Source code for das.kapre.backend_keras
# -*- coding: utf-8 -*-
from __future__ import absolute_import
import numpy as np
from tensorflow.keras import backend as K
[docs]def amplitude_to_decibel(x, amin: float = 1e-10, dynamic_range: float = 80.0):
"""Convert (linear) amplitude to decibel (log10(x)).
>>> x[x<amin] = amin # clip everythin below amin
>>> y = 10 * log(x) / log(10) # log transform
>>> y = ... # rescale dyn range to [-80, 0]
Args:
x (Tensor): Tensor
amin (float, optional): Minimal amplitude. Smaller values are clipped to this. Defaults to 1e-10 (dB).
dynamic_range (float, optional): Dynamic range. Defaults to 80.0 (dB).
Returns:
[Tensor]: Tensor with the values converted to dB
"""
log_spec = 10 * K.log(K.maximum(x, amin)) / np.log(10).astype(K.floatx())
if K.ndim(x) > 1:
axis = tuple(range(K.ndim(x))[1:])
else:
axis = None
log_spec = log_spec - K.max(log_spec, axis=axis, keepdims=True) # [-?, 0]
log_spec = K.maximum(log_spec, -1 * dynamic_range) # [-80, 0]
return log_spec