mfcc.h File Reference

Mel-Frequency Cepstrum Coefficients object. More...

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Typedefs
typedef struct _aubio_mfcc_t	aubio_mfcc_t
	mfcc object

Functions
aubio_mfcc_t *	new_aubio_mfcc (uint_t buf_size, uint_t n_filters, uint_t n_coeffs, uint_t samplerate)
	create mfcc object More...
void	del_aubio_mfcc (aubio_mfcc_t *mf)
	delete mfcc object More...
void	aubio_mfcc_do (aubio_mfcc_t *mf, const cvec_t *in, fvec_t *out)
	mfcc object processing More...
uint_t	aubio_mfcc_set_power (aubio_mfcc_t *mf, smpl_t power)
	set power parameter More...
smpl_t	aubio_mfcc_get_power (aubio_mfcc_t *mf)
	get power parameter More...
uint_t	aubio_mfcc_set_scale (aubio_mfcc_t *mf, smpl_t scale)
	set scaling parameter More...
smpl_t	aubio_mfcc_get_scale (aubio_mfcc_t *mf)
	get scaling parameter More...
uint_t	aubio_mfcc_set_mel_coeffs (aubio_mfcc_t *mf, smpl_t fmin, smpl_t fmax)
	Mel filterbank initialization. More...
uint_t	aubio_mfcc_set_mel_coeffs_htk (aubio_mfcc_t *mf, smpl_t fmin, smpl_t fmax)
	Mel filterbank initialization. More...
uint_t	aubio_mfcc_set_mel_coeffs_slaney (aubio_mfcc_t *mf)
	Mel filterbank initialization (Auditory Toolbox's parameters) More...

Detailed Description

Mel-Frequency Cepstrum Coefficients object.

This object computes MFCC coefficients on an input cvec_t.

The implementation follows the specifications established by Malcolm Slaney in its Auditory Toolbox, available online at the following address (see file mfcc.m):

https://engineering.purdue.edu/~malcolm/interval/1998-010/

Definition in file mfcc.h.

Function Documentation

aubio_mfcc_do()

void aubio_mfcc_do	(	aubio_mfcc_t *	mf,
		const cvec_t *	in,
		fvec_t *	out
	)

mfcc object processing

Parameters

mf	mfcc object as returned by new_aubio_mfcc
in	input spectrum (buf_size long)
out	output mel coefficients buffer (n_coeffs long)

Examples:

spectral/test-mfcc.c.

aubio_mfcc_get_power()

smpl_t aubio_mfcc_get_power

(

aubio_mfcc_t *

mf

)

get power parameter

Parameters

mf	mfcc object, as returned by new_aubio_mfcc()

Returns

current power parameter. Defaults to 1.

See aubio_filterbank_get_power().

aubio_mfcc_get_scale()

smpl_t aubio_mfcc_get_scale

(

aubio_mfcc_t *

mf

)

get scaling parameter

Parameters

mf	mfcc object, as returned by new_aubio_mfcc()

Returns

current scaling parameter. Defaults to 1.

aubio_mfcc_set_mel_coeffs()

uint_t aubio_mfcc_set_mel_coeffs	(	aubio_mfcc_t *	mf,
		smpl_t	fmin,
		smpl_t	fmax
	)

Mel filterbank initialization.

Parameters

mf	mfcc object
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.

See also

aubio_filterbank_set_mel_coeffs()

aubio_mfcc_set_mel_coeffs_htk()

uint_t aubio_mfcc_set_mel_coeffs_htk	(	aubio_mfcc_t *	mf,
		smpl_t	fmin,
		smpl_t	fmax
	)

Mel filterbank initialization.

Parameters

mf	mfcc object
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.

See also

aubio_filterbank_set_mel_coeffs_htk()

aubio_mfcc_set_mel_coeffs_slaney()

uint_t aubio_mfcc_set_mel_coeffs_slaney

(

aubio_mfcc_t *

mf

)

Mel filterbank initialization (Auditory Toolbox's parameters)

Parameters

mf	mfcc object

The filter coefficients are built to match exactly Malcolm Slaney's Auditory Toolbox implementation. The number of filters should be 40.

This is the default filterbank when mf was created with n_filters = 40.

See also

aubio_filterbank_set_mel_coeffs_slaney()

aubio_mfcc_set_power()

uint_t aubio_mfcc_set_power	(	aubio_mfcc_t *	mf,
		smpl_t	power
	)

set power parameter

Parameters

mf	mfcc object, as returned by new_aubio_mfcc()
power	Raise norm of the input spectrum norm to this power before computing filterbank. Defaults to 1.

See aubio_filterbank_set_power().

aubio_mfcc_set_scale()

uint_t aubio_mfcc_set_scale	(	aubio_mfcc_t *	mf,
		smpl_t	scale
	)

set scaling parameter

Parameters

mf	mfcc object, as returned by new_aubio_mfcc()
scale	Scaling value to apply.

Scales the output of the filterbank after taking its logarithm and before computing the DCT. Defaults to 1.

del_aubio_mfcc()

void del_aubio_mfcc

(

aubio_mfcc_t *

mf

)

delete mfcc object

Parameters

mf	mfcc object as returned by new_aubio_mfcc

Examples:

spectral/test-mfcc.c.

new_aubio_mfcc()

aubio_mfcc_t* new_aubio_mfcc	(	uint_t	buf_size,
		uint_t	n_filters,
		uint_t	n_coeffs,
		uint_t	samplerate
	)

create mfcc object

Parameters

buf_size	size of analysis buffer (and length the FFT transform)
samplerate	audio sampling rate
n_coeffs	number of desired coefficients
n_filters	number of desired filters

Examples:

spectral/test-mfcc.c.