Source code for pypianoroll.outputs

"""Output interfaces.


- save
- to_pretty_midi
- write



import json
import zipfile
from copy import deepcopy
from operator import attrgetter
from pathlib import Path
from typing import TYPE_CHECKING, Dict, Union

import numpy as np
import pretty_midi
import scipy.stats
from pretty_midi import Instrument, PrettyMIDI

from .track import BinaryTrack, StandardTrack
from .utils import decompose_sparse

    from .multitrack import Multitrack

__all__ = [


[docs]def save( path: Union[str, Path], multitrack: "Multitrack", compressed: bool = True ): """Save a Multitrack object to a NPZ file. Parameters ---------- path : str or Path Path to the NPZ file to save. multitrack : :class:`pypianoroll.Multitrack` Multitrack to save. compressed : bool, default: True Whether to save to a compressed NPZ file. Notes ----- To reduce the file size, the piano rolls are first converted to instances of :class:`scipy.sparse.csc_matrix`. The component arrays are then collected and saved to a npz file. See Also -------- :func:`pypianoroll.load` : Load a NPZ file into a Multitrack object. :func:`pypianoroll.write` : Write a Multitrack object to a MIDI file. """ info_dict: Dict = { "resolution": multitrack.resolution, "name":, } array_dict = {} if multitrack.tempo is not None: array_dict["tempo"] = multitrack.tempo if multitrack.downbeat is not None: array_dict["downbeat"] = multitrack.downbeat for idx, track in enumerate(multitrack.tracks): array_dict.update( decompose_sparse(track.pianoroll, "pianoroll_" + str(idx)) ) info_dict[str(idx)] = { "program": track.program, "is_drum": track.is_drum, "name":, } if compressed: np.savez_compressed(path, **array_dict) else: np.savez(path, **array_dict) compression = zipfile.ZIP_DEFLATED if compressed else zipfile.ZIP_STORED with zipfile.ZipFile(path, "a") as zip_file: zip_file.writestr("info.json", json.dumps(info_dict), compression)
[docs]def to_pretty_midi( multitrack: "Multitrack", default_tempo: float = None, default_velocity: int = DEFAULT_VELOCITY, ) -> PrettyMIDI: """Return a Multitrack object as a PrettyMIDI object. Parameters ---------- default_tempo : int, default: `pypianoroll.DEFAULT_TEMPO` (120) Default tempo to use. If attribute `tempo` is available, use its first element. default_velocity : int, default: `pypianoroll.DEFAULT_VELOCITY` (64) Default velocity to assign to binarized tracks. Returns ------- :class:`pretty_midi.PrettyMIDI` Converted PrettyMIDI object. Notes ----- - Tempo changes are not supported. - Time signature changes are not supported. - The velocities of the converted piano rolls will be clipped to [0, 127]. - Adjacent nonzero values of the same pitch will be considered a single note with their mean as its velocity. """ if default_tempo is not None: tempo = default_tempo elif multitrack.tempo is not None: tempo = float(scipy.stats.hmean(multitrack.tempo)) else: tempo = DEFAULT_TEMPO # Create a PrettyMIDI instance midi = PrettyMIDI(initial_tempo=tempo) # Compute length of a time step time_step_length = 60.0 / tempo / multitrack.resolution for track in multitrack.tracks: instrument = Instrument( program=track.program, is_drum=track.is_drum, ) if isinstance(track, BinaryTrack): processed = track.set_nonzeros(default_velocity) elif isinstance(track, StandardTrack): copied = deepcopy(track) processed = copied.clip() else: raise ValueError( f"Expect BinaryTrack or StandardTrack, but got {type(track)}." ) clipped = processed.pianoroll.astype(np.uint8) binarized = clipped > 0 padded = np.pad(binarized, ((1, 1), (0, 0)), "constant") diff = np.diff(padded.astype(np.int8), axis=0) positives = np.nonzero((diff > 0).T) pitches = positives[0] note_ons = positives[1] note_on_times = time_step_length * note_ons note_offs = np.nonzero((diff < 0).T)[1] note_off_times = time_step_length * note_offs for idx, pitch in enumerate(pitches): velocity = np.mean(clipped[note_ons[idx] : note_offs[idx], pitch]) note = pretty_midi.Note( velocity=int(velocity), pitch=pitch, start=note_on_times[idx], end=note_off_times[idx], ) instrument.notes.append(note) instrument.notes.sort(key=attrgetter("start")) midi.instruments.append(instrument) return midi
[docs]def write(path: str, multitrack: "Multitrack"): """Write a Multitrack object to a MIDI file. Parameters ---------- path : str Path to write the file. multitrack : :class:`pypianoroll.Multitrack` Multitrack to save. See Also -------- :func:`` : Read a MIDI file into a Multitrack object. :func:`` : Save a Multitrack object to a NPZ file. """ return to_pretty_midi(multitrack).write(str(path))