"""Input interfaces.
Functions
---------
- load
- from_pretty_midi
- read
"""
import json
from pathlib import Path
from typing import Union
import numpy as np
from pretty_midi import PrettyMIDI
from .multitrack import DEFAULT_RESOLUTION, Multitrack
from .track import BinaryTrack, StandardTrack, Track
from .utils import reconstruct_sparse
__all__ = ["load", "from_pretty_midi", "read"]
[docs]def load(path: Union[str, Path]) -> Multitrack:
"""Load a NPZ file into a Multitrack object.
Supports only files previously saved by :func:`pypianoroll.save`.
Parameters
----------
path : str or Path
Path to the file to load.
See Also
--------
:func:`pypianoroll.save` : Save a Multitrack object to a NPZ file.
:func:`pypianoroll.read` : Read a MIDI file into a Multitrack
object.
"""
with np.load(path) as loaded:
if "info.json" not in loaded:
raise RuntimeError("Cannot find `info.json` in the NPZ file.")
# Load the info dictionary
info_dict = json.loads(loaded["info.json"].decode("utf-8"))
# Get the resolution
resolution = info_dict.get("resolution")
# Look for `beat_resolution` for backward compatibility
if resolution is None:
resolution = info_dict.get("beat_resolution")
if resolution is None:
raise RuntimeError(
"Cannot find `resolution` or `beat_resolution` in "
"`info.json`."
)
# Load the tracks
idx = 0
tracks = []
while str(idx) in info_dict:
name = info_dict[str(idx)].get("name")
program = info_dict[str(idx)].get("program")
is_drum = info_dict[str(idx)].get("is_drum")
pianoroll = reconstruct_sparse(loaded, "pianoroll_" + str(idx))
if pianoroll.dtype == np.bool_:
track: Track = BinaryTrack(
name=name,
program=program,
is_drum=is_drum,
pianoroll=pianoroll,
)
elif pianoroll.dtype == np.uint8:
track = StandardTrack(
name=name,
program=program,
is_drum=is_drum,
pianoroll=pianoroll,
)
else:
track = Track(
name=name,
program=program,
is_drum=is_drum,
pianoroll=pianoroll,
)
tracks.append(track)
idx += 1
return Multitrack(
name=info_dict["name"],
resolution=resolution,
tempo=loaded.get("tempo"),
downbeat=loaded.get("downbeat"),
tracks=tracks,
)
[docs]def from_pretty_midi(
midi: PrettyMIDI,
resolution: int = DEFAULT_RESOLUTION,
mode: str = "max",
algorithm: str = "normal",
collect_onsets_only: bool = False,
first_beat_time: float = None,
) -> Multitrack:
"""Return a Multitrack object converted from a PrettyMIDI object.
Parse a :class:`pretty_midi.PrettyMIDI` object. The data type of the
resulting piano rolls is automatically determined (int if 'mode' is
'sum' and np.uint8 if `mode` is 'max').
Parameters
----------
midi : :class:`pretty_midi.PrettyMIDI`
PrettyMIDI object to parse.
mode : {'max', 'sum'}, default: 'max'
Merging strategy for duplicate notes.
algorithm : {'normal', 'strict', 'custom'}, default: 'normal'
Algorithm for finding the location of the first beat (see
Notes).
collect_onsets_only : bool, default: False
True to collect only the onset of the notes (i.e. note on
events) in all tracks, where the note off and duration
information are discarded. False to parse regular piano rolls.
first_beat_time : float, optional
Location of the first beat, in sec. Required and only
effective when using 'custom' algorithm.
Returns
-------
:class:`pypianoroll.Multitrack`
Converted Multitrack object.
Notes
-----
There are three algorithms for finding the location of the first
beat:
- 'normal' : Estimate the location of the first beat using
:meth:`pretty_midi.PrettyMIDI.estimate_beat_start`.
- 'strict' : Set the location of the first beat to the time of the
first time signature change. Raise a RuntimeError if no time
signature change is found.
- 'custom' : Set the location of the first beat to the value of
argument `first_beat_time`. Raise a ValueError if
`first_beat_time` is not given.
If an incomplete beat before the first beat is found, an additional
beat will be added before the (estimated) beat starting time.
However, notes before the (estimated) beat starting time for more
than one beat are dropped.
"""
if mode not in ("max", "sum"):
raise ValueError("`mode` must be either 'max' or 'sum'.")
# Set first_beat_time for 'normal' and 'strict' modes
if algorithm == "normal":
if midi.time_signature_changes:
midi.time_signature_changes.sort(key=lambda x: x.time)
first_beat_time = midi.time_signature_changes[0].time
else:
first_beat_time = midi.estimate_beat_start()
elif algorithm == "strict":
if not midi.time_signature_changes:
raise RuntimeError(
"No time signature change event found. Unable to set beat "
"start time using 'strict' algorithm."
)
midi.time_signature_changes.sort(key=lambda x: x.time)
first_beat_time = midi.time_signature_changes[0].time
elif algorithm == "custom":
if first_beat_time is None:
raise TypeError(
"`first_beat_time` must be given when using 'custom' "
"algorithm."
)
if first_beat_time < 0.0:
raise ValueError("`first_beat_time` must be a positive number.")
else:
raise ValueError(
"`algorithm` must be one of 'normal', 'strict' or 'custom'."
)
# get tempo change event times and contents
tc_times, tempi = midi.get_tempo_changes()
arg_sorted = np.argsort(tc_times)
tc_times = tc_times[arg_sorted]
tempi = tempi[arg_sorted]
beat_times = midi.get_beats(first_beat_time)
if not beat_times.size:
raise ValueError("Cannot get beat timings to quantize the piano roll.")
beat_times.sort()
n_beats = len(beat_times)
n_time_steps = resolution * n_beats
# Parse downbeat array
if not midi.time_signature_changes:
downbeat = None
else:
downbeat = np.zeros((n_time_steps, 1), bool)
downbeat[0] = True
start = 0
end = start
for idx, tsc in enumerate(midi.time_signature_changes[:-1]):
end += np.searchsorted(
beat_times[end:], midi.time_signature_changes[idx + 1].time
)
start_idx = start * resolution
end_idx = end * resolution
stride = tsc.numerator * resolution
downbeat[start_idx:end_idx:stride] = True
start = end
# Build tempo array
one_more_beat = 2 * beat_times[-1] - beat_times[-2]
beat_times_one_more = np.append(beat_times, one_more_beat)
bpm = 60.0 / np.diff(beat_times_one_more)
tempo = np.tile(bpm, (1, 24)).reshape(-1, 1)
# Parse the tracks
tracks = []
for instrument in midi.instruments:
if mode == "max":
pianoroll = np.zeros((n_time_steps, 128), np.uint8)
else:
pianoroll = np.zeros((n_time_steps, 128), int)
pitches = np.array(
[
note.pitch
for note in instrument.notes
if note.end > first_beat_time
]
)
note_on_times = np.array(
[
note.start
for note in instrument.notes
if note.end > first_beat_time
]
)
beat_indices = np.searchsorted(beat_times, note_on_times) - 1
remained = note_on_times - beat_times[beat_indices]
ratios = remained / (
beat_times_one_more[beat_indices + 1] - beat_times[beat_indices]
)
rounded = np.round((beat_indices + ratios) * resolution)
note_ons = rounded.astype(int)
if collect_onsets_only:
pianoroll[note_ons, pitches] = True
elif instrument.is_drum:
velocities = [
note.velocity
for note in instrument.notes
if note.end > first_beat_time
]
pianoroll[note_ons, pitches] = velocities
else:
note_off_times = np.array(
[
note.end
for note in instrument.notes
if note.end > first_beat_time
]
)
beat_indices = np.searchsorted(beat_times, note_off_times) - 1
remained = note_off_times - beat_times[beat_indices]
ratios = remained / (
beat_times_one_more[beat_indices + 1]
- beat_times[beat_indices]
)
note_offs = ((beat_indices + ratios) * resolution).astype(int)
for idx, start in enumerate(note_ons):
end = note_offs[idx]
velocity = instrument.notes[idx].velocity
if velocity < 1:
continue
if 0 < start < n_time_steps:
if pianoroll[start - 1, pitches[idx]]:
pianoroll[start - 1, pitches[idx]] = 0
if end < n_time_steps - 1:
if pianoroll[end, pitches[idx]]:
end -= 1
if mode == "max":
pianoroll[start:end, pitches[idx]] += velocity
else:
maximum = np.maximum(
pianoroll[start:end, pitches[idx]], velocity
)
pianoroll[start:end, pitches[idx]] = maximum
if mode == "max":
track: Track = StandardTrack(
name=str(instrument.name),
program=int(instrument.program),
is_drum=bool(instrument.is_drum),
pianoroll=pianoroll,
)
else:
track = Track(
name=str(instrument.name),
program=int(instrument.program),
is_drum=bool(instrument.is_drum),
pianoroll=pianoroll,
)
tracks.append(track)
return Multitrack(
resolution=resolution, tempo=tempo, downbeat=downbeat, tracks=tracks
)
[docs]def read(path: Union[str, Path], **kwargs) -> Multitrack:
"""Read a MIDI file into a Multitrack object.
Parameters
----------
path : str or Path
Path to the file to read.
**kwargs
Keyword arguments to pass to
:func:`pypianoroll.from_pretty_midi`.
See Also
--------
:func:`pypianoroll.write` : Write a Multitrack object to a MIDI
file.
:func:`pypianoroll.load` : Load a NPZ file into a Multitrack object.
"""
return from_pretty_midi(PrettyMIDI(str(path)), **kwargs)