freeswitch/libs/ilbc/src/getCBvec.c

/*
 * iLBC - a library for the iLBC codec
 *
 * getCBvec.c - The iLBC low bit rate speech codec.
 *
 * Adapted by Steve Underwood <steveu@coppice.org> from the reference
 * iLBC code supplied in RFC3951.
 *
 * Original code Copyright (C) The Internet Society (2004).
 * All changes to produce this version Copyright (C) 2008 by Steve Underwood
 * All Rights Reserved.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *
 * $Id: getCBvec.c,v 1.2 2008/03/06 12:27:38 steveu Exp $
 */

/*! \file */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <inttypes.h>
#include <string.h>

#include "ilbc.h"
#include "constants.h"
#include "getCBvec.h"

/*----------------------------------------------------------------*
 *  Construct codebook vector for given index.
 *---------------------------------------------------------------*/

void getCBvec(float *cbvec,     /* (o) Constructed codebook vector */
              float *mem,       /* (i) Codebook buffer */
              int index,        /* (i) Codebook index */
              int lMem,         /* (i) Length of codebook buffer */
              int cbveclen)     /* (i) Codebook vector length */
{
    int j;
    int k;
    int n;
    int memInd;
    int sFilt;
    float tmpbuf[CB_MEML];
    int base_size;
    int ilow;
    int ihigh;
    float alfa;
    float alfa1;

    /* Determine size of codebook sections */
    base_size = lMem - cbveclen + 1;

    if (cbveclen == SUBL)
        base_size += cbveclen/2;

    /* No filter -> First codebook section */
    if (index < lMem - cbveclen + 1)
    {
        /* First non-interpolated vectors */
        k = index + cbveclen;
        /* Get vector */
        memcpy(cbvec, mem + lMem - k, cbveclen*sizeof(float));
    }
    else if (index < base_size)
    {
        k = 2*(index - (lMem - cbveclen + 1)) + cbveclen;

        ihigh = k/2;
        ilow = ihigh - 5;

        /* Copy first noninterpolated part */
        memcpy(cbvec, mem + lMem - k/2, ilow*sizeof(float));

        /* Interpolation */
        alfa1 = 0.2f;
        alfa = 0.0f;
        for (j = ilow;  j < ihigh;  j++)
        {
            cbvec[j] = (1.0f - alfa)*mem[lMem - k/2 + j] + alfa*mem[lMem - k + j];
            alfa += alfa1;
        }

        /* Copy second noninterpolated part */
        memcpy(cbvec + ihigh, mem + lMem - k + ihigh, (cbveclen - ihigh)*sizeof(float));
    }
    /* Higher codebook section based on filtering */
    else
    {
        if (index - base_size < lMem - cbveclen + 1)
        {
            float tempbuff2[CB_MEML + CB_FILTERLEN + 1];
            float *pos;
            const float *pp;
            const float *pp1;

            /* Non-interpolated vectors */
            memset(tempbuff2, 0, CB_HALFFILTERLEN*sizeof(float));
            memcpy(&tempbuff2[CB_HALFFILTERLEN], mem, lMem*sizeof(float));
            memset(&tempbuff2[lMem + CB_HALFFILTERLEN], 0, (CB_HALFFILTERLEN + 1)*sizeof(float));

            k = index - base_size + cbveclen;
            sFilt = lMem - k;
            memInd = sFilt + 1 - CB_HALFFILTERLEN;

            /* do filtering */
            pos = cbvec;
            memset(pos, 0, cbveclen*sizeof(float));
            for (n = 0;  n < cbveclen;  n++)
            {
                pp = &tempbuff2[memInd + n + CB_HALFFILTERLEN];
                pp1 = &cbfiltersTbl[CB_FILTERLEN - 1];
                for (j = 0;  j < CB_FILTERLEN;  j++)
                    (*pos) += (*pp++)*(*pp1--);
                pos++;
            }
        }
        else
        {
            float tempbuff2[CB_MEML + CB_FILTERLEN + 1];
            float *pos;
            const float *pp;
            const float *pp1;
            int i;

            /* Interpolated vectors */
            memset(tempbuff2, 0, CB_HALFFILTERLEN*sizeof(float));
            memcpy(&tempbuff2[CB_HALFFILTERLEN], mem, lMem*sizeof(float));
            memset(&tempbuff2[lMem + CB_HALFFILTERLEN], 0, (CB_HALFFILTERLEN + 1)*sizeof(float));

            k = 2*(index-base_size - (lMem - cbveclen + 1)) + cbveclen;
            sFilt = lMem - k;
            memInd = sFilt + 1 - CB_HALFFILTERLEN;

            /* do filtering */
            pos = &tmpbuf[sFilt];
            memset(pos, 0, k*sizeof(float));
            for (i = 0;  i < k;  i++)
            {
                pp = &tempbuff2[memInd + i + CB_HALFFILTERLEN];
                pp1 = &cbfiltersTbl[CB_FILTERLEN - 1];
                for (j = 0;  j < CB_FILTERLEN;  j++)
                    (*pos) += (*pp++)*(*pp1--);
                pos++;
            }

            ihigh = k/2;
            ilow = ihigh - 5;

            /* Copy first noninterpolated part */
            memcpy(cbvec, tmpbuf + lMem - k/2, ilow*sizeof(float));

            /* interpolation */
            alfa1 = 0.2f;
            alfa = 0.0f;
            for (j = ilow;  j < ihigh;  j++)
            {
                cbvec[j] = (1.0f - alfa)*tmpbuf[lMem - k/2 + j]+alfa*tmpbuf[lMem - k + j];
                alfa += alfa1;
            }
            /* Copy second noninterpolated part */
            memcpy(cbvec + ihigh, tmpbuf + lMem - k + ihigh, (cbveclen - ihigh)*sizeof(float));
        }
    }
}