from typing import Dict, Tuple
import librosa
import numpy as np
import scipy.io.wavfile
import scipy.signal
import soundfile as sf
from TTS.tts.utils.helpers import StandardScaler
from TTS.utils.audio.numpy_transforms import compute_f0
# pylint: disable=too-many-public-methods
class AudioProcessor(object):
"""Audio Processor for TTS.
Note:
All the class arguments are set to default values to enable a flexible initialization
of the class with the model config. They are not meaningful for all the arguments.
Args:
sample_rate (int, optional):
target audio sampling rate. Defaults to None.
resample (bool, optional):
enable/disable resampling of the audio clips when the target sampling rate does not match the original sampling rate. Defaults to False.
num_mels (int, optional):
number of melspectrogram dimensions. Defaults to None.
log_func (int, optional):
log exponent used for converting spectrogram aplitude to DB.
min_level_db (int, optional):
minimum db threshold for the computed melspectrograms. Defaults to None.
frame_shift_ms (int, optional):
milliseconds of frames between STFT columns. Defaults to None.
frame_length_ms (int, optional):
milliseconds of STFT window length. Defaults to None.
hop_length (int, optional):
number of frames between STFT columns. Used if ```frame_shift_ms``` is None. Defaults to None.
win_length (int, optional):
STFT window length. Used if ```frame_length_ms``` is None. Defaults to None.
ref_level_db (int, optional):
reference DB level to avoid background noise. In general <20DB corresponds to the air noise. Defaults to None.
fft_size (int, optional):
FFT window size for STFT. Defaults to 1024.
power (int, optional):
Exponent value applied to the spectrogram before GriffinLim. Defaults to None.
preemphasis (float, optional):
Preemphasis coefficient. Preemphasis is disabled if == 0.0. Defaults to 0.0.
signal_norm (bool, optional):
enable/disable signal normalization. Defaults to None.
symmetric_norm (bool, optional):
enable/disable symmetric normalization. If set True normalization is performed in the range [-k, k] else [0, k], Defaults to None.
max_norm (float, optional):
```k``` defining the normalization range. Defaults to None.
mel_fmin (int, optional):
minimum filter frequency for computing melspectrograms. Defaults to None.
mel_fmax (int, optional):
maximum filter frequency for computing melspectrograms. Defaults to None.
pitch_fmin (int, optional):
minimum filter frequency for computing pitch. Defaults to None.
pitch_fmax (int, optional):
maximum filter frequency for computing pitch. Defaults to None.
spec_gain (int, optional):
gain applied when converting amplitude to DB. Defaults to 20.
stft_pad_mode (str, optional):
Padding mode for STFT. Defaults to 'reflect'.
clip_norm (bool, optional):
enable/disable clipping the our of range values in the normalized audio signal. Defaults to True.
griffin_lim_iters (int, optional):
Number of GriffinLim iterations. Defaults to None.
do_trim_silence (bool, optional):
enable/disable silence trimming when loading the audio signal. Defaults to False.
trim_db (int, optional):
DB threshold used for silence trimming. Defaults to 60.
do_sound_norm (bool, optional):
enable/disable signal normalization. Defaults to False.
do_amp_to_db_linear (bool, optional):
enable/disable amplitude to dB conversion of linear spectrograms. Defaults to True.
do_amp_to_db_mel (bool, optional):
enable/disable amplitude to dB conversion of mel spectrograms. Defaults to True.
do_rms_norm (bool, optional):
enable/disable RMS volume normalization when loading an audio file. Defaults to False.
db_level (int, optional):
dB level used for rms normalization. The range is -99 to 0. Defaults to None.
stats_path (str, optional):
Path to the computed stats file. Defaults to None.
verbose (bool, optional):
enable/disable logging. Defaults to True.
"""
def __init__(
self,
sample_rate=None,
resample=False,
num_mels=None,
log_func="np.log10",
min_level_db=None,
frame_shift_ms=None,
frame_length_ms=None,
hop_length=None,
win_length=None,
ref_level_db=None,
fft_size=1024,
power=None,
preemphasis=0.0,
signal_norm=None,
symmetric_norm=None,
max_norm=None,
mel_fmin=None,
mel_fmax=None,
pitch_fmax=None,
pitch_fmin=None,
spec_gain=20,
stft_pad_mode="reflect",
clip_norm=True,
griffin_lim_iters=None,
do_trim_silence=False,
trim_db=60,
do_sound_norm=False,
do_amp_to_db_linear=True,
do_amp_to_db_mel=True,
do_rms_norm=False,
db_level=None,
stats_path=None,
verbose=True,
**_,
):
# setup class attributed
self.sample_rate = sample_rate
self.resample = resample
self.num_mels = num_mels
self.log_func = log_func
self.min_level_db = min_level_db or 0
self.frame_shift_ms = frame_shift_ms
self.frame_length_ms = frame_length_ms
self.ref_level_db = ref_level_db
self.fft_size = fft_size
self.power = power
self.preemphasis = preemphasis
self.griffin_lim_iters = griffin_lim_iters
self.signal_norm = signal_norm
self.symmetric_norm = symmetric_norm
self.mel_fmin = mel_fmin or 0
self.mel_fmax = mel_fmax
self.pitch_fmin = pitch_fmin
self.pitch_fmax = pitch_fmax
self.spec_gain = float(spec_gain)
self.stft_pad_mode = stft_pad_mode
self.max_norm = 1.0 if max_norm is None else float(max_norm)
self.clip_norm = clip_norm
self.do_trim_silence = do_trim_silence
self.trim_db = trim_db
self.do_sound_norm = do_sound_norm
self.do_amp_to_db_linear = do_amp_to_db_linear
self.do_amp_to_db_mel = do_amp_to_db_mel
self.do_rms_norm = do_rms_norm
self.db_level = db_level
self.stats_path = stats_path
# setup exp_func for db to amp conversion
if log_func == "np.log":
self.base = np.e
elif log_func == "np.log10":
self.base = 10
else:
raise ValueError(" [!] unknown `log_func` value.")
# setup stft parameters
if hop_length is None:
# compute stft parameters from given time values
self.hop_length, self.win_length = self._stft_parameters()
else:
# use stft parameters from config file
self.hop_length = hop_length
self.win_length = win_length
assert min_level_db != 0.0, " [!] min_level_db is 0"
assert (
self.win_length <= self.fft_size
), f" [!] win_length cannot be larger than fft_size - {self.win_length} vs {self.fft_size}"
members = vars(self)
if verbose:
print(" > Setting up Audio Processor...")
for key, value in members.items():
print(" | > {}:{}".format(key, value))
# create spectrogram utils
self.mel_basis = self._build_mel_basis()
self.inv_mel_basis = np.linalg.pinv(self._build_mel_basis())
# setup scaler
if stats_path and signal_norm:
mel_mean, mel_std, linear_mean, linear_std, _ = self.load_stats(stats_path)
self.setup_scaler(mel_mean, mel_std, linear_mean, linear_std)
self.signal_norm = True
self.max_norm = None
self.clip_norm = None
self.symmetric_norm = None
@staticmethod
def init_from_config(config: "Coqpit", verbose=True):
if "audio" in config:
return AudioProcessor(verbose=verbose, **config.audio)
return AudioProcessor(verbose=verbose, **config)
### setting up the parameters ###
def _build_mel_basis(
self,
) -> np.ndarray:
"""Build melspectrogram basis.
Returns:
np.ndarray: melspectrogram basis.
"""
if self.mel_fmax is not None:
assert self.mel_fmax <= self.sample_rate // 2
return librosa.filters.mel(
sr=self.sample_rate, n_fft=self.fft_size, n_mels=self.num_mels, fmin=self.mel_fmin, fmax=self.mel_fmax
)
def _stft_parameters(
self,
) -> Tuple[int, int]:
"""Compute the real STFT parameters from the time values.
Returns:
Tuple[int, int]: hop length and window length for STFT.
"""
factor = self.frame_length_ms / self.frame_shift_ms
assert (factor).is_integer(), " [!] frame_shift_ms should divide frame_length_ms"
hop_length = int(self.frame_shift_ms / 1000.0 * self.sample_rate)
win_length = int(hop_length * factor)
return hop_length, win_length
### normalization ###
def normalize(self, S: np.ndarray) -> np.ndarray:
"""Normalize values into `[0, self.max_norm]` or `[-self.max_norm, self.max_norm]`
Args:
S (np.ndarray): Spectrogram to normalize.
Raises:
RuntimeError: Mean and variance is computed from incompatible parameters.
Returns:
np.ndarray: Normalized spectrogram.
"""
# pylint: disable=no-else-return
S = S.copy()
if self.signal_norm:
# mean-var scaling
if hasattr(self, "mel_scaler"):
if S.shape[0] == self.num_mels:
return self.mel_scaler.transform(S.T).T
elif S.shape[0] == self.fft_size / 2:
return self.linear_scaler.transform(S.T).T
else:
raise RuntimeError(" [!] Mean-Var stats does not match the given feature dimensions.")
# range normalization
S -= self.ref_level_db # discard certain range of DB assuming it is air noise
S_norm = (S - self.min_level_db) / (-self.min_level_db)
if self.symmetric_norm:
S_norm = ((2 * self.max_norm) * S_norm) - self.max_norm
if self.clip_norm:
S_norm = np.clip(
S_norm, -self.max_norm, self.max_norm # pylint: disable=invalid-unary-operand-type
)
return S_norm
else:
S_norm = self.max_norm * S_norm
if self.clip_norm:
S_norm = np.clip(S_norm, 0, self.max_norm)
return S_norm
else:
return S
def denormalize(self, S: np.ndarray) -> np.ndarray:
"""Denormalize spectrogram values.
Args:
S (np.ndarray): Spectrogram to denormalize.
Raises:
RuntimeError: Mean and variance are incompatible.
Returns:
np.ndarray: Denormalized spectrogram.
"""
# pylint: disable=no-else-return
S_denorm = S.copy()
if self.signal_norm:
# mean-var scaling
if hasattr(self, "mel_scaler"):
if S_denorm.shape[0] == self.num_mels:
return self.mel_scaler.inverse_transform(S_denorm.T).T
elif S_denorm.shape[0] == self.fft_size / 2:
return self.linear_scaler.inverse_transform(S_denorm.T).T
else:
raise RuntimeError(" [!] Mean-Var stats does not match the given feature dimensions.")
if self.symmetric_norm:
if self.clip_norm:
S_denorm = np.clip(
S_denorm, -self.max_norm, self.max_norm # pylint: disable=invalid-unary-operand-type
)
S_denorm = ((S_denorm + self.max_norm) * -self.min_level_db / (2 * self.max_norm)) + self.min_level_db
return S_denorm + self.ref_level_db
else:
if self.clip_norm:
S_denorm = np.clip(S_denorm, 0, self.max_norm)
S_denorm = (S_denorm * -self.min_level_db / self.max_norm) + self.min_level_db
return S_denorm + self.ref_level_db
else:
return S_denorm
### Mean-STD scaling ###
def load_stats(self, stats_path: str) -> Tuple[np.array, np.array, np.array, np.array, Dict]:
"""Loading mean and variance statistics from a `npy` file.
Args:
stats_path (str): Path to the `npy` file containing
Returns:
Tuple[np.array, np.array, np.array, np.array, Dict]: loaded statistics and the config used to
compute them.
"""
stats = np.load(stats_path, allow_pickle=True).item() # pylint: disable=unexpected-keyword-arg
mel_mean = stats["mel_mean"]
mel_std = stats["mel_std"]
linear_mean = stats["linear_mean"]
linear_std = stats["linear_std"]
stats_config = stats["audio_config"]
# check all audio parameters used for computing stats
skip_parameters = ["griffin_lim_iters", "stats_path", "do_trim_silence", "ref_level_db", "power"]
for key in stats_config.keys():
if key in skip_parameters:
continue
if key not in ["sample_rate", "trim_db"]:
assert (
stats_config[key] == self.__dict__[key]
), f" [!] Audio param {key} does not match the value used for computing mean-var stats. {stats_config[key]} vs {self.__dict__[key]}"
return mel_mean, mel_std, linear_mean, linear_std, stats_config
# pylint: disable=attribute-defined-outside-init
def setup_scaler(
self, mel_mean: np.ndarray, mel_std: np.ndarray, linear_mean: np.ndarray, linear_std: np.ndarray
) -> None:
"""Initialize scaler objects used in mean-std normalization.
Args:
mel_mean (np.ndarray): Mean for melspectrograms.
mel_std (np.ndarray): STD for melspectrograms.
linear_mean (np.ndarray): Mean for full scale spectrograms.
linear_std (np.ndarray): STD for full scale spectrograms.
"""
self.mel_scaler = StandardScaler()
self.mel_scaler.set_stats(mel_mean, mel_std)
self.linear_scaler = StandardScaler()
self.linear_scaler.set_stats(linear_mean, linear_std)
### DB and AMP conversion ###
# pylint: disable=no-self-use
def _amp_to_db(self, x: np.ndarray) -> np.ndarray:
"""Convert amplitude values to decibels.
Args:
x (np.ndarray): Amplitude spectrogram.
Returns:
np.ndarray: Decibels spectrogram.
"""
return self.spec_gain * _log(np.maximum(1e-5, x), self.base)
# pylint: disable=no-self-use
def _db_to_amp(self, x: np.ndarray) -> np.ndarray:
"""Convert decibels spectrogram to amplitude spectrogram.
Args:
x (np.ndarray): Decibels spectrogram.
Returns:
np.ndarray: Amplitude spectrogram.
"""
return _exp(x / self.spec_gain, self.base)
### Preemphasis ###
def apply_preemphasis(self, x: np.ndarray) -> np.ndarray:
"""Apply pre-emphasis to the audio signal. Useful to reduce the correlation between neighbouring signal values.
Args:
x (np.ndarray): Audio signal.
Raises:
RuntimeError: Preemphasis coeff is set to 0.
Returns:
np.ndarray: Decorrelated audio signal.
"""
if self.preemphasis == 0:
raise RuntimeError(" [!] Preemphasis is set 0.0.")
return scipy.signal.lfilter([1, -self.preemphasis], [1], x)
def apply_inv_preemphasis(self, x: np.ndarray) -> np.ndarray:
"""Reverse pre-emphasis."""
if self.preemphasis == 0:
raise RuntimeError(" [!] Preemphasis is set 0.0.")
return scipy.signal.lfilter([1], [1, -self.preemphasis], x)
### SPECTROGRAMs ###
def _linear_to_mel(self, spectrogram: np.ndarray) -> np.ndarray:
"""Project a full scale spectrogram to a melspectrogram.
Args:
spectrogram (np.ndarray): Full scale spectrogram.
Returns:
np.ndarray: Melspectrogram
"""
return np.dot(self.mel_basis, spectrogram)
def _mel_to_linear(self, mel_spec: np.ndarray) -> np.ndarray:
"""Convert a melspectrogram to full scale spectrogram."""
return np.maximum(1e-10, np.dot(self.inv_mel_basis, mel_spec))
def spectrogram(self, y: np.ndarray) -> np.ndarray:
"""Compute a spectrogram from a waveform.
Args:
y (np.ndarray): Waveform.
Returns:
np.ndarray: Spectrogram.
"""
if self.preemphasis != 0:
D = self._stft(self.apply_preemphasis(y))
else:
D = self._stft(y)
if self.do_amp_to_db_linear:
S = self._amp_to_db(np.abs(D))
else:
S = np.abs(D)
return self.normalize(S).astype(np.float32)
def melspectrogram(self, y: np.ndarray) -> np.ndarray:
"""Compute a melspectrogram from a waveform."""
if self.preemphasis != 0:
D = self._stft(self.apply_preemphasis(y))
else:
D = self._stft(y)
if self.do_amp_to_db_mel:
S = self._amp_to_db(self._linear_to_mel(np.abs(D)))
else:
S = self._linear_to_mel(np.abs(D))
return self.normalize(S).astype(np.float32)
def inv_spectrogram(self, spectrogram: np.ndarray) -> np.ndarray:
"""Convert a spectrogram to a waveform using Griffi-Lim vocoder."""
S = self.denormalize(spectrogram)
S = self._db_to_amp(S)
# Reconstruct phase
if self.preemphasis != 0:
return self.apply_inv_preemphasis(self._griffin_lim(S**self.power))
return self._griffin_lim(S**self.power)
def inv_melspectrogram(self, mel_spectrogram: np.ndarray) -> np.ndarray:
"""Convert a melspectrogram to a waveform using Griffi-Lim vocoder."""
D = self.denormalize(mel_spectrogram)
S = self._db_to_amp(D)
S = self._mel_to_linear(S) # Convert back to linear
if self.preemphasis != 0:
return self.apply_inv_preemphasis(self._griffin_lim(S**self.power))
return self._griffin_lim(S**self.power)
def out_linear_to_mel(self, linear_spec: np.ndarray) -> np.ndarray:
"""Convert a full scale linear spectrogram output of a network to a melspectrogram.
Args:
linear_spec (np.ndarray): Normalized full scale linear spectrogram.
Returns:
np.ndarray: Normalized melspectrogram.
"""
S = self.denormalize(linear_spec)
S = self._db_to_amp(S)
S = self._linear_to_mel(np.abs(S))
S = self._amp_to_db(S)
mel = self.normalize(S)
return mel
### STFT and ISTFT ###
def _stft(self, y: np.ndarray) -> np.ndarray:
"""Librosa STFT wrapper.
Args:
y (np.ndarray): Audio signal.
Returns:
np.ndarray: Complex number array.
"""
return librosa.stft(
y=y,
n_fft=self.fft_size,
hop_length=self.hop_length,
win_length=self.win_length,
pad_mode=self.stft_pad_mode,
window="hann",
center=True,
)
def _istft(self, y: np.ndarray) -> np.ndarray:
"""Librosa iSTFT wrapper."""
return librosa.istft(y, hop_length=self.hop_length, win_length=self.win_length)
def _griffin_lim(self, S):
angles = np.exp(2j * np.pi * np.random.rand(*S.shape))
try:
S_complex = np.abs(S).astype(np.complex)
except AttributeError: # np.complex is deprecated since numpy 1.20.0
S_complex = np.abs(S).astype(complex)
y = self._istft(S_complex * angles)
if not np.isfinite(y).all():
print(" [!] Waveform is not finite everywhere. Skipping the GL.")
return np.array([0.0])
for _ in range(self.griffin_lim_iters):
angles = np.exp(1j * np.angle(self._stft(y)))
y = self._istft(S_complex * angles)
return y
def compute_stft_paddings(self, x, pad_sides=1):
"""Compute paddings used by Librosa's STFT. Compute right padding (final frame) or both sides padding
(first and final frames)"""
assert pad_sides in (1, 2)
pad = (x.shape[0] // self.hop_length + 1) * self.hop_length - x.shape[0]
if pad_sides == 1:
return 0, pad
return pad // 2, pad // 2 + pad % 2
def compute_f0(self, x: np.ndarray) -> np.ndarray:
"""Compute pitch (f0) of a waveform using the same parameters used for computing melspectrogram.
Args:
x (np.ndarray): Waveform.
Returns:
np.ndarray: Pitch.
Examples:
>>> WAV_FILE = filename = librosa.example('vibeace')
>>> from TTS.config import BaseAudioConfig
>>> from TTS.utils.audio import AudioProcessor
>>> conf = BaseAudioConfig(pitch_fmax=640, pitch_fmin=1)
>>> ap = AudioProcessor(**conf)
>>> wav = ap.load_wav(WAV_FILE, sr=ap.sample_rate)[:5 * ap.sample_rate]
>>> pitch = ap.compute_f0(wav)
"""
assert self.pitch_fmax is not None, " [!] Set `pitch_fmax` before caling `compute_f0`."
assert self.pitch_fmin is not None, " [!] Set `pitch_fmin` before caling `compute_f0`."
# align F0 length to the spectrogram length
if len(x) % self.hop_length == 0:
x = np.pad(x, (0, self.hop_length // 2), mode=self.stft_pad_mode)
f0 = compute_f0(
x=x,
pitch_fmax=self.pitch_fmax,
pitch_fmin=self.pitch_fmin,
hop_length=self.hop_length,
win_length=self.win_length,
sample_rate=self.sample_rate,
stft_pad_mode=self.stft_pad_mode,
center=True,
)
return f0
### Audio Processing ###
def find_endpoint(self, wav: np.ndarray, min_silence_sec=0.8) -> int:
"""Find the last point without silence at the end of a audio signal.
Args:
wav (np.ndarray): Audio signal.
threshold_db (int, optional): Silence threshold in decibels. Defaults to -40.
min_silence_sec (float, optional): Ignore silences that are shorter then this in secs. Defaults to 0.8.
Returns:
int: Last point without silence.
"""
window_length = int(self.sample_rate * min_silence_sec)
hop_length = int(window_length / 4)
threshold = self._db_to_amp(-self.trim_db)
for x in range(hop_length, len(wav) - window_length, hop_length):
if np.max(wav[x : x + window_length]) < threshold:
return x + hop_length
return len(wav)
def trim_silence(self, wav):
"""Trim silent parts with a threshold and 0.01 sec margin"""
margin = int(self.sample_rate * 0.01)
wav = wav[margin:-margin]
return librosa.effects.trim(wav, top_db=self.trim_db, frame_length=self.win_length, hop_length=self.hop_length)[
0
]
@staticmethod
def sound_norm(x: np.ndarray) -> np.ndarray:
"""Normalize the volume of an audio signal.
Args:
x (np.ndarray): Raw waveform.
Returns:
np.ndarray: Volume normalized waveform.
"""
return x / abs(x).max() * 0.95
@staticmethod
def _rms_norm(wav, db_level=-27):
r = 10 ** (db_level / 20)
a = np.sqrt((len(wav) * (r**2)) / np.sum(wav**2))
return wav * a
def rms_volume_norm(self, x: np.ndarray, db_level: float = None) -> np.ndarray:
"""Normalize the volume based on RMS of the signal.
Args:
x (np.ndarray): Raw waveform.
Returns:
np.ndarray: RMS normalized waveform.
"""
if db_level is None:
db_level = self.db_level
assert -99 <= db_level <= 0, " [!] db_level should be between -99 and 0"
wav = self._rms_norm(x, db_level)
return wav
### save and load ###
def load_wav(self, filename: str, sr: int = None) -> np.ndarray:
"""Read a wav file using Librosa and optionally resample, silence trim, volume normalize.
Resampling slows down loading the file significantly. Therefore it is recommended to resample the file before.
Args:
filename (str): Path to the wav file.
sr (int, optional): Sampling rate for resampling. Defaults to None.
Returns:
np.ndarray: Loaded waveform.
"""
if self.resample:
# loading with resampling. It is significantly slower.
x, sr = librosa.load(filename, sr=self.sample_rate)
elif sr is None:
# SF is faster than librosa for loading files
x, sr = sf.read(filename)
assert self.sample_rate == sr, "%s vs %s" % (self.sample_rate, sr)
else:
x, sr = librosa.load(filename, sr=sr)
if self.do_trim_silence:
try:
x = self.trim_silence(x)
except ValueError:
print(f" [!] File cannot be trimmed for silence - {filename}")
if self.do_sound_norm:
x = self.sound_norm(x)
if self.do_rms_norm:
x = self.rms_volume_norm(x, self.db_level)
return x
def save_wav(self, wav: np.ndarray, path: str, sr: int = None) -> None:
"""Save a waveform to a file using Scipy.
Args:
wav (np.ndarray): Waveform to save.
path (str): Path to a output file.
sr (int, optional): Sampling rate used for saving to the file. Defaults to None.
"""
if self.do_rms_norm:
wav_norm = self.rms_volume_norm(wav, self.db_level) * 32767
else:
wav_norm = wav * (32767 / max(0.01, np.max(np.abs(wav))))
scipy.io.wavfile.write(path, sr if sr else self.sample_rate, wav_norm.astype(np.int16))
def get_duration(self, filename: str) -> float:
"""Get the duration of a wav file using Librosa.
Args:
filename (str): Path to the wav file.
"""
return librosa.get_duration(filename=filename)
@staticmethod
def mulaw_encode(wav: np.ndarray, qc: int) -> np.ndarray:
mu = 2**qc - 1
# wav_abs = np.minimum(np.abs(wav), 1.0)
signal = np.sign(wav) * np.log(1 + mu * np.abs(wav)) / np.log(1.0 + mu)
# Quantize signal to the specified number of levels.
signal = (signal + 1) / 2 * mu + 0.5
return np.floor(
signal,
)
@staticmethod
def mulaw_decode(wav, qc):
"""Recovers waveform from quantized values."""
mu = 2**qc - 1
x = np.sign(wav) / mu * ((1 + mu) ** np.abs(wav) - 1)
return x
@staticmethod
def encode_16bits(x):
return np.clip(x * 2**15, -(2**15), 2**15 - 1).astype(np.int16)
@staticmethod
def quantize(x: np.ndarray, bits: int) -> np.ndarray:
"""Quantize a waveform to a given number of bits.
Args:
x (np.ndarray): Waveform to quantize. Must be normalized into the range `[-1, 1]`.
bits (int): Number of quantization bits.
Returns:
np.ndarray: Quantized waveform.
"""
return (x + 1.0) * (2**bits - 1) / 2
@staticmethod
def dequantize(x, bits):
"""Dequantize a waveform from the given number of bits."""
return 2 * x / (2**bits - 1) - 1
def _log(x, base):
if base == 10:
return np.log10(x)
return np.log(x)
def _exp(x, base):
if base == 10:
return np.power(10, x)
return np.exp(x)