📄 qgain795.c
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#include "qgain795.h"
#include "basic_op.h"
#include "bitno_tab.h"
#define LTP_GAIN_THR1 2721 /* 2721 Q13 = 0.3322 ~= 1.0 / (10*log10(2)) */#define LTP_GAIN_THR2 5443 /* 5443 Q13 = 0.6644 ~= 2.0 / (10*log10(2)) */
#define NMAX 9 /* largest N used in median calculation */
/************************************************************************* * * FUNCTION: MR795_gain_code_quant3 * * PURPOSE: Pre-quantization of codebook gains, given three possible * LTP gains (using predicted codebook gain) * *************************************************************************/static void MR795_gain_code_quant3(Word16 exp_gcode0, Word16 gcode0, Word16 g_pitch_cand[], Word16 g_pitch_cind[],
Word16 frac_coeff[],Word16 exp_coeff[],Word16 *gain_pit, Word16 *gain_pit_ind, Word16 *gain_cod,
Word16 *gain_cod_ind, Word16 *qua_ener_MR122, Word16 *qua_ener )
{ const Word16 *p ,*pqua_gain_code = qua_gain_code;
Word16 i, j, cod_ind, pit_ind; Word16 e_max, exp_code; Word16 g_pitch, g2_pitch, g_code, g2_code_h, g2_code_l; Word16 g_pit_cod_h, g_pit_cod_l; Word16 coeff[5], coeff_lo[5]; Word16 exp_max[5]; Word32 L_tmp, L_tmp0, dist_min;
Word16 t1,t2;
Word16 *pexp_coeff = exp_coeff, *pfrac_coeff = frac_coeff , *pg_pitch_cand = g_pitch_cand;
/* * The error energy (sum) to be minimized consists of five terms, t[0..4]. * * t[0] = gp^2 * <y1 y1> * t[1] = -2*gp * <xn y1> * t[2] = gc^2 * <y2 y2> * t[3] = -2*gc * <xn y2> * t[4] = 2*gp*gc * <y1 y2> * */ /* determine the scaling exponent for g_code: ec = ec0 - 10 */ exp_code = exp_gcode0-10; /* calculate exp_max[i] = s[i]-1 */ exp_max[0] = pexp_coeff[0]-13;
exp_max[1] = pexp_coeff[1]-14;
exp_max[2] = pexp_coeff[2] + 15 + (exp_code<<1);
exp_max[3] = pexp_coeff[3] + exp_code;
exp_max[4] = pexp_coeff[4] + exp_code + 1 ;
/*-------------------------------------------------------------------* * Find maximum exponent: * * ~~~~~~~~~~~~~~~~~~~~~~ * * * * For the sum operation, all terms must have the same scaling; * * that scaling should be low enough to prevent overflow. There- * * fore, the maximum scale is determined and all coefficients are * * re-scaled: * * * * e_max = max(exp_max[i]) + 1; * * e = exp_max[i]-e_max; e <= 0! * * c[i] = c[i]*2^e * *-------------------------------------------------------------------*/ e_max = exp_max[0];
t1 = exp_max[1] > exp_max[2] ? exp_max[1] : exp_max[2];
t2 = exp_max[3] > exp_max[4] ? exp_max[3] : exp_max[4];
t1 = t1 > t2 ? t1: t2;
e_max = e_max < t1 ? t1 : e_max;
e_max ++; /* To avoid overflow */ for (i = 0; i < 5; i++) { j = e_max- exp_max[i]; L_tmp = pfrac_coeff[i]<<16 ;
if(j>= 31)
{
L_tmp = L_tmp < 0 ? -1 : 0;
}
else
{
j = j< -32 ? -32 :j;
L_tmp = j>=0 ? L_tmp>>j :( L_tmp>( MAX_32>> -j) ? MAX_32 : ( L_tmp < (MIN_32 >> -j) ? MIN_32 : L_tmp << - j));
}
coeff[i] = (Word16)(L_tmp>>16); coeff_lo[i] =(L_tmp - (coeff[i]<<16))>>1; } /*-------------------------------------------------------------------* * Codebook search: * * ~~~~~~~~~~~~~~~~ * * * * For each of the candiates LTP gains in g_pitch_cand[], the terms * * t[0..4] are calculated from the values in the table (and the * * pitch gain candidate) and summed up; the result is the mean * * squared error for the LPT/CB gain pair. The index for the mini- * * mum MSE is stored and finally used to retrieve the quantized CB * * gain * *-------------------------------------------------------------------*/ /* start with "infinite" MSE */ dist_min = MAX_32; cod_ind = 0; pit_ind = 0; /* loop through LTP gain candidates */ for (j = 0; j < 3; j++) { /* pre-calculate terms only dependent on pitch gain */ g_pitch = pg_pitch_cand[j];
g2_pitch = (g_pitch* g_pitch>>15);
L_tmp0 = (coeff[0]*g2_pitch<<1) + ((coeff_lo[0]*g2_pitch>>15)<<1);
L_tmp0 += (coeff[1]*g_pitch<<1) + ((coeff_lo[1]*g_pitch>>15)<<1); p = &pqua_gain_code[0];
for (i = 0; i < NB_QUA_CODE; i++) { g_code = *p++; p++; /* skip log2(g_fac) */ p++; /* skip 20*log10(g_fac) */ g_code = (g_code* gcode0>>15); L_tmp = (g_code* g_code<<1);
g2_code_h = (Word16)(L_tmp>>16); g2_code_l = (L_tmp -(g2_code_h<<16))>>1; L_tmp = (g_code*g_pitch <<1 );
g_pit_cod_h = (Word16)(L_tmp>>16); g_pit_cod_l = (L_tmp - (g_pit_cod_h<<16))>>1;
L_tmp = L_tmp0 + (coeff[2]*g2_code_h<<1) +(((coeff[2]*g2_code_l>>15) + (coeff_lo[2]*g2_code_h>>15))<<1);
L_tmp += (coeff[3]*g_code<<1) +((coeff_lo[3]*g_code>>15)<<1);
L_tmp += (coeff[4]*g_pit_cod_h<<1) + (((coeff[4]*g_pit_cod_l>>15) + (coeff_lo[4]*g_pit_cod_h>>15))<<1); /* store table index if MSE for this index is lower than the minimum MSE seen so far; also store the pitch gain for this (so far) lowest MSE */ if (L_tmp < dist_min) { dist_min = L_tmp; cod_ind = i;
pit_ind = j;
} } } /*------------------------------------------------------------------* * read quantized gains and new values for MA predictor memories * * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ * *------------------------------------------------------------------*/ /* Read the quantized gains */ p = &pqua_gain_code[cod_ind+ cod_ind+cod_ind];
g_code = *p++; *qua_ener_MR122 = *p++; *qua_ener = *p; /*------------------------------------------------------------------* * calculate final fixed codebook gain: * * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ * * * * gc = gc0 * g * *------------------------------------------------------------------*/ L_tmp = (g_code* gcode0<<1);
L_tmp = 9 > exp_gcode0 ? L_tmp>> (9-exp_gcode0) : L_tmp << (exp_gcode0-9); *gain_cod = (Word16)(L_tmp>>16); *gain_cod_ind = cod_ind; *gain_pit = g_pitch_cand[pit_ind]; *gain_pit_ind = g_pitch_cind[pit_ind];
}/************************************************************************* * * FUNCTION: MR795_gain_code_quant_mod * * PURPOSE: Modified quantization of the MR795 codebook gain * * Uses pre-computed energy coefficients in frac_en[]/exp_en[] * * frac_en[0]*2^exp_en[0] = <res res> // LP residual energy * frac_en[1]*2^exp_en[1] = <exc exc> // LTP residual energy * frac_en[2]*2^exp_en[2] = <exc code> // LTP/CB innovation dot product * frac_en[3]*2^exp_en[3] = <code code> // CB innovation energy * *************************************************************************/static Word16 MR795_gain_code_quant_mod(Word16 gain_pit, Word16 exp_gcode0, Word16 gcode0, Word16 frac_en[], Word16 exp_en[],
Word16 alpha, Word16 gain_cod_unq, Word16 *gain_cod, Word16 *qua_ener_MR122, Word16 *qua_ener )
{
const Word16 *p;
Word16 i, index, tmp,tmp1,tmp2;
Word16 one_alpha;
Word16 exp, e_max;
Word16 g2_pitch, g_code;
Word16 g2_code_h, g2_code_l;
Word16 d2_code_h, d2_code_l;
Word16 coeff[5], coeff_lo[5], exp_coeff[5];
Word32 L_tmp,L_tmp1,L_tmp2, L_t0, L_t1, dist_min;
Word16 gain_code,t1,t2;
/* calculate scalings of the constant terms*/
gain_code = 10 - exp_gcode0 < 0 ? *gain_cod >> (exp_gcode0-10) : (*gain_cod >= (MAX_16>> (10 - exp_gcode0)) ? MAX_16 : *gain_cod << (10 - exp_gcode0) );
g2_pitch = gain_pit*gain_pit >>15 ;
one_alpha = 32767-alpha+1; /* 32768 - alpha */
/* alpha <= 0.5 -> mult. by 2 to keep precision; compensate in exponent */
tmp = alpha*frac_en[1]>>14;
/* directly store in 32 bit variable because no further mult. required */
L_t1 = tmp*g2_pitch<<1;
exp_coeff[1] = exp_en[1]-15;
tmp = alpha*frac_en[2] >>14;
coeff[2] = tmp*gain_pit >> 15;
exp = exp_gcode0 -10;
exp_coeff[2] = exp_en[2] + exp;
coeff[3] = alpha*frac_en[3] >>14;
exp = (exp_gcode0<<1) - 7;
exp_coeff[3] = exp_en[3] + exp;
coeff[4] = (one_alpha* frac_en[3] >> 15);
exp_coeff[4] = (exp_coeff[3]+1);
L_tmp = alpha*frac_en[0] << 1;
L_t0 = sqrt_l_exp (L_tmp, &exp); /* normalization included in sqrt_l_exp */
exp += 47;
exp_coeff[0] = exp_en[0] - exp;
/*
* Determine the maximum exponent occuring in the distance calculation
* and adjust all fractions accordingly (including a safety margin)
*
*/
/* find max(e[1..4],e[0]+31) */
e_max = exp_coeff[0] + 31;
t1 = exp_coeff[1] > exp_coeff[2] ? exp_coeff[1] : exp_coeff[2];
t2 = exp_coeff[3] > exp_coeff[4] ? exp_coeff[3] : exp_coeff[4];
t1 = t1 > t2 ? t1 : t2;
e_max = e_max > t1 ? e_max : t1;
/*
/* scale c[1] (requires no further multiplication) */
tmp = e_max -exp_coeff[1];
L_t1 = tmp>0 ? L_t1>>tmp : L_t1 << -tmp;
/* scale c[2..4] (used in Mpy_32_16 in the quantizer loop) */
tmp = e_max -exp_coeff[2];
tmp1 = e_max -exp_coeff[3];
tmp2 = e_max -exp_coeff[4];
L_tmp = (coeff[2] << 16);
L_tmp = tmp>0 ? L_tmp >> tmp : L_tmp << -tmp;
L_tmp1 = (coeff[3] << 16);
L_tmp1 = tmp1>0 ? L_tmp1 >> tmp1 : L_tmp1 << -tmp1;
L_tmp2 = (coeff[4] << 16);
L_tmp2 = tmp2>0 ? L_tmp2 >> tmp2 : L_tmp2 << -tmp2;
coeff[2] = (Word16)(L_tmp >> 16);
coeff_lo[2] = (L_tmp - (coeff[2] <<16))>>1;
coeff[3] = (Word16)(L_tmp1 >> 16);
coeff_lo[3] = (L_tmp1 - (coeff[3] <<16))>>1;
coeff[4] = (Word16)(L_tmp2 >> 16);
coeff_lo[4] = (L_tmp2 - (coeff[4] <<16))>>1;
/* scale c[0] (requires no further multiplication) */
exp = e_max- 31; /* new exponent */
tmp = exp-exp_coeff[0] ;
L_t0 = tmp >= 0? L_t0 >>(tmp>>1) : L_t0 << -(tmp>>1);
/* perform correction by 1/sqrt(2) if exponent difference is odd */
if ((tmp & 0x1) != 0)
{
coeff[0] = (Word16)(L_t0 >> 16);
coeff_lo[0] = (L_t0 - (coeff[0]<<16 ))>>1;
L_t0 = coeff[0]*46340 + ((coeff_lo[0]*23170>>15)<<1);
}
/* search the quantizer table for the lowest value
of the search criterion */
dist_min = MAX_32;
index = 0;
p = &qua_gain_code[0];
for (i = 0; i < NB_QUA_CODE; i++)
{
g_code = *p++; /* this is g_fac (Q11) */
p++; /* skip log2(g_fac) */
p++; /* skip 20*log10(g_fac) */
g_code = (g_code*gcode0 >> 15);
/* only continue if gc[i] < 2.0*gc
which is equiv. to g_code (Q10-ec0) < gain_code (Q11-ec0) */
if ( g_code >= gain_code)
break;
L_tmp = g_code* g_code << 1;
g2_code_h = (Word16)(L_tmp >> 16);
g2_code_l = (L_tmp - (g2_code_h<<16))>>1;
tmp = g_code- gain_cod_unq;
L_tmp = tmp* tmp << 1;
d2_code_h = (Word16)(L_tmp>>16);
d2_code_l = (L_tmp -(d2_code_h<<16))>>1;
/* t2, t3, t4 */
L_tmp = L_t1 + (coeff[2]*g_code<<1) + ((coeff_lo[2]*g_code>>15)<<1);
L_tmp += (coeff[3]*g2_code_h <<1) + (((coeff[3]*g2_code_l>>15) + (coeff_lo[3]*g2_code_h>>15))<<1);
L_tmp = sqrt_l_exp (L_tmp, &exp);
L_tmp = (exp>>1) >= 0 ? L_tmp >> (exp>>1) : L_tmp << -(exp>>1);
/* d2 */
tmp = (L_tmp - L_t0 + 0x00008000)>>16;
L_tmp = tmp*tmp << 1;
/* dist */
L_tmp += (coeff[4]*d2_code_h<<1) + (((coeff_lo[4]*d2_code_h>>15) +(coeff[4]*d2_code_l>>15))<<1);
/* store table index if distance measure for this
index is lower than the minimum seen so far */
index = L_tmp < dist_min ? i : index;
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