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

peak detection algorithm and functions More...

#include "sms.h"

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Functions
static sfloat	PeakInterpolation (sfloat fMaxVal, sfloat fLeftBinVal, sfloat fRightBinVal, sfloat *pFDiffFromMax)
	function used for the parabolic interpolation of the spectral peaks
static int	FindNextMax (sfloat *pFMagSpectrum, int iHighBinBound, int *pICurrentLoc, sfloat *pFMaxVal, sfloat fMinPeakMag)
	detect the next local maximum in the spectrum
static int	FindNextPeak (sfloat *pFMagSpectrum, int iHighestBin, int *pICurrentLoc, sfloat *pFPeakMag, sfloat *pFPeakLoc, sfloat fMinPeakMag)
	function to detect the next spectral peak
static sfloat	GetPhaseVal (sfloat *pPhaseSpectrum, sfloat fPeakLoc)
	get the corresponding phase value for a given peak
int	sms_detectPeaks (int sizeSpec, sfloat *pMag, sfloat *pPhase, SMS_Peak *pSpectralPeaks, SMS_PeakParams *pPeakParams)
	find the prominent spectral peaks

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Detailed Description

peak detection algorithm and functions

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Function Documentation

static int FindNextMax	(	sfloat *	pFMagSpectrum,
		int	iHighBinBound,
		int *	pICurrentLoc,
		sfloat *	pFMaxVal,
		sfloat	fMinPeakMag
	)			[static]

detect the next local maximum in the spectrum

stores the value in pFMaxVal

Todo:

export this to sms.h and wrap in pysms

Parameters:

	pFMagSpectrum	magnitude spectrum
	iHighBinBound	highest bin to search
	pICurrentLoc	current bin location
	pFMaxVal	value of the maximum found
	fMinPeakMag	minimum magnitude to accept a peak

Returns:

the bin location of the maximum

References sfloat.

Referenced by FindNextPeak().

static int FindNextPeak	(	sfloat *	pFMagSpectrum,
		int	iHighestBin,
		int *	pICurrentLoc,
		sfloat *	pFPeakMag,
		sfloat *	pFPeakLoc,
		sfloat	fMinPeakMag
	)			[static]

function to detect the next spectral peak

Parameters:

	pFMagSpectrum	magnitude spectrum
	iHighestBin	highest bin to search
	pICurrentLoc	current bin location
	pFPeakMag	magnitude value of peak
	pFPeakLoc	location of peak
	fMinPeakMag	minimum magnitude to accept a peak

Returns:

1 if found, 0 if not

References FindNextMax(), PeakInterpolation(), and sfloat.

Referenced by sms_detectPeaks().

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static sfloat GetPhaseVal	(	sfloat *	pPhaseSpectrum,
		sfloat	fPeakLoc
	)			[static]

get the corresponding phase value for a given peak

performs linear interpolation for a more accurate phase

Parameters:

	pPhaseSpectrum	phase spectrum
	fPeakLoc	location of peak

Returns:

the phase value

References PI, sfloat, and TWO_PI.

Referenced by sms_detectPeaks().

static sfloat PeakInterpolation	(	sfloat	fMaxVal,
		sfloat	fLeftBinVal,
		sfloat	fRightBinVal,
		sfloat *	pFDiffFromMax
	)			[static]

function used for the parabolic interpolation of the spectral peaks

it performs the interpolation in a log scale and stores the location in pFDiffFromMax and

Parameters:

	fMaxVal	value of max bin
	fLeftBinVal	value for left bin
	fRightBinVal	value for right bin
	pFDiffFromMax	location of the tip as the difference from the top bin

Returns:

the peak height

Referenced by FindNextPeak().

int sms_detectPeaks	(	int	sizeSpec,
		sfloat *	pMag,
		sfloat *	pPhase,
		SMS_Peak *	pSpectralPeaks,
		SMS_PeakParams *	pPeakParams
	)

find the prominent spectral peaks

uses a dB spectrum

Parameters:

	sizeSpec	size of magnitude spectrum
	pMag	pointer to power spectrum
	pPhase	pointer to phase spectrum
	pSpectralPeaks	pointer to array of peaks
	pPeakParams	peak detection parameters

Returns:

the number of peaks found

References SMS_Peak::fFreq, SMS_PeakParams::fHighestFreq, FindNextPeak(), SMS_PeakParams::fLowestFreq, SMS_Peak::fMag, SMS_PeakParams::fMinPeakMag, SMS_Peak::fPhase, GetPhaseVal(), SMS_PeakParams::iMaxPeaks, SMS_PeakParams::iSamplingRate, MAX, MIN, and sfloat.

Referenced by sms_analyzeFrame().

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