LPC Class Reference
[Analysis]

Compute Warped LPC coefficients, Pitch and Power [STILL UNDER TESTING!]. More...

#include <LPC.h>

Inherits Marsyas::MarSystem.

Private Member Functions
void	autocorrelationWarped (const realvec &in, realvec &r, mrs_real &pitch, mrs_real lambda)
void	LevinsonDurbin (const realvec &r, realvec &a, realvec &k, mrs_real &e)
mrs_real	predictionError (const realvec &data, const realvec &coeffs)

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Detailed Description

Compute Warped LPC coefficients, Pitch and Power [STILL UNDER TESTING!].

Linear Prediction Coefficients (LPC). Features commonly used in Speech Recognition research. This class is a modification of the original Marsyas0.1 LPC class. The following differences apply:

• order now reflects the LPC order (and returns <order> coefficients plus pitch and gain)
• It is possible to define a pole-shifting parameter, gamma (default value = 1.0 => no shifting)
• It is possible to define a warping factor, lambda (defualt value = 0.0 => no warping)

Code by Luís Gustavo Martins - lmartins@inescporto.pt May 2006

Definition at line 44 of file LPC.h.

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Member Function Documentation

void autocorrelationWarped	(	const realvec &	in,
		realvec &	r,
		mrs_real &	pitch,
		mrs_real	lambda
	)			[private]

Warped autocorrelation for LPC calculation Based on the code from: http://www.musicdsp.org/showone.php?id=137 Also estimates the pitch (only tested for lambda = 0), and updates the pitch_ member variable

Parameters:

	in	input audio frame
	r	autocorrelation output vector size (LPCorder + 1)
	pitch	pitch estimate calculated by autocorrelation
	lambda	frequency resolution (warp)

Definition at line 97 of file LPC.cpp.

References realvec::getData(), and realvec::getSize().

void LevinsonDurbin	(	const realvec &	r,
		realvec &	a,
		realvec &	k,
		mrs_real &	e
	)			[private]

Levinson-Durbin Recursion Algorithm Based on the code from: http://www.musicdsp.org/showone.php?id=137

Parameters:

	r	input vector of autocorrelation coeffs
	a	output vector with the alpha LPC coeffs => a = [1 a(1) a(2) ... a(order_-1)]
	k	output vector with the reflection coeffs
	e	prediction error

Definition at line 200 of file LPC.cpp.

References realvec::getData().

mrs_real predictionError	(	const realvec &	data,
		const realvec &	coeffs
	)			[private]

LPC RMS Prediction Error Updates the power_ member variable with the calculated value of the RMS perdiction error

Parameters:

	data	audio frame
	coeffs	LPC alpha coeffs

Definition at line 262 of file LPC.cpp.

References realvec::getSize().

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The documentation for this class was generated from the following files:

• /home/marsyas/marsyas/src/marsyas/LPC.h
• /home/marsyas/marsyas/src/marsyas/LPC.cpp