# Database Structure
(database-structure)=

After downloading or building the database, you'll end up with an individual directory for each track in the database. The filename is constructed in the form `bandleader-trackname-musician1musician2-year-mbzid`. Names are given in the format `surnamefirstinitial`, e.g. Bill Evans would become `evansb`. In most cases, the bandleader is the pianist, and `musician1musician2` are the bassist and drummer, respectively. In cases where another musician was the bandleader, the pianist always takes priority in the ordering of names.

Inside each directory are the following files:
- `*_onset.csv` files: contain the raw onsets for `piano`, `bass`, and `drums`, with one onset per line;
- `beats.csv`: contain the onsets matched to each beat, as well as the estimated metre and downbeats, with one beat per line;
- `piano_midi.mid`: contains the automatically transcribed piano midi;
- `metadata.json`: contains (surprisingly) track and recording metadata.

## Recording metadata

The metadata files contain the following fields for every recording:

| Field               | Type | Description                                                                                   |
|---------------------|------|-----------------------------------------------------------------------------------------------|
| `track_name`        | str  | Title of the recording                                                                        |
| `album_name`        | str  | Title of the earliest album released that contains the track                                  |
| `in_30_corpus`      | bool | Whether the track is in smaller JTD-300 subset of the data                                    |
| `recording_year`    | int  | Year of recording                                                                             |
| `channel_overrides` | dict | Key-value pairs relating to panning: `piano: l` means the piano is panned to the left channel |
| `mbz_id`            | str  | Unique ID assigned to the track on MusicBrainz                                                |
| `time_signature`    | int  | The number of quarter note beats per measure for the track                                    |
| `first_downbeat`    | int  | The first clear quarter note downbeat in the track                                            |
| `rating_audio`      | int  | Subjective rating (1–3, 3 = best) of source-separation quality                                |
| `rating_detection`  | int  | Subjective rating of onset detection quality                                                  |
| `links`             | dict | YouTube URL for the recording                                                                 |
| `excerpt_duration`  | str  | Duration of recording, in `Minutes:Seconds` format                                            |
| `timestamps`        | dict | Start and end timestamps for the piano solo in the recording                                  |
| `musicians`         | dict | Key-value pairs of the musicians included in the recording                                    |
| `fname`             | str  | Audio filename                                                                                |