"""Pitch-based representation input interface."""
from operator import attrgetter
from typing import List
import numpy as np
from numpy import ndarray
from ..classes import Note, Track
from ..music import DEFAULT_RESOLUTION, Music
[docs]def from_pitch_representation(
array: ndarray,
resolution: int = DEFAULT_RESOLUTION,
program: int = 0,
is_drum: bool = False,
use_hold_state: bool = False,
default_velocity: int = 64,
) -> Music:
"""Decode pitch-based representation into a Music object.
Parameters
----------
array : ndarray
Array in pitch-based representation to decode. Will be casted to
integer if not of integer type.
resolution : int
Time steps per quarter note. Defaults to
`muspy.DEFAULT_RESOLUTION`.
program : int, optional
Program number according to General MIDI specification [1].
Acceptable values are 0 to 127. Defaults to 0 (Acoustic Grand
Piano).
is_drum : bool, optional
A boolean indicating if it is a percussion track. Defaults to
False.
use_hold_state : bool
Whether to use a special state for holds. Defaults to False.
default_velocity : int
Default velocity value to use when decoding. Defaults to 64.
Returns
-------
:class:`muspy.Music`
Decoded Music object.
References
----------
[1] https://www.midi.org/specifications/item/gm-level-1-sound-set
"""
# Cast the array to integer
if not np.issubdtype(array.dtype, np.integer):
array = array.astype(np.int)
# Find the note boundaries
notes: List[Note] = []
diff = np.diff(array.flatten(), prepend=-1, append=-1)
boundaries = np.nonzero(diff)[0]
# Decode pitches
if use_hold_state:
is_awaiting_hold = False
for start, end in zip(boundaries[:-1], boundaries[1:]):
# Skip rests
if array[start] == 128:
is_awaiting_hold = False
continue
# Hold
if array[start] == 129:
# Skip a hold that does not follow any pitch
if not is_awaiting_hold:
continue
notes[-1].duration += end - start
is_awaiting_hold = False
# Pitch
else:
note = Note(
time=start,
pitch=array[start],
duration=end - start,
velocity=default_velocity,
)
notes.append(note)
is_awaiting_hold = True
else:
for start, end in zip(boundaries[:-1], boundaries[1:]):
# Skip rests
if array[start] == 128:
continue
# Pitch
note = Note(
time=start,
pitch=array[start],
duration=end - start,
velocity=default_velocity,
)
notes.append(note)
# Sort the notes
notes.sort(key=attrgetter("time", "pitch", "duration", "velocity"))
# Create the Track and Music objects
track = Track(program=program, is_drum=is_drum, notes=notes)
music = Music(resolution=resolution, tracks=[track])
return music