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/*
* Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "lpc_analysis.h"
#include "settings.h"
#include "codec.h"
#include "entropy_coding.h"
#include <math.h>
#include <string.h>
#define LEVINSON_EPS 1.0e-10
/* window */
/* Matlab generation code:
* t = (1:256)/257; r = 1-(1-t).^.45; w = sin(r*pi).^3; w = w/sum(w); plot((1:256)/8, w); grid;
* for k=1:16, fprintf(1, '%.8f, ', w(k*16 + (-15:0))); fprintf(1, '\n'); end
*/
static const double kLpcCorrWindow[WINLEN] = {
0.00000000, 0.00000001, 0.00000004, 0.00000010, 0.00000020,
0.00000035, 0.00000055, 0.00000083, 0.00000118, 0.00000163,
0.00000218, 0.00000283, 0.00000361, 0.00000453, 0.00000558, 0.00000679,
0.00000817, 0.00000973, 0.00001147, 0.00001342, 0.00001558,
0.00001796, 0.00002058, 0.00002344, 0.00002657, 0.00002997,
0.00003365, 0.00003762, 0.00004190, 0.00004651, 0.00005144, 0.00005673,
0.00006236, 0.00006837, 0.00007476, 0.00008155, 0.00008875,
0.00009636, 0.00010441, 0.00011290, 0.00012186, 0.00013128,
0.00014119, 0.00015160, 0.00016252, 0.00017396, 0.00018594, 0.00019846,
0.00021155, 0.00022521, 0.00023946, 0.00025432, 0.00026978,
0.00028587, 0.00030260, 0.00031998, 0.00033802, 0.00035674,
0.00037615, 0.00039626, 0.00041708, 0.00043863, 0.00046092, 0.00048396,
0.00050775, 0.00053233, 0.00055768, 0.00058384, 0.00061080,
0.00063858, 0.00066720, 0.00069665, 0.00072696, 0.00075813,
0.00079017, 0.00082310, 0.00085692, 0.00089164, 0.00092728, 0.00096384,
0.00100133, 0.00103976, 0.00107914, 0.00111947, 0.00116077,
0.00120304, 0.00124630, 0.00129053, 0.00133577, 0.00138200,
0.00142924, 0.00147749, 0.00152676, 0.00157705, 0.00162836, 0.00168070,
0.00173408, 0.00178850, 0.00184395, 0.00190045, 0.00195799,
0.00201658, 0.00207621, 0.00213688, 0.00219860, 0.00226137,
0.00232518, 0.00239003, 0.00245591, 0.00252284, 0.00259079, 0.00265977,
0.00272977, 0.00280078, 0.00287280, 0.00294582, 0.00301984,
0.00309484, 0.00317081, 0.00324774, 0.00332563, 0.00340446,
0.00348421, 0.00356488, 0.00364644, 0.00372889, 0.00381220, 0.00389636,
0.00398135, 0.00406715, 0.00415374, 0.00424109, 0.00432920,
0.00441802, 0.00450754, 0.00459773, 0.00468857, 0.00478001,
0.00487205, 0.00496464, 0.00505775, 0.00515136, 0.00524542, 0.00533990,
0.00543476, 0.00552997, 0.00562548, 0.00572125, 0.00581725,
0.00591342, 0.00600973, 0.00610612, 0.00620254, 0.00629895,
0.00639530, 0.00649153, 0.00658758, 0.00668341, 0.00677894, 0.00687413,
0.00696891, 0.00706322, 0.00715699, 0.00725016, 0.00734266,
0.00743441, 0.00752535, 0.00761540, 0.00770449, 0.00779254,
0.00787947, 0.00796519, 0.00804963, 0.00813270, 0.00821431, 0.00829437,
0.00837280, 0.00844949, 0.00852436, 0.00859730, 0.00866822,
0.00873701, 0.00880358, 0.00886781, 0.00892960, 0.00898884,
0.00904542, 0.00909923, 0.00915014, 0.00919805, 0.00924283, 0.00928436,
0.00932252, 0.00935718, 0.00938821, 0.00941550, 0.00943890,
0.00945828, 0.00947351, 0.00948446, 0.00949098, 0.00949294,
0.00949020, 0.00948262, 0.00947005, 0.00945235, 0.00942938, 0.00940099,
0.00936704, 0.00932738, 0.00928186, 0.00923034, 0.00917268,
0.00910872, 0.00903832, 0.00896134, 0.00887763, 0.00878706,
0.00868949, 0.00858478, 0.00847280, 0.00835343, 0.00822653, 0.00809199,
0.00794970, 0.00779956, 0.00764145, 0.00747530, 0.00730103,
0.00711857, 0.00692787, 0.00672888, 0.00652158, 0.00630597,
0.00608208, 0.00584994, 0.00560962, 0.00536124, 0.00510493, 0.00484089,
0.00456935, 0.00429062, 0.00400505, 0.00371310, 0.00341532,
0.00311238, 0.00280511, 0.00249452, 0.00218184, 0.00186864,
0.00155690, 0.00124918, 0.00094895, 0.00066112, 0.00039320, 0.00015881
};
double WebRtcIsac_LevDurb(double *a, double *k, double *r, int order)
{
double sum, alpha;
int m, m_h, i;
alpha = 0; //warning -DH
a[0] = 1.0;
if (r[0] < LEVINSON_EPS) { /* if r[0] <= 0, set LPC coeff. to zero */
for (i = 0; i < order; i++) {
k[i] = 0;
a[i+1] = 0;
}
} else {
a[1] = k[0] = -r[1]/r[0];
alpha = r[0] + r[1] * k[0];
for (m = 1; m < order; m++){
sum = r[m + 1];
for (i = 0; i < m; i++){
sum += a[i+1] * r[m - i];
}
k[m] = -sum / alpha;
alpha += k[m] * sum;
m_h = (m + 1) >> 1;
for (i = 0; i < m_h; i++){
sum = a[i+1] + k[m] * a[m - i];
a[m - i] += k[m] * a[i+1];
a[i+1] = sum;
}
a[m+1] = k[m];
}
}
return alpha;
}
//was static before, but didn't work with MEX file
void WebRtcIsac_GetVars(const double *input, const WebRtc_Word16 *pitchGains_Q12,
double *oldEnergy, double *varscale)
{
double nrg[4], chng, pg;
int k;
double pitchGains[4]={0,0,0,0};;
/* Calculate energies of first and second frame halfs */
nrg[0] = 0.0001;
for (k = QLOOKAHEAD/2; k < (FRAMESAMPLES_QUARTER + QLOOKAHEAD) / 2; k++) {
nrg[0] += input[k]*input[k];
}
nrg[1] = 0.0001;
for ( ; k < (FRAMESAMPLES_HALF + QLOOKAHEAD) / 2; k++) {
nrg[1] += input[k]*input[k];
}
nrg[2] = 0.0001;
for ( ; k < (FRAMESAMPLES*3/4 + QLOOKAHEAD) / 2; k++) {
nrg[2] += input[k]*input[k];
}
nrg[3] = 0.0001;
for ( ; k < (FRAMESAMPLES + QLOOKAHEAD) / 2; k++) {
nrg[3] += input[k]*input[k];
}
/* Calculate average level change */
chng = 0.25 * (fabs(10.0 * log10(nrg[3] / nrg[2])) +
fabs(10.0 * log10(nrg[2] / nrg[1])) +
fabs(10.0 * log10(nrg[1] / nrg[0])) +
fabs(10.0 * log10(nrg[0] / *oldEnergy)));
/* Find average pitch gain */
pg = 0.0;
for (k=0; k<4; k++)
{
pitchGains[k] = ((float)pitchGains_Q12[k])/4096;
pg += pitchGains[k];
}
pg *= 0.25;
/* If pitch gain is low and energy constant - increase noise level*/
/* Matlab code:
pg = 0:.01:.45; plot(pg, 0.0 + 1.0 * exp( -1.0 * exp(-200.0 * pg.*pg.*pg) / (1.0 + 0.4 * 0) ))
*/
*varscale = 0.0 + 1.0 * exp( -1.4 * exp(-200.0 * pg*pg*pg) / (1.0 + 0.4 * chng) );
*oldEnergy = nrg[3];
}
void
WebRtcIsac_GetVarsUB(
const double* input,
double* oldEnergy,
double* varscale)
{
double nrg[4], chng;
int k;
/* Calculate energies of first and second frame halfs */
nrg[0] = 0.0001;
for (k = 0; k < (FRAMESAMPLES_QUARTER) / 2; k++) {
nrg[0] += input[k]*input[k];
}
nrg[1] = 0.0001;
for ( ; k < (FRAMESAMPLES_HALF) / 2; k++) {
nrg[1] += input[k]*input[k];
}
nrg[2] = 0.0001;
for ( ; k < (FRAMESAMPLES*3/4) / 2; k++) {
nrg[2] += input[k]*input[k];
}
nrg[3] = 0.0001;
for ( ; k < (FRAMESAMPLES) / 2; k++) {
nrg[3] += input[k]*input[k];
}
/* Calculate average level change */
chng = 0.25 * (fabs(10.0 * log10(nrg[3] / nrg[2])) +
fabs(10.0 * log10(nrg[2] / nrg[1])) +
fabs(10.0 * log10(nrg[1] / nrg[0])) +
fabs(10.0 * log10(nrg[0] / *oldEnergy)));
/* If pitch gain is low and energy constant - increase noise level*/
/* Matlab code:
pg = 0:.01:.45; plot(pg, 0.0 + 1.0 * exp( -1.0 * exp(-200.0 * pg.*pg.*pg) / (1.0 + 0.4 * 0) ))
*/
*varscale = exp( -1.4 / (1.0 + 0.4 * chng) );
*oldEnergy = nrg[3];
}
void WebRtcIsac_GetLpcCoefLb(double *inLo, double *inHi, MaskFiltstr *maskdata,
double signal_noise_ratio, const WebRtc_Word16 *pitchGains_Q12,
double *lo_coeff, double *hi_coeff)
{
int k, n, j, pos1, pos2;
double varscale;
double DataLo[WINLEN], DataHi[WINLEN];
double corrlo[ORDERLO+2], corrlo2[ORDERLO+1];
double corrhi[ORDERHI+1];
double k_veclo[ORDERLO], k_vechi[ORDERHI];
double a_LO[ORDERLO+1], a_HI[ORDERHI+1];
double tmp, res_nrg;
double FwdA, FwdB;
/* hearing threshold level in dB; higher value gives more noise */
const double HearThresOffset = -28.0;
/* bandwdith expansion factors for low- and high band */
const double gammaLo = 0.9;
const double gammaHi = 0.8;
/* less-noise-at-low-frequencies factor */
double aa;
/* convert from dB to signal level */
const double H_T_H = pow(10.0, 0.05 * HearThresOffset);
double S_N_R = pow(10.0, 0.05 * signal_noise_ratio) / 3.46; /* divide by sqrt(12) */
/* change quallevel depending on pitch gains and level fluctuations */
WebRtcIsac_GetVars(inLo, pitchGains_Q12, &(maskdata->OldEnergy), &varscale);
/* less-noise-at-low-frequencies factor */
aa = 0.35 * (0.5 + 0.5 * varscale);
/* replace data in buffer by new look-ahead data */
for (pos1 = 0; pos1 < QLOOKAHEAD; pos1++)
maskdata->DataBufferLo[pos1 + WINLEN - QLOOKAHEAD] = inLo[pos1];
for (k = 0; k < SUBFRAMES; k++) {
/* Update input buffer and multiply signal with window */
for (pos1 = 0; pos1 < WINLEN - UPDATE/2; pos1++) {
maskdata->DataBufferLo[pos1] = maskdata->DataBufferLo[pos1 + UPDATE/2];
maskdata->DataBufferHi[pos1] = maskdata->DataBufferHi[pos1 + UPDATE/2];
DataLo[pos1] = maskdata->DataBufferLo[pos1] * kLpcCorrWindow[pos1];
DataHi[pos1] = maskdata->DataBufferHi[pos1] * kLpcCorrWindow[pos1];
}
pos2 = k * UPDATE/2;
for (n = 0; n < UPDATE/2; n++, pos1++) {
maskdata->DataBufferLo[pos1] = inLo[QLOOKAHEAD + pos2];
maskdata->DataBufferHi[pos1] = inHi[pos2++];
DataLo[pos1] = maskdata->DataBufferLo[pos1] * kLpcCorrWindow[pos1];
DataHi[pos1] = maskdata->DataBufferHi[pos1] * kLpcCorrWindow[pos1];
}
/* Get correlation coefficients */
WebRtcIsac_AutoCorr(corrlo, DataLo, WINLEN, ORDERLO+1); /* computing autocorrelation */
WebRtcIsac_AutoCorr(corrhi, DataHi, WINLEN, ORDERHI);
/* less noise for lower frequencies, by filtering/scaling autocorrelation sequences */
corrlo2[0] = (1.0+aa*aa) * corrlo[0] - 2.0*aa * corrlo[1];
tmp = (1.0 + aa*aa);
for (n = 1; n <= ORDERLO; n++) {
corrlo2[n] = tmp * corrlo[n] - aa * (corrlo[n-1] + corrlo[n+1]);
}
tmp = (1.0+aa) * (1.0+aa);
for (n = 0; n <= ORDERHI; n++) {
corrhi[n] = tmp * corrhi[n];
}
/* add white noise floor */
corrlo2[0] += 1e-6;
corrhi[0] += 1e-6;
FwdA = 0.01;
FwdB = 0.01;
/* recursive filtering of correlation over subframes */
for (n = 0; n <= ORDERLO; n++) {
maskdata->CorrBufLo[n] = FwdA * maskdata->CorrBufLo[n] + corrlo2[n];
corrlo2[n] = ((1.0-FwdA)*FwdB) * maskdata->CorrBufLo[n] + (1.0-FwdB) * corrlo2[n];
}
for (n = 0; n <= ORDERHI; n++) {
maskdata->CorrBufHi[n] = FwdA * maskdata->CorrBufHi[n] + corrhi[n];
corrhi[n] = ((1.0-FwdA)*FwdB) * maskdata->CorrBufHi[n] + (1.0-FwdB) * corrhi[n];
}
/* compute prediction coefficients */
WebRtcIsac_LevDurb(a_LO, k_veclo, corrlo2, ORDERLO);
WebRtcIsac_LevDurb(a_HI, k_vechi, corrhi, ORDERHI);
/* bandwidth expansion */
tmp = gammaLo;
for (n = 1; n <= ORDERLO; n++) {
a_LO[n] *= tmp;
tmp *= gammaLo;
}
/* residual energy */
res_nrg = 0.0;
for (j = 0; j <= ORDERLO; j++) {
for (n = 0; n <= j; n++) {
res_nrg += a_LO[j] * corrlo2[j-n] * a_LO[n];
}
for (n = j+1; n <= ORDERLO; n++) {
res_nrg += a_LO[j] * corrlo2[n-j] * a_LO[n];
}
}
/* add hearing threshold and compute the gain */
*lo_coeff++ = S_N_R / (sqrt(res_nrg) / varscale + H_T_H);
/* copy coefficients to output array */
for (n = 1; n <= ORDERLO; n++) {
*lo_coeff++ = a_LO[n];
}
/* bandwidth expansion */
tmp = gammaHi;
for (n = 1; n <= ORDERHI; n++) {
a_HI[n] *= tmp;
tmp *= gammaHi;
}
/* residual energy */
res_nrg = 0.0;
for (j = 0; j <= ORDERHI; j++) {
for (n = 0; n <= j; n++) {
res_nrg += a_HI[j] * corrhi[j-n] * a_HI[n];
}
for (n = j+1; n <= ORDERHI; n++) {
res_nrg += a_HI[j] * corrhi[n-j] * a_HI[n];
}
}
/* add hearing threshold and compute of the gain */
*hi_coeff++ = S_N_R / (sqrt(res_nrg) / varscale + H_T_H);
/* copy coefficients to output array */
for (n = 1; n <= ORDERHI; n++) {
*hi_coeff++ = a_HI[n];
}
}
}
/******************************************************************************
* WebRtcIsac_GetLpcCoefUb()
*
* Compute LP coefficients and correlation coefficients. At 12 kHz LP
* coefficients of the first and the last sub-frame is computed. At 16 kHz
* LP coefficients of 4th, 8th and 12th sub-frames are computed. We always
* compute correlation coefficients of all sub-frames.
*
* Inputs:
* -inSignal : Input signal
* -maskdata : a structure keeping signal from previous frame.
* -bandwidth : specifies if the codec is in 0-16 kHz mode or
* 0-12 kHz mode.
*
* Outputs:
* -lpCoeff : pointer to a buffer where A-polynomials are
* written to (first coeff is 1 and it is not
* written)
* -corrMat : a matrix where correlation coefficients of each
* sub-frame are written to one row.
* -varscale : a scale used to compute LPC gains.
*/
void
WebRtcIsac_GetLpcCoefUb(
double* inSignal,
MaskFiltstr* maskdata,
double* lpCoeff,
double corrMat[][UB_LPC_ORDER + 1],
double* varscale,
WebRtc_Word16 bandwidth)
{
int frameCntr, activeFrameCntr, n, pos1, pos2;
WebRtc_Word16 criterion1;
WebRtc_Word16 criterion2;
WebRtc_Word16 numSubFrames = SUBFRAMES * (1 + (bandwidth == isac16kHz));
double data[WINLEN];
double corrSubFrame[UB_LPC_ORDER+2];
double reflecCoeff[UB_LPC_ORDER];
double aPolynom[UB_LPC_ORDER+1];
double tmp;
/* bandwdith expansion factors */
const double gamma = 0.9;
/* change quallevel depending on pitch gains and level fluctuations */
WebRtcIsac_GetVarsUB(inSignal, &(maskdata->OldEnergy), varscale);
/* replace data in buffer by new look-ahead data */
for(frameCntr = 0, activeFrameCntr = 0; frameCntr < numSubFrames;
frameCntr++)
{
if(frameCntr == SUBFRAMES)
{
// we are in 16 kHz
varscale++;
WebRtcIsac_GetVarsUB(&inSignal[FRAMESAMPLES_HALF],
&(maskdata->OldEnergy), varscale);
}
/* Update input buffer and multiply signal with window */
for(pos1 = 0; pos1 < WINLEN - UPDATE/2; pos1++)
{
maskdata->DataBufferLo[pos1] = maskdata->DataBufferLo[pos1 +
UPDATE/2];
data[pos1] = maskdata->DataBufferLo[pos1] * kLpcCorrWindow[pos1];
}
pos2 = frameCntr * UPDATE/2;
for(n = 0; n < UPDATE/2; n++, pos1++, pos2++)
{
maskdata->DataBufferLo[pos1] = inSignal[pos2];
data[pos1] = maskdata->DataBufferLo[pos1] * kLpcCorrWindow[pos1];
}
/* Get correlation coefficients */
/* computing autocorrelation */
WebRtcIsac_AutoCorr(corrSubFrame, data, WINLEN, UB_LPC_ORDER+1);
memcpy(corrMat[frameCntr], corrSubFrame,
(UB_LPC_ORDER+1)*sizeof(double));
criterion1 = ((frameCntr == 0) || (frameCntr == (SUBFRAMES - 1))) &&
(bandwidth == isac12kHz);
criterion2 = (((frameCntr+1) % 4) == 0) &&
(bandwidth == isac16kHz);
if(criterion1 || criterion2)
{
/* add noise */
corrSubFrame[0] += 1e-6;
/* compute prediction coefficients */
WebRtcIsac_LevDurb(aPolynom, reflecCoeff, corrSubFrame,
UB_LPC_ORDER);
/* bandwidth expansion */
tmp = gamma;
for (n = 1; n <= UB_LPC_ORDER; n++)
{
*lpCoeff++ = aPolynom[n] * tmp;
tmp *= gamma;
}
activeFrameCntr++;
}
}
}
/******************************************************************************
* WebRtcIsac_GetLpcGain()
*
* Compute the LPC gains for each sub-frame, given the LPC of each sub-frame
* and the corresponding correlation coefficients.
*
* Inputs:
* -signal_noise_ratio : the desired SNR in dB.
* -numVecs : number of sub-frames
* -corrMat : a matrix of correlation coefficients where
* each row is a set of correlation coefficients of
* one sub-frame.
* -varscale : a scale computed when WebRtcIsac_GetLpcCoefUb()
* is called.
*
* Outputs:
* -gain : pointer to a buffer where LP gains are written.
*
*/
void
WebRtcIsac_GetLpcGain(
double signal_noise_ratio,
const double* filtCoeffVecs,
int numVecs,
double* gain,
double corrMat[][UB_LPC_ORDER + 1],
const double* varscale)
{
WebRtc_Word16 j, n;
WebRtc_Word16 subFrameCntr;
double aPolynom[ORDERLO + 1];
double res_nrg;
const double HearThresOffset = -28.0;
const double H_T_H = pow(10.0, 0.05 * HearThresOffset);
/* divide by sqrt(12) = 3.46 */
const double S_N_R = pow(10.0, 0.05 * signal_noise_ratio) / 3.46;
aPolynom[0] = 1;
for(subFrameCntr = 0; subFrameCntr < numVecs; subFrameCntr++)
{
if(subFrameCntr == SUBFRAMES)
{
// we are in second half of a SWB frame. use new varscale
varscale++;
}
memcpy(&aPolynom[1], &filtCoeffVecs[(subFrameCntr * (UB_LPC_ORDER + 1)) +
1], sizeof(double) * UB_LPC_ORDER);
/* residual energy */
res_nrg = 0.0;
for(j = 0; j <= UB_LPC_ORDER; j++)
{
for(n = 0; n <= j; n++)
{
res_nrg += aPolynom[j] * corrMat[subFrameCntr][j-n] *
aPolynom[n];
}
for(n = j+1; n <= UB_LPC_ORDER; n++)
{
res_nrg += aPolynom[j] * corrMat[subFrameCntr][n-j] *
aPolynom[n];
}
}
/* add hearing threshold and compute the gain */
gain[subFrameCntr] = S_N_R / (sqrt(res_nrg) / *varscale + H_T_H);
}
}