io.musicxml

musicxml

MusicXML in and out: read a file into an OmkGraph holding one Score, and write a Score of a graph back out.

The reader records what the file asserts and nothing more (no derived chord durations, no bar lines the file does not have), tolerates what notation programs actually export (a pickup numbered 0, voices reused for unrelated fragments, held notes re-voiced across a bar line, wrong <syllabic> flags), and warns with an OmkWarning for every musical fact it cannot place. Presentation (layout, stems, beams, positions, fonts) is dropped silently. What the writer will need back and the model cannot hold goes in node.meta["musicxml"], which OMK itself never reads; reader documents the keys.

from openmusickit.io.musicxml import read, write
graph = read("score.mxl")
write(graph, "copy.musicxml")

The writer is the reader’s inverse, rule by rule: read(write(read(f))) is equivalent (OmkGraph.is_equivalent) to read(f), and a graph stripped of its bar grid and of the bar lines its meters imply writes the same document. It refuses only when there is no score to write, and warns for what it leaves out. read’s docstring shows a whole small document going in, write’s a small graph going out. Whether an export kept the music is compare(canonicalize(a), canonicalize(b)): canonical reduces two documents to what they say musically and lists the differences. The design, the mapping rule by rule, and what is deliberately left out are in _plans/musicxml.md.