (Kong et al. 2020, CC BY 4.0) placed on our existing energy scale (median ~0.65). It agrees better with human listener ratings than the RMS loudness it replaced (checked on two independent rating datasets); tracks the model has not reached yet still carry the RMS value."
},
"loudness_db": {
"anyOf": [
{
"type": "number"
},
{
"type": "null"
}
],
"title": "Loudness Db",
"description": "Integrated loudness in dBFS."
},
"danceability": {
"anyOf": [
{
"type": "number",
"maximum": 1.0,
"minimum": 0.0
},
{
"type": "null"
}
],
"title": "Danceability",
"description": "How suitable the track is for dancing [0–1], on AcousticBrainz's scale: AcousticBrainz's classifier where a recording has it, otherwise a model built on PANNs embeddings (Kong et al. 2020, CC BY 4.0) and trained on AcousticBrainz labels."
},
"valence": {
"anyOf": [
{
"type": "number",
"maximum": 1.0,
"minimum": 0.0
},
{
"type": "null"
}
],
"title": "Valence",
"description": "Musical positiveness [0–1] of the 30-second preview (high = happy/uplifting, low = sad/dark), from a PANNs-based model (Kong et al. 2020, CC BY 4.0) placed on our existing valence scale (median ~0.48). It agrees better with human listener ratings than the signal heuristic it replaced on two of three independent rating datasets; it still partly tracks energy, so treat it as a sorting aid. Tracks the model has not reached yet carry the heuristic value."
},
"speechiness": {
"anyOf": [
{
"type": "number",
"maximum": 1.0,
"minimum": 0.0
},
{
"type": "null"
}
],
"title": "Speechiness",
"description": "Spoken word presence [0–1]. Null for catalogue tracks for now."
},
"instrumentalness": {
"anyOf": [
{
"type": "number",
"maximum": 1.0,
"minimum": 0.0
},
{
"type": "null"
}
],
"title": "Instrumentalness",
"description": "Likelihood [0–1] that the 30-second preview has no vocals, from a model on PANNs embeddings (Kong et al. 2020, CC BY 4.0) trained on the vocal/no-vocal labels of the MUSAN corpus (Snyder et al. 2015, CC BY 4.0). Describes the preview, not the whole track. Null where a track has not been through the model yet."
},
"liveness": {
"anyOf": [
{
"type": "number",
"maximum": 1.0,
"minimum": 0.0
},
{
"type": "null"
}
],
"title": "Liveness",
"description": "Live performance likelihood [0–1]. Null for catalogue tracks for now (not measured reliably enough to serve)."
},
"acousticness": {
"anyOf": [
{
"type": "number",
"maximum": 1.0,
"minimum": 0.0
},
{
"type": "null"
}
],
"title": "Acousticness",
"description": "Acousticness [0–1]: AcousticBrainz's classifier where available, otherwise a model built on PANNs embeddings (Kong et al. 2020, CC BY 4.0) and trained on AcousticBrainz labels."
},
"time_signature": {
"anyOf": [
{
"type": "integer"
},
{
"type": "null"
}
],
"title": "Time Signature",
"description": "Beats per bar. ASSUMED 4 (4/4) for every track we analyse, not measured: no meter estimator we have tested beats a constant 4 on a mostly 4/4 catalogue. Kept in the Spotify response shape for compatibility; do not filter or branch on it."
},
"mood": {
"anyOf": [
{
"type": "string"
},
{
"type": "null"
}
],
"title": "Mood",
"description": "MIREX-style mood category: happy, calm, sad, tense, energetic, melancholic, or neutral."
},
"mood_vector": {
"anyOf": [
{
"additionalProperties": {
"type": "number"
},
"type": "object"
},
{
"type": "null"
}
],
"title": "Mood Vector",
"description": "Dimensional mood scores [0–1] across five axes: `happy`, `sad`, `aggressive`, `relaxed`, `party`. Populated when an AcousticBrainz high-level match is found; `null` otherwise."
},
"onset_rate": {
"anyOf": [
{
"type": "number"
},
{
"type": "null"
}
],
"title": "Onset Rate",
"description": "Onset events per second from AcousticBrainz low-level analysis. Higher values indicate more rhythmic or percussive content. Populated when an AcousticBrainz match is found; `null` otherwise."
},
"dynamic_complexity": {
"anyOf": [
{
"type": "number"
},
{
"type": "null"
}
],
"title": "Dynamic Complexity",
"description": "Loudness variation over the track (dB), from AcousticBrainz low-level analysis. Higher values mean wider dynamic range; lower values mean more compressed mastering. Populated when an AcousticBrainz match is found; `null` otherwise."
},
"tuning_frequency": {
"anyOf": [
{
"type": "number"
},
{
"type": "null"
}
],
"title": "Tuning Frequency",
"description": "Estimated A4 reference frequency in Hz, from AcousticBrainz tonal analysis. Modern recordings cluster near 440 Hz; older or non-Western recordings may diverge. Populated when an AcousticBrainz match is found; `null` otherwise."
},
"average_loudness": {
"anyOf": [
{
"type": "number"
},
{
"type": "null"
}
],
"title": "Average Loudness",
"description": "Average loudness as a normalised value [0–1] from AcousticBrainz low-level analysis. Distinct from `loudness_db` (which is dBFS from this service's own analysis). Populated when an AcousticBrainz match is found; `null` otherwise."
},
"genre": {
"anyOf": [
{
"type": "string"
},
{
"type": "null"
}
],
"tit
# --- truncated at 32 KB (35 KB total) ---
# Full source: https://artifacts.apis.io/freqblog-com/json-schema/freqblog-com-identify-response-schema.json
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