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293 lines
7.9 KiB
293 lines
7.9 KiB
14 years ago
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/* Copyright (C) 2002 Jean-Marc Valin
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File: filters.c
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Various analysis/synthesis filters
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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- Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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- Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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- Neither the name of the Xiph.org Foundation nor the names of its
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contributors may be used to endorse or promote products derived from
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this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR
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CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "filters.h"
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#include "stack_alloc.h"
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#include <math.h>
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void bw_lpc(float gamma, float *lpc_in, float *lpc_out, int order)
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{
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int i;
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float tmp=1;
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for (i=0;i<order+1;i++)
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{
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lpc_out[i] = tmp * lpc_in[i];
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tmp *= gamma;
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}
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}
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#ifdef _USE_SSE
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#include "filters_sse.h"
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#else
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void filter_mem2(float *x, float *num, float *den, float *y, int N, int ord, float *mem)
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{
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int i,j;
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float xi,yi;
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for (i=0;i<N;i++)
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{
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xi=x[i];
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y[i] = num[0]*xi + mem[0];
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yi=y[i];
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for (j=0;j<ord-1;j++)
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{
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mem[j] = mem[j+1] + num[j+1]*xi - den[j+1]*yi;
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}
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mem[ord-1] = num[ord]*xi - den[ord]*yi;
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}
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}
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void iir_mem2(float *x, float *den, float *y, int N, int ord, float *mem)
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{
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int i,j;
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for (i=0;i<N;i++)
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{
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y[i] = x[i] + mem[0];
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for (j=0;j<ord-1;j++)
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{
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mem[j] = mem[j+1] - den[j+1]*y[i];
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}
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mem[ord-1] = - den[ord]*y[i];
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}
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}
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#endif
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void fir_mem2(float *x, float *num, float *y, int N, int ord, float *mem)
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{
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int i,j;
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float xi;
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for (i=0;i<N;i++)
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{
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xi=x[i];
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y[i] = num[0]*xi + mem[0];
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for (j=0;j<ord-1;j++)
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{
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mem[j] = mem[j+1] + num[j+1]*xi;
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}
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mem[ord-1] = num[ord]*xi;
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}
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}
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void syn_percep_zero(float *xx, float *ak, float *awk1, float *awk2, float *y, int N, int ord, char *stack)
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{
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int i;
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float *mem = PUSH(stack,ord, float);
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for (i=0;i<ord;i++)
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mem[i]=0;
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filter_mem2(xx, awk1, ak, y, N, ord, mem);
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for (i=0;i<ord;i++)
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mem[i]=0;
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iir_mem2(y, awk2, y, N, ord, mem);
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}
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void residue_percep_zero(float *xx, float *ak, float *awk1, float *awk2, float *y, int N, int ord, char *stack)
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{
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int i;
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float *mem = PUSH(stack,ord, float);
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for (i=0;i<ord;i++)
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mem[i]=0;
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filter_mem2(xx, ak, awk1, y, N, ord, mem);
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for (i=0;i<ord;i++)
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mem[i]=0;
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fir_mem2(y, awk2, y, N, ord, mem);
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}
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void qmf_decomp(float *xx, float *aa, float *y1, float *y2, int N, int M, float *mem, char *stack)
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{
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int i,j,k,M2;
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float *a;
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float *x;
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float *x2;
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a = PUSH(stack, M, float);
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x = PUSH(stack, N+M-1, float);
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x2=x+M-1;
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M2=M>>1;
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for (i=0;i<M;i++)
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a[M-i-1]=aa[i];
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for (i=0;i<M-1;i++)
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x[i]=mem[M-i-2];
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for (i=0;i<N;i++)
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x[i+M-1]=xx[i];
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for (i=0,k=0;i<N;i+=2,k++)
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{
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y1[k]=0;
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y2[k]=0;
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for (j=0;j<M2;j++)
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{
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y1[k]+=a[j]*(x[i+j]+x2[i-j]);
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y2[k]-=a[j]*(x[i+j]-x2[i-j]);
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j++;
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y1[k]+=a[j]*(x[i+j]+x2[i-j]);
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y2[k]+=a[j]*(x[i+j]-x2[i-j]);
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}
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}
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for (i=0;i<M-1;i++)
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mem[i]=xx[N-i-1];
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}
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/* By segher */
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void fir_mem_up(float *x, float *a, float *y, int N, int M, float *mem, char *stack)
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/* assumptions:
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all odd x[i] are zero -- well, actually they are left out of the array now
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N and M are multiples of 4 */
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{
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int i, j;
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float *xx=PUSH(stack, M+N-1, float);
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for (i = 0; i < N/2; i++)
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xx[2*i] = x[N/2-1-i];
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for (i = 0; i < M - 1; i += 2)
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xx[N+i] = mem[i+1];
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for (i = 0; i < N; i += 4) {
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float y0, y1, y2, y3;
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float x0;
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y0 = y1 = y2 = y3 = 0.f;
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x0 = xx[N-4-i];
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for (j = 0; j < M; j += 4) {
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float x1;
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float a0, a1;
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a0 = a[j];
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a1 = a[j+1];
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x1 = xx[N-2+j-i];
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y0 += a0 * x1;
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y1 += a1 * x1;
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y2 += a0 * x0;
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y3 += a1 * x0;
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a0 = a[j+2];
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a1 = a[j+3];
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x0 = xx[N+j-i];
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y0 += a0 * x0;
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y1 += a1 * x0;
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y2 += a0 * x1;
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y3 += a1 * x1;
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}
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y[i] = y0;
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y[i+1] = y1;
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y[i+2] = y2;
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y[i+3] = y3;
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}
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for (i = 0; i < M - 1; i += 2)
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mem[i+1] = xx[i];
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}
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void comp_filter_mem_init (CombFilterMem *mem)
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{
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mem->last_pitch=0;
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mem->last_pitch_gain[0]=mem->last_pitch_gain[1]=mem->last_pitch_gain[2]=0;
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mem->smooth_gain=1;
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}
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void comb_filter(
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float *exc, /*decoded excitation*/
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float *new_exc, /*enhanced excitation*/
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float *ak, /*LPC filter coefs*/
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int p, /*LPC order*/
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int nsf, /*sub-frame size*/
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int pitch, /*pitch period*/
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float *pitch_gain, /*pitch gain (3-tap)*/
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float comb_gain, /*gain of comb filter*/
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CombFilterMem *mem
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)
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{
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int i;
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float exc_energy=0, new_exc_energy=0;
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float gain;
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float step;
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float fact;
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/*Compute excitation energy prior to enhancement*/
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for (i=0;i<nsf;i++)
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exc_energy+=exc[i]*exc[i];
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/*Some gain adjustment is pitch is too high or if unvoiced*/
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{
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float g=0;
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g = .5*fabs(pitch_gain[0]+pitch_gain[1]+pitch_gain[2] +
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mem->last_pitch_gain[0] + mem->last_pitch_gain[1] + mem->last_pitch_gain[2]);
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if (g>1.3)
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comb_gain*=1.3/g;
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if (g<.5)
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comb_gain*=2*g;
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}
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step = 1.0/nsf;
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fact=0;
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/*Apply pitch comb-filter (filter out noise between pitch harmonics)*/
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for (i=0;i<nsf;i++)
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{
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fact += step;
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new_exc[i] = exc[i] + comb_gain * fact * (
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pitch_gain[0]*exc[i-pitch+1] +
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pitch_gain[1]*exc[i-pitch] +
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pitch_gain[2]*exc[i-pitch-1]
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)
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+ comb_gain * (1-fact) * (
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mem->last_pitch_gain[0]*exc[i-mem->last_pitch+1] +
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mem->last_pitch_gain[1]*exc[i-mem->last_pitch] +
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mem->last_pitch_gain[2]*exc[i-mem->last_pitch-1]
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);
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}
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mem->last_pitch_gain[0] = pitch_gain[0];
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mem->last_pitch_gain[1] = pitch_gain[1];
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mem->last_pitch_gain[2] = pitch_gain[2];
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mem->last_pitch = pitch;
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/*Gain after enhancement*/
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for (i=0;i<nsf;i++)
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new_exc_energy+=new_exc[i]*new_exc[i];
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/*Compute scaling factor and normalize energy*/
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gain = sqrt(exc_energy)/sqrt(.1+new_exc_energy);
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if (gain < .5)
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gain=.5;
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if (gain>1)
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gain=1;
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for (i=0;i<nsf;i++)
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{
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mem->smooth_gain = .96*mem->smooth_gain + .04*gain;
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new_exc[i] *= mem->smooth_gain;
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}
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}
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