sspmod_fft.c File Reference

Fast Fourier analysis and synthesis. More...

Functions
int	spr_fft_ana_setup (SprSspInfo *Info, const char **descript, void *aux_info)
int	spr_fft_syn_setup (SprSspInfo *Info, const char **descript, void *aux_info)
int	spr_fft_ana_process (SprSspInfo *Info, const void *frame_in, void *frame_out)
int	spr_fft_syn_process (SprSspInfo *Info, const void *frame_in, void *frame_out)
void	spr_fft_free (SprSspInfo *Info)

Detailed Description

Fast Fourier analysis and synthesis.

For the analysis, the results can be stored in four ways, depending on the type:

POWER

power is stored in out[i], i=0,1,2,...,nfft/2

LOGPOW

log of power (dB) is stored in out[i], i=0,1,2,...,nfft/2

POW_PHAS

power is stored in out[i], i=0,2,4,...,nfft
phase is stored in out[i], i=1,3,5,...,nfft+1

COMPLEX

real part is stored in out[i], i=0,2,4,...,nfft
imaginary part is stored in out[i], i=1,3,5,...,nfft+1

Synthesis only works for POW_PHAS and COMPLEX. The input should be in the same form as given by the analysis.

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[anafft]
type <COMPLEX/POW_PHAS/POWER/LOGPOW>(POWER) [dB_low](-379)
Type of the results, default POWER. When converting to dB, assure that the output is never lower than <dB_low>.
nfft <number>
Number of points in FFT

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[synfft]
% This module does not take options

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See Also

ssp_master.c

Author

Weiye Ma (algorithm)

Jacques Duchateau (conversion to ssp routines)

Date

1 Dec 1991 and 3 Nov 1994