Module note_seq.melody_encoder_decoder
Classes for converting between Melody objects and models inputs/outputs.
MelodyOneHotEncoding is an encoder_decoder.OneHotEncoding that specifies a one- hot encoding for Melody events, i.e. MIDI pitch values plus note-off and no- event.
KeyMelodyEncoderDecoder is an encoder_decoder.EventSequenceEncoderDecoder that specifies an encoding of Melody objects into input vectors and output labels for use by melody models.
Expand source code
# Copyright 2021 The Magenta Authors.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Classes for converting between Melody objects and models inputs/outputs.
MelodyOneHotEncoding is an encoder_decoder.OneHotEncoding that specifies a one-
hot encoding for Melody events, i.e. MIDI pitch values plus note-off and no-
event.
KeyMelodyEncoderDecoder is an encoder_decoder.EventSequenceEncoderDecoder that
specifies an encoding of Melody objects into input vectors and output labels for
use by melody models.
"""
import collections
from note_seq import constants
from note_seq import encoder_decoder
from note_seq import melodies_lib
NUM_SPECIAL_MELODY_EVENTS = constants.NUM_SPECIAL_MELODY_EVENTS
MELODY_NOTE_OFF = constants.MELODY_NOTE_OFF
MELODY_NO_EVENT = constants.MELODY_NO_EVENT
MIN_MIDI_PITCH = constants.MIN_MIDI_PITCH
MAX_MIDI_PITCH = constants.MAX_MIDI_PITCH
NOTES_PER_OCTAVE = constants.NOTES_PER_OCTAVE
DEFAULT_STEPS_PER_BAR = constants.DEFAULT_STEPS_PER_BAR
DEFAULT_LOOKBACK_DISTANCES = encoder_decoder.DEFAULT_LOOKBACK_DISTANCES
class MelodyOneHotEncoding(encoder_decoder.OneHotEncoding):
"""Basic one hot encoding for melody events.
Encodes melody events as follows:
0 = no event,
1 = note-off event,
[2, self.num_classes) = note-on event for that pitch relative to the
[self._min_note, self._max_note) range.
"""
def __init__(self, min_note, max_note):
"""Initializes a MelodyOneHotEncoding object.
Args:
min_note: The minimum midi pitch the encoded melody events can have.
max_note: The maximum midi pitch (exclusive) the encoded melody events
can have.
Raises:
ValueError: If `min_note` or `max_note` are outside the midi range, or if
`max_note` is not greater than `min_note`.
"""
if min_note < MIN_MIDI_PITCH:
raise ValueError('min_note must be >= 0. min_note is %d.' % min_note)
if max_note > MAX_MIDI_PITCH + 1:
raise ValueError('max_note must be <= 128. max_note is %d.' % max_note)
if max_note <= min_note:
raise ValueError('max_note must be greater than min_note')
self._min_note = min_note
self._max_note = max_note
@property
def num_classes(self):
return self._max_note - self._min_note + NUM_SPECIAL_MELODY_EVENTS
@property
def default_event(self):
return MELODY_NO_EVENT
def encode_event(self, event):
"""Collapses a melody event value into a zero-based index range.
Args:
event: A Melody event value. -2 = no event, -1 = note-off event,
[0, 127] = note-on event for that midi pitch.
Returns:
An int in the range [0, self.num_classes). 0 = no event,
1 = note-off event, [2, self.num_classes) = note-on event for
that pitch relative to the [self._min_note, self._max_note) range.
Raises:
ValueError: If `event` is a MIDI note not between self._min_note and
self._max_note, or an invalid special event value.
"""
if event < -NUM_SPECIAL_MELODY_EVENTS:
raise ValueError('invalid melody event value: %d' % event)
if 0 <= event < self._min_note:
raise ValueError('melody event less than min note: %d < %d' % (
event, self._min_note))
if event >= self._max_note:
raise ValueError('melody event greater than max note: %d >= %d' % (
event, self._max_note))
if event < 0:
return event + NUM_SPECIAL_MELODY_EVENTS
return event - self._min_note + NUM_SPECIAL_MELODY_EVENTS
def decode_event(self, index):
"""Expands a zero-based index value to its equivalent melody event value.
Args:
index: An int in the range [0, self._num_model_events).
0 = no event, 1 = note-off event,
[2, self._num_model_events) = note-on event for that pitch relative
to the [self._min_note, self._max_note) range.
Returns:
A Melody event value. -2 = no event, -1 = note-off event,
[0, 127] = note-on event for that midi pitch.
"""
if index < NUM_SPECIAL_MELODY_EVENTS:
return index - NUM_SPECIAL_MELODY_EVENTS
return index - NUM_SPECIAL_MELODY_EVENTS + self._min_note
class KeyMelodyEncoderDecoder(encoder_decoder.EventSequenceEncoderDecoder):
"""A MelodyEncoderDecoder that encodes repeated events, time, and key."""
def __init__(self, min_note, max_note, lookback_distances=None,
binary_counter_bits=7):
"""Initializes the KeyMelodyEncoderDecoder.
Args:
min_note: The minimum midi pitch the encoded melody events can have.
max_note: The maximum midi pitch (exclusive) the encoded melody events can
have.
lookback_distances: A list of step intervals to look back in history to
encode both the following event and whether the current step is a
repeat. If None, use default lookback distances.
binary_counter_bits: The number of input bits to use as a counter for the
metric position of the next note.
"""
if lookback_distances is None:
self._lookback_distances = DEFAULT_LOOKBACK_DISTANCES
else:
self._lookback_distances = lookback_distances
self._binary_counter_bits = binary_counter_bits
self._min_note = min_note
self._note_range = max_note - min_note
@property
def input_size(self):
return (self._note_range + # current note
2 + # note vs. silence
1 + # attack or not
1 + # ascending or not
len(self._lookback_distances) + # whether note matches lookbacks
self._binary_counter_bits + # binary counters
1 + # start of bar or not
NOTES_PER_OCTAVE + # total key estimate
NOTES_PER_OCTAVE) # recent key estimate
@property
def num_classes(self):
return (self._note_range + NUM_SPECIAL_MELODY_EVENTS +
len(self._lookback_distances))
@property
def default_event_label(self):
return self._note_range
def events_to_input(self, events, position):
"""Returns the input vector for the given position in the melody.
Returns a self.input_size length list of floats. Assuming
self._min_note = 48, self._note_range = 36, two lookback distances, and
seven binary counters, then self.input_size = 74. Each index represents a
different input signal to the model.
Indices [0, 73]:
[0, 35]: A note is playing at that pitch [48, 84).
36: Any note is playing.
37: Silence is playing.
38: The current event is the note-on event of the currently playing note.
39: Whether the melody is currently ascending or descending.
40: The last event is repeating (first lookback distance).
41: The last event is repeating (second lookback distance).
[42, 48]: Time keeping toggles.
49: The next event is the start of a bar.
[50, 61]: The keys the current melody is in.
[62, 73]: The keys the last 3 notes are in.
Args:
events: A note_seq.Melody object.
position: An integer event position in the melody.
Returns:
An input vector, an self.input_size length list of floats.
"""
current_note = None
is_attack = False
is_ascending = None
last_3_notes = collections.deque(maxlen=3)
sub_melody = melodies_lib.Melody(events[:position + 1])
for note in sub_melody:
if note == MELODY_NO_EVENT:
is_attack = False
elif note == MELODY_NOTE_OFF:
current_note = None
else:
is_attack = True
current_note = note
if last_3_notes:
if note > last_3_notes[-1]:
is_ascending = True
if note < last_3_notes[-1]:
is_ascending = False
if note in last_3_notes:
last_3_notes.remove(note)
last_3_notes.append(note)
input_ = [0.0] * self.input_size
offset = 0
if current_note:
# The pitch of current note if a note is playing.
input_[offset + current_note - self._min_note] = 1.0
# A note is playing.
input_[offset + self._note_range] = 1.0
else:
# Silence is playing.
input_[offset + self._note_range + 1] = 1.0
offset += self._note_range + 2
# The current event is the note-on event of the currently playing note.
if is_attack:
input_[offset] = 1.0
offset += 1
# Whether the melody is currently ascending or descending.
if is_ascending is not None:
input_[offset] = 1.0 if is_ascending else -1.0
offset += 1
# Last event is repeating N bars ago.
for i, lookback_distance in enumerate(self._lookback_distances):
lookback_position = position - lookback_distance
if (lookback_position >= 0 and
events[position] == events[lookback_position]):
input_[offset] = 1.0
offset += 1
# Binary time counter giving the metric location of the *next* note.
n = len(sub_melody)
for i in range(self._binary_counter_bits):
input_[offset] = 1.0 if (n // 2 ** i) % 2 else -1.0
offset += 1
# The next event is the start of a bar.
if len(sub_melody) % DEFAULT_STEPS_PER_BAR == 0:
input_[offset] = 1.0
offset += 1
# The keys the current melody is in.
key_histogram = sub_melody.get_major_key_histogram()
max_val = max(key_histogram)
for i, key_val in enumerate(key_histogram):
if key_val == max_val:
input_[offset] = 1.0
offset += 1
# The keys the last 3 notes are in.
last_3_note_melody = melodies_lib.Melody(list(last_3_notes))
key_histogram = last_3_note_melody.get_major_key_histogram()
max_val = max(key_histogram)
for i, key_val in enumerate(key_histogram):
if key_val == max_val:
input_[offset] = 1.0
offset += 1
assert offset == self.input_size
return input_
def events_to_label(self, events, position):
"""Returns the label for the given position in the melody.
Returns an int in the range [0, self.num_classes). Assuming
self._min_note = 48, self._note_range = 36, and two lookback distances,
then self.num_classes = 40.
Values [0, 39]:
[0, 35]: Note-on event for midi pitch [48, 84).
36: No event.
37: Note-off event.
38: Repeat first lookback (takes precedence over above values).
39: Repeat second lookback (takes precedence over above values).
Args:
events: A note_seq.Melody object.
position: An integer event position in the melody.
Returns:
A label, an integer.
"""
if (position < self._lookback_distances[-1] and
events[position] == MELODY_NO_EVENT):
return self._note_range + len(self._lookback_distances) + 1
# If the last event repeated N bars ago.
for i, lookback_distance in reversed(
list(enumerate(self._lookback_distances))):
lookback_position = position - lookback_distance
if (lookback_position >= 0 and
events[position] == events[lookback_position]):
return self._note_range + 2 + i
# If last event was a note-off event.
if events[position] == MELODY_NOTE_OFF:
return self._note_range + 1
# If last event was a no event.
if events[position] == MELODY_NO_EVENT:
return self._note_range
# If last event was a note-on event, the pitch of that note.
return events[position] - self._min_note
def class_index_to_event(self, class_index, events):
"""Returns the melody event for the given class index.
This is the reverse process of the self.events_to_label method.
Args:
class_index: An int in the range [0, self.num_classes).
events: The note_seq.Melody events list of the current melody.
Returns:
A note_seq.Melody event value.
"""
# Repeat N bars ago.
for i, lookback_distance in reversed(
list(enumerate(self._lookback_distances))):
if class_index == self._note_range + 2 + i:
if len(events) < lookback_distance:
return MELODY_NO_EVENT
return events[-lookback_distance]
# Note-off event.
if class_index == self._note_range + 1:
return MELODY_NOTE_OFF
# No event:
if class_index == self._note_range:
return MELODY_NO_EVENT
# Note-on event for that midi pitch.
return self._min_note + class_indexClasses
class KeyMelodyEncoderDecoder (min_note, max_note, lookback_distances=None, binary_counter_bits=7)-
A MelodyEncoderDecoder that encodes repeated events, time, and key.
Initializes the KeyMelodyEncoderDecoder.
Args
min_note- The minimum midi pitch the encoded melody events can have.
max_note- The maximum midi pitch (exclusive) the encoded melody events can have.
lookback_distances- A list of step intervals to look back in history to encode both the following event and whether the current step is a repeat. If None, use default lookback distances.
binary_counter_bits- The number of input bits to use as a counter for the metric position of the next note.
Expand source code
class KeyMelodyEncoderDecoder(encoder_decoder.EventSequenceEncoderDecoder): """A MelodyEncoderDecoder that encodes repeated events, time, and key.""" def __init__(self, min_note, max_note, lookback_distances=None, binary_counter_bits=7): """Initializes the KeyMelodyEncoderDecoder. Args: min_note: The minimum midi pitch the encoded melody events can have. max_note: The maximum midi pitch (exclusive) the encoded melody events can have. lookback_distances: A list of step intervals to look back in history to encode both the following event and whether the current step is a repeat. If None, use default lookback distances. binary_counter_bits: The number of input bits to use as a counter for the metric position of the next note. """ if lookback_distances is None: self._lookback_distances = DEFAULT_LOOKBACK_DISTANCES else: self._lookback_distances = lookback_distances self._binary_counter_bits = binary_counter_bits self._min_note = min_note self._note_range = max_note - min_note @property def input_size(self): return (self._note_range + # current note 2 + # note vs. silence 1 + # attack or not 1 + # ascending or not len(self._lookback_distances) + # whether note matches lookbacks self._binary_counter_bits + # binary counters 1 + # start of bar or not NOTES_PER_OCTAVE + # total key estimate NOTES_PER_OCTAVE) # recent key estimate @property def num_classes(self): return (self._note_range + NUM_SPECIAL_MELODY_EVENTS + len(self._lookback_distances)) @property def default_event_label(self): return self._note_range def events_to_input(self, events, position): """Returns the input vector for the given position in the melody. Returns a self.input_size length list of floats. Assuming self._min_note = 48, self._note_range = 36, two lookback distances, and seven binary counters, then self.input_size = 74. Each index represents a different input signal to the model. Indices [0, 73]: [0, 35]: A note is playing at that pitch [48, 84). 36: Any note is playing. 37: Silence is playing. 38: The current event is the note-on event of the currently playing note. 39: Whether the melody is currently ascending or descending. 40: The last event is repeating (first lookback distance). 41: The last event is repeating (second lookback distance). [42, 48]: Time keeping toggles. 49: The next event is the start of a bar. [50, 61]: The keys the current melody is in. [62, 73]: The keys the last 3 notes are in. Args: events: A note_seq.Melody object. position: An integer event position in the melody. Returns: An input vector, an self.input_size length list of floats. """ current_note = None is_attack = False is_ascending = None last_3_notes = collections.deque(maxlen=3) sub_melody = melodies_lib.Melody(events[:position + 1]) for note in sub_melody: if note == MELODY_NO_EVENT: is_attack = False elif note == MELODY_NOTE_OFF: current_note = None else: is_attack = True current_note = note if last_3_notes: if note > last_3_notes[-1]: is_ascending = True if note < last_3_notes[-1]: is_ascending = False if note in last_3_notes: last_3_notes.remove(note) last_3_notes.append(note) input_ = [0.0] * self.input_size offset = 0 if current_note: # The pitch of current note if a note is playing. input_[offset + current_note - self._min_note] = 1.0 # A note is playing. input_[offset + self._note_range] = 1.0 else: # Silence is playing. input_[offset + self._note_range + 1] = 1.0 offset += self._note_range + 2 # The current event is the note-on event of the currently playing note. if is_attack: input_[offset] = 1.0 offset += 1 # Whether the melody is currently ascending or descending. if is_ascending is not None: input_[offset] = 1.0 if is_ascending else -1.0 offset += 1 # Last event is repeating N bars ago. for i, lookback_distance in enumerate(self._lookback_distances): lookback_position = position - lookback_distance if (lookback_position >= 0 and events[position] == events[lookback_position]): input_[offset] = 1.0 offset += 1 # Binary time counter giving the metric location of the *next* note. n = len(sub_melody) for i in range(self._binary_counter_bits): input_[offset] = 1.0 if (n // 2 ** i) % 2 else -1.0 offset += 1 # The next event is the start of a bar. if len(sub_melody) % DEFAULT_STEPS_PER_BAR == 0: input_[offset] = 1.0 offset += 1 # The keys the current melody is in. key_histogram = sub_melody.get_major_key_histogram() max_val = max(key_histogram) for i, key_val in enumerate(key_histogram): if key_val == max_val: input_[offset] = 1.0 offset += 1 # The keys the last 3 notes are in. last_3_note_melody = melodies_lib.Melody(list(last_3_notes)) key_histogram = last_3_note_melody.get_major_key_histogram() max_val = max(key_histogram) for i, key_val in enumerate(key_histogram): if key_val == max_val: input_[offset] = 1.0 offset += 1 assert offset == self.input_size return input_ def events_to_label(self, events, position): """Returns the label for the given position in the melody. Returns an int in the range [0, self.num_classes). Assuming self._min_note = 48, self._note_range = 36, and two lookback distances, then self.num_classes = 40. Values [0, 39]: [0, 35]: Note-on event for midi pitch [48, 84). 36: No event. 37: Note-off event. 38: Repeat first lookback (takes precedence over above values). 39: Repeat second lookback (takes precedence over above values). Args: events: A note_seq.Melody object. position: An integer event position in the melody. Returns: A label, an integer. """ if (position < self._lookback_distances[-1] and events[position] == MELODY_NO_EVENT): return self._note_range + len(self._lookback_distances) + 1 # If the last event repeated N bars ago. for i, lookback_distance in reversed( list(enumerate(self._lookback_distances))): lookback_position = position - lookback_distance if (lookback_position >= 0 and events[position] == events[lookback_position]): return self._note_range + 2 + i # If last event was a note-off event. if events[position] == MELODY_NOTE_OFF: return self._note_range + 1 # If last event was a no event. if events[position] == MELODY_NO_EVENT: return self._note_range # If last event was a note-on event, the pitch of that note. return events[position] - self._min_note def class_index_to_event(self, class_index, events): """Returns the melody event for the given class index. This is the reverse process of the self.events_to_label method. Args: class_index: An int in the range [0, self.num_classes). events: The note_seq.Melody events list of the current melody. Returns: A note_seq.Melody event value. """ # Repeat N bars ago. for i, lookback_distance in reversed( list(enumerate(self._lookback_distances))): if class_index == self._note_range + 2 + i: if len(events) < lookback_distance: return MELODY_NO_EVENT return events[-lookback_distance] # Note-off event. if class_index == self._note_range + 1: return MELODY_NOTE_OFF # No event: if class_index == self._note_range: return MELODY_NO_EVENT # Note-on event for that midi pitch. return self._min_note + class_indexAncestors
Methods
def class_index_to_event(self, class_index, events)-
Returns the melody event for the given class index.
This is the reverse process of the self.events_to_label method.
Args
class_index- An int in the range [0, self.num_classes).
events- The note_seq.Melody events list of the current melody.
Returns
A note_seq.Melody event value.
Expand source code
def class_index_to_event(self, class_index, events): """Returns the melody event for the given class index. This is the reverse process of the self.events_to_label method. Args: class_index: An int in the range [0, self.num_classes). events: The note_seq.Melody events list of the current melody. Returns: A note_seq.Melody event value. """ # Repeat N bars ago. for i, lookback_distance in reversed( list(enumerate(self._lookback_distances))): if class_index == self._note_range + 2 + i: if len(events) < lookback_distance: return MELODY_NO_EVENT return events[-lookback_distance] # Note-off event. if class_index == self._note_range + 1: return MELODY_NOTE_OFF # No event: if class_index == self._note_range: return MELODY_NO_EVENT # Note-on event for that midi pitch. return self._min_note + class_index def events_to_input(self, events, position)-
Returns the input vector for the given position in the melody.
Returns a self.input_size length list of floats. Assuming self._min_note = 48, self._note_range = 36, two lookback distances, and seven binary counters, then self.input_size = 74. Each index represents a different input signal to the model.
Indices [0, 73]: [0, 35]: A note is playing at that pitch [48, 84). 36: Any note is playing. 37: Silence is playing. 38: The current event is the note-on event of the currently playing note. 39: Whether the melody is currently ascending or descending. 40: The last event is repeating (first lookback distance). 41: The last event is repeating (second lookback distance). [42, 48]: Time keeping toggles. 49: The next event is the start of a bar. [50, 61]: The keys the current melody is in. [62, 73]: The keys the last 3 notes are in.
Args
events- A note_seq.Melody object.
position- An integer event position in the melody.
Returns
An input vector, an self.input_size length list of floats.
Expand source code
def events_to_input(self, events, position): """Returns the input vector for the given position in the melody. Returns a self.input_size length list of floats. Assuming self._min_note = 48, self._note_range = 36, two lookback distances, and seven binary counters, then self.input_size = 74. Each index represents a different input signal to the model. Indices [0, 73]: [0, 35]: A note is playing at that pitch [48, 84). 36: Any note is playing. 37: Silence is playing. 38: The current event is the note-on event of the currently playing note. 39: Whether the melody is currently ascending or descending. 40: The last event is repeating (first lookback distance). 41: The last event is repeating (second lookback distance). [42, 48]: Time keeping toggles. 49: The next event is the start of a bar. [50, 61]: The keys the current melody is in. [62, 73]: The keys the last 3 notes are in. Args: events: A note_seq.Melody object. position: An integer event position in the melody. Returns: An input vector, an self.input_size length list of floats. """ current_note = None is_attack = False is_ascending = None last_3_notes = collections.deque(maxlen=3) sub_melody = melodies_lib.Melody(events[:position + 1]) for note in sub_melody: if note == MELODY_NO_EVENT: is_attack = False elif note == MELODY_NOTE_OFF: current_note = None else: is_attack = True current_note = note if last_3_notes: if note > last_3_notes[-1]: is_ascending = True if note < last_3_notes[-1]: is_ascending = False if note in last_3_notes: last_3_notes.remove(note) last_3_notes.append(note) input_ = [0.0] * self.input_size offset = 0 if current_note: # The pitch of current note if a note is playing. input_[offset + current_note - self._min_note] = 1.0 # A note is playing. input_[offset + self._note_range] = 1.0 else: # Silence is playing. input_[offset + self._note_range + 1] = 1.0 offset += self._note_range + 2 # The current event is the note-on event of the currently playing note. if is_attack: input_[offset] = 1.0 offset += 1 # Whether the melody is currently ascending or descending. if is_ascending is not None: input_[offset] = 1.0 if is_ascending else -1.0 offset += 1 # Last event is repeating N bars ago. for i, lookback_distance in enumerate(self._lookback_distances): lookback_position = position - lookback_distance if (lookback_position >= 0 and events[position] == events[lookback_position]): input_[offset] = 1.0 offset += 1 # Binary time counter giving the metric location of the *next* note. n = len(sub_melody) for i in range(self._binary_counter_bits): input_[offset] = 1.0 if (n // 2 ** i) % 2 else -1.0 offset += 1 # The next event is the start of a bar. if len(sub_melody) % DEFAULT_STEPS_PER_BAR == 0: input_[offset] = 1.0 offset += 1 # The keys the current melody is in. key_histogram = sub_melody.get_major_key_histogram() max_val = max(key_histogram) for i, key_val in enumerate(key_histogram): if key_val == max_val: input_[offset] = 1.0 offset += 1 # The keys the last 3 notes are in. last_3_note_melody = melodies_lib.Melody(list(last_3_notes)) key_histogram = last_3_note_melody.get_major_key_histogram() max_val = max(key_histogram) for i, key_val in enumerate(key_histogram): if key_val == max_val: input_[offset] = 1.0 offset += 1 assert offset == self.input_size return input_ def events_to_label(self, events, position)-
Returns the label for the given position in the melody.
Returns an int in the range [0, self.num_classes). Assuming self._min_note = 48, self._note_range = 36, and two lookback distances, then self.num_classes = 40. Values [0, 39]: [0, 35]: Note-on event for midi pitch [48, 84). 36: No event. 37: Note-off event. 38: Repeat first lookback (takes precedence over above values). 39: Repeat second lookback (takes precedence over above values).
Args
events- A note_seq.Melody object.
position- An integer event position in the melody.
Returns
A label, an integer.
Expand source code
def events_to_label(self, events, position): """Returns the label for the given position in the melody. Returns an int in the range [0, self.num_classes). Assuming self._min_note = 48, self._note_range = 36, and two lookback distances, then self.num_classes = 40. Values [0, 39]: [0, 35]: Note-on event for midi pitch [48, 84). 36: No event. 37: Note-off event. 38: Repeat first lookback (takes precedence over above values). 39: Repeat second lookback (takes precedence over above values). Args: events: A note_seq.Melody object. position: An integer event position in the melody. Returns: A label, an integer. """ if (position < self._lookback_distances[-1] and events[position] == MELODY_NO_EVENT): return self._note_range + len(self._lookback_distances) + 1 # If the last event repeated N bars ago. for i, lookback_distance in reversed( list(enumerate(self._lookback_distances))): lookback_position = position - lookback_distance if (lookback_position >= 0 and events[position] == events[lookback_position]): return self._note_range + 2 + i # If last event was a note-off event. if events[position] == MELODY_NOTE_OFF: return self._note_range + 1 # If last event was a no event. if events[position] == MELODY_NO_EVENT: return self._note_range # If last event was a note-on event, the pitch of that note. return events[position] - self._min_note
Inherited members
class MelodyOneHotEncoding (min_note, max_note)-
Basic one hot encoding for melody events.
Encodes melody events as follows: 0 = no event, 1 = note-off event, [2, self.num_classes) = note-on event for that pitch relative to the [self._min_note, self._max_note) range.
Initializes a MelodyOneHotEncoding object.
Args
min_note- The minimum midi pitch the encoded melody events can have.
max_note- The maximum midi pitch (exclusive) the encoded melody events can have.
Raises
ValueError- If
min_noteormax_noteare outside the midi range, or ifmax_noteis not greater thanmin_note.
Expand source code
class MelodyOneHotEncoding(encoder_decoder.OneHotEncoding): """Basic one hot encoding for melody events. Encodes melody events as follows: 0 = no event, 1 = note-off event, [2, self.num_classes) = note-on event for that pitch relative to the [self._min_note, self._max_note) range. """ def __init__(self, min_note, max_note): """Initializes a MelodyOneHotEncoding object. Args: min_note: The minimum midi pitch the encoded melody events can have. max_note: The maximum midi pitch (exclusive) the encoded melody events can have. Raises: ValueError: If `min_note` or `max_note` are outside the midi range, or if `max_note` is not greater than `min_note`. """ if min_note < MIN_MIDI_PITCH: raise ValueError('min_note must be >= 0. min_note is %d.' % min_note) if max_note > MAX_MIDI_PITCH + 1: raise ValueError('max_note must be <= 128. max_note is %d.' % max_note) if max_note <= min_note: raise ValueError('max_note must be greater than min_note') self._min_note = min_note self._max_note = max_note @property def num_classes(self): return self._max_note - self._min_note + NUM_SPECIAL_MELODY_EVENTS @property def default_event(self): return MELODY_NO_EVENT def encode_event(self, event): """Collapses a melody event value into a zero-based index range. Args: event: A Melody event value. -2 = no event, -1 = note-off event, [0, 127] = note-on event for that midi pitch. Returns: An int in the range [0, self.num_classes). 0 = no event, 1 = note-off event, [2, self.num_classes) = note-on event for that pitch relative to the [self._min_note, self._max_note) range. Raises: ValueError: If `event` is a MIDI note not between self._min_note and self._max_note, or an invalid special event value. """ if event < -NUM_SPECIAL_MELODY_EVENTS: raise ValueError('invalid melody event value: %d' % event) if 0 <= event < self._min_note: raise ValueError('melody event less than min note: %d < %d' % ( event, self._min_note)) if event >= self._max_note: raise ValueError('melody event greater than max note: %d >= %d' % ( event, self._max_note)) if event < 0: return event + NUM_SPECIAL_MELODY_EVENTS return event - self._min_note + NUM_SPECIAL_MELODY_EVENTS def decode_event(self, index): """Expands a zero-based index value to its equivalent melody event value. Args: index: An int in the range [0, self._num_model_events). 0 = no event, 1 = note-off event, [2, self._num_model_events) = note-on event for that pitch relative to the [self._min_note, self._max_note) range. Returns: A Melody event value. -2 = no event, -1 = note-off event, [0, 127] = note-on event for that midi pitch. """ if index < NUM_SPECIAL_MELODY_EVENTS: return index - NUM_SPECIAL_MELODY_EVENTS return index - NUM_SPECIAL_MELODY_EVENTS + self._min_noteAncestors
Methods
def decode_event(self, index)-
Expands a zero-based index value to its equivalent melody event value.
Args
index- An int in the range [0, self._num_model_events). 0 = no event, 1 = note-off event, [2, self._num_model_events) = note-on event for that pitch relative to the [self._min_note, self._max_note) range.
Returns
A Melody event value. -2 = no event, -1 = note-off event, [0, 127] = note-on event for that midi pitch.
Expand source code
def decode_event(self, index): """Expands a zero-based index value to its equivalent melody event value. Args: index: An int in the range [0, self._num_model_events). 0 = no event, 1 = note-off event, [2, self._num_model_events) = note-on event for that pitch relative to the [self._min_note, self._max_note) range. Returns: A Melody event value. -2 = no event, -1 = note-off event, [0, 127] = note-on event for that midi pitch. """ if index < NUM_SPECIAL_MELODY_EVENTS: return index - NUM_SPECIAL_MELODY_EVENTS return index - NUM_SPECIAL_MELODY_EVENTS + self._min_note def encode_event(self, event)-
Collapses a melody event value into a zero-based index range.
Args
event- A Melody event value. -2 = no event, -1 = note-off event, [0, 127] = note-on event for that midi pitch.
Returns
An int in the range [0, self.num_classes). 0 = no event, 1 = note-off event, [2, self.num_classes) = note-on event for that pitch relative to the [self._min_note, self._max_note) range.
Raises
ValueError- If
eventis a MIDI note not between self._min_note and self._max_note, or an invalid special event value.
Expand source code
def encode_event(self, event): """Collapses a melody event value into a zero-based index range. Args: event: A Melody event value. -2 = no event, -1 = note-off event, [0, 127] = note-on event for that midi pitch. Returns: An int in the range [0, self.num_classes). 0 = no event, 1 = note-off event, [2, self.num_classes) = note-on event for that pitch relative to the [self._min_note, self._max_note) range. Raises: ValueError: If `event` is a MIDI note not between self._min_note and self._max_note, or an invalid special event value. """ if event < -NUM_SPECIAL_MELODY_EVENTS: raise ValueError('invalid melody event value: %d' % event) if 0 <= event < self._min_note: raise ValueError('melody event less than min note: %d < %d' % ( event, self._min_note)) if event >= self._max_note: raise ValueError('melody event greater than max note: %d >= %d' % ( event, self._max_note)) if event < 0: return event + NUM_SPECIAL_MELODY_EVENTS return event - self._min_note + NUM_SPECIAL_MELODY_EVENTS
Inherited members