/Users/richardeakin/projects/libsms/trunk/src/filters.c File Reference

various filters More...

#include "sms.h"

Include dependency graph for filters.c:

Defines
#define	SMS_EMPH_COEF   .9
	coefficient for pre_emphasis filter
Functions
sfloat	sms_preEmphasis (float fInput)
sfloat	sms_deEmphasis (sfloat fInput)
static sfloat	ZeroPoleFilter (float *pFa, sfloat *pFb, int nCoeff, sfloat fInput)
	function to implement a zero-pole filter
void	sms_filterHighPass (int sizeResidual, sfloat *pResidual, int iSamplingRate)
	function to filter a waveform with a high-pass filter
void	sms_filterArray (sfloat *pFArray, int size1, int size2, sfloat *pFOutArray)
	a spectral filter

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Detailed Description

various filters

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Define Documentation

#define SMS_EMPH_COEF   .9

coefficient for pre_emphasis filter

Referenced by sms_deEmphasis(), and sms_preEmphasis().

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Function Documentation

sfloat sms_deEmphasis

(

sfloat

fInput

)

References sfloat, and SMS_EMPH_COEF.

Referenced by sms_synthesize(), and sms_writeResSound().

void sms_filterArray	(	sfloat *	pFArray,
		int	size1,
		int	size2,
		sfloat *	pFOutArray
	)

a spectral filter

filter each point of the current array by the surounding points using a triangular window

Parameters:

	pFArray	two dimensional input array
	size1	vertical size of pFArray
	size2	horizontal size of pFArray
	pFOutArray	output array of size size1

References sfloat.

Referenced by FilterMagEnv().

void sms_filterHighPass	(	int	sizeResidual,
		sfloat *	pResidual,
		int	iSamplingRate
	)

function to filter a waveform with a high-pass filter

cutoff =1500 Hz

Todo:

this filter only works on sample rates up to 48k?

Parameters:

	sizeResidual	size of signal
	pResidual	pointer to residual signal
	iSamplingRate	sampling rate of signal

References sfloat, and ZeroPoleFilter().

Referenced by sms_analyze().

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sfloat sms_preEmphasis

(

float

fInput

)

References sfloat, and SMS_EMPH_COEF.

Referenced by sms_fillSoundBuffer().

static sfloat ZeroPoleFilter	(	float *	pFa,
		sfloat *	pFb,
		int	nCoeff,
		sfloat	fInput
	)			[static]

function to implement a zero-pole filter

Todo:

will forgetting to reset pD to zero at the beginning of a new analysis (when there are multiple analyses within the life of one program) cause problems?

Parameters:

	pFa	pointer to numerator coefficients
	pFb	pointer to denominator coefficients
	nCoeff	number of coefficients
	fInput	input sample

Returns:

value is the filtered sample

References sfloat.

Referenced by sms_filterHighPass().