CorFunc.java

package org.mobicents.media.server.impl.dsp.audio.g729;

public class CorFunc {

	/*----------------------------------------------------------------------------
	 * corr_xy2 - compute the correlation products needed for gain computation
	 *----------------------------------------------------------------------------
	 */
	public static void corr_xy2(
	 float xn[],            /* input : target vector x[0:l_subfr] */
	 float y1[],            /* input : filtered adaptive codebook vector */
	 float y2[],            /* input : filtered 1st codebook innovation */
	 float g_coeff[]        /* output: <y2,y2> , -2<xn,y2> , and 2<y1,y2>*/
	)
	{
	   float y2y2, xny2, y1y2;
	   int i;

	   y2y2= (float)0.01;
	   for (i = 0; i < LD8KConstants.L_SUBFR; i++) y2y2 += y2[i]*y2[i];
	   g_coeff[2] = y2y2 ;

	   xny2 = (float)0.01;
	   for (i = 0; i < LD8KConstants.L_SUBFR; i++) xny2+= xn[i]*y2[i];
	   g_coeff[3] = (float)-2.0* xny2;

	   y1y2 = (float)0.01;
	   for (i = 0; i < LD8KConstants.L_SUBFR; i++) y1y2 += y1[i]*y2[i];
	   g_coeff[4] = (float)2.0* y1y2 ;

	   return;

	}

	/*--------------------------------------------------------------------------*
	 *  Function  cor_h_x()                                                     *
	 *  ~~~~~~~~~~~~~~~~~~~~                                                    *
	 * Compute  correlations of input response h[] with the target vector X[].  *
	 *--------------------------------------------------------------------------*/

	public static void cor_h_x(
	     float h[],        /* (i) :Impulse response of filters      */
	     float x[],        /* (i) :Target vector                    */
	     float d[]         /* (o) :Correlations between h[] and x[] */
	)
	{
	   int i, j;
	   float  s;

	   for (i = 0; i < LD8KConstants.L_SUBFR; i++)
	   {
	     s = (float)0.0;
	     for (j = i; j <  LD8KConstants.L_SUBFR; j++)
	       s += x[j] * h[j-i];
	     d[i] = s;
	   }

	   return;
	}


}