Playlistparser

Tool for parsing DJ software playlists. Currently supports Engine DJ, Rekordbox, Serato, Traktor, and VirtualDJ. Part of Slipmat.io music tools.

Free hosted version of this tool: https://slipmat.io/tools/playlistconverter/

Installing

uv add playlistparser

Command line

uvx playlistparser parse myplaylist.nml

1. Technotronic - Pump Up The Jam (Edit)
2. Guru Josh - Infinity (1990s... Time for the Guru 12" Mix)

Rekordbox · 2 tracks

--json gives every field of every track:

{
  "tracks": [
    {
      "title": "Pump Up The Jam (Edit)",
      "artist": "Technotronic",
      "album": "",
      "key": "",
      "duration": 216,
      "year": 1989,
      "bpm": 124.0,
      "file_path": "",
      "vendor_id": ""
    }
  ],
  "summary": { "playlist_type": "REKORDBOX", "track_count": 1 }
}

Exit code is 1 if the file can't be parsed.

Usage

One end-to-end example covering format detection, streaming, required fields, aggregates, per-track data and every exception you need to handle:

import logging

from playlistparser import (
    MalformedPlaylistError,
    MissingFieldError,
    PlaylistParser,
    PlaylistParserError,
    PlaylistType,
    UnknownFormatError,
)

logging.basicConfig(level=logging.INFO)

try:
    # Construct a parser. All keyword arguments are optional.
    #
    #   require        — fail fast if any listed field is missing on a row.
    #                    If the format itself can't expose the field (e.g. Serato
    #                    has no bpm), MissingFieldError is raised before track
    #                    parsing. CSV detection reads the header first.
    #   as_type        — override format detection (use for unusual file
    #                    extensions); otherwise the format is detected from the
    #                    extension, and for .csv from the header row.
    #   default_artist — substituted when a row has no artist field.
    #
    # Recoverable per-row warnings are emitted via stdlib `logging` under the
    # `playlistparser.parsers.*` logger names — configure logging at the root
    # (or route through structlog with `structlog.stdlib.LoggerFactory()`).
    pl = PlaylistParser(
        "history.csv",
        require=["title", "artist"],
        default_artist="Unknown Artist",
        # as_type=PlaylistType.ENGINE,  # uncomment to bypass detection
    )

    # Detected format (PlaylistType enum: ENGINE, REKORDBOX, SERATO,
    # TRAKTOR, VIRTUALDJ). For .csv this triggers a one-time header sniff.
    print(f"Format: {pl.playlist_type.name}")

    # Stream tracks. Iteration is lazy — each pass re-reads the file unless
    # you materialise with .to_list() (cached for the lifetime of the parser).
    for track in pl:
        # str(track) → "Artist - Title"
        print(track)

        # Track is a frozen dataclass with these fields (all always present;
        # unsupported / missing values are 0 or ""):
        #   title: str, artist: str, album: str, key: str
        #   duration: int (seconds), year: int, bpm: float
        #   file_path: str, vendor_id: str
        print(track.bpm, track.year, track.duration_str())  # e.g. "128.0 2024 6:42"

        # Serialise for JSON / DB. no_meta=True keeps only title + artist.
        payload = track.as_dict()

    # Aggregates materialise the full list once and cache it.
    print(f"{pl.track_count} tracks, {pl.total_duration}s total")

    # Explicit materialisation if you need the list directly.
    tracks = pl.to_list()

except UnknownFormatError as e:
    # Extension not recognised, or CSV header didn't match any known format.
    # Pass as_type=PlaylistType.X to override.
    print(f"Unsupported file: {e}")

except MissingFieldError as e:
    # A required field was missing — either unsupported by the format
    # (raised before parsing) or absent on a specific row.
    # e.field, e.line, e.track_title are available for diagnostics.
    print(f"Missing '{e.field}' on line {e.line}: {e.track_title!r}")

except MalformedPlaylistError as e:
    # Structural problem with the file (bad XML, truncated row, etc).
    # e.path and e.line locate the problem.
    print(f"Corrupt playlist: {e}")

except PlaylistParserError as e:
    # Base class — catch this if you don't care which of the above fired.
    print(f"Could not parse playlist: {e}")

except FileNotFoundError:
    # The library does not check existence in the constructor; the file is
    # opened on the first iteration / aggregate access.
    print("Playlist file does not exist")

Parsing progress

Pass a callback to stream() when displaying progress:

def report_progress(tracks_done, total_tracks, bytes_read, bytes_total):
    byte_percent = bytes_read / bytes_total if bytes_total else 1
    print(tracks_done, total_tracks, byte_percent)


for track in PlaylistParser("set.nml").stream(on_progress=report_progress):
    save(track)

Byte progress is monotonic and completes even when malformed source records are skipped. When available, track totals count source records, so tracks_done can finish below total_tracks when records are skipped. total_tracks is None when the source has no valid count, such as a Traktor collection without a valid ENTRIES value. Delimited formats count logical records in a pre-pass.

Supported formats and fields

CSV formats are detected by sniffing the header row.

BPM is a float rounded to one decimal place. Traktor's vendor_id is its ENTRY.AUDIO_ID.

Developing

• uv run ruff format - format
• uv run ruff check --fix --extend-fixable F401 - lint
• uv run ty check - typecheck
• uv run pytest - run test suite

Contributing

Contributions are welcome! Please follow the code of conduct when interacting with others.

Elsewhere

• Follow @uninen.net on Bluesky
• Read my continuously updating learnings from Python / TypeScript and other Web development topics from my Today I Learned site

Licence

Copyright © 2022, Ville Säävuori. Released under the GNU Affero General Public License v3.0.

Commercial licenses are also available.