filterbank_mel.h File Reference

Filterbank object coefficients initialization. More...

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Functions
uint_t	aubio_filterbank_set_triangle_bands (aubio_filterbank_t *fb, const fvec_t *freqs, smpl_t samplerate)
	filterbank initialization with triangular and overlapping bands
uint_t	aubio_filterbank_set_mel_coeffs_slaney (aubio_filterbank_t *fb, smpl_t samplerate)
	filterbank initialization for Mel filters using Slaney's coefficients
uint_t	aubio_filterbank_set_mel_coeffs (aubio_filterbank_t *fb, smpl_t samplerate, smpl_t fmin, smpl_t fmax)
	Mel filterbank initialization.
uint_t	aubio_filterbank_set_mel_coeffs_htk (aubio_filterbank_t *fb, smpl_t samplerate, smpl_t fmin, smpl_t fmax)
	Mel filterbank initialization.

Detailed Description

Filterbank object coefficients initialization.

Functions to create set the aubio_filterbank_t coefficients to

• aubio_filterbank_set_triangle_bands: overlapping triangular bands,
• aubio_filterbank_set_mel_coeffs_slaney: Mel frequency bands.

Definition in file filterbank_mel.h.

Function Documentation

aubio_filterbank_set_mel_coeffs()

uint_t aubio_filterbank_set_mel_coeffs	(	aubio_filterbank_t *	fb,
		smpl_t	samplerate,
		smpl_t	fmin,
		smpl_t	fmax )

Mel filterbank initialization.

Parameters

fb	filterbank object
samplerate	audio sampling rate
fmin	start frequency, in Hz
fmax	end frequency, in Hz

The filterbank will be initialized with bands linearly spaced in the mel scale, from fmin to fmax.

References

Malcolm Slaney, Auditory Toolbox Version 2, Technical Report #1998-010 https://engineering.purdue.edu/~malcolm/interval/1998-010/

aubio_filterbank_set_mel_coeffs_htk()

uint_t aubio_filterbank_set_mel_coeffs_htk	(	aubio_filterbank_t *	fb,
		smpl_t	samplerate,
		smpl_t	fmin,
		smpl_t	fmax )

Mel filterbank initialization.

Parameters

fb	filterbank object
samplerate	audio sampling rate
fmin	start frequency, in Hz
fmax	end frequency, in Hz

The bank of filters will be initalized to to cover linearly spaced bands in the Htk mel scale, from fmin to fmax.

References

Douglas O'Shaughnessy (1987). Speech communication: human and machine. Addison-Wesley. p. 150. ISBN 978-0-201-16520-3.

HTK Speech Recognition Toolkit: http://htk.eng.cam.ac.uk/

aubio_filterbank_set_mel_coeffs_slaney()

uint_t aubio_filterbank_set_mel_coeffs_slaney	(	aubio_filterbank_t *	fb,
		smpl_t	samplerate )

filterbank initialization for Mel filters using Slaney's coefficients

Parameters

fb	filterbank object
samplerate	audio sampling rate, in Hz

The filter coefficients are built to match exactly Malcolm Slaney's Auditory Toolbox implementation (see file mfcc.m). The number of filters should be 40.

References

Malcolm Slaney, Auditory Toolbox Version 2, Technical Report #1998-010 https://engineering.purdue.edu/~malcolm/interval/1998-010/

Examples

spectral/test-filterbank_mel.c.

aubio_filterbank_set_triangle_bands()

uint_t aubio_filterbank_set_triangle_bands	(	aubio_filterbank_t *	fb,
		const fvec_t *	freqs,
		smpl_t	samplerate )

filterbank initialization with triangular and overlapping bands

Parameters

fb	filterbank object
freqs	arbitrary array of boundary frequencies
samplerate	audio sampling rate

This function computes the coefficients of the filterbank based on the boundaries found in freqs, in Hz, and using triangular overlapping bands.