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Detect pitch of audio files
"""Detect pitch of audio files.
Requires:
* [aubio](https://pypi.org/project/aubio/)
* [NumPy](https://pypi.org/project/numpy/)
"""
import statistics
import aubio
import numpy as np
__all__ = ("detect_pitch", "estimate_root_note", "remove_outliers")
def remove_outliers(a, constant=1.5):
"""Remove outliers in given series using interquartile range (IQR)."""
if not isinstance(a, np.ndarray):
a = np.array(list(a))
upper_quartile = np.percentile(a, 75)
lower_quartile = np.percentile(a, 25)
IQR = (upper_quartile - lower_quartile) * constant
quartile_set = (lower_quartile - IQR, upper_quartile + IQR)
return [y for y in a.tolist() if y >= quartile_set[0] and y <= quartile_set[1]]
def detect_pitch(
source,
method="default",
tolerance=0.8, # got value from aubio Python demos
threshold=-70.0,
unit="Hz",
buf_size=1024,
hop_size=256,
samplerate=0,
channels=0,
):
"""Detect pitches of given audio source.
Supported methods: `yinfft`, `yin`, `yinfast`, `fcomb`, `mcomb`,
`schmitt`, `specacf`, `default` (`yinfft`).
"""
if not isinstance(source, aubio.source):
source = aubio.source(
source, hop_size=hop_size, samplerate=samplerate, channels=channels
)
with source:
pitchdetect = aubio.pitch(
method=method,
buf_size=buf_size,
hop_size=hop_size,
samplerate=source.samplerate,
)
pitchdetect.set_tolerance(tolerance)
pitchdetect.set_silence(threshold)
pitchdetect.set_unit(unit)
results = []
nframes = 0
while True:
block, read = source()
confidence = pitchdetect.get_confidence()
results.append((nframes, pitchdetect(block)[0], confidence))
nframes += read
if read < source.hop_size:
break
return results
def estimate_root_note(fn, start=0, end=None):
"""Estimate root MIDI note of given sample using harmonic mean of detected pitches.
Outliers of detected pitches are removed using interquartile range.
"""
data = detect_pitch(fn, unit="midi")
if start or end:
data = data[start:end if end is not None else len(data)]
return statistics.harmonic_mean(
remove_outliers([i[1] for i in data])
)
if __name__ == "__main__":
import sys
if len(sys.argv) < 2:
sys.exit("usage: pitchdetect.py <wavfile>")
data = detect_pitch(sys.argv[1])
cleaned = remove_outliers([i[1] for i in data])
print("Simple mean: {:.4f} Hz".format(statistics.mean(cleaned)))
print("Geometric mean: {:.4f} Hz".format(statistics.geometric_mean(cleaned)))
print("Harmonic mean: {:.4f} Hz".format(statistics.harmonic_mean(cleaned)))
print("Median: {:.4f} Hz".format(statistics.median(cleaned)))
print("Standard dev.: {:.6f}\n".format(statistics.stdev(cleaned)))
print("MIDI note: {}".format(estimate_root_note(sys.argv[1])))
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