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