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3699b0a | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 | """Convert waveforms without changing their declared duration."""
from __future__ import annotations
import math
import unicodedata
from dataclasses import dataclass
import numpy as np
from numpy.typing import NDArray
from scipy.signal import resample_poly
Waveform = NDArray[np.float32]
CLIPPING_THRESHOLD = 0.999
@dataclass(frozen=True)
class Signal:
samples: int
rate_hz: int
peak: float
rms_dbfs: float | None
clipping_fraction: float
def text_key(text: str) -> str:
return ' '.join(unicodedata.normalize('NFC', text).split())
def validate_waveform(waveform: Waveform, rate_hz: int) -> None:
if waveform.ndim != 1 or waveform.size == 0 or rate_hz <= 0:
message = f'invalid waveform shape={waveform.shape}, rate_hz={rate_hz}'
raise ValueError(message)
if not np.isfinite(waveform).all():
offset = int(np.flatnonzero(~np.isfinite(waveform))[0])
message = f'non-finite waveform value={waveform[offset]} at sample={offset}'
raise ValueError(message)
def measure_signal(waveform: Waveform, rate_hz: int) -> Signal:
validate_waveform(waveform, rate_hz)
rms = float(np.sqrt(np.mean(np.square(waveform, dtype=np.float64))))
return Signal(waveform.size, rate_hz, float(np.abs(waveform).max()), 20 * math.log10(rms) if rms > 0 else None, float(np.mean(np.abs(waveform) >= CLIPPING_THRESHOLD)))
def resample_waveform(waveform: Waveform, rate_hz: int, target_rate_hz: int=24000) -> Waveform:
validate_waveform(waveform, rate_hz)
if target_rate_hz <= 0:
message = f'invalid target_rate_hz={target_rate_hz}'
raise ValueError(message)
divisor = math.gcd(rate_hz, target_rate_hz)
converted = np.asarray(resample_poly(waveform, target_rate_hz // divisor, rate_hz // divisor, window=('kaiser', 8.6)), dtype=np.float32)
expected = (waveform.size * target_rate_hz + rate_hz - 1) // rate_hz
if converted.size != expected:
message = f'resampling returned {converted.size} samples, expected {expected}'
raise ValueError(message)
validate_waveform(converted, target_rate_hz)
return converted
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