@doot-games/simfile

Read and write StepMania .sm files and the native Doot song package. Pure string work, no DOM.

StepMania .sm

toSM(chart, meta?) serializes a chart. parseSM(text) reads the first dance-single chart back into { title, artist, bpm, offset, difficulty, notes }.

Note characters follow the spec: 0 empty, 1 tap, 2 hold head, 3 hold or roll tail, 4 roll head, M mine. Column order is Left, Down, Up, Right. Measures are comma-delimited, each four beats subdivided evenly by its row count up to 192 rows. #OFFSET is written as the negative of the first-beat offset, matching StepMania where a negative offset means the audio leads in before beat 0.

meta may set title, artist, author, music, and musicExt. Drop the audio into the song folder named to match #MUSIC.

Native package

toPackage(record, opts?) writes a JSON envelope for full-fidelity round trips including edits. parsePackage(json) reads it back. Audio rides along as a base64 data URL when opts.audio is supplied, or is left out for a metadata-only package. This is the format that preserves everything the browser library record holds.