net.java.sip.communicator.impl.neomedia.codec.audio.silk
Class Silk_NLSF2A

java.lang.Object
  net.java.sip.communicator.impl.neomedia.codec.audio.silk.Silk_NLSF2A

public class Silk_NLSF2A
extends Object

conversion between prediction filter coefficients and LSFs order should be even a piecewise linear approximation maps LSF <-> cos(LSF) therefore the result is not accurate LSFs, but the two function are accurate inverses of each other.

Author:

Jing Dai, Dingxin Xu

Constructor Summary

Silk_NLSF2A()

Method Summary

(package private) static void	SKP_Silk_NLSF2A_find_poly(int[] out, int[] cLSF, int cLSF_offset, int dd) helper function for NLSF2A(..).
(package private) static void	SKP_Silk_NLSF2A(short[] a, int[] NLSF, int d) compute whitening filter coefficients from normalized line spectral frequencies.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Silk_NLSF2A

public Silk_NLSF2A()

Method Detail

SKP_Silk_NLSF2A_find_poly

static void SKP_Silk_NLSF2A_find_poly(int[] out,
                                      int[] cLSF,
                                      int cLSF_offset,
                                      int dd)

helper function for NLSF2A(..).

Parameters:

out - intermediate polynomial, Q20.

cLSF - vector of interleaved 2*cos(LSFs), Q20.

cLSF_offset - offset of valid data.

dd - polynomial order (= 1/2 * filter order).

SKP_Silk_NLSF2A

static void SKP_Silk_NLSF2A(short[] a,
                            int[] NLSF,
                            int d)

compute whitening filter coefficients from normalized line spectral frequencies.

Parameters:

a - monic whitening filter coefficients in Q12, [d].

NLSF - normalized line spectral frequencies in Q15, [d].

d - filter order (should be even).