git-svn-id: http://webrtc.googlecode.com/svn/trunk@4 4adac7df-926f-26a2-2b94-8c16560cd09d
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niklase@google.com
217
modules/audio_coding/codecs/iSAC/main/source/lattice.c
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217
modules/audio_coding/codecs/iSAC/main/source/lattice.c
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/*
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* Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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/*
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* lattice.c
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*
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* contains the normalized lattice filter routines (MA and AR) for iSAC codec
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*
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*/
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#include "settings.h"
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#include "codec.h"
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#include <math.h>
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#include <memory.h>
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#ifdef ANDROID
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#include <stdlib.h>
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#endif
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/* filter the signal using normalized lattice filter */
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/* MA filter */
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void WebRtcIsac_NormLatticeFilterMa(int orderCoef,
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float *stateF,
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float *stateG,
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float *lat_in,
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double *filtcoeflo,
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double *lat_out)
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{
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int n,k,i,u,temp1;
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int ord_1 = orderCoef+1;
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float sth[MAX_AR_MODEL_ORDER];
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float cth[MAX_AR_MODEL_ORDER];
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float inv_cth[MAX_AR_MODEL_ORDER];
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double a[MAX_AR_MODEL_ORDER+1];
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float f[MAX_AR_MODEL_ORDER+1][HALF_SUBFRAMELEN], g[MAX_AR_MODEL_ORDER+1][HALF_SUBFRAMELEN];
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float gain1;
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for (u=0;u<SUBFRAMES;u++)
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{
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/* set the Direct Form coefficients */
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temp1 = u*ord_1;
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a[0] = 1;
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memcpy(a+1, filtcoeflo+temp1+1, sizeof(double) * (ord_1-1));
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/* compute lattice filter coefficients */
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WebRtcIsac_Dir2Lat(a,orderCoef,sth,cth);
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/* compute the gain */
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gain1 = (float)filtcoeflo[temp1];
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for (k=0;k<orderCoef;k++)
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{
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gain1 *= cth[k];
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inv_cth[k] = 1/cth[k];
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}
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/* normalized lattice filter */
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/*****************************/
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/* initial conditions */
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for (i=0;i<HALF_SUBFRAMELEN;i++)
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{
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f[0][i] = lat_in[i + u * HALF_SUBFRAMELEN];
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g[0][i] = lat_in[i + u * HALF_SUBFRAMELEN];
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}
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/* get the state of f&g for the first input, for all orders */
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for (i=1;i<ord_1;i++)
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{
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f[i][0] = inv_cth[i-1]*(f[i-1][0] + sth[i-1]*stateG[i-1]);
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g[i][0] = cth[i-1]*stateG[i-1] + sth[i-1]* f[i][0];
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}
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/* filtering */
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for(k=0;k<orderCoef;k++)
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{
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for(n=0;n<(HALF_SUBFRAMELEN-1);n++)
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{
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f[k+1][n+1] = inv_cth[k]*(f[k][n+1] + sth[k]*g[k][n]);
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g[k+1][n+1] = cth[k]*g[k][n] + sth[k]* f[k+1][n+1];
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}
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}
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for(n=0;n<HALF_SUBFRAMELEN;n++)
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{
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lat_out[n + u * HALF_SUBFRAMELEN] = gain1 * f[orderCoef][n];
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}
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/* save the states */
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for (i=0;i<ord_1;i++)
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{
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stateF[i] = f[i][HALF_SUBFRAMELEN-1];
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stateG[i] = g[i][HALF_SUBFRAMELEN-1];
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}
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/* process next frame */
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}
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return;
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}
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/*///////////////////AR filter ///////////////////////////////*/
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/* filter the signal using normalized lattice filter */
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void WebRtcIsac_NormLatticeFilterAr(int orderCoef,
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float *stateF,
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float *stateG,
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double *lat_in,
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double *lo_filt_coef,
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float *lat_out)
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{
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int n,k,i,u,temp1;
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int ord_1 = orderCoef+1;
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float sth[MAX_AR_MODEL_ORDER];
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float cth[MAX_AR_MODEL_ORDER];
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double a[MAX_AR_MODEL_ORDER+1];
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float ARf[MAX_AR_MODEL_ORDER+1][HALF_SUBFRAMELEN], ARg[MAX_AR_MODEL_ORDER+1][HALF_SUBFRAMELEN];
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float gain1,inv_gain1;
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for (u=0;u<SUBFRAMES;u++)
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{
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/* set the denominator and numerator of the Direct Form */
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temp1 = u*ord_1;
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a[0] = 1;
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memcpy(a+1, lo_filt_coef+temp1+1, sizeof(double) * (ord_1-1));
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WebRtcIsac_Dir2Lat(a,orderCoef,sth,cth);
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gain1 = (float)lo_filt_coef[temp1];
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for (k=0;k<orderCoef;k++)
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{
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gain1 = cth[k]*gain1;
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}
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/* initial conditions */
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inv_gain1 = 1/gain1;
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for (i=0;i<HALF_SUBFRAMELEN;i++)
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{
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ARf[orderCoef][i] = (float)lat_in[i + u * HALF_SUBFRAMELEN]*inv_gain1;
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}
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for (i=orderCoef-1;i>=0;i--) //get the state of f&g for the first input, for all orders
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{
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ARf[i][0] = cth[i]*ARf[i+1][0] - sth[i]*stateG[i];
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ARg[i+1][0] = sth[i]*ARf[i+1][0] + cth[i]* stateG[i];
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}
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ARg[0][0] = ARf[0][0];
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for(n=0;n<(HALF_SUBFRAMELEN-1);n++)
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{
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for(k=orderCoef-1;k>=0;k--)
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{
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ARf[k][n+1] = cth[k]*ARf[k+1][n+1] - sth[k]*ARg[k][n];
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ARg[k+1][n+1] = sth[k]*ARf[k+1][n+1] + cth[k]* ARg[k][n];
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}
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ARg[0][n+1] = ARf[0][n+1];
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}
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memcpy(lat_out+u * HALF_SUBFRAMELEN, &(ARf[0][0]), sizeof(float) * HALF_SUBFRAMELEN);
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/* cannot use memcpy in the following */
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for (i=0;i<ord_1;i++)
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{
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stateF[i] = ARf[i][HALF_SUBFRAMELEN-1];
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stateG[i] = ARg[i][HALF_SUBFRAMELEN-1];
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}
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}
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return;
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}
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/* compute the reflection coefficients using the step-down procedure*/
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/* converts the direct form parameters to lattice form.*/
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/* a and b are vectors which contain the direct form coefficients,
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according to
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A(z) = a(1) + a(2)*z + a(3)*z^2 + ... + a(M+1)*z^M
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B(z) = b(1) + b(2)*z + b(3)*z^2 + ... + b(M+1)*z^M
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*/
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void WebRtcIsac_Dir2Lat(double *a,
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int orderCoef,
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float *sth,
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float *cth)
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{
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int m, k;
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float tmp[MAX_AR_MODEL_ORDER];
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float tmp_inv, cth2;
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sth[orderCoef-1] = (float)a[orderCoef];
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cth2 = 1.0f - sth[orderCoef-1] * sth[orderCoef-1];
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cth[orderCoef-1] = (float)sqrt(cth2);
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for (m=orderCoef-1; m>0; m--)
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{
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tmp_inv = 1.0f / cth2;
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for (k=1; k<=m; k++)
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{
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tmp[k] = ((float)a[k] - sth[m] * (float)a[m-k+1]) * tmp_inv;
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}
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for (k=1; k<m; k++)
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{
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a[k] = tmp[k];
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}
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sth[m-1] = tmp[m];
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cth2 = 1 - sth[m-1] * sth[m-1];
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cth[m-1] = (float)sqrt(cth2);
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}
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}
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