gainquant.c File Reference

#include <string.h>
#include <math.h>
#include "constants.h"
#include "filter.h"

Include dependency graph for gainquant.c:

Go to the source code of this file.

Functions
float	gaindequant (int index, float maxIn, int cblen)
float	gainquant (float in, float maxIn, int cblen, int *index)

Function Documentation

gaindequant()

float gaindequant	(	int	index,
		float	maxIn,
		int	cblen
	)

Definition at line 83 of file gainquant.c.

References gain_sq3Tbl, gain_sq4Tbl, and gain_sq5Tbl.

Referenced by iCBConstruct().

    {
       float scale;

       /* obtain correct scale factor */

       scale=(float)fabs(maxIn);

       if (scale<0.1) {
           scale=(float)0.1;
       }

       /* select the quantization table and return the decoded value */

       if (cblen==8) {
           return scale*gain_sq3Tbl[index];
       } else if (cblen==16) {
           return scale*gain_sq4Tbl[index];
       }
       else if (cblen==32) {
           return scale*gain_sq5Tbl[index];
       }

       return 0.0;
   }

gainquant()

float gainquant	(	float	in,
		float	maxIn,
		int	cblen,
		int *	index
	)

Definition at line 27 of file gainquant.c.

References gain_sq3Tbl, gain_sq4Tbl, and gain_sq5Tbl.

Referenced by iCBSearch().

    {
       int i, tindex;
       float minmeasure,measure, *cb, scale;

       /* ensure a lower bound on the scaling factor */

       scale=maxIn;

       if (scale<0.1) {
           scale=(float)0.1;
       }

       /* select the quantization table */

       if (cblen == 8) {
           cb = gain_sq3Tbl;
       } else if (cblen == 16) {
           cb = gain_sq4Tbl;
       } else  {
           cb = gain_sq5Tbl;
       }

       /* select the best index in the quantization table */

       minmeasure=10000000.0;
       tindex=0;
       for (i=0; i<cblen; i++) {





           measure=(in-scale*cb[i])*(in-scale*cb[i]);

           if (measure<minmeasure) {
               tindex=i;
               minmeasure=measure;
           }
       }
       *index=tindex;

       /* return the quantized value */

       return scale*cb[tindex];
   }