MFCC F32

Macros
#define	MFCC_INIT_F32(LEN)

Functions
RISCV_DSP_ATTRIBUTE void	riscv_mfcc_f32 (const riscv_mfcc_instance_f32 *S, float32_t *pSrc, float32_t *pDst, float32_t *pTmp)
	MFCC F32. More...
RISCV_DSP_ATTRIBUTE riscv_status	riscv_mfcc_init_f32 (riscv_mfcc_instance_f32 *S, uint32_t fftLen, uint32_t nbMelFilters, uint32_t nbDctOutputs, const float32_t *dctCoefs, const uint32_t *filterPos, const uint32_t *filterLengths, const float32_t *filterCoefs, const float32_t *windowCoefs)
	Generic initialization of the MFCC F32 instance structure. More...

Detailed Description

Macro Definition Documentation

MFCC_INIT_F32

#define MFCC_INIT_F32

(

LEN

)

Function Documentation

riscv_mfcc_f32()

RISCV_DSP_ATTRIBUTE void riscv_mfcc_f32	(	const riscv_mfcc_instance_f32 *	S,
		float32_t *	pSrc,
		float32_t *	pDst,
		float32_t *	pTmp
	)

MFCC F32.

Parameters

[in]	S	points to the mfcc instance structure
[in]	pSrc	points to the input samples
[out]	pDst	points to the output MFCC values
[in,out]	pTmp	points to a temporary buffer of complex

Description

The number of input samples if the FFT length used when initializing the instance data structure.

The temporary buffer has a 2*fft length size when MFCC is implemented with CFFT. It has length FFT Length + 2 when implemented with RFFT (default implementation).

The source buffer is modified by this function.

riscv_mfcc_init_f32()

RISCV_DSP_ATTRIBUTE riscv_status riscv_mfcc_init_f32	(	riscv_mfcc_instance_f32 *	S,
		uint32_t	fftLen,
		uint32_t	nbMelFilters,
		uint32_t	nbDctOutputs,
		const float32_t *	dctCoefs,
		const uint32_t *	filterPos,
		const uint32_t *	filterLengths,
		const float32_t *	filterCoefs,
		const float32_t *	windowCoefs
	)

Generic initialization of the MFCC F32 instance structure.

Parameters

[out]	S	points to the mfcc instance structure
[in]	fftLen	fft length
[in]	nbMelFilters	number of Mel filters
[in]	nbDctOutputs	number of Dct outputs
[in]	dctCoefs	points to an array of DCT coefficients
[in]	filterPos	points of the array of filter positions
[in]	filterLengths	points to the array of filter lengths
[in]	filterCoefs	points to the array of filter coefficients
[in]	windowCoefs	points to the array of window coefficients

Returns

error status

Description

The matrix of Mel filter coefficients is sparse. Most of the coefficients are zero. To avoid multiplying the spectrogram by those zeros, the filter is applied only to a given position in the spectrogram and on a given number of FFT bins (the filter length). It is the reason for the arrays filterPos and filterLengths.

window coefficients can describe (for instance) a Hamming window. The array has the same size as the FFT length.

The folder Scripts is containing a Python script which can be used to generate the filter, dct and window arrays.

This function should be used only if you don't know the FFT sizes that you'll need at build time. The use of this function will prevent the linker from removing the FFT tables that are not needed and the library code size will be bigger than needed.

If you use NMSIS-DSP as a static library, and if you know the MFCC sizes that you need at build time, then it is better to use the initialization functions defined for each MFCC size.