MusicXML Reader

MusicXML → ABC reader

The reader is the reverse direction: MusicXML → croma's Score → ABC (or re-emitted MusicXML). It inverts croma's own writer and reads foreign MusicXML dialects (abc2xml, MuseScore, Finale, Sibelius). It is a proven, un-gated capability and ships in the default CLI build.

croma read score.musicxml --format abc    # MusicXML -> ABC
croma read score.musicxml --format xml    # re-emit MusicXML (the writer's inverse)
croma read score.musicxml --format dump   # debug-print the reconstructed Score
croma musicxml2abc score.musicxml         # = read --format abc

Evidence

Gate	Result (10k corpus)
Self-loop XML re-emission (write_musicxml(read_musicxml(xml)))	9,935 / 9,935
Foreign-dialect parity vs music21	98.50%

The writer is the spec: the reader inverts croma's dialect exactly and never mirrors an abc2xml-ism. Foreign dialects are read gracefully (with diagnostics), never mimicked back into the writer.

Library vs CLI: where the dependency lives

The reader's only dependency is roxmltree, and it is opt-in:

• croma-core (library) — the reader is behind the musicxml-reader feature, so the default library build stays zero-dependency and crates.io-publishable. Enable it with cargo add croma-core --features musicxml-reader, then call read_musicxml(xml) -> ParseReport<Score> (Library-Usage#enabling-the-musicxml-reader).
• croma-cli (binary) — the reader is promoted (un-gated) and on by default, so roxmltree reaches the CLI binary. A cargo build -p croma-cli --no-default-features build omits the reader, the two subcommands, and the dependency.

Full reference

Reader coverage, the foreign-dialect policy, the ABC-projection completion pass (complete_score_for_abc), the reader → ABC structural round-trip (97.9%, 9,724 / 9,933 in-scope), and the adjudicated residual are documented in detail in docs/musicxml-reader.md.

See also: CLI-Usage · How-its-Proven · Conversion-Challenges (the lossy-intermediate round-trip cases and the deferred items).