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import torch
import numpy as np
import librosa.util as librosa_util
from scipy.signal import get_window
def window_sumsquare(
window,
n_frames,
hop_length,
win_length,
n_fft,
dtype=np.float32,
norm=None,
):
"""
# from librosa 0.6
Compute the sum-square envelope of a window function at a given hop length.
This is used to estimate modulation effects induced by windowing
observations in short-time fourier transforms.
Parameters
----------
window : string, tuple, number, callable, or list-like
Window specification, as in `get_window`
n_frames : int > 0
The number of analysis frames
hop_length : int > 0
The number of samples to advance between frames
win_length : [optional]
The length of the window function. By default, this matches `n_fft`.
n_fft : int > 0
The length of each analysis frame.
dtype : np.dtype
The data type of the output
Returns
-------
wss : np.ndarray, shape=`(n_fft + hop_length * (n_frames - 1))`
The sum-squared envelope of the window function
"""
if win_length is None:
win_length = n_fft
n = n_fft + hop_length * (n_frames - 1)
x = np.zeros(n, dtype=dtype)
# Compute the squared window at the desired length
win_sq = get_window(window, win_length, fftbins=True)
win_sq = librosa_util.normalize(win_sq, norm=norm) ** 2
win_sq = librosa_util.pad_center(win_sq, n_fft)
# Fill the envelope
for i in range(n_frames):
sample = i * hop_length
x[sample : min(n, sample + n_fft)] += win_sq[: max(0, min(n_fft, n - sample))]
return x
def griffin_lim(magnitudes, stft_fn, n_iters=30):
"""
PARAMS
------
magnitudes: spectrogram magnitudes
stft_fn: STFT class with transform (STFT) and inverse (ISTFT) methods
"""
angles = np.angle(np.exp(2j * np.pi * np.random.rand(*magnitudes.size())))
angles = angles.astype(np.float32)
angles = torch.autograd.Variable(torch.from_numpy(angles))
signal = stft_fn.inverse(magnitudes, angles).squeeze(1)
for i in range(n_iters):
_, angles = stft_fn.transform(signal)
signal = stft_fn.inverse(magnitudes, angles).squeeze(1)
return signal
def dynamic_range_compression(x, normalize_fun=torch.log, C=1, clip_val=1e-5):
"""
PARAMS
------
C: compression factor
"""
return normalize_fun(torch.clamp(x, min=clip_val) * C)
def dynamic_range_decompression(x, C=1):
"""
PARAMS
------
C: compression factor used to compress
"""
return torch.exp(x) / C
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