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@@ -1,459 +0,0 @@
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-import numpy as np
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-from scipy.fftpack import dct
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-
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-
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-# ---------- feature-window ----------
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-
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-def sliding_window(x, window_size, window_shift):
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- shape = x.shape[:-1] + (x.shape[-1] - window_size + 1, window_size)
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- strides = x.strides + (x.strides[-1],)
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- return np.lib.stride_tricks.as_strided(x, shape=shape, strides=strides)[::window_shift]
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-
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-
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-def func_num_frames(num_samples, window_size, window_shift, snip_edges):
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- if snip_edges:
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- if num_samples < window_size:
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- return 0
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- else:
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- return 1 + ((num_samples - window_size) // window_shift)
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- else:
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- return (num_samples + (window_shift // 2)) // window_shift
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-
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-
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-def func_dither(waveform, dither_value):
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- if dither_value == 0.0:
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- return waveform
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- waveform += np.random.normal(size=waveform.shape).astype(waveform.dtype) * dither_value
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- return waveform
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-
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-
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-def func_remove_dc_offset(waveform):
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- return waveform - np.mean(waveform)
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-
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-
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-def func_log_energy(waveform):
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- return np.log(np.dot(waveform, waveform).clip(min=np.finfo(waveform.dtype).eps))
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-
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-
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-def func_preemphasis(waveform, preemph_coeff):
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- if preemph_coeff == 0.0:
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- return waveform
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- assert 0 < preemph_coeff <= 1
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- waveform[1:] -= preemph_coeff * waveform[:-1]
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- waveform[0] -= preemph_coeff * waveform[0]
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- return waveform
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-
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-
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-def sine(M):
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- if M < 1:
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- return np.array([])
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- if M == 1:
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- return np.ones(1, float)
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- n = np.arange(0, M)
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- return np.sin(np.pi*n/(M-1))
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-
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-
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-def povey(M):
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- if M < 1:
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- return np.array([])
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- if M == 1:
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- return np.ones(1, float)
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- n = np.arange(0, M)
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- return (0.5 - 0.5*np.cos(2.0*np.pi*n/(M-1)))**0.85
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-
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-
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-def feature_window_function(window_type, window_size, blackman_coeff):
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- assert window_size > 0
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- if window_type == 'hanning':
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- return np.hanning(window_size)
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- elif window_type == 'sine':
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- return sine(window_size)
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- elif window_type == 'hamming':
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- return np.hamming(window_size)
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- elif window_type == 'povey':
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- return povey(window_size)
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- elif window_type == 'rectangular':
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- return np.ones(window_size)
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- elif window_type == 'blackman':
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- window_func = np.blackman(window_size)
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- if blackman_coeff == 0.42:
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- return window_func
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- else:
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- return window_func - 0.42 + blackman_coeff
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- else:
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- raise ValueError('Invalid window type {}'.format(window_type))
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-
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-
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-def process_window(window, dither, remove_dc_offset, preemphasis_coefficient, window_function, raw_energy):
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- if dither != 0.0:
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- window = func_dither(window, dither)
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- if remove_dc_offset:
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- window = func_remove_dc_offset(window)
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- if raw_energy:
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- log_energy = func_log_energy(window)
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- if preemphasis_coefficient != 0.0:
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- window = func_preemphasis(window, preemphasis_coefficient)
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- window *= window_function
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- if not raw_energy:
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- log_energy = func_log_energy(window)
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- return window, log_energy
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-
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-
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-def extract_window(waveform, blackman_coeff, dither, window_size, window_shift,
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- preemphasis_coefficient, raw_energy, remove_dc_offset,
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- snip_edges, window_type, dtype):
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- num_samples = len(waveform)
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- num_frames = func_num_frames(num_samples, window_size, window_shift, snip_edges)
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- num_samples_ = (num_frames - 1) * window_shift + window_size
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- if snip_edges:
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- waveform = waveform[:num_samples_]
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- else:
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- offset = window_shift // 2 - window_size // 2
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- waveform = np.concatenate([
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- waveform[-offset - 1::-1],
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- waveform,
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- waveform[:-(offset + num_samples_ - num_samples + 1):-1]
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- ])
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- frames = sliding_window(waveform, window_size=window_size, window_shift=window_shift)
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- frames = frames.astype(dtype)
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- log_enery = np.empty(frames.shape[0], dtype=dtype)
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- for i in range(frames.shape[0]):
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- frames[i], log_enery[i] = process_window(
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- window=frames[i],
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- dither=dither,
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- remove_dc_offset=remove_dc_offset,
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- preemphasis_coefficient=preemphasis_coefficient,
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- window_function=feature_window_function(
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- window_type=window_type,
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- window_size=window_size,
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- blackman_coeff=blackman_coeff
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- ).astype(dtype),
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- raw_energy=raw_energy
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- )
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- return frames, log_enery
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-
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-# ---------- feature-window ----------
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-
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-
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-# ---------- feature-functions ----------
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-
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-def compute_spectrum(frames, n):
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- complex_spec = np.fft.rfft(frames, n)
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- return np.absolute(complex_spec)
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-
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-
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-def compute_power_spectrum(frames, n):
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- return np.square(compute_spectrum(frames, n))
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-
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-
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-def apply_cmvn_sliding_internal(feat, center=False, window=600, min_window=100, norm_vars=False):
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- num_frames, feat_dim = feat.shape
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- std = 1
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- if center:
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- if num_frames <= window:
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- mean = feat.mean(axis=0, keepdims=True).repeat(num_frames, axis=0)
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- if norm_vars:
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- std = feat.std(axis=0, keepdims=True).repeat(num_frames, axis=0)
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- else:
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- feat1 = feat[:window]
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- feat2 = sliding_window(feat.T, window, 1)
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- feat3 = feat[-window:]
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- mean1 = feat1.mean(axis=0, keepdims=True).repeat(window // 2, axis=0)
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- mean2 = feat2.mean(axis=2).T
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- mean3 = feat3.mean(axis=0, keepdims=True).repeat((window - 1) // 2, axis=0)
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- mean = np.concatenate([mean1, mean2, mean3])
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- if norm_vars:
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- std1 = feat1.std(axis=0, keepdims=True).repeat(window // 2, axis=0)
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- std2 = feat2.std(axis=2).T
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- std3 = feat3.mean(axis=0, keepdims=True).repeat((window - 1) // 2, axis=0)
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- std = np.concatenate([std1, std2, std3])
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- else:
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- if num_frames <= min_window:
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- mean = feat.mean(axis=0, keepdims=True).repeat(num_frames, axis=0)
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- if norm_vars:
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- std = feat.std(axis=0, keepdims=True).repeat(num_frames, axis=0)
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- else:
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- feat1 = feat[:min_window]
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- mean1 = feat1.mean(axis=0, keepdims=True).repeat(min_window, axis=0)
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- feat2_cumsum = np.cumsum(feat[:window], axis=0)[min_window:]
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- cumcnt = np.arange(min_window + 1, min(window, num_frames) + 1, dtype=feat.dtype)[:, np.newaxis]
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- mean2 = feat2_cumsum / cumcnt
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- mean = np.concatenate([mean1, mean2])
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- if norm_vars:
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- std1 = feat1.std(axis=0, keepdims=True).repeat(min_window, axis=0)
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- feat2_power_cumsum = np.cumsum(np.square(feat[:window]), axis=0)[min_window:]
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- std2 = np.sqrt(feat2_power_cumsum / cumcnt - np.square(mean2))
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- std = np.concatenate([std1, std2])
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- if num_frames > window:
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- feat3 = sliding_window(feat.T, window, 1)
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- mean3 = feat3.mean(axis=2).T
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- mean = np.concatenate([mean, mean3[1:]])
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- if norm_vars:
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- std3 = feat3.std(axis=2).T
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- std = np.concatenate([std, std3[1:]])
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- feat = (feat - mean) / std
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- return feat
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-
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-# ---------- feature-functions ----------
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-
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-
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-# ---------- mel-computations ----------
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-
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-def inverse_mel_scale(mel_freq):
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- return 700.0 * (np.exp(mel_freq / 1127.0) - 1.0)
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-
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-
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-def mel_scale(freq):
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- return 1127.0 * np.log(1.0 + freq / 700.0)
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-
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-
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-def compute_mel_banks(num_bins, sample_frequency, low_freq, high_freq, n):
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- """ Compute Mel banks.
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-
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- :param num_bins: Number of triangular mel-frequency bins
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- :param sample_frequency: Waveform data sample frequency
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- :param low_freq: Low cutoff frequency for mel bins
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- :param high_freq: High cutoff frequency for mel bins (if <= 0, offset from Nyquist)
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- :param n: Window size
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- :return: Mel banks.
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- """
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- assert num_bins >= 3, 'Must have at least 3 mel bins'
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- num_fft_bins = n // 2
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-
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- nyquist = 0.5 * sample_frequency
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- if high_freq <= 0:
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- high_freq = nyquist + high_freq
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- assert 0 <= low_freq < high_freq <= nyquist
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-
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- fft_bin_width = sample_frequency / n
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-
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- mel_low_freq = mel_scale(low_freq)
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- mel_high_freq = mel_scale(high_freq)
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- mel_freq_delta = (mel_high_freq - mel_low_freq) / (num_bins + 1)
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-
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- mel_banks = np.zeros([num_bins, num_fft_bins + 1])
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- for i in range(num_bins):
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- left_mel = mel_low_freq + mel_freq_delta * i
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- center_mel = left_mel + mel_freq_delta
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- right_mel = center_mel + mel_freq_delta
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- for j in range(num_fft_bins):
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- mel = mel_scale(fft_bin_width * j)
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- if left_mel < mel < right_mel:
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- if mel <= center_mel:
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- mel_banks[i, j] = (mel - left_mel) / (center_mel - left_mel)
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- else:
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- mel_banks[i, j] = (right_mel - mel) / (right_mel - center_mel)
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- return mel_banks
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-
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-
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-def compute_lifter_coeffs(q, M):
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- """ Compute liftering coefficients (scaling on cepstral coeffs)
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- the zeroth index is C0, which is not affected.
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-
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- :param q: Number of lifters
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- :param M: Number of coefficients
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- :return: Lifters.
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- """
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- if M < 1:
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- return np.array([])
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- if M == 1:
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- return np.ones(1, float)
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- n = np.arange(0, M)
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- return 1 + 0.5*np.sin(np.pi*n/q)*q
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-
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-# ---------- mel-computations ----------
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-
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-
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-# ---------- compute-fbank-feats ----------
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-
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-def compute_fbank_feats(
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- waveform,
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- blackman_coeff=0.42,
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- dither=1.0,
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- energy_floor=1.0,
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- frame_length=25,
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- frame_shift=10,
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- high_freq=0,
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- low_freq=20,
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- num_mel_bins=23,
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- preemphasis_coefficient=0.97,
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- raw_energy=True,
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- remove_dc_offset=True,
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- round_to_power_of_two=True,
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- sample_frequency=16000,
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- snip_edges=True,
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- use_energy=False,
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- use_log_fbank=True,
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- use_power=True,
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- window_type='povey',
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- dtype=np.float32):
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- """ Compute (log) Mel filter bank energies
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-
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- :param waveform: Input waveform.
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- :param blackman_coeff: Constant coefficient for generalized Blackman window. (float, default = 0.42)
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- :param dither: Dithering constant (0.0 means no dither). If you turn this off, you should set the --energy-floor option, e.g. to 1.0 or 0.1 (float, default = 1)
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- :param energy_floor: Floor on energy (absolute, not relative) in FBANK computation. Only makes a difference if --use-energy=true; only necessary if --dither=0.0. Suggested values: 0.1 or 1.0 (float, default = 0)
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- :param frame_length: Frame length in milliseconds (float, default = 25)
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- :param frame_shift: Frame shift in milliseconds (float, default = 10)
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- :param high_freq: High cutoff frequency for mel bins (if <= 0, offset from Nyquist) (float, default = 0)
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- :param low_freq: Low cutoff frequency for mel bins (float, default = 20)
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- :param num_mel_bins: Number of triangular mel-frequency bins (int, default = 23)
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- :param preemphasis_coefficient: Coefficient for use in signal preemphasis (float, default = 0.97)
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- :param raw_energy: If true, compute energy before preemphasis and windowing (bool, default = true)
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- :param remove_dc_offset: Subtract mean from waveform on each frame (bool, default = true)
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- :param round_to_power_of_two: If true, round window size to power of two by zero-padding input to FFT. (bool, default = true)
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- :param sample_frequency: Waveform data sample frequency (must match the waveform file, if specified there) (float, default = 16000)
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- :param snip_edges: If true, end effects will be handled by outputting only frames that completely fit in the file, and the number of frames depends on the frame-length. If false, the number of frames depends only on the frame-shift, and we reflect the data at the ends. (bool, default = true)
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- :param use_energy: Add an extra energy output. (bool, default = false)
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- :param use_log_fbank: If true, produce log-filterbank, else produce linear. (bool, default = true)
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- :param use_power: If true, use power, else use magnitude. (bool, default = true)
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- :param window_type: Type of window ("hamming"|"hanning"|"povey"|"rectangular"|"sine"|"blackmann") (string, default = "povey")
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- :param dtype: Type of array (np.float32|np.float64) (dtype or string, default=np.float32)
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- :return: (Log) Mel filter bank energies.
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- """
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- window_size = int(frame_length * sample_frequency * 0.001)
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- window_shift = int(frame_shift * sample_frequency * 0.001)
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- frames, log_energy = extract_window(
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- waveform=waveform,
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- blackman_coeff=blackman_coeff,
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- dither=dither,
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- window_size=window_size,
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- window_shift=window_shift,
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- preemphasis_coefficient=preemphasis_coefficient,
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- raw_energy=raw_energy,
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- remove_dc_offset=remove_dc_offset,
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- snip_edges=snip_edges,
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- window_type=window_type,
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- dtype=dtype
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- )
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- if round_to_power_of_two:
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- n = 1
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- while n < window_size:
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- n *= 2
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- else:
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- n = window_size
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- if use_power:
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- spectrum = compute_power_spectrum(frames, n)
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- else:
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- spectrum = compute_spectrum(frames, n)
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- mel_banks = compute_mel_banks(
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- num_bins=num_mel_bins,
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- sample_frequency=sample_frequency,
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- low_freq=low_freq,
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- high_freq=high_freq,
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- n=n
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- ).astype(dtype)
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- feat = np.dot(spectrum, mel_banks.T)
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- if use_log_fbank:
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- feat = np.log(feat.clip(min=np.finfo(dtype).eps))
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- if use_energy:
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- if energy_floor > 0.0:
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- log_energy.clip(min=np.math.log(energy_floor))
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- return feat, log_energy
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- return feat
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-
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-# ---------- compute-fbank-feats ----------
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-
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-
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-# ---------- compute-mfcc-feats ----------
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-
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-def compute_mfcc_feats(
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- waveform,
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- blackman_coeff=0.42,
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- cepstral_lifter=22,
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- dither=1.0,
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- energy_floor=0.0,
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- frame_length=25,
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- frame_shift=10,
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- high_freq=0,
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- low_freq=20,
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- num_ceps=13,
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- num_mel_bins=23,
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- preemphasis_coefficient=0.97,
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- raw_energy=True,
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- remove_dc_offset=True,
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- round_to_power_of_two=True,
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- sample_frequency=16000,
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- snip_edges=True,
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- use_energy=True,
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- window_type='povey',
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- dtype=np.float32):
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- """ Compute mel-frequency cepstral coefficients
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-
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- :param waveform: Input waveform.
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- :param blackman_coeff: Constant coefficient for generalized Blackman window. (float, default = 0.42)
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- :param cepstral_lifter: Constant that controls scaling of MFCCs (float, default = 22)
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- :param dither: Dithering constant (0.0 means no dither). If you turn this off, you should set the --energy-floor option, e.g. to 1.0 or 0.1 (float, default = 1)
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- :param energy_floor: Floor on energy (absolute, not relative) in MFCC computation. Only makes a difference if --use-energy=true; only necessary if --dither=0.0. Suggested values: 0.1 or 1.0 (float, default = 0)
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- :param frame_length: Frame length in milliseconds (float, default = 25)
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- :param frame_shift: Frame shift in milliseconds (float, default = 10)
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- :param high_freq: High cutoff frequency for mel bins (if <= 0, offset from Nyquist) (float, default = 0)
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- :param low_freq: Low cutoff frequency for mel bins (float, default = 20)
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- :param num_ceps: Number of cepstra in MFCC computation (including C0) (int, default = 13)
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|
- :param num_mel_bins: Number of triangular mel-frequency bins (int, default = 23)
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- :param preemphasis_coefficient: Coefficient for use in signal preemphasis (float, default = 0.97)
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- :param raw_energy: If true, compute energy before preemphasis and windowing (bool, default = true)
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|
- :param remove_dc_offset: Subtract mean from waveform on each frame (bool, default = true)
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|
- :param round_to_power_of_two: If true, round window size to power of two by zero-padding input to FFT. (bool, default = true)
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|
- :param sample_frequency: Waveform data sample frequency (must match the waveform file, if specified there) (float, default = 16000)
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|
- :param snip_edges: If true, end effects will be handled by outputting only frames that completely fit in the file, and the number of frames depends on the frame-length. If false, the number of frames depends only on the frame-shift, and we reflect the data at the ends. (bool, default = true)
|
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|
- :param use_energy: Use energy (not C0) in MFCC computation (bool, default = true)
|
|
|
- :param window_type: Type of window ("hamming"|"hanning"|"povey"|"rectangular"|"sine"|"blackmann") (string, default = "povey")
|
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|
- :param dtype: Type of array (np.float32|np.float64) (dtype or string, default=np.float32)
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- :return: Mel-frequency cespstral coefficients.
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|
|
- """
|
|
|
- feat, log_energy = compute_fbank_feats(
|
|
|
- waveform=waveform,
|
|
|
- blackman_coeff=blackman_coeff,
|
|
|
- dither=dither,
|
|
|
- energy_floor=energy_floor,
|
|
|
- frame_length=frame_length,
|
|
|
- frame_shift=frame_shift,
|
|
|
- high_freq=high_freq,
|
|
|
- low_freq=low_freq,
|
|
|
- num_mel_bins=num_mel_bins,
|
|
|
- preemphasis_coefficient=preemphasis_coefficient,
|
|
|
- raw_energy=raw_energy,
|
|
|
- remove_dc_offset=remove_dc_offset,
|
|
|
- round_to_power_of_two=round_to_power_of_two,
|
|
|
- sample_frequency=sample_frequency,
|
|
|
- snip_edges=snip_edges,
|
|
|
- use_energy=use_energy,
|
|
|
- use_log_fbank=True,
|
|
|
- use_power=True,
|
|
|
- window_type=window_type,
|
|
|
- dtype=dtype
|
|
|
- )
|
|
|
- feat = dct(feat, type=2, axis=1, norm='ortho')[:, :num_ceps]
|
|
|
- lifter_coeffs = compute_lifter_coeffs(cepstral_lifter, num_ceps).astype(dtype)
|
|
|
- feat = feat * lifter_coeffs
|
|
|
- if use_energy:
|
|
|
- feat[:, 0] = log_energy
|
|
|
- return feat
|
|
|
-
|
|
|
-# ---------- compute-mfcc-feats ----------
|
|
|
-
|
|
|
-
|
|
|
-# ---------- apply-cmvn-sliding ----------
|
|
|
-
|
|
|
-def apply_cmvn_sliding(feat, center=False, window=600, min_window=100, norm_vars=False):
|
|
|
- """ Apply sliding-window cepstral mean (and optionally variance) normalization
|
|
|
-
|
|
|
- :param feat: Cepstrum.
|
|
|
- :param center: If true, use a window centered on the current frame (to the extent possible, modulo end effects). If false, window is to the left. (bool, default = false)
|
|
|
- :param window: Window in frames for running average CMN computation (int, default = 600)
|
|
|
- :param min_window: Minimum CMN window used at start of decoding (adds latency only at start). Only applicable if center == false, ignored if center==true (int, default = 100)
|
|
|
- :param norm_vars: If true, normalize variance to one. (bool, default = false)
|
|
|
- :return: Normalized cepstrum.
|
|
|
- """
|
|
|
- # double-precision
|
|
|
- feat = apply_cmvn_sliding_internal(
|
|
|
- feat=feat.astype(np.float64),
|
|
|
- center=center,
|
|
|
- window=window,
|
|
|
- min_window=min_window,
|
|
|
- norm_vars=norm_vars
|
|
|
- ).astype(feat.dtype)
|
|
|
- return feat
|
|
|
-
|
|
|
-# ---------- apply-cmvn-sliding ----------
|