ref: c78ac707b07a3c8dea4685274cb6f1b3ba1ea93f
dir: /amr-wb/pred_lt4.c/
/*-------------------------------------------------------------------*
* PRED_LT4.C *
*-------------------------------------------------------------------*
* Compute the result of long term prediction with fractionnal *
* interpolation of resolution 1/4. *
* *
* On return exc[0..L_subfr-1] contains the interpolated signal *
* (adaptive codebook excitation) *
*-------------------------------------------------------------------*/
#include "typedef.h"
#include "basic_op.h"
#include "count.h"
#define UP_SAMP 4
#define L_INTERPOL2 16
/* 1/4 resolution interpolation filter (-3 dB at 0.856*fs/2) in Q14 */
static Word16 inter4_2[UP_SAMP * 2 * L_INTERPOL2] =
{
0, 1, 2, 1,
-2, -7, -10, -7,
4, 19, 28, 22,
-2, -33, -55, -49,
-10, 47, 91, 92,
38, -52, -133, -153,
-88, 43, 175, 231,
165, -9, -209, -325,
-275, -60, 226, 431,
424, 175, -213, -544,
-619, -355, 153, 656,
871, 626, -16, -762,
-1207, -1044, -249, 853,
1699, 1749, 780, -923,
-2598, -3267, -2147, 968,
5531, 10359, 14031, 15401,
14031, 10359, 5531, 968,
-2147, -3267, -2598, -923,
780, 1749, 1699, 853,
-249, -1044, -1207, -762,
-16, 626, 871, 656,
153, -355, -619, -544,
-213, 175, 424, 431,
226, -60, -275, -325,
-209, -9, 165, 231,
175, 43, -88, -153,
-133, -52, 38, 92,
91, 47, -10, -49,
-55, -33, -2, 22,
28, 19, 4, -7,
-10, -7, -2, 1,
2, 1, 0, 0
};
/*** Coefficients in floating point
static float inter4_2[UP_SAMP*L_INTERPOL2+1] = {
0.940000,
0.856390, 0.632268, 0.337560, 0.059072,
-0.131059, -0.199393, -0.158569, -0.056359,
0.047606, 0.106749, 0.103705, 0.052062,
-0.015182, -0.063705, -0.073660, -0.046497,
-0.000983, 0.038227, 0.053143, 0.040059,
0.009308, -0.021674, -0.037767, -0.033186,
-0.013028, 0.010702, 0.025901, 0.026318,
0.013821, -0.003645, -0.016813, -0.019855,
-0.012766, -0.000530, 0.010080, 0.014122,
0.010657, 0.002594, -0.005363, -0.009344,
-0.008101, -0.003182, 0.002330, 0.005635,
0.005562, 0.002844, -0.000627, -0.002993,
-0.003362, -0.002044, -0.000116, 0.001315,
0.001692, 0.001151, 0.000259, -0.000417,
-0.000618, -0.000434, -0.000133, 0.000063,
0.000098, 0.000048, 0.000007, 0.000000};
***/
void Pred_lt4(
Word16 exc[], /* in/out: excitation buffer */
Word16 T0, /* input : integer pitch lag */
Word16 frac, /* input : fraction of lag */
Word16 L_subfr /* input : subframe size */
)
{
Word16 i, j, k, *x;
Word32 L_sum;
x = &exc[-T0];
move16();
frac = negate(frac);
test();
if (frac < 0)
{
frac = add(frac, UP_SAMP);
x--;
move16();
}
x = x - L_INTERPOL2 + 1;
move16();
for (j = 0; j < L_subfr; j++)
{
L_sum = 0L; move32();
for (i = 0, k = sub(sub(UP_SAMP, 1), frac); i < 2 * L_INTERPOL2; i++, k += UP_SAMP)
{
L_sum = L_mac(L_sum, x[i], inter4_2[k]);
}
L_sum = L_shl(L_sum, 1);
exc[j] = round(L_sum);
move16();
x++;
}
return;
}