📄 exc_lbc.c
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**
** Links to text: Sections 2.14, 2.18 & 3.4
**
** Arguments:
**
** Word16 *Tv delayed excitation
** Word16 *PrevExc Previous excitation vector
** Word16 Lag Closed loop pitch lag
**
** Outputs:
**
** Word16 *Tv delayed excitation
**
** Return value: None
**
*/
void Get_Rez( Word16 *Tv, Word16 *PrevExc, Word16 Lag )
{
int i ;
for ( i = 0 ; i < ClPitchOrd/2 ; i ++ )
Tv[i] = PrevExc[PitchMax - (int) Lag - ClPitchOrd/2 + i] ;
for ( i = 0 ; i < SubFrLen+ClPitchOrd/2 ; i ++ )
Tv[ClPitchOrd/2+i] = PrevExc[PitchMax - (int)Lag + i%(int)Lag] ;
return;
}
/*
**
** Function: Decod_Acbk()
**
** Description: Computes the adaptive codebook contribution from the previous
** excitation vector.
** With the gain index, the closed loop pitch lag, the jitter
** which when added to this pitch lag gives the actual closed
** loop value, and after having selected the proper codebook,
** the pitch contribution is reconstructed using the previous
** excitation buffer.
**
** Links to text: Sections 2.14, 2.18 & 3.4
**
** Arguments:
**
** Word16 *Tv Reconstructed excitation vector
** Word16 *PrevExc Previous excitation vector
** Word16 Olp closed-loop pitch period
** Word16 Lid Jitter around pitch period
** Word16 Gid Gain vector index in 5- dimensional
** adaptive gain vector codebook
**
** Outputs:
**
** Word16 *Tv Reconstructed excitation vector
**
** Return value: None
**
*/
void Decod_Acbk( Word16 *Tv, Word16 *PrevExc, Word16 Olp, Word16 Lid,
Word16 Gid )
{
int i,j ;
Word32 Acc0 ;
Word16 RezBuf[SubFrLen+ClPitchOrd-1] ;
Word16 *sPnt ;
Get_Rez( RezBuf, PrevExc, (Word16)(Olp - (Word16)Pstep + Lid) ) ;
/* Select Quantization tables */
i = 0 ;
if ( WrkRate == Rate63 ) {
if ( Olp >= (Word16) (SubFrLen-2) ) i ++ ;
}
else {
i = 1;
}
sPnt = AcbkGainTablePtr[i] ;
sPnt += (int)Gid*20 ;
for ( i = 0 ; i < SubFrLen ; i ++ ) {
Acc0 = (Word32) 0 ;
for ( j = 0 ; j < ClPitchOrd ; j ++ )
Acc0 = L_mac( Acc0, RezBuf[i+j], sPnt[j] ) ;
Acc0 = L_shl( Acc0, (Word16) 1 ) ;
Tv[i] = round( Acc0 ) ;
}
return;
}
/*
**
** Function: ACELP_LBC_code()
**
** Description: Find Algebraic codebook for low bit rate LBC encoder
**
** Links to text: Section 2.16
**
** Arguments:
**
** Word16 X[] Target vector. (in Q0)
** Word16 h[] Impulse response. (in Q12)
** Word16 T0 Pitch period.
** Word16 code[] Innovative vector. (in Q12)
** Word16 gain Innovative vector gain. (in Q0)
** Word16 sign Signs of the 4 pulses.
** Word16 shift Shift of the innovative vector
** Word16 gain_T0 Gain for pitch synchronous fiter
**
** Inputs :
**
** Word16 X[] Target vector. (in Q0)
** Word16 h[] Impulse response. (in Q12)
** Word16 T0 Pitch period.
** Word16 gain_T0 Gain for pitch synchronous fiter
**
** Outputs:
**
** Word16 code[] Innovative vector. (in Q12)
** Word16 gain Innovative vector gain. (in Q0)
** Word16 sign Signs of the 4 pulses.
** Word16 shift Shift of the innovative vector.
**
** Return value:
**
** Word16 index Innovative codebook index
**
*/
Word16 ACELP_LBC_code(Word16 X[], Word16 h[], Word16 T0, Word16 code[],
Word16 *ind_gain, Word16 *shift, Word16 *sign, Word16 gain_T0)
{
Word16 i, index, gain_q;
Word16 Dn[SubFrLen2], tmp_code[SubFrLen2];
Word16 rr[DIM_RR];
/*
* Include fixed-gain pitch contribution into impulse resp. h[]
* Find correlations of h[] needed for the codebook search.
*/
for (i = 0; i < SubFrLen; i++) /* Q13 --> Q12*/
h[i] = shr(h[i], 1);
if (T0 < SubFrLen-2) {
for (i = T0; i < SubFrLen; i++) /* h[i] += gain_T0*h[i-T0] */
h[i] = add(h[i], mult(h[i-T0], gain_T0));
}
Cor_h(h, rr);
/*
* Compute correlation of target vector with impulse response.
*/
Cor_h_X(h, X, Dn);
/*
* Find innovative codebook.
* rr input matrix autocorrelation
* output filtered codeword
*/
index = D4i64_LBC(Dn, rr, h, tmp_code, rr, shift, sign);
/*
* Compute innovation vector gain.
* Include fixed-gain pitch contribution into code[].
*/
*ind_gain = G_code(X, rr, &gain_q);
for (i = 0; i < SubFrLen; i++) {
code[i] = i_mult(tmp_code[i], gain_q);
}
if(T0 < SubFrLen-2)
for (i = T0; i < SubFrLen; i++) /* code[i] += gain_T0*code[i-T0] */
code[i] = add(code[i], mult(code[i-T0], gain_T0));
return index;
}
/*
**
** Function: Cor_h()
**
** Description: Compute correlations of h[] needed for the codebook search.
**
** Links to text: Section 2.16
**
** Arguments:
**
** Word16 h[] Impulse response.
** Word16 rr[] Correlations.
**
** Outputs:
**
** Word16 rr[] Correlations.
**
** Return value : None
*/
void Cor_h(Word16 *H, Word16 *rr)
{
Word16 *rri0i0, *rri1i1, *rri2i2, *rri3i3;
Word16 *rri0i1, *rri0i2, *rri0i3;
Word16 *rri1i2, *rri1i3, *rri2i3;
Word16 *p0, *p1, *p2, *p3;
Word16 *ptr_hd, *ptr_hf, *ptr_h1, *ptr_h2;
Word32 cor;
Word16 i, k, ldec, l_fin_sup, l_fin_inf;
Word16 h[SubFrLen2];
/* Scaling for maximum precision */
cor = 0;
for(i=0; i<SubFrLen; i++)
cor = L_mac(cor, H[i], H[i]);
if(extract_h(cor) > 32000 ) {
for(i=0; i<SubFrLen; i++) h[i+4] = shr(H[i], 1);
}
else {
k = norm_l(cor);
k = shr(k, 1);
for(i=0; i<SubFrLen; i++) h[i+4] = shl(H[i], k);
}
for(i=0; i<4; i++) h[i] = 0;
/* 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;
/*
* Compute rri0i0[], rri1i1[], rri2i2[] and rri3i3[]
*/
p0 = rri0i0 + NB_POS-1; /* Init pointers to last position of rrixix[] */
p1 = rri1i1 + NB_POS-1;
p2 = rri2i2 + NB_POS-1;
p3 = rri3i3 + NB_POS-1;
ptr_h1 = h;
cor = 0;
for(i=0; i<NB_POS; i++) {
cor = L_mac(cor, *ptr_h1, *ptr_h1); ptr_h1++;
cor = L_mac(cor, *ptr_h1, *ptr_h1); ptr_h1++;
*p3-- = extract_h(cor);
cor = L_mac(cor, *ptr_h1, *ptr_h1); ptr_h1++;
cor = L_mac(cor, *ptr_h1, *ptr_h1); ptr_h1++;
*p2-- = extract_h(cor);
cor = L_mac(cor, *ptr_h1, *ptr_h1); ptr_h1++;
cor = L_mac(cor, *ptr_h1, *ptr_h1); ptr_h1++;
*p1-- = extract_h(cor);
cor = L_mac(cor, *ptr_h1, *ptr_h1); ptr_h1++;
cor = L_mac(cor, *ptr_h1, *ptr_h1); ptr_h1++;
*p0-- = extract_h(cor);
}
/*
* Compute elements of: rri0i1[], rri0i3[], rri1i2[] and rri2i3[]
*/
l_fin_sup = MSIZE-1;
l_fin_inf = l_fin_sup-(Word16)1;
ldec = NB_POS+1;
ptr_hd = h;
ptr_hf = ptr_hd + 2;
for(k=0; k<NB_POS; k++) {
p3 = rri2i3 + l_fin_sup;
p2 = rri1i2 + l_fin_sup;
p1 = rri0i1 + l_fin_sup;
p0 = rri0i3 + l_fin_inf;
cor = 0;
ptr_h1 = ptr_hd;
ptr_h2 = ptr_hf;
for(i=k+(Word16)1; i<NB_POS; i++ ) {
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
*p3 = extract_h(cor);
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
*p2 = extract_h(cor);
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
*p1 = extract_h(cor);
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
*p0 = extract_h(cor);
p3 -= ldec;
p2 -= ldec;
p1 -= ldec;
p0 -= ldec;
}
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
*p3 = extract_h(cor);
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
*p2 = extract_h(cor);
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
*p1 = extract_h(cor);
l_fin_sup -= NB_POS;
l_fin_inf--;
ptr_hf += STEP;
}
/*
* Compute elements of: rri0i2[], rri1i3[]
*/
ptr_hd = h;
ptr_hf = ptr_hd + 4;
l_fin_sup = MSIZE-1;
l_fin_inf = l_fin_sup-(Word16)1;
for(k=0; k<NB_POS; k++) {
p3 = rri1i3 + l_fin_sup;
p2 = rri0i2 + l_fin_sup;
p1 = rri1i3 + l_fin_inf;
p0 = rri0i2 + l_fin_inf;
cor = 0;
ptr_h1 = ptr_hd;
ptr_h2 = ptr_hf;
for(i=k+(Word16)1; i<NB_POS; i++ ) {
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
*p3 = extract_h(cor);
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
*p2 = extract_h(cor);
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
*p1 = extract_h(cor);
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
*p0 = extract_h(cor);
p3 -= ldec;
p2 -= ldec;
p1 -= ldec;
p0 -= ldec;
}
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
*p3 = extract_h(cor);
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
*p2 = extract_h(cor);
l_fin_sup -= NB_POS;
l_fin_inf--;
ptr_hf += STEP;
}
/*
* Compute elements of: rri0i1[], rri0i3[], rri1i2[] and rri2i3[]
*/
ptr_hd = h;
ptr_hf = ptr_hd + 6;
l_fin_sup = MSIZE-1;
l_fin_inf = l_fin_sup-(Word16)1;
for(k=0; k<NB_POS; k++) {
p3 = rri0i3 + l_fin_sup;
p2 = rri2i3 + l_fin_inf;
p1 = rri1i2 + l_fin_inf;
p0 = rri0i1 + l_fin_inf;
ptr_h1 = ptr_hd;
ptr_h2 = ptr_hf;
cor = 0;
for(i=k+(Word16)1; i<NB_POS; i++ ) {
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
*p3 = extract_h(cor);
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
*p2 = extract_h(cor);
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
*p1 = extract_h(cor);
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
*p0 = extract_h(cor);
p3 -= ldec;
p2 -= ldec;
p1 -= ldec;
p0 -= ldec;
}
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
cor = L_mac(cor, *ptr_h1, *ptr_h2); ptr_h1++; ptr_h2++;
*p3 = extract_h(cor);
l_fin_sup -= NB_POS;
l_fin_inf--;
ptr_hf += STEP;
}
return;
}
/*
**
** Function: Corr_h_X()
**
** Description: Compute correlations of input response h[] with
** the target vector X[].
**
** Links to the text: Section 2.16
**
** Arguments:
**
** Word16 h[] Impulse response.
** Word16 X[] Target vector.
** Word16 D[] Correlations.
**
** Outputs:
**
** Word16 D[] Correlations.
**
** Return value: None
*/
void Cor_h_X(Word16 h[], Word16 X[], Word16 D[])
{
Word16 i, j;
Word32 s, max;
Word32 y32[SubFrLen];
/* first keep the result on 32 bits and find absolute maximum */
max = 0;
for (i = 0; i < SubFrLen; i++) {
s = 0;
for (j = i; j < SubFrLen; j++)
s = L_mac(s, X[j], h[j-i]);
y32[i] = s;
s = L_abs(s);
if(s > max) max = s;
}
/*
* Find the number of right shifts to do on y32[]
* so that maximum is on 13 bits
*/
j = norm_l(max);
if( sub(j,16) > 0) j = 16;
j = sub(18, j);
for(i=0; i<SubFrLen; i++)
D[i] = extract_l( L_shr(y32[i], j) );
return;
}
/*
** Function: Reset_max_time()
**
** Description: This function should be called at the beginning
** of each frame.
**
** Links to the text: Section 2.16
**
** Arguments: None
**
** Inputs: None
**
** Outputs:
**
** Word16 extra
**
** Return value: None
**
*/
static Word16 extra;
void reset_max_time(void)
{
extra = 120;
return;
}
/*
**
** Function: D4i64_LBC
**
** Description: Algebraic codebook for LBC.
** -> 17 bits; 4 pulses in a frame of 60 samples
**
** The code length is 60, containing 4 nonzero pulses
** i0, i1, i2, i3. Each pulse can have 8 possible
** positions (positive or negative):
**
** i0 (+-1) : 0, 8, 16, 24, 32, 40, 48, 56
** i1 (+-1) : 2, 10, 18, 26, 34, 42, 50, 58
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