📄 exc_lbc.c
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** i2 (+-1) : 4, 12, 20, 28, 36, 44, 52, (60)
** i3 (+-1) : 6, 14, 22, 30, 38, 46, 54, (62)
**
** All the pulse can be shifted by one.
** The last position of the last 2 pulses falls outside the
** frame and signifies that the pulse is not present.
** The threshold controls if a section of the innovative
** codebook should be searched or not.
**
** Links to the text: Section 2.16
**
** Input arguments:
**
** Word16 Dn[] Correlation between target vector and impulse response h[]
** Word16 rr[] Correlations of impulse response h[]
** Word16 h[] Impulse response of filters
**
** Output arguments:
**
** Word16 cod[] Selected algebraic codeword
** Word16 y[] Filtered codeword
** Word16 code_shift Shift of the codeword
** Word16 sign Signs of the 4 pulses.
**
** Return value:
**
** Word16 Index of selected codevector
**
*/
Word16 D4i64_LBC(Word16 Dn[], Word16 rr[], Word16 h[], Word16 cod[],
Word16 y[], Word16 *code_shift, Word16 *sign)
{
Word16 i0, i1, i2, i3, ip0, ip1, ip2, ip3;
Word16 i, j, time;
Word16 shif, shift;
Word16 ps0, ps1, ps2, ps3, alp, alp0;
Word32 alp1, alp2, alp3, L32;
Word16 ps0a, ps1a, ps2a;
Word16 ps3c, psc, alpha;
Word16 means, max0, max1, max2, thres;
Word16 *rri0i0, *rri1i1, *rri2i2, *rri3i3;
Word16 *rri0i1, *rri0i2, *rri0i3;
Word16 *rri1i2, *rri1i3, *rri2i3;
Word16 *ptr_ri0i0, *ptr_ri1i1, *ptr_ri2i2, *ptr_ri3i3;
Word16 *ptr_ri0i1, *ptr_ri0i2, *ptr_ri0i3;
Word16 *ptr_ri1i2, *ptr_ri1i3, *ptr_ri2i3;
Word16 *ptr1_ri0i1, *ptr1_ri0i2, *ptr1_ri0i3;
Word16 *ptr1_ri1i2, *ptr1_ri1i3, *ptr1_ri2i3;
Word16 p_sign[SubFrLen2/2];
/* Init pointers */
rri0i0 = rr;
rri1i1 = rri0i0 + NB_POS;
rri2i2 = rri1i1 + NB_POS;
rri3i3 = rri2i2 + NB_POS;
rri0i1 = rri3i3 + NB_POS;
rri0i2 = rri0i1 + MSIZE;
rri0i3 = rri0i2 + MSIZE;
rri1i2 = rri0i3 + MSIZE;
rri1i3 = rri1i2 + MSIZE;
rri2i3 = rri1i3 + MSIZE;
/*
* Extend the backward filtered target vector by zeros
*/
for (i = SubFrLen; i < SubFrLen2; i++) Dn[i] = 0;
/*
* Chose the sign of the impulse.
*/
for (i=0; i<SubFrLen; i+=2) {
if( add(Dn[i],Dn[i+1]) >= 0) {
p_sign[i/2] = 1;
}
else {
p_sign[i/2] = -1;
Dn[i] = -Dn[i];
Dn[i+1] = -Dn[i+1];
}
}
p_sign[30] = p_sign[31] = 1;
/*
* Compute the search threshold after three pulses
*/
/* odd positions */
/* Find maximum of Dn[i0]+Dn[i1]+Dn[i2] */
max0 = Dn[0];
max1 = Dn[2];
max2 = Dn[4];
for (i = 8; i < SubFrLen; i+=STEP) {
if (Dn[i] > max0) max0 = Dn[i];
if (Dn[i+2] > max1) max1 = Dn[i+2];
if (Dn[i+4] > max2) max2 = Dn[i+4];
}
max0 = add(max0, max1);
max0 = add(max0, max2);
/* Find means of Dn[i0]+Dn[i1]+Dn[i2] */
L32 = 0;
for (i = 0; i < SubFrLen; i+=STEP) {
L32 = L_mac(L32, Dn[i], 1);
L32 = L_mac(L32, Dn[i+2], 1);
L32 = L_mac(L32, Dn[i+4], 1);
}
means =extract_l( L_shr(L32, 4));
/* thres = means + (max0-means)*threshold; */
thres = sub(max0, means);
thres = mult(thres, threshold);
thres = add(thres, means);
/* even positions */
/* Find maximum of Dn[i0]+Dn[i1]+Dn[i2] */
max0 = Dn[1];
max1 = Dn[3];
max2 = Dn[5];
for (i = 9; i < SubFrLen; i+=STEP) {
if (Dn[i] > max0) max0 = Dn[i];
if (Dn[i+2] > max1) max1 = Dn[i+2];
if (Dn[i+4] > max2) max2 = Dn[i+4];
}
max0 = add(max0, max1);
max0 = add(max0, max2);
/* Find means of Dn[i0]+Dn[i1]+Dn[i2] */
L32 = 0;
for (i = 1; i < SubFrLen; i+=STEP) {
L32 = L_mac(L32, Dn[i], 1);
L32 = L_mac(L32, Dn[i+2], 1);
L32 = L_mac(L32, Dn[i+4], 1);
}
means =extract_l( L_shr(L32, 4));
/* max1 = means + (max0-means)*threshold */
max1 = sub(max0, means);
max1 = mult(max1, threshold);
max1 = add(max1, means);
/* Keep maximum threshold between odd and even position */
if(max1 > thres) thres = max1;
/*
* Modification of rrixiy[] to take signs into account.
*/
ptr_ri0i1 = rri0i1;
ptr_ri0i2 = rri0i2;
ptr_ri0i3 = rri0i3;
ptr1_ri0i1 = rri0i1;
ptr1_ri0i2 = rri0i2;
ptr1_ri0i3 = rri0i3;
for(i0=0; i0<SubFrLen/2; i0+=STEP/2) {
for(i1=2/2; i1<SubFrLen/2; i1+=STEP/2) {
*ptr_ri0i1++ = i_mult(*ptr1_ri0i1++,
i_mult(p_sign[i0], p_sign[i1]));
*ptr_ri0i2++ = i_mult(*ptr1_ri0i2++,
i_mult(p_sign[i0], p_sign[i1+1]));
*ptr_ri0i3++ = i_mult(*ptr1_ri0i3++,
i_mult(p_sign[i0], p_sign[i1+2]));
}
}
ptr_ri1i2 = rri1i2;
ptr_ri1i3 = rri1i3;
ptr1_ri1i2 = rri1i2;
ptr1_ri1i3 = rri1i3;
for(i1=2/2; i1<SubFrLen/2; i1+=STEP/2) {
for(i2=4/2; i2<SubFrLen2/2; i2+=STEP/2) {
*ptr_ri1i2++ = i_mult(*ptr1_ri1i2++,
i_mult(p_sign[i1], p_sign[i2]));
*ptr_ri1i3++ = i_mult(*ptr1_ri1i3++,
i_mult(p_sign[i1], p_sign[i2+1]));
}
}
ptr_ri2i3 = rri2i3;
ptr1_ri2i3 = rri2i3;
for(i2=4/2; i2<SubFrLen2/2; i2+=STEP/2) {
for(i3=6/2; i3<SubFrLen2/2; i3+=STEP/2)
*ptr_ri2i3++ = i_mult(*ptr1_ri2i3++, i_mult(p_sign[i2], p_sign[i3]));
}
/*
* Search the optimum positions of the four pulses which maximize
* square(correlation) / energy
* The search is performed in four nested loops. At each loop, one
* pulse contribution is added to the correlation and energy.
*
* The fourth loop is entered only if the correlation due to the
* contribution of the first three pulses exceeds the preset
* threshold.
*/
/* Default values */
ip0 = 0;
ip1 = 2;
ip2 = 4;
ip3 = 6;
shif = 0;
psc = 0;
alpha = 32767;
time = add(max_time, extra);
/* Four loops to search innovation code. */
/* Init. pointers that depend on first loop */
ptr_ri0i0 = rri0i0;
ptr_ri0i1 = rri0i1;
ptr_ri0i2 = rri0i2;
ptr_ri0i3 = rri0i3;
/* first pulse loop */
for (i0 = 0; i0 < SubFrLen; i0 += STEP) {
ps0 = Dn[i0];
ps0a = Dn[i0+1];
alp0 = *ptr_ri0i0++;
/* Init. pointers that depend on second loop */
ptr_ri1i1 = rri1i1;
ptr_ri1i2 = rri1i2;
ptr_ri1i3 = rri1i3;
/* second pulse loop */
for (i1 = 2; i1 < SubFrLen; i1 += STEP) {
ps1 = add(ps0, Dn[i1]);
ps1a = add(ps0a, Dn[i1+1]);
/* alp1 = alp0 + *ptr_ri1i1++ + 2.0 * ( *ptr_ri0i1++); */
alp1 = L_mult(alp0, 1);
alp1 = L_mac(alp1, *ptr_ri1i1++, 1);
alp1 = L_mac(alp1, *ptr_ri0i1++, 2);
/* Init. pointers that depend on third loop */
ptr_ri2i2 = rri2i2;
ptr_ri2i3 = rri2i3;
/* third pulse loop */
for (i2 = 4; i2 < SubFrLen2; i2 += STEP) {
ps2 = add(ps1, Dn[i2]);
ps2a = add(ps1a, Dn[i2+1]);
/* alp2 = alp1 + *ptr_ri2i2++
+ 2.0 * (*ptr_ri0i2++ + *ptr_ri1i2++); */
alp2 = L_mac(alp1, *ptr_ri2i2++, 1);
alp2 = L_mac(alp2, *ptr_ri0i2++, 2);
alp2 = L_mac(alp2, *ptr_ri1i2++, 2);
/* Decide the shift */
shift = 0;
if(ps2a > ps2) {
shift = 1;
ps2 = ps2a;
}
/* Test threshold */
if ( ps2 > thres) {
/* Init. pointers that depend on 4th loop */
ptr_ri3i3 = rri3i3;
/* 4th pulse loop */
for (i3 = 6; i3 < SubFrLen2; i3 += STEP) {
ps3 = add(ps2, Dn[i3+shift]);
/* alp3 = alp2 + (*ptr_ri3i3++) +
2 x ( (*ptr_ri0i3++) +
(*ptr_ri1i3++) +
(*ptr_ri2i3++) ) */
alp3 = L_mac(alp2, *ptr_ri3i3++, 1);
alp3 = L_mac(alp3, *ptr_ri0i3++, 2);
alp3 = L_mac(alp3, *ptr_ri1i3++, 2);
alp3 = L_mac(alp3, *ptr_ri2i3++, 2);
alp = extract_l(L_shr(alp3, 5));
ps3c = mult(ps3, ps3);
if( L_mult(ps3c, alpha) > L_mult(psc, alp) ) {
psc = ps3c;
alpha = alp;
ip0 = i0;
ip1 = i1;
ip2 = i2;
ip3 = i3;
shif = shift;
}
} /* end of for i3 = */
time --;
if(time <= 0 ) goto end_search; /* Max time finish */
ptr_ri0i3 -= NB_POS;
ptr_ri1i3 -= NB_POS;
} /* end of if >thres */
else {
ptr_ri2i3 += NB_POS;
}
} /* end of for i2 = */
ptr_ri0i2 -= NB_POS;
ptr_ri1i3 += NB_POS;
} /* end of for i1 = */
ptr_ri0i2 += NB_POS;
ptr_ri0i3 += NB_POS;
} /* end of for i0 = */
end_search:
extra = time;
/* Set the sign of impulses */
i0 = p_sign[shr(ip0, 1)];
i1 = p_sign[shr(ip1, 1)];
i2 = p_sign[shr(ip2, 1)];
i3 = p_sign[shr(ip3, 1)];
/* Find the codeword corresponding to the selected positions */
for(i=0; i<SubFrLen; i++) cod[i] = 0;
if(shif > 0) {
ip0 = add(ip0 ,1);
ip1 = add(ip1 ,1);
ip2 = add(ip2 ,1);
ip3 = add(ip3 ,1);
}
cod[ip0] = i0;
cod[ip1] = i1;
if(ip2<SubFrLen) cod[ip2] = i2;
if(ip3<SubFrLen) cod[ip3] = i3;
/* find the filtered codeword */
for (i = 0; i < SubFrLen; i++) y[i] = 0;
if(i0 > 0)
for(i=ip0, j=0; i<SubFrLen; i++, j++)
y[i] = add(y[i], h[j]);
else
for(i=ip0, j=0; i<SubFrLen; i++, j++)
y[i] = sub(y[i], h[j]);
if(i1 > 0)
for(i=ip1, j=0; i<SubFrLen; i++, j++)
y[i] = add(y[i], h[j]);
else
for(i=ip1, j=0; i<SubFrLen; i++, j++)
y[i] = sub(y[i], h[j]);
if(ip2 < SubFrLen) {
if(i2 > 0)
for(i=ip2, j=0; i<SubFrLen; i++, j++)
y[i] = add(y[i], h[j]);
else
for(i=ip2, j=0; i<SubFrLen; i++, j++)
y[i] = sub(y[i], h[j]);
}
if(ip3 < SubFrLen) {
if(i3 > 0)
for(i=ip3, j=0; i<SubFrLen; i++, j++)
y[i] = add(y[i], h[j]);
else
for(i=ip3, j=0; i<SubFrLen; i++, j++)
y[i] = sub(y[i], h[j]);
}
/* find codebook index; 17-bit address */
*code_shift = shif;
*sign = 0;
if(i0 > 0) *sign = add(*sign, 1);
if(i1 > 0) *sign = add(*sign, 2);
if(i2 > 0) *sign = add(*sign, 4);
if(i3 > 0) *sign = add(*sign, 8);
i = shr(ip0, 3);
i = add(i, shl(shr(ip1, 3), 3));
i = add(i, shl(shr(ip2, 3), 6));
i = add(i, shl(shr(ip3, 3), 9));
return i;
}
/*
**
** Function: G_code()
**
** Description: Compute the gain of innovative code.
**
**
** Links to the text: Section 2.16
**
** Input arguments:
**
** Word16 X[] Code target. (in Q0)
** Word16 Y[] Filtered innovation code. (in Q12)
**
** Output:
**
** Word16 *gain_q Gain of innovation code. (in Q0)
**
** Return value:
**
** Word16 index of innovation code gain
**
*/
Word16 G_code(Word16 X[], Word16 Y[], Word16 *gain_q)
{
Word16 i;
Word16 xy, yy, exp_xy, exp_yy, gain, gain_nq;
Word32 L_xy, L_yy;
Word16 dist, dist_min;
/* Scale down Y[] by 8 to avoid overflow */
for(i=0; i<SubFrLen; i++)
Y[i] = shr(Y[i], 3);
/* Compute scalar product <X[],Y[]> */
L_xy = 0L;
for(i=0; i<SubFrLen; i++)
L_xy = L_mac(L_xy, X[i], Y[i]);
exp_xy = norm_l(L_xy);
xy = extract_h( L_shl(L_xy, exp_xy) );
if(xy <= 0) {
gain = 0;
*gain_q =FcbkGainTable[gain];
return(gain);
}
/* Compute scalar product <Y[],Y[]> */
L_yy = 0L;
for(i=0; i<SubFrLen; i++)
L_yy = L_mac(L_yy, Y[i], Y[i]);
exp_yy = norm_l(L_yy);
yy = extract_h( L_shl(L_yy, exp_yy) );
/* compute gain = xy/yy */
xy = shr(xy, 1); /* Be sure xy < yy */
gain_nq = div_s( xy, yy);
i = add(exp_xy, 5); /* Denormalization of division */
i = sub(i, exp_yy);
gain_nq = shr(gain_nq, i);
gain = (Word16) 0;
dist_min = sub(gain_nq, FcbkGainTable[0]);
dist_min = abs_s(dist_min);
for ( i = 1; i <NumOfGainLev ; i ++ ) {
dist = sub(gain_nq, FcbkGainTable[i]);
dist =abs_s(dist);
if ( dist< dist_min) {
dist_min = dist;
gain = (Word16) i ;
}
}
*gain_q = FcbkGainTable[gain];
return(gain);
}
/*
**
** Function: search_T0()
**
** Description: Gets parameters of pitch synchronous filter
**
** Links to the text: Section 2.16
**
** Arguments:
**
** Word16 T0 Decoded pitch lag
** Word16 Gid Gain vector index in the adaptive gain vector codebook
** Word16 *gain_T0 Pitch synchronous gain
**
** Outputs:
**
** Word16 *gain_T0 Pitch synchronous filter gain
**
** Return Value:
**
** Word16 T0_mod Pitch synchronous filter lag
*/
Word16 search_T0 ( Word16 T0, Word16 Gid, Word16 *gain_T0)
{
Word16 T0_mod;
T0_mod = T0+epsi170[Gid];
*gain_T0 = gain170[Gid];
return(T0_mod);
}
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