def infer_dense_chords_for_sequence(
sequence, instrument=None, min_notes_per_chord=3):
"""Infers chords for a NoteSequence and adds them as TextAnnotations.
For each set of simultaneously-active notes in a NoteSequence (optionally for
only one instrument), infers a chord symbol and adds it to NoteSequence as a
TextAnnotation. Every change in the set of active notes will result in a new
chord symbol unless the new set is smaller than `min_notes_per_chord`.
If `sequence` is quantized, simultaneity will be determined by quantized steps
instead of time.
Not to be confused with the chord inference in magenta.music.chord_inference
that attempts to infer a more natural chord sequence with changes at regular
metric intervals.
Args:
sequence: The NoteSequence for which chords will be inferred. Will be
modified in place.
instrument: The instrument number whose notes will be used for chord
inference. If None, all instruments will be used.
min_notes_per_chord: The minimum number of simultaneous notes for which to
infer a chord.
Raises:
ChordSymbolException: If a chord cannot be determined for a set of
simultaneous notes in `sequence`.
"""
notes = [note for note in sequence.notes
if not note.is_drum and (instrument is None or
note.instrument == instrument)]
sorted_notes = sorted(notes, key=lambda note: note.start_time)
# If the sequence is quantized, use quantized steps instead of time.
if is_quantized_sequence(sequence):
note_start = lambda note: note.quantized_start_step
note_end = lambda note: note.quantized_end_step
else:
note_start = lambda note: note.start_time
note_end = lambda note: note.end_time
# Sort all note start and end events.
onsets = [(note_start(note), idx, False)
for idx, note in enumerate(sorted_notes)]
offsets = [(note_end(note), idx, True)
for idx, note in enumerate(sorted_notes)]
events = sorted(onsets + offsets)
current_time = 0
current_figure = constants.NO_CHORD
active_notes = set()
for time, idx, is_offset in events:
if time > current_time:
active_pitches = set(sorted_notes[idx].pitch for idx in active_notes)
if len(active_pitches) >= min_notes_per_chord:
# Infer a chord symbol for the active pitches.
figure = chord_symbols_lib.pitches_to_chord_symbol(active_pitches)
if figure != current_figure:
# Add a text annotation to the sequence.
text_annotation = sequence.text_annotations.add()
text_annotation.text = figure
text_annotation.annotation_type = CHORD_SYMBOL
if is_quantized_sequence(sequence):
text_annotation.time = (
current_time * sequence.quantization_info.steps_per_quarter)
text_annotation.quantized_step = current_time
else:
text_annotation.time = current_time
current_figure = figure
current_time = time
if is_offset:
active_notes.remove(idx)
else:
active_notes.add(idx)
assert not active_notes
def testPitchesToChordSymbol(self):
# Test basic triads.
figure = chord_symbols_lib.pitches_to_chord_symbol([60, 64, 67])
self.assertEqual('C', figure)
figure = chord_symbols_lib.pitches_to_chord_symbol([45, 48, 52])
self.assertEqual('Am', figure)
figure = chord_symbols_lib.pitches_to_chord_symbol([63, 66, 69])
self.assertEqual('Ebo', figure)
figure = chord_symbols_lib.pitches_to_chord_symbol([71, 75, 79])
self.assertEqual('B+', figure)
# Test basic inversions.
figure = chord_symbols_lib.pitches_to_chord_symbol([59, 62, 67])
self.assertEqual('G/B', figure)
figure = chord_symbols_lib.pitches_to_chord_symbol([65, 70, 73])
self.assertEqual('Bbm/F', figure)
# Test suspended chords.
figure = chord_symbols_lib.pitches_to_chord_symbol([62, 67, 69])
self.assertEqual('Dsus', figure)
figure = chord_symbols_lib.pitches_to_chord_symbol([55, 60, 62, 65])
self.assertEqual('Gsus7', figure)
figure = chord_symbols_lib.pitches_to_chord_symbol([67, 69, 74])
self.assertEqual('Gsus2', figure)
# Test more complex chords.
figure = chord_symbols_lib.pitches_to_chord_symbol([45, 46, 50, 53])
self.assertEqual('Bbmaj7/A', figure)
figure = chord_symbols_lib.pitches_to_chord_symbol(
[63, 67, 70, 72, 74])
self.assertEqual('Cm9/Eb', figure)
figure = chord_symbols_lib.pitches_to_chord_symbol(
[53, 60, 64, 67, 70])
self.assertEqual('C7/F', figure)
# Test chords with modifications.
figure = chord_symbols_lib.pitches_to_chord_symbol(
[67, 71, 72, 74, 77])
self.assertEqual('G7(add4)', figure)
figure = chord_symbols_lib.pitches_to_chord_symbol(
[64, 68, 71, 74, 79])
self.assertEqual('E7(#9)', figure)
figure = chord_symbols_lib.pitches_to_chord_symbol([60, 62, 64, 67])
self.assertEqual('C(add2)', figure)
figure = chord_symbols_lib.pitches_to_chord_symbol(
[60, 64, 68, 70, 75])
self.assertEqual('C+7(#9)', figure)
# Test invalid chord.
with self.assertRaises(chord_symbols_lib.ChordSymbolError):
chord_symbols_lib.pitches_to_chord_symbol(
[60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71])
def infer_chords_for_sequence(sequence,
instrument=None,
min_notes_per_chord=3):
"""Infers chords for a NoteSequence and adds them as TextAnnotations.
For each set of simultaneously-active notes in a NoteSequence (optionally for
only one instrument), infers a chord symbol and adds it to NoteSequence as a
TextAnnotation. Every change in the set of active notes will result in a new
chord symbol unless the new set is smaller than `min_notes_per_chord`.
If `sequence` is quantized, simultaneity will be determined by quantized steps
instead of time.
Args:
sequence: The NoteSequence for which chords will be inferred. Will be
modified in place.
instrument: The instrument number whose notes will be used for chord
inference. If None, all instruments will be used.
min_notes_per_chord: The minimum number of simultaneous notes for which to
infer a chord.
Raises:
ChordSymbolException: If a chord cannot be determined for a set of
simultaneous notes in `sequence`.
"""
notes = [
note for note in sequence.notes if not note.is_drum and (
instrument is None or note.instrument == instrument)
]
sorted_notes = sorted(notes, key=lambda note: note.start_time)
# If the sequence is quantized, use quantized steps instead of time.
if is_quantized_sequence(sequence):
note_start = lambda note: note.quantized_start_step
note_end = lambda note: note.quantized_end_step
else:
note_start = lambda note: note.start_time
note_end = lambda note: note.end_time
# Sort all note start and end events.
onsets = [(note_start(note), idx, False)
for idx, note in enumerate(sorted_notes)]
offsets = [(note_end(note), idx, True)
for idx, note in enumerate(sorted_notes)]
events = sorted(onsets + offsets)
current_time = 0
current_figure = constants.NO_CHORD
active_notes = set()
for time, idx, is_offset in events:
if time > current_time:
active_pitches = set(sorted_notes[idx].pitch
for idx in active_notes)
if len(active_pitches) >= min_notes_per_chord:
# Infer a chord symbol for the active pitches.
figure = chord_symbols_lib.pitches_to_chord_symbol(
active_pitches)
if figure != current_figure:
# Add a text annotation to the sequence.
text_annotation = sequence.text_annotations.add()
text_annotation.text = figure
text_annotation.annotation_type = CHORD_SYMBOL
if is_quantized_sequence(sequence):
text_annotation.time = (
current_time *
sequence.quantization_info.steps_per_quarter)
text_annotation.quantized_step = current_time
else:
text_annotation.time = current_time
current_figure = figure
current_time = time
if is_offset:
active_notes.remove(idx)
else:
active_notes.add(idx)
assert not active_notes
def testPitchesToChordSymbol(self):
# Test basic triads.
figure = chord_symbols_lib.pitches_to_chord_symbol(
[60, 64, 67])
self.assertEqual('C', figure)
figure = chord_symbols_lib.pitches_to_chord_symbol(
[45, 48, 52])
self.assertEqual('Am', figure)
figure = chord_symbols_lib.pitches_to_chord_symbol(
[63, 66, 69])
self.assertEqual('Ebo', figure)
figure = chord_symbols_lib.pitches_to_chord_symbol(
[71, 75, 79])
self.assertEqual('B+', figure)
# Test basic inversions.
figure = chord_symbols_lib.pitches_to_chord_symbol(
[59, 62, 67])
self.assertEqual('G/B', figure)
figure = chord_symbols_lib.pitches_to_chord_symbol(
[65, 70, 73])
self.assertEqual('Bbm/F', figure)
# Test suspended chords.
figure = chord_symbols_lib.pitches_to_chord_symbol(
[62, 67, 69])
self.assertEqual('Dsus', figure)
figure = chord_symbols_lib.pitches_to_chord_symbol(
[55, 60, 62, 65])
self.assertEqual('Gsus7', figure)
figure = chord_symbols_lib.pitches_to_chord_symbol(
[67, 69, 74])
self.assertEqual('Gsus2', figure)
# Test more complex chords.
figure = chord_symbols_lib.pitches_to_chord_symbol(
[45, 46, 50, 53])
self.assertEqual('Bbmaj7/A', figure)
figure = chord_symbols_lib.pitches_to_chord_symbol(
[63, 67, 70, 72, 74])
self.assertEqual('Cm9/Eb', figure)
figure = chord_symbols_lib.pitches_to_chord_symbol(
[53, 60, 64, 67, 70])
self.assertEqual('C7/F', figure)
# Test chords with modifications.
figure = chord_symbols_lib.pitches_to_chord_symbol(
[67, 71, 72, 74, 77])
self.assertEqual('G7(add4)', figure)
figure = chord_symbols_lib.pitches_to_chord_symbol(
[64, 68, 71, 74, 79])
self.assertEqual('E7(#9)', figure)
figure = chord_symbols_lib.pitches_to_chord_symbol(
[60, 62, 64, 67])
self.assertEqual('C(add2)', figure)
figure = chord_symbols_lib.pitches_to_chord_symbol(
[60, 64, 68, 70, 75])
self.assertEqual('C+7(#9)', figure)
# Test invalid chord.
with self.assertRaises(chord_symbols_lib.ChordSymbolException):
chord_symbols_lib.pitches_to_chord_symbol(
[60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71])