# Copyright 2016 Google Inc. All Rights Reserved.
#
# 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.
"""A MelodyEncoderDecoder specific to the attention RNN model."""
import collections
# internal imports
from magenta.music import constants
from magenta.music 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
NOTES_PER_OCTAVE = constants.NOTES_PER_OCTAVE
STEPS_PER_BAR = 16 # This code assumes the melodies have 16 steps per bar.
MIN_NOTE = 48 # Inclusive
MAX_NOTE = 84 # Exclusive
TRANSPOSE_TO_KEY = 0 # C Major
# The number of special input indices and label values other than the events
# in the note range.
NUM_SPECIAL_INPUTS = 14 + NOTES_PER_OCTAVE * 2
NUM_SPECIAL_CLASSES = 2
NUM_BINARY_TIME_COUNTERS = 7
# Must be sorted in ascending order.
LOOKBACK_DISTANCES = [STEPS_PER_BAR, STEPS_PER_BAR * 2]
class MelodyEncoderDecoder(melodies_lib.MelodyEncoderDecoder):
"""A MelodyEncoderDecoder specific to the attention RNN model.
Attributes:
note_range: The number of different note pitches used by this model.
"""
def __init__(self):
"""Initializes the MelodyEncoderDecoder."""
super(MelodyEncoderDecoder, self).__init__(MIN_NOTE, MAX_NOTE,
TRANSPOSE_TO_KEY)
self.note_range = self.max_note - self.min_note
@property
def input_size(self):
return self.note_range + NUM_SPECIAL_INPUTS
@property
def num_classes(self):
return self.note_range + NUM_SPECIAL_MELODY_EVENTS + NUM_SPECIAL_CLASSES
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 MIN_NOTE = 48
and MAX_NOTE = 84, then self.input_size = 74. Each index represents a
different input signal to the model.
Indices [0, 74):
[0, 36): 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 1 bar ago.
41: The last event is repeating 2 bars ago.
[42, 49): Time keeping toggles.
49: The next event is the start of a bar.
[50, 62): The keys the current melody is in.
[62, 74): The keys the last 3 notes are in.
Args:
events: A melodies_lib.MonophonicMelody 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.MonophonicMelody()
sub_melody.from_event_list(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
if current_note:
# The pitch of current note if a note is playing.
input_[current_note - self.min_note] = 1.0
# A note is playing.
input_[self.note_range] = 1.0
else:
# Silence is playing.
input_[self.note_range + 1] = 1.0
# The current event is the note-on event of the currently playing note.
if is_attack:
input_[self.note_range + 2] = 1.0
# Whether the melody is currently ascending or descending.
if is_ascending is not None:
input_[self.note_range + 3] = 1.0 if is_ascending else -1.0
# Last event is repeating N bars ago.
for i, lookback_distance in enumerate(LOOKBACK_DISTANCES):
lookback_position = position - lookback_distance
if (lookback_position >= 0 and
events[position] == events[lookback_position]):
input_[self.note_range + 4 + i] = 1.0
# Binary time counter giving the metric location of the *next* note.
n = len(sub_melody)
for i in range(NUM_BINARY_TIME_COUNTERS):
input_[self.note_range + 6 + i] = 1.0 if (n / 2 ** i) % 2 else -1.0
# The next event is the start of a bar.
if len(sub_melody) % STEPS_PER_BAR == 0:
input_[self.note_range + 13] = 1.0
# 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_[self.note_range + 14 + i] = 1.0
# The keys the last 3 notes are in.
last_3_note_melody = melodies_lib.MonophonicMelody()
last_3_note_melody.from_event_list(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_[self.note_range + 14 + NOTES_PER_OCTAVE + i] = 1.0
return input_
def events_to_label(self, events, position):
"""Returns the label for the given position in the melody.
Returns an int the range [0, self.num_classes). Assuming MIN_NOTE = 48
and MAX_NOTE = 84, then self.num_classes = 40.
Values [0, 40):
[0, 36): Note-on event for midi pitch [48, 84).
36: No event.
37: Note-off event.
38: Repeat 1 bar ago (takes precedence over above values).
39: Repeat 2 bars ago (takes precedence over above values).
Args:
events: A melodies_lib.MonophonicMelody object.
position: An integer event position in the melody.
Returns:
A label, an integer.
"""
if (position < LOOKBACK_DISTANCES[-1] and
events[position] == MELODY_NO_EVENT):
return self.note_range + len(LOOKBACK_DISTANCES) + 1
# If the last event repeated N bars ago.
for i, lookback_distance in reversed(list(enumerate(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.melody_to_label method.
Args:
class_index: An int in the range [0, self.num_classes).
events: The melodies_lib.MonophonicMelody events list of the current
melody.
Returns:
A melodies_lib.MonophonicMelody event value.
"""
# Repeat N bars ago.
for i, lookback_distance in reversed(list(enumerate(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