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import math
import numbers
from typing import Optional
import numpy as np
from fairseq.data.audio.feature_transforms import (
AudioFeatureTransform,
register_audio_feature_transform,
)
@register_audio_feature_transform("specaugment")
class SpecAugmentTransform(AudioFeatureTransform):
"""SpecAugment (https://arxiv.org/abs/1904.08779)"""
@classmethod
def from_config_dict(cls, config=None):
_config = {} if config is None else config
return SpecAugmentTransform(
_config.get("time_warp_W", 0),
_config.get("freq_mask_N", 0),
_config.get("freq_mask_F", 0),
_config.get("time_mask_N", 0),
_config.get("time_mask_T", 0),
_config.get("time_mask_p", 0.0),
_config.get("mask_value", None),
)
def __init__(
self,
time_warp_w: int = 0,
freq_mask_n: int = 0,
freq_mask_f: int = 0,
time_mask_n: int = 0,
time_mask_t: int = 0,
time_mask_p: float = 0.0,
mask_value: Optional[float] = 0.0,
):
# Sanity checks
assert mask_value is None or isinstance(
mask_value, numbers.Number
), f"mask_value (type: {type(mask_value)}) must be None or a number"
if freq_mask_n > 0:
assert freq_mask_f > 0, (
f"freq_mask_F ({freq_mask_f}) "
f"must be larger than 0 when doing freq masking."
)
if time_mask_n > 0:
assert time_mask_t > 0, (
f"time_mask_T ({time_mask_t}) must be larger than 0 when "
f"doing time masking."
)
self.time_warp_w = time_warp_w
self.freq_mask_n = freq_mask_n
self.freq_mask_f = freq_mask_f
self.time_mask_n = time_mask_n
self.time_mask_t = time_mask_t
self.time_mask_p = time_mask_p
self.mask_value = mask_value
def __repr__(self):
return (
self.__class__.__name__
+ "("
+ ", ".join(
[
f"time_warp_w={self.time_warp_w}",
f"freq_mask_n={self.freq_mask_n}",
f"freq_mask_f={self.freq_mask_f}",
f"time_mask_n={self.time_mask_n}",
f"time_mask_t={self.time_mask_t}",
f"time_mask_p={self.time_mask_p}",
]
)
+ ")"
)
def __call__(self, spectrogram):
assert len(spectrogram.shape) == 2, "spectrogram must be a 2-D tensor."
distorted = spectrogram.copy() # make a copy of input spectrogram.
num_frames = spectrogram.shape[0] # or 'tau' in the paper.
num_freqs = spectrogram.shape[1] # or 'miu' in the paper.
mask_value = self.mask_value
if mask_value is None: # if no value was specified, use local mean.
mask_value = spectrogram.mean()
if num_frames == 0:
return spectrogram
if num_freqs < self.freq_mask_f:
return spectrogram
if self.time_warp_w > 0:
if 2 * self.time_warp_w < num_frames:
import cv2
w0 = np.random.randint(self.time_warp_w, num_frames - self.time_warp_w)
w = np.random.randint(-self.time_warp_w + 1, self.time_warp_w)
upper, lower = distorted[:w0, :], distorted[w0:, :]
upper = cv2.resize(
upper, dsize=(num_freqs, w0 + w), interpolation=cv2.INTER_LINEAR
)
lower = cv2.resize(
lower,
dsize=(num_freqs, num_frames - w0 - w),
interpolation=cv2.INTER_LINEAR,
)
distorted = np.concatenate((upper, lower), axis=0)
for _i in range(self.freq_mask_n):
f = np.random.randint(0, self.freq_mask_f)
f0 = np.random.randint(0, num_freqs - f)
if f != 0:
distorted[:, f0 : f0 + f] = mask_value
max_time_mask_t = min(
self.time_mask_t, math.floor(num_frames * self.time_mask_p)
)
if max_time_mask_t < 1:
return distorted
for _i in range(self.time_mask_n):
t = np.random.randint(0, max_time_mask_t)
t0 = np.random.randint(0, num_frames - t)
if t != 0:
distorted[t0 : t0 + t, :] = mask_value
return distorted
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