Dataset card: 20 synthetic tracks with stems, MIDI and exact annotations

README.md

@@ -1,3 +1,159 @@
 ---
 license: cc-by-4.0
+pretty_name: Nullsample Multitrack
+task_categories:
+- audio-classification
+- audio-to-audio
+tags:
+- music
+- synthetic
+- procedural-audio
+- multitrack
+- stems
+- source-separation
+- music-transcription
+- drum-transcription
+- beat-tracking
+- chord-recognition
+- key-detection
+- midi
+- mir
+size_categories:
+- n<1K
+configs:
+- config_name: default
+  data_files:
+  - split: train
+    path: "mix/*"
 ---
+
+# Nullsample Multitrack
+
+**20 complete tracks generated from code, with zero samples. Each comes with its mix, six
+stems, a MIDI file and exact annotations**: tempo, downbeats, key, the chord in every bar, the sections,
+every drum hit by instrument and every note of every part. That is 40,060 drum hits and 32,919
+notes over 37 minutes of music.
+
+The labels are not estimated and not hand-annotated. They are the score the audio was synthesised from,
+so they are exact by construction. No recordings, samples or trained models were used. Every sound is
+computed from oscillators, noise, envelopes and filters by
+[Nullsample](https://nullsample.maqsudjon.com) ([source](https://github.com/maqsudjon-cell/nullsample),
+AGPL-3.0). Nothing in the audio came from anyone else's recording.
+
+**Every track can be reproduced bit for bit from its seed**, on any machine. The engine avoids the
+platform-dependent `Math.sin`/`exp`/`pow` and is tested byte-identical across Node and browsers. You can
+listen to any seed at `https://nullsample.maqsudjon.com/generate/#s=<seed>`, or render the lossless WAV
+yourself:
+
+```bash
+git clone https://github.com/maqsudjon-cell/nullsample && cd nullsample && git checkout b6adf10
+npm install && npm run render -- --seed NULL-0001 --out NULL-0001.wav
+npm run dataset -- --out ./dataset        # this whole dataset
+```
+
+The audio came from engine commit `c912de6` (`engine_commit` in every annotation file). The
+checkout above has the same engine plus the script that wrote this dataset.
+
+## What it is good for
+
+- **Source separation:** six stems per track (drums, 808 bass, lead, arp, pads, fx).
+- **Drum and note transcription:** onsets and notes that are exact to the sample.
+- **Beat, downbeat and tempo tracking.**
+- **Key and chord recognition, and structure segmentation.**
+- **Testing an MIR tool against ground truth** before trusting it on real recordings.
+
+## Files
+
+| Path | What |
+|---|---|
+| `mix/<seed>.mp3` | the track, MP3 192 kbps, 44.1 kHz stereo |
+| `mix/metadata.csv` | one row per track: tempo, key, scale, bars, length, form, sections, chords. The viewer reads it. |
+| `stems/{drums,bass808,lead,arp,pads,fx}/<seed>.mp3` | each part rendered on its own, MP3 128 kbps |
+| `annotations/<seed>.json` | the labels, times in seconds |
+| `midi/<seed>.mid` | the same notes as a Standard MIDI File |
+
+### `annotations/<seed>.json`
+
+```json
+{
+ "seed": "CLIP-N0ISE", "tempo_bpm": 152.5, "time_signature": "4/4", "bars": 68, "duration": 109.516,
+ "downbeats": [0, 1.5738, 3.1475, ...],
+ "key": { "tonic": "G", "scale": "phrygian", "scale_intervals": [0,1,3,5,7,8,10] },
+ "form": "double-drop",
+ "sections": [{ "name": "intro", "start": 0, "end": 6.2951, "intensity": 0.12 }, ...],
+ "chords": [{ "start": 0, "end": 1.5738, "chord": "Gsus2", "root": "G", "voicing": "sus2", "notes": [55,57,62] }, ...],
+ "drums": { "kick": [{ "time": 6.2951, "velocity": 1 }, ...],
+            "hatClosed": [{ "time": 6.2951, "velocity": 0.825 }, ...],
+            "hatOpen": [{ "time": 6.4918, "velocity": 0.629 }, ...],
+            "rim": [{ "time": 6.4918, "velocity": 0.317 }, ...],
+            "snare": [{ "time": 6.6885, "velocity": 0.995 }, ...],
+            "clap": [{ "time": 7.4754, "velocity": 1 }, ...] },
+ "notes": { "bass808": [{ "start": 5.9016, "end": 6, "midi": 24, "velocity": 0.686 }, ...],
+            "lead": [{ "start": 6.2951, "end": 6.3934, "midi": 94, "velocity": 1 }, ...],
+            "arp": [{ "start": 37.7703, "end": 37.8146, "midi": 110, "velocity": 0.95 }, ...],
+            "pads": [{ "start": 0, "end": 1.3849, "midi": 67, "velocity": 0.8 }, ...] },
+ "fx": [{ "kind": "riser", "start": 3.1475, "end": 6.2951 }, ...],
+ "regenerate": "https://nullsample.maqsudjon.com/generate/#s=CLIP-N0ISE",
+ "engine_commit": "c912de6da8dc5c66871a8acb8c0441a2d4666193"
+}
+```
+
+The MIDI files have 480 ticks per beat and the track's tempo. They have a tempo track with the sections
+as markers, the drums on channel 10 (General MIDI: kick 36, rim 37, snare 38, clap 39, closed hat 42,
+open hat 46), and one track each for `bass808`, `lead`, `arp` and `pads`. Velocities in the JSON are
+0–1. The pads are chords with no velocity of their own, written at 0.8. Chord names: `5` is a power chord, `m` minor, `m7`, `sus2`, `sus4`, `add9`, `m(add9)`.
+
+## The tracks
+
+Tempo 151–159.5 BPM. Scales: phrygian, minorPentatonic, naturalMinor, harmonicMinor, phrygianDominant.
+
+| Seed | BPM | Key | Form | Length | Sections |
+|---|---|---|---|---|---|
+| `CLIP-N0ISE` | 152.5 | G phrygian | double-drop | 1:50 | intro drop break drop2 break2 drop3 outro |
+| `DUCK-UNDER` | 155 | F minorPentatonic | double-drop | 1:48 | intro drop break drop2 break2 drop3 outro |
+| `FOLD-BACK3` | 159 | C# minorPentatonic | double-drop | 1:45 | intro drop break drop2 break2 drop3 outro |
+| `GLASS-EDGE` | 156.5 | G naturalMinor | cold-open | 1:47 | drop verse drop2 verse2 drop3 outro |
+| `GRID-LOCK4` | 159.5 | A# harmonicMinor | long-build | 1:57 | intro build drop break drop2 outro |
+| `HARD-CODE1` | 158 | A naturalMinor | double-drop | 1:46 | intro drop break drop2 break2 drop3 outro |
+| `K7M2-QX4B` | 154.5 | D harmonicMinor | long-break | 1:42 | intro build drop break drop2 outro |
+| `LAST-CALL9` | 154 | B naturalMinor | cold-open | 1:48 | drop verse drop2 verse2 drop3 outro |
+| `NULL-0001` | 155 | E minorPentatonic | sustained | 1:54 | intro hold lift hold2 lift2 outro |
+| `OSC-ILLATE` | 156.5 | A harmonicMinor | cold-open | 1:47 | drop verse drop2 verse2 drop3 outro |
+| `PHRY-GIAN9` | 156 | E phrygian | straight-in | 1:53 | drop break drop2 bridge drop3 outro |
+| `PRIME-DLAY` | 155.5 | D harmonicMinor | arc | 1:54 | intro build drop break drop2 bridge outro |
+| `RAGE-88KK` | 156.5 | C# harmonicMinor | sustained | 1:53 | intro hold lift hold2 lift2 outro |
+| `SAW-STACK5` | 155 | E naturalMinor | cold-open | 1:48 | drop verse drop2 verse2 drop3 outro |
+| `SEED-4242X` | 154 | D# phrygian | straight-in | 1:55 | drop break drop2 bridge drop3 outro |
+| `SINE-WAVE7` | 159.5 | F# naturalMinor | sustained | 1:51 | intro hold lift hold2 lift2 outro |
+| `SUB-DROP01` | 158 | A harmonicMinor | long-build | 1:58 | intro build drop break drop2 outro |
+| `TAPE-NULL2` | 151 | F phrygianDominant | long-break | 1:44 | intro build drop break drop2 outro |
+| `VOID-7X2A` | 151.5 | C naturalMinor | long-break | 1:44 | intro build drop break drop2 outro |
+| `ZERO-SAMPL` | 159 | A phrygian | straight-in | 1:51 | drop break drop2 bridge drop3 outro |
+
+## Limits
+
+- **One style.** All tracks come from one preset (energetic electronic, hyperpop-like), so this is
+  not a sample of music in general. It is small: use it to test and probe models, or as a clean
+  supplement, not as a training corpus on its own.
+- **Stems do not sum exactly to the mix.** Each stem is its bus rendered alone through the master
+  chain at a fixed drive. The mix also has mix-wide effects (tape stops, stutters) and a limiter
+  that reacts to everything at once.
+- **MP3, to keep it small.** Annotation times come from the engine's sample positions. Decoders
+  that honour the LAME gapless header, such as ffmpeg and most libraries, line up within a few
+  milliseconds. For lossless audio, render the seed.
+- The synthesis parameters behind each sound are not included.
+
+## Licence
+
+The audio, MIDI and annotations: **CC BY 4.0**. Please credit "Nullsample (nullsample.maqsudjon.com)".
+The engine that made them: [AGPL-3.0](https://github.com/maqsudjon-cell/nullsample). Audio you render
+yourself with it is yours.
+
+```bibtex
+@misc{nullsample_multitrack,
+  title  = {Nullsample Multitrack: synthetic music with exact annotations},
+  author = {Polatov, Maqsudjon},
+  year   = {2026},
+  url    = {https://nullsample.maqsudjon.com}
+}
+```