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java.lang.Objectedu.cmu.sphinx.frontend.frequencywarp.LinearPredictor
Computes the linear predictive model using the Levinson-Durbin algorithm. Linear prediction assumes that a signal can be model as a linear combination of previous samples, that is, the current sample x[i] can be modeled as:
x[i] = a[0] + a[1] * x[i - 1] + a[2] * x[i - 2] + ...The summation on the right hand side of the equation involves a finite number of terms. The number of previous samples used is the order of the linear prediction. This class also provides a method to compute LPC cepstra, that is, the cepstra computed from LPC coefficients, as well as a method to compute the bilinear transformation of the LPC
Constructor Summary | |
LinearPredictor(int order)
Constructs a LinearPredictor with the given order. |
Method Summary | |
double[] |
getARFilter(double[] autocor)
Routine to compute Linear Prediction Coefficients for a frame of speech. |
double[] |
getBilinearCepstra(double warp,
int nbilincepstra)
Computes a bi-linear frequency warped version of the LPC cepstrum from the LPC cepstrum. |
double[] |
getData(int ceporder)
Computes LPC Cepstra from the AR predictor parameters and alpha using a recursion invented by Oppenheim et al. |
double[] |
reflectionCoeffsToARParameters(double[] RC,
int lpcorder)
Computes AR parameters from a given set of reflection coefficients. |
Methods inherited from class java.lang.Object |
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
public LinearPredictor(int order)
order
- the order of the LinearPredictorMethod Detail |
public double[] getARFilter(double[] autocor)
autocor
- public double[] reflectionCoeffsToARParameters(double[] RC, int lpcorder)
RC
- double array of reflection coefficients. The RC array
must begin at 1 (RC[0] is a dummy value)lpcorder
- AR order desired
public double[] getData(int ceporder)
0.75 * LPCorder <= ceporder <= 1.25 * LPCorder
ceporder
- is the order of the LPC cepstral vector to be
computed.
public double[] getBilinearCepstra(double warp, int nbilincepstra)
warp
- is the warping coefficient. For 16KHz speech 0.6 is
good valued.nbilincepstra
- is the number of bilinear cepstral values to
be computed from the linear frequency cepstrum.
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