283 lines
10 KiB
Python
283 lines
10 KiB
Python
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# Copyright 2016 Google Inc. All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""A read_only pretty_midi-like wrapper for music21 score objects.
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It exposes a small set of score attrbutes from music21, mostly chosen to
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support magenta.protobuf.NoteSequence.
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"""
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from collections import namedtuple
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import hashlib
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# internal imports
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import music21
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# Default qpm if tempo mark not available.
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_DEFAULT_QPM = 120
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TimeSignature = namedtuple('TimeSignature',
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['time', 'numerator', 'denominator'])
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Tempo = namedtuple('Tempo', ['time', 'qpm'])
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KeySignature = namedtuple('KeySignature', ['time', 'key', 'num_sharps', 'mode',
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'tonic_pitchclass'])
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PartInfo = namedtuple('PartInfo', ['index', 'name'])
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# TODO(annahuang): Add octave.
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Note = namedtuple('Note', ['pitch_midi', 'pitch_name', 'start_time', 'end_time',
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'part_index'])
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class PrettyMusic21Error(Exception):
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"""Exception for music attributes violating what PrettyMusic21 supports."""
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pass
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def _extract_key_signature_attributes(key_signature):
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"""Extracts attributes of key signatures from music21.key.KeySignature.
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Args:
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key_signature: A music21.key.KeySignature object.
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Returns:
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tonic_pitch_name: A string that specifies the pitch name of the tonic in the
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key extracted from key_signature.
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key_signature.sharps: An integer specifying the nubmer of sharps in this
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key signature.
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mode: A string giving the mode, usually 'major' or 'minor'
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Raises:
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TypeError: When key_signature is not of the expected type
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music21.key.KeySignature.
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PrettyMusic21Error: When the number of sharps in key_signature is out of
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the expected range.
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AttributeError: When key_signature does not have the mode attribute.
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"""
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if not isinstance(key_signature, music21.key.KeySignature):
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raise TypeError(
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'Type Music21.key.KeySignature expected but %s type received.' %
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(type(key_signature)))
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if key_signature.sharps < -7 or key_signature.sharps > 7:
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raise PrettyMusic21Error(
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'Key Signatures with more than 7 sharps are flats are not supported.')
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try:
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mode = key_signature.mode
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except AttributeError:
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mode = None
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if mode is not None and mode.lower() == 'minor':
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# To convert a major key to its relative minor, plus 3 to the number of
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# sharps and get the corresponding major key pitch name.
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# For example, 3 flats (-3) is Eb major, or c minor. While -3 + 3 is C.
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tonic_pitch = music21.key.sharpsToPitch(key_signature.sharps + 3)
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else:
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# Assume to be major.
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tonic_pitch = music21.key.sharpsToPitch(key_signature.sharps)
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tonic_pitch_name = tonic_pitch.name.replace('-', 'b')
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if mode is not None and mode.lower() == 'minor':
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tonic_pitch_name = tonic_pitch_name.lower()
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return tonic_pitch_name, key_signature.sharps, mode, tonic_pitch.pitchClass
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class PrettyMusic21(object):
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"""A read_only pretty_midi-like wrapper for music21 score objects.
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Args:
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score: A PrettyMusic21 object.
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filename: A string for the source filename from which the score was
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extracted.
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"""
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# TODO(annahuang): Should raise an error when parts don't share same markings.
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# (time sig, key sig, tempo, etc),
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# as note sequence proto assumes these are the same for all parts.
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# To do this, we can loop through the top voice, and get the measures
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# for where the a marking changes
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# and then check to make sure all the other voices have the same change.
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# TODO(annahuang): Add performance time.
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# Time currently is symbolic, and does not take tempo markings into account.
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# Look at: http://web.mit.edu/music21/doc/moduleReference/moduleBase.html
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# #music21.base.Music21Object.seconds
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# Search Stream.metronomeMarkBoundaries(srcObj=None)
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# in http://web.mit.edu/music21/doc/moduleReference/moduleStream.html
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def __init__(self, score, filename=None):
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self._score = score
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self._parts = [part.semiFlat for part in score.parts]
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self._filename = filename
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@property
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def id(self):
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"""Uses a hash of the score string as id."""
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# TODO(annahuang): Check why the hash is not the same for scores created
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# from the same file.
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converter = music21.converter.subConverters.ConverterText()
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return hashlib.sha1(str(converter.write(self._score, None)))
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@property
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def title(self):
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"""Returns the title of the score if available."""
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if self._score.metadata is not None:
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return self._score.metadata.title
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return self._filename
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@property
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def composer(self):
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"""Returns the composer of the score if available."""
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if self._score.metadata is not None:
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return self._score.metadata.composer
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return None
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@property
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def filename(self):
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return self._filename
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@property
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def total_time(self):
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"""Returns the total quarterLength duration of the score."""
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return self._convert_time(self._score.duration.quarterLength)
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@property
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def time_signature_changes(self):
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"""Collects unique time signature changes, and add pick-up when necessary.
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Returns:
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A list of unique TimeSignature namedtuples, sorted by the time attribute.
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Raises:
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PrettyMusic21Error: When a time signature is not within a measure
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container.
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"""
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# TODO(annahuang): Don't assume all voices have the same time signature.
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# Assumes time signatures are always embedded in a measure.
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time_sig_changes = set()
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for part in self._parts:
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for time_sig in part.getElementsByClass('TimeSignature'):
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measure = time_sig.getContextByClass('Measure')
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if measure is None:
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raise PrettyMusic21Error('Time signatures need to be in a measure.')
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global_time = self._convert_time(part.elementOffset(time_sig))
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if measure.duration.quarterLength < time_sig.barDuration.quarterLength:
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# First, add the pick-up time signature.
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pickup_time_sig = music21.meter.bestTimeSignature(measure)
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pickup_time_sig_change = TimeSignature(global_time,
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pickup_time_sig.numerator,
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pickup_time_sig.denominator)
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time_sig_changes.add(pickup_time_sig_change)
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global_time = self._convert_time(global_time +
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measure.duration.quarterLength)
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# Add the full time signature.
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full_time_sig_change = TimeSignature(global_time, time_sig.numerator,
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time_sig.denominator)
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time_sig_changes.add(full_time_sig_change)
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return sorted(time_sig_changes, key=lambda x: x.time)
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@property
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def tempo_changes(self):
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"""Collects unique tempo changes. If no tempo, defaults to _DEFAULT_QPM.
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Returns:
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A list of unique Tempo namedtuples, sorted by the time attribute.
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"""
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tempo_changes = set()
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for part in self._parts:
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for metronome_mark in part.getElementsByClass('MetronomeMark'):
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global_time = self._convert_time(part.elementOffset(metronome_mark))
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tempo_change = Tempo(global_time, metronome_mark.number)
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tempo_changes.add(tempo_change)
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if not tempo_changes:
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tempo_changes.add(Tempo(0, _DEFAULT_QPM))
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return sorted(tempo_changes, key=lambda x: x.time)
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@property
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def key_signature_changes(self):
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"""Collects unique key signature changes.
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Returns:
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A list of unique KeySignature namedtuples, sorted by the time attribute.
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"""
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key_sig_changes = set()
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for part in self._parts:
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for ks in part.getElementsByClass('KeySignature'):
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global_time = self._convert_time(part.elementOffset(ks))
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key_sig_change = KeySignature(global_time,
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*(_extract_key_signature_attributes(ks)))
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key_sig_changes.add(key_sig_change)
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return sorted(key_sig_changes, key=lambda x: x.time)
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@property
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def part_infos(self):
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"""Collects part information as global index in score and part name.
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Returns:
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A list of unique PartInfo namedtuples.
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"""
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parts_infos = []
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for part_num, part in enumerate(self._parts):
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index = part_num
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parts_info = PartInfo(index, part.id)
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parts_infos.append(parts_info)
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return parts_infos
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@property
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def parts(self):
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"""Collects all the notes, each part in a list.
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Returns:
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A list of lists of Note namedtuples.
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"""
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simple_parts = []
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for part_num, part in enumerate(self._parts):
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simple_part = []
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for music21_note in part.getElementsByClass('Note'):
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pitch_midi = music21_note.pitch.midi
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# TODO(annahuang): Add octave.
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pitch_name = music21_note.pitch.name.replace('-', 'b')
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# TODO(annahuang): Distinguish between symbolic and performance time.
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start_time = self._convert_time(part.elementOffset(music21_note))
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end_time = start_time + self._convert_time(
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music21_note.duration.quarterLength)
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part_index = part_num
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note = Note(pitch_midi, pitch_name, start_time, end_time, part_index)
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simple_part.append(note)
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# TODO(annahuang): Add note.numerator and note.denominator.
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simple_parts.append(simple_part)
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return simple_parts
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@property
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def sorted_notes(self):
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"""Sorts all the notes according to start_time time.
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Returns:
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A list of all Note namedtuples, sorted by start time.
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"""
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flatted_notes = []
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for part in self.parts:
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flatted_notes.extend(part)
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return sorted(flatted_notes, key=lambda x: x.start_time)
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def _convert_time(self, quarter_length):
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"""Transforms quarter-note counts into seconds according to _DEFAULT_QPM.
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Args:
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quarter_length: A float that specifies duration in quarter-note units.
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Returns:
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A float in seconds.
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"""
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# TODO(annahuang): Take tempo change into account.
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# Time is in quarter-note counts from the beginning of the score.
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return quarter_length * 60.0 / _DEFAULT_QPM
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