`athena.transform.feats.mel_spectrum`¶

This model extracts MelSpectrum features per frame.

Module Contents¶

Classes¶

MelSpectrum

Computing filter banks is applying triangular filters on a Mel-scale to the magnitude

class athena.transform.feats.mel_spectrum.MelSpectrum(config: dict)¶

Bases: athena.transform.feats.base_frontend.BaseFrontend

Computing filter banks is applying triangular filters on a Mel-scale to the magnitude spectrum to extract frequency bands, which based on MelSpectrum of Librosa.

Parameters: config – contains twelve optional parameters.

Shape:

output: \((T, F)\).

Examples::

>>> config = {'output_type': 3, 'filterbank_channel_count': 23}
>>> melspectrum_op = MelSpectrum.params(config).instantiate()
>>> melspectrum_out = melspectrum_op('test.wav', 16000)

classmethod params(config=None)¶

Set params.

Parameters

config – contains the following twelve optional parameters:
'window_length' – Window length in seconds. (float, default = 0.025),
'frame_length' – Hop length in seconds. (float, default = 0.010),
'snip_edges' – If 1, the last frame (shorter than window_length) will be cutoff. If 2, 1 // 2 frame_length data will be padded to data. (int, default = 1),
'preEph_coeff' – Coefficient for use in frame-signal preemphasis. (float, default = 0.0),
'window_type' – Type of window (“hamm”|”hann”|”povey”|”rect”|”blac”|”tria”). (string, default = “hann”)
'remove_dc_offset' – Subtract mean from waveform on each frame. (bool, default = False)
'is_fbank' – If true, compute power spetrum without frame energy. If false, using the frame energy instead of the square of the constant component of the signal. (bool, default = true)
'output_type' – If 1, return power spectrum. If 2, return log-power spectrum. (int, default = 1)
'upper_frequency_limit' – High cutoff frequency for mel bins (if <= 0, offset from Nyquist) (float, default = 0)
'lower_frequency_limit' – Low cutoff frequency for mel bins (float, default = 60)
'filterbank_channel_count' – Number of triangular mel-frequency bins. (float, default = 40)
'dither' – Dithering constant (0.0 means no dither). (float, default = 0.0) [add robust to training]

Note

Return an object of class HParams, which is a set of hyperparameters as name-value pairs.

call(audio_data, sample_rate)¶

Caculate logmelspectrum of audio data.