nnmnkwii.preprocessing.mulaw_quantize¶

nnmnkwii.preprocessing.mulaw_quantize(x, mu=256)[source]¶

Mu-Law companding + quantize

Parameters

x (array-like) – Input signal. Each value of input signal must be in range of [-1, 1].
mu (number) – Compression parameter μ.

Returns

Quantized signal (dtype=int)

y ∈ [0, mu] if x ∈ [-1, 1]
y ∈ [0, mu) if x ∈ [-1, 1)

Return type

array-like

Note

If you want to get quantized values of range [0, mu) (not [0, mu]), then you need to provide input signal of range [-1, 1).

Examples

>>> from scipy.io import wavfile
>>> import pysptk
>>> import numpy as np
>>> from nnmnkwii import preprocessing as P
>>> fs, x = wavfile.read(pysptk.util.example_audio_file())
>>> x = (x / 32768.0).astype(np.float32)
>>> y = P.mulaw_quantize(x)
>>> print(y.min(), y.max(), y.dtype)
15 246 int64