"""MusicXML input interface."""
import xml.etree.ElementTree as ET
from collections import OrderedDict
from functools import reduce
from operator import attrgetter
from pathlib import Path
from typing import Dict, List, Optional, Tuple, TypeVar, Union
from xml.etree.ElementTree import Element
from zipfile import ZipFile
import numpy as np
from ..classes import (
Beat,
KeySignature,
Lyric,
Metadata,
Note,
Tempo,
TimeSignature,
Track,
)
from ..music import DEFAULT_RESOLUTION, Music
from ..utils import CIRCLE_OF_FIFTHS, MODE_CENTERS, NOTE_MAP, NOTE_TYPE_MAP
T = TypeVar("T")
[docs]class MusicXMLError(Exception):
"""An error class for MusicXML related exceptions."""
def _gcd(a: int, b: int) -> int:
"""Return greatest common divisor using Euclid's Algorithm.
Code copied from https://stackoverflow.com/a/147539.
"""
while b:
a, b = b, a % b
return a
def _lcm_two_args(a: int, b: int) -> int:
"""Return least common multiple.
Code copied from https://stackoverflow.com/a/147539.
"""
return a * b // _gcd(a, b)
def _lcm(*args: int) -> int:
"""Return lcm of args.
Code copied from https://stackoverflow.com/a/147539.
"""
return reduce(_lcm_two_args, args) # type: ignore
def _get_text(
element: Element,
path: str,
default: T = None,
remove_newlines: bool = False,
) -> Union[str, T]:
"""Return the text of the first matching element."""
elem = element.find(path)
if elem is not None and elem.text is not None:
if remove_newlines:
return " ".join(elem.text.splitlines())
return elem.text
return default # type: ignore
def _get_required(element: Element, path: str) -> Element:
"""Return a required element; raise ValueError if not found."""
elem = element.find(path)
if elem is None:
raise MusicXMLError(
f"Element `{path}` is required for an '{element.tag}' element."
)
return elem
def _get_required_attr(element: Element, attr: str) -> str:
"""Return a required attribute; raise MusicXMLError if not found."""
attribute = element.get(attr)
if attribute is None:
raise MusicXMLError(
f"Attribute '{attr}' is required for an '{element.tag}' element."
)
return attribute
def _get_required_text(
element: Element, path: str, remove_newlines: bool = False
) -> str:
"""Return a required text; raise MusicXMLError if not found."""
elem = _get_required(element, path)
if elem.text is None:
raise MusicXMLError(
f"Text content '{path}' of an element '{element.tag}' must not be "
"empty."
)
if remove_newlines:
return " ".join(elem.text.splitlines())
return elem.text
def parse_metronome_elem(elem: Element) -> Optional[float]:
"""Return a qpm value parsed from a metronome element."""
beat_unit = _get_text(elem, "beat-unit")
if beat_unit is not None:
per_minute = _get_text(elem, "per-minute")
if per_minute is not None and beat_unit in NOTE_TYPE_MAP:
qpm = NOTE_TYPE_MAP[beat_unit] * float(per_minute)
if elem.find("beat-unit-dot") is not None:
qpm *= 1.5
return qpm
return None
def parse_key_elem(elem: Element) -> Tuple[int, str, int, str]:
"""Return the key parsed from a key element."""
mode = _get_text(elem, "mode", "major")
fifths = int(_get_required_text(elem, "fifths"))
if mode is None:
return None, None, fifths, None
idx = MODE_CENTERS[mode] + fifths
if idx < 0 or idx > 20:
return None, mode, fifths, None # type: ignore
root, root_str = CIRCLE_OF_FIFTHS[MODE_CENTERS[mode] + fifths]
return root, mode, fifths, root_str
def parse_time_elem(elem: Element) -> Tuple[int, int]:
"""Return the numerator and denominator of a time element."""
# Numerator
beats = _get_required_text(elem, "beats")
if "+" in beats:
numerator = sum(int(beat) for beat in beats.split("+"))
else:
numerator = int(beats)
# Denominator
beat_type = _get_required_text(elem, "beat-type")
if "+" in beat_type:
raise RuntimeError(
"Compound time signatures with separate fractions "
"are not supported."
)
denominator = int(beat_type)
return numerator, denominator
def parse_pitch_elem(elem: Element) -> Tuple[int, str]:
"""Return the pitch and pitch_str of a pitch element."""
step = _get_required_text(elem, "step")
octave = int(_get_required_text(elem, "octave"))
alter = int(_get_text(elem, "alter", 0))
pitch = 12 * (octave + 1) + NOTE_MAP[step] + alter
if alter > 0:
pitch_str = step + "#" * alter + str(octave)
elif alter < 0:
pitch_str = step + "b" * (-alter) + str(octave)
else:
pitch_str = step + str(octave)
return pitch, pitch_str
def parse_unpitched_elem(elem: Element) -> Tuple[int, str]:
"""Return the pitch and pitch_str of an unpitched element."""
step = _get_required_text(elem, "display-step")
octave = int(_get_required_text(elem, "display-octave"))
pitch = 12 * (octave + 1) + NOTE_MAP[step]
pitch_str = step + str(octave)
return pitch, pitch_str
def parse_lyric_elem(elem: Element) -> str:
"""Return the lyric text parsed from a lyric element."""
text = _get_required_text(elem, "text")
syllabic_elem = elem.find("syllabic")
if syllabic_elem is not None:
if syllabic_elem.text == "begin":
text = f"{text} -"
elif syllabic_elem.text == "middle":
text = f"- {text} -"
elif syllabic_elem.text == "end":
text = f"- {text}"
return text
def get_measure_ordering(elem: Element) -> List[int]:
"""Return a list of measure indices parsed from a part element.
This function returns the ordering of measures, considering all
repeats and jumps.
"""
# Measure indices
measure_indices = []
# Repeats
last_repeat = 0
count_repeat = 1
count_ending = 1
# Coda, tocoda, dacapo, segno, dalsegno, fine
is_after_jump = False
is_dacapo = False
is_fine = False
is_dalsegno = False
is_segno = False
is_after_segno = False
is_tocoda = False
is_coda = False
is_after_coda = False
# Iterate over all elements
measure_idx = 0
measure_elems = list(elem.findall("measure"))
while measure_idx < len(measure_elems):
# Get the measure element
measure_elem = measure_elems[measure_idx]
# Handle segno
if is_dalsegno and not is_after_segno:
# Look for segno
for sound_elem in measure_elem.findall("sound"):
if sound_elem.get("segno") is not None:
is_segno = True
for sound_elem in measure_elem.findall("direction/sound"):
if sound_elem.get("segno") is not None:
is_segno = True
# Skip if it is not segno
if not is_segno:
measure_idx += 1
continue
is_after_segno = True
# Handle coda
if is_tocoda and not is_after_coda:
# Look for coda
for sound_elem in measure_elem.findall("sound"):
if sound_elem.get("coda") is not None:
is_coda = True
for sound_elem in measure_elem.findall("direction/sound"):
if sound_elem.get("coda") is not None:
is_coda = True
# Skip if it is not coda
if not is_coda:
measure_idx += 1
continue
is_after_coda = True
# Set the default next measure
next_measure_idx = measure_idx + 1
# Sound element
for sound_elem in measure_elem.findall("sound"):
if is_after_jump:
# Tocoda
if sound_elem.get("tocoda") is not None:
is_tocoda = True
# Fine
if sound_elem.get("fine") is not None:
is_fine = True
else:
# Dacapo
if sound_elem.get("dacapo") is not None:
is_dacapo = True
next_measure_idx = 0
# Daselgno
if sound_elem.get("dalsegno") is not None:
is_dalsegno = True
next_measure_idx = 0
# Sound elements under direction elements
for sound_elem in measure_elem.findall("direction/sound"):
if is_after_jump:
# Tocoda
if sound_elem.get("tocoda") is not None:
is_tocoda = True
# Fine
if sound_elem.get("fine") is not None:
is_fine = True
else:
# Dacapo
if sound_elem.get("dacapo") is not None:
is_dacapo = True
next_measure_idx = 0
# Daselgno
if sound_elem.get("dalsegno") is not None:
is_dalsegno = True
next_measure_idx = 0
# Break the loop if it is fine
if is_after_jump and is_fine:
measure_indices.append(measure_idx)
break
# Ending elements
ending_elem = measure_elem.find("barline/ending")
if ending_elem is not None:
ending_num_attr = _get_required_attr(ending_elem, "number")
ending_num = [int(num) for num in ending_num_attr.split(",")]
# Skip the current measure if not the correct ending
if count_ending not in ending_num:
measure_idx += 1
continue
# Repeat elements
repeat_elem = measure_elem.find("barline/repeat")
if repeat_elem is not None:
direction = _get_required_attr(repeat_elem, "direction")
if direction == "forward":
last_repeat = measure_idx
elif direction == "backward":
# Get after-jump infomation
after_jump_attr = repeat_elem.get("after-jump")
if after_jump_attr is None or after_jump_attr == "no":
after_jump = False
else:
after_jump = True
if not is_after_jump or (is_after_jump and after_jump):
# Get repeat-times infomation
repeat_times_attr = repeat_elem.get("times")
if repeat_times_attr is None:
repeat_times = 2
else:
repeat_times = int(repeat_times_attr)
# Check if repeat times has reached
if count_repeat < repeat_times:
count_repeat += 1
count_ending += 1
next_measure_idx = last_repeat
else:
count_repeat = 1
count_ending = 1
else:
raise MusicXMLError(
"Unknown direction for a `repeat` element : "
f"{direction}"
)
# Append the current measure index to the list to be return
measure_indices.append(measure_idx)
if not is_after_jump and (is_dacapo or is_dalsegno):
is_after_jump = True
measure_idx = next_measure_idx
return measure_indices
def get_beats(
downbeat_times: List[int],
time_signatures: List[TimeSignature],
resolution: int = DEFAULT_RESOLUTION,
is_sorted: bool = False,
) -> List[Beat]:
"""Return beats given downbeat positions and time signatures.
Parameters
----------
downbeat_times : sequence of int
Positions of the downbeats.
time_signatures : sequence of :class:`muspy.TimeSignature`
Time signature objects.
resolution : int, default: `muspy.DEFAULT_RESOLUTION` (24)
Time steps per quarter note.
is_sorted : bool, default: False
Whether the downbeat times and time signatures are sorted.
Returns
-------
list of :class:`muspy.Beat`
Computed beats.
"""
# Return a list of downbeats if no time signatures is given
if not time_signatures:
return [
Beat(time=int(round(time)), is_downbeat=True)
for time in downbeat_times
]
# Sort the downbeats and time signatures if necessary
if not is_sorted:
downbeat_times = sorted(downbeat_times)
time_signatures = sorted(time_signatures, key=attrgetter("time"))
# Compute the beats
beats: List[Beat] = []
sign_idx = 0
downbeat_idx = 0
while downbeat_idx < len(downbeat_times):
# Select the correct time signatures
if (
sign_idx + 1 < len(time_signatures)
and downbeat_times[downbeat_idx]
< time_signatures[sign_idx + 1].time
):
sign_idx += 1
continue
# Set time signature
time_sign = time_signatures[sign_idx]
beat_resolution = resolution / (time_sign.denominator / 4)
# Get the next downbeat
if downbeat_idx < len(downbeat_times) - 1:
end: float = downbeat_times[downbeat_idx + 1]
else:
end = (
downbeat_times[downbeat_idx]
+ beat_resolution * time_sign.numerator
)
# Append the downbeat
start = int(round(downbeat_times[downbeat_idx]))
beats.append(Beat(time=start, is_downbeat=True))
# Append beats
beat_times = np.arange(start + beat_resolution, end, beat_resolution)
for time in beat_times:
beats.append(Beat(time=int(round(time)), is_downbeat=False))
downbeat_idx += 1
return beats
def parse_meta_part_elem(
part_elem: Element, resolution: int, measure_indices: List[int]
) -> Tuple[List[Tempo], List[KeySignature], List[TimeSignature], List[Beat]]:
"""Return data parsed from a meta part element.
This function only parses the tempos, key and time signatures. Use
`parse_part_elem` to parse the notes and lyrics.
"""
# Initialize lists
tempos: List[Tempo] = []
key_signatures: List[KeySignature] = []
time_signatures: List[TimeSignature] = []
# Initialize variables
time = 0
division = 1
downbeat_times: List[int] = []
# Iterate over all elements
measure_elems = list(part_elem.findall("measure"))
for measure_idx in measure_indices:
# Get the measure element
measure_elem = measure_elems[measure_idx]
# Collect the measure start times
downbeat_times.append(time)
# Initialize position
position = 0
last_note_position = None
# Iterating over all elements in the current measure
for elem in measure_elem:
# Attributes elements
if elem.tag == "attributes":
# Division elements
division_elem = elem.find("divisions")
if (
division_elem is not None
and division_elem.text is not None
):
division = int(division_elem.text)
# Key elements
key_elem = elem.find("key")
if key_elem is not None:
root, mode, fifths, root_str = parse_key_elem(key_elem)
key_signatures.append(
KeySignature(
time=time + position,
root=root,
mode=mode,
fifths=fifths,
root_str=root_str,
)
)
# Time signatures
time_elem = elem.find("time")
if time_elem is not None:
numerator, denominator = parse_time_elem(time_elem)
time_signatures.append(
TimeSignature(
time=time + position,
numerator=numerator,
denominator=denominator,
)
)
# Sound element
elif elem.tag == "sound":
# Tempo elements
tempo = elem.get("tempo")
if tempo is not None:
tempos.append(Tempo(time + position, float(tempo)))
# Direction elements
elif elem.tag == "direction":
# TODO: Handle textual tempo markings
tempo_set = False
# Sound elements
sound_elem_ = elem.find("sound")
if sound_elem_ is not None:
# Tempo directions
tempo = sound_elem_.get("tempo")
if tempo is not None:
tempos.append(
Tempo(time=time + position, qpm=float(tempo))
)
tempo_set = True
# Metronome elements
if not tempo_set:
metronome_elem = elem.find("direction-type/metronome")
if metronome_elem is not None:
qpm = parse_metronome_elem(metronome_elem)
if qpm is not None:
tempos.append(Tempo(time=time + position, qpm=qpm))
# Note elements
elif elem.tag == "note":
# TODO: Handle voice information
# Rest elements
rest_elem = elem.find("rest")
if rest_elem is not None:
# Move time position forward if it is a rest
duration = int(_get_required_text(elem, "duration"))
position += round(duration * resolution / division)
continue
# Cue notes
if elem.find("cue") is not None:
continue
# Chord elements
if elem.find("chord") is not None:
# Move time position backward if it is in a chord
if last_note_position is not None:
position = last_note_position
# Grace notes
grace_elem = elem.find("grace")
if grace_elem is not None:
continue
# Get duration
# TODO: Should we look for a duration or type element?
duration = int(_get_required_text(elem, "duration"))
# Move time position forward if it is not in chord
last_note_position = position
position += round(duration * resolution / division)
# Forward elements
elif elem.tag == "forward":
duration = int(_get_required_text(elem, "duration"))
position += round(duration * resolution / division)
# Backup elements
elif elem.tag == "backup":
duration = int(_get_required_text(elem, "duration"))
position -= round(duration * resolution / division)
time += position
# Sort tempos, key and time signatures
tempos.sort(key=attrgetter("time"))
key_signatures.sort(key=attrgetter("time"))
time_signatures.sort(key=attrgetter("time"))
# Get the beats
beats = get_beats(
downbeat_times, time_signatures, resolution, is_sorted=True
)
return tempos, key_signatures, time_signatures, beats
def parse_part_elem(
part_elem: Element,
resolution: int,
instrument_info: dict,
measure_indices: List[int],
) -> Tuple[Dict[str, List[Note]], List[Lyric]]:
"""Return notes and lyrics parsed from a part element.
This function only parses the notes and lyrics. Use
`parse_meta_part_elem` to parse the tempos, key and time signatures.
"""
# Initialize lists
notes: Dict[str, List[Note]] = {
instrument_id: [] for instrument_id in instrument_info
}
lyrics: List[Lyric] = []
# Initialize variables
time = 0
velocity = 64
division = 1
default_instrument_id = next(iter(instrument_info))
transpose_semitone = 0
transpose_octave = 0
# Create a dictionary to handle ties
ties: Dict[Tuple[str, int], int] = {}
# Iterate over all elements
measure_elems = list(part_elem.findall("measure"))
for measure_idx in measure_indices:
# Get the measure element
measure_elem = measure_elems[measure_idx]
# Initialize position
position = 0
last_note_position = None
# Iterating over all elements in the current measure
for elem in measure_elem:
# Attributes elements
if elem.tag == "attributes":
# Division elements
division_elem = elem.find("divisions")
if (
division_elem is not None
and division_elem.text is not None
):
division = int(division_elem.text)
# Transpose elements
transpose_elem = elem.find("transpose")
if transpose_elem is not None:
transpose_semitone = int(
_get_required_text(transpose_elem, "chromatic")
)
octave_change = _get_text(transpose_elem, "octave-change")
if octave_change is not None:
transpose_octave = int(octave_change)
# Sound element
elif elem.tag == "sound":
# Dynamics elements
dynamics = elem.get("dynamics")
if dynamics is not None:
velocity = round(float(dynamics))
# Direction elements
elif elem.tag == "direction":
# TODO: Handle textual dynamic markings
# Sound elements
sound_elem_ = elem.find("sound")
if sound_elem_ is not None:
# Dynamic directions
dynamics = sound_elem_.get("dynamics")
if dynamics is not None:
velocity = round(float(dynamics))
# Note elements
elif elem.tag == "note":
# TODO: Handle voice information
# Rest elements
rest_elem = elem.find("rest")
if rest_elem is not None:
# Move time position forward if it is a rest
duration = int(_get_required_text(elem, "duration"))
position += round(duration * resolution / division)
continue
# Cue notes
if elem.find("cue") is not None:
continue
# Chord elements
if elem.find("chord") is not None:
# Move time position backward if it is in a chord
if last_note_position is not None:
position = last_note_position
# Get pitch number and string
unpitched_elem = elem.find("unpitched")
if unpitched_elem is not None:
# Unpitched notes
pitch, pitch_str = parse_unpitched_elem(unpitched_elem)
else:
# Normal pitches
pitch, pitch_str = parse_pitch_elem(
_get_required(elem, "pitch")
)
pitch += 12 * transpose_octave + transpose_semitone
# Get instrument information
instrument_elem = elem.find("instrument")
if instrument_elem is not None:
instrument_id = _get_required_text(instrument_elem, "id")
if instrument_id not in instrument_info:
raise MusicXMLError(
"ID of an 'instrument' element must be predefined "
"in a 'score-instrument' element."
)
else:
instrument_id = default_instrument_id
# Grace notes
grace_elem = elem.find("grace")
if grace_elem is not None:
note_type = _get_required_text(elem, "type")
notes[instrument_id].append(
Note(
time=time + position,
pitch=pitch,
duration=round(
NOTE_TYPE_MAP[note_type] * resolution
),
velocity=velocity,
pitch_str=pitch_str,
)
)
continue
# Get duration
# TODO: Should we look for a duration or type element?
duration = int(_get_required_text(elem, "duration"))
# Check if it is a tied note
# TODO: Should we look for a tie or tied element?
is_outgoing_tie = False
for tie_elem in elem.findall("tie"):
if tie_elem.get("type") == "start":
is_outgoing_tie = True
# Check if it is an incoming tied note
note_key = (instrument_id, pitch)
if note_key in ties:
note_idx = ties[note_key]
notes[instrument_id][note_idx].duration += round(
duration * resolution / division
)
if is_outgoing_tie:
ties[note_key] = note_idx
else:
del ties[note_key]
else:
# Create a new note and append it to the note list
notes[instrument_id].append(
Note(
time=time + position,
pitch=pitch,
duration=round(duration * resolution / division),
velocity=velocity,
pitch_str=pitch_str,
)
)
if is_outgoing_tie:
ties[note_key] = len(notes[instrument_id]) - 1
# Lyrics
lyric_elem = elem.find("lyric")
if lyric_elem is not None:
lyric_text = parse_lyric_elem(lyric_elem)
lyrics.append(
Lyric(time=time + position, lyric=lyric_text)
)
# Move time position forward if it is not in chord
last_note_position = position
position += round(duration * resolution / division)
# Forward elements
elif elem.tag == "forward":
duration = int(_get_required_text(elem, "duration"))
position += round(duration * resolution / division)
# Backup elements
elif elem.tag == "backup":
duration = int(_get_required_text(elem, "duration"))
position -= round(duration * resolution / division)
time += position
# Sort notes
for instrument_notes in notes.values():
instrument_notes.sort(
key=attrgetter("time", "pitch", "duration", "velocity")
)
# Sort lyrics
lyrics.sort(key=attrgetter("time"))
return notes, lyrics
def parse_metadata(root: Element) -> Metadata:
"""Return a Metadata object parsed from a MusicXML file."""
# Title is usually stored in movement-title. See
# https://www.musicxml.com/tutorial/file-structure/score-header-entity/
title = _get_text(root, "movement-title", remove_newlines=True)
if not title:
title = _get_text(root, "work/work-title", remove_newlines=True)
# Creators and copyrights
creators = []
copyrights = []
identification_elem = root.find("identification")
if identification_elem is not None:
for creator_elem in identification_elem.findall("creator"):
if creator_elem.text:
creators.append(creator_elem.text)
for right_elem in identification_elem.findall("rights"):
if right_elem.text:
copyrights.append(right_elem.text)
return Metadata(
title=title,
creators=creators,
copyright=" ".join(copyrights) if copyrights else None,
source_format="musicxml",
)
def _get_root(path: Union[str, Path], compressed: bool = None):
"""Return the root of the element tree."""
if compressed is None:
compressed = str(path).endswith(".mxl")
if not compressed:
tree = ET.parse(str(path))
return tree.getroot()
# Find out the main MusicXML file in the compressed ZIP archive
# according to the official tutorial (see
# https://www.musicxml.com/tutorial/compressed-mxl-files/).
zip_file = ZipFile(str(path))
if "META-INF/container.xml" not in zip_file.namelist():
raise MusicXMLError("Container file ('container.xml') not found.")
container = ET.fromstring(zip_file.read("META-INF/container.xml"))
rootfile = container.find("rootfiles/rootfile")
if rootfile is None:
raise MusicXMLError(
"Element 'rootfile' tag not found in the container file "
"('container.xml')."
)
filename = _get_required_attr(rootfile, "full-path")
return ET.fromstring(zip_file.read(filename))
def _get_divisions(root: Element):
"""Return a list of divisions."""
divisions = []
for division_elem in root.findall("part/measure/attributes/divisions"):
if division_elem.text is None:
continue
if not float(division_elem.text).is_integer():
raise MusicXMLError(
"Noninteger 'division' values are not supported."
)
divisions.append(int(division_elem.text))
return divisions
def parse_score_part_elem(elem: Element) -> Tuple[str, OrderedDict]:
"""Return part information parsed from a score part element."""
# Part ID
part_id = _get_required_attr(elem, "id")
# Part name
part_name = _get_text(elem, "part-name", remove_newlines=True)
# Instruments
part_info: OrderedDict = OrderedDict()
for score_instrument_elem in elem.findall("score-instrument"):
instrument_id = _get_required_attr(score_instrument_elem, "id")
part_info[instrument_id] = OrderedDict()
part_info[instrument_id]["name"] = _get_text(
score_instrument_elem,
"instrument-name",
part_name,
remove_newlines=True,
)
for midi_instrument_elem in elem.findall("midi-instrument"):
instrument_id = _get_required_attr(midi_instrument_elem, "id")
if instrument_id not in part_info:
if instrument_id == part_id:
instrument_id = ""
part_info[""] = {"name": part_name}
else:
raise MusicXMLError(
"ID of a 'midi-instrument' element must be predefined "
"in a 'score-instrument' element."
)
part_info[instrument_id]["program"] = int(
_get_text(midi_instrument_elem, "midi-program", 0)
)
part_info[instrument_id]["is_drum"] = (
int(_get_text(midi_instrument_elem, "midi-channel", 0)) == 10
)
if not part_info:
part_info[""] = {"name": part_name}
for value in part_info.values():
if "program" not in value:
value["program"] = 0
if "is_drum" not in value:
value["is_drum"] = False
return part_id, part_info
[docs]def read_musicxml(
path: Union[str, Path], resolution: int = None, compressed: bool = None
) -> Music:
"""Read a MusicXML file into a Music object.
Parameters
----------
path : str or Path
Path to the MusicXML file to read.
resolution : int, optional
Time steps per quarter note. Defaults to the least common
multiple of all divisions.
compressed : bool, optional
Whether it is a compressed MusicXML file. Defaults to infer
from the filename.
Returns
-------
:class:`muspy.Music`
Converted Music object.
"""
# Get element tree root
root = _get_root(path, compressed)
if root.tag == "score-timewise":
raise ValueError("MusicXML file with timewise type is not supported.")
# Meta data
metadata = parse_metadata(root)
metadata.source_filename = Path(path).name
# Set resolution to the least common multiple of all divisions
if resolution is None:
divisions = _get_divisions(root)
resolution = _lcm(*divisions) if divisions else 1
# Part information
part_info: OrderedDict = OrderedDict()
for part_elem in root.findall("part-list/score-part"):
part_id, info = parse_score_part_elem(part_elem)
part_info[part_id] = info
# Get the meta staff, assuming the first staff
meta_part_elem = root.find("part")
# Return empty music object with metadata if no staff is found
if meta_part_elem is None:
return Music(metadata=metadata, resolution=resolution)
# Parse measure ordering from the meta part, expanding all repeats
# and jumps
measure_indices = get_measure_ordering(meta_part_elem)
# Parse the meta part element
tempos, key_signatures, time_signatures, beats = parse_meta_part_elem(
meta_part_elem, resolution, measure_indices
)
# Initialize lists
tracks: List[Track] = []
# Raise an error if part-list information is missing for a
# multi-part piece
if not part_info:
if len(root.findall("part")) > 1:
raise MusicXMLError(
"Part-list information is required for a multi-part piece."
)
part_elem = _get_required(root, "part")
instrument_info = {"": {"program": 0, "is_drum": False}}
notes, lyrics = parse_part_elem(
part_elem, resolution, instrument_info, measure_indices
)
tracks.append(
Track(program=0, is_drum=False, notes=notes[""], lyrics=lyrics)
)
else:
# Iterate over all parts and measures
for part_elem in root.findall("part"):
part_id = part_elem.get("id")
if part_id is None:
if len(root.findall("part")) > 1:
continue
part_id = next(iter(part_info))
if part_id not in part_info:
continue
# Parse part
notes, lyrics = parse_part_elem(
part_elem, resolution, part_info[part_id], measure_indices
)
# Extend lists
for instrument_id, instrument_notes in notes.items():
track = Track(
program=part_info[part_id][instrument_id]["program"],
is_drum=part_info[part_id][instrument_id]["is_drum"],
name=part_info[part_id][instrument_id]["name"],
notes=instrument_notes,
lyrics=lyrics,
)
tracks.append(track)
# Make sure everything is sorted
tempos.sort(key=attrgetter("time"))
key_signatures.sort(key=attrgetter("time"))
time_signatures.sort(key=attrgetter("time"))
for track in tracks:
track.notes.sort(
key=attrgetter("time", "pitch", "duration", "velocity")
)
track.lyrics.sort(key=attrgetter("time"))
return Music(
metadata=metadata,
resolution=resolution,
tempos=tempos,
key_signatures=key_signatures,
time_signatures=time_signatures,
beats=beats,
tracks=tracks,
)