ref: 444f41c6fcdf4142c6bca1c6c76df2e4603a24a8
dir: /amr-wb/decim54.c/
/*-------------------------------------------------------------------*
* DECIM54.C *
*-------------------------------------------------------------------*
* Decim_12k8 : decimation of 16kHz signal to 12.8kHz. *
* Oversamp_16k : oversampling from 12.8kHz to 16kHz. *
*-------------------------------------------------------------------*/
#include "typedef.h"
#include "basic_op.h"
#include "acelp.h"
#include "count.h"
#include "cnst.h"
#define FAC4 4
#define FAC5 5
#define INV_FAC5 6554 /* 1/5 in Q15 */
#define DOWN_FAC 26215 /* 4/5 in Q15 */
#define UP_FAC 20480 /* 5/4 in Q14 */
#define NB_COEF_DOWN 15
#define NB_COEF_UP 12
/* Local functions */
static void Down_samp(
Word16 * sig, /* input: signal to downsampling */
Word16 * sig_d, /* output: downsampled signal */
Word16 L_frame_d /* input: length of output */
);
static void Up_samp(
Word16 * sig_d, /* input: signal to oversampling */
Word16 * sig_u, /* output: oversampled signal */
Word16 L_frame /* input: length of output */
);
static Word16 Interpol( /* return result of interpolation */
Word16 * x, /* input vector */
Word16 * fir, /* filter coefficient */
Word16 frac, /* fraction (0..resol) */
Word16 resol, /* resolution */
Word16 nb_coef /* number of coefficients */
);
/* 1/5 resolution interpolation filter (in Q14) */
/* -1.5dB @ 6kHz, -6dB @ 6.4kHz, -10dB @ 6.6kHz, -20dB @ 6.9kHz, -25dB @ 7kHz, -55dB @ 8kHz */
static Word16 fir_up[120] =
{
-1, -4, -7, -6, 0,
12, 24, 30, 23, 0,
-33, -62, -73, -52, 0,
68, 124, 139, 96, 0,
-119, -213, -235, -160, 0,
191, 338, 368, 247, 0,
-291, -510, -552, -369, 0,
430, 752, 812, 542, 0,
-634, -1111, -1204, -809, 0,
963, 1708, 1881, 1288, 0,
-1616, -2974, -3432, -2496, 0,
3792, 8219, 12368, 15317, 16384,
15317, 12368, 8219, 3792, 0,
-2496, -3432, -2974, -1616, 0,
1288, 1881, 1708, 963, 0,
-809, -1204, -1111, -634, 0,
542, 812, 752, 430, 0,
-369, -552, -510, -291, 0,
247, 368, 338, 191, 0,
-160, -235, -213, -119, 0,
96, 139, 124, 68, 0,
-52, -73, -62, -33, 0,
23, 30, 24, 12, 0,
-6, -7, -4, -1, 0
};
static Word16 fir_down[120] =
{ /* table x4/5 */
-1, -3, -6, -5,
0, 9, 19, 24,
18, 0, -26, -50,
-58, -41, 0, 54,
99, 111, 77, 0,
-95, -170, -188, -128,
0, 153, 270, 294,
198, 0, -233, -408,
-441, -295, 0, 344,
601, 649, 434, 0,
-507, -888, -964, -647,
0, 770, 1366, 1505,
1030, 0, -1293, -2379,
-2746, -1997, 0, 3034,
6575, 9894, 12254, 13107,
12254, 9894, 6575, 3034,
0, -1997, -2746, -2379,
-1293, 0, 1030, 1505,
1366, 770, 0, -647,
-964, -888, -507, 0,
434, 649, 601, 344,
0, -295, -441, -408,
-233, 0, 198, 294,
270, 153, 0, -128,
-188, -170, -95, 0,
77, 111, 99, 54,
0, -41, -58, -50,
-26, 0, 18, 24,
19, 9, 0, -5,
-6, -3, -1, 0
};
void Init_Decim_12k8(
Word16 mem[] /* output: memory (2*NB_COEF_DOWN) set to zeros */
)
{
Set_zero(mem, 2 * NB_COEF_DOWN);
return;
}
void Decim_12k8(
Word16 sig16k[], /* input: signal to downsampling */
Word16 lg, /* input: length of input */
Word16 sig12k8[], /* output: decimated signal */
Word16 mem[] /* in/out: memory (2*NB_COEF_DOWN) */
)
{
Word16 lg_down;
Word16 signal[L_FRAME16k + (2 * NB_COEF_DOWN)];
Copy(mem, signal, 2 * NB_COEF_DOWN);
Copy(sig16k, signal + (2 * NB_COEF_DOWN), lg);
lg_down = mult(lg, DOWN_FAC);
Down_samp(signal + NB_COEF_DOWN, sig12k8, lg_down);
Copy(signal + lg, mem, 2 * NB_COEF_DOWN);
return;
}
void Init_Oversamp_16k(
Word16 mem[] /* output: memory (2*NB_COEF_UP) set to zeros */
)
{
Set_zero(mem, 2 * NB_COEF_UP);
return;
}
void Oversamp_16k(
Word16 sig12k8[], /* input: signal to oversampling */
Word16 lg, /* input: length of input */
Word16 sig16k[], /* output: oversampled signal */
Word16 mem[] /* in/out: memory (2*NB_COEF_UP) */
)
{
Word16 lg_up;
Word16 signal[L_SUBFR + (2 * NB_COEF_UP)];
Copy(mem, signal, 2 * NB_COEF_UP);
Copy(sig12k8, signal + (2 * NB_COEF_UP), lg);
lg_up = shl(mult(lg, UP_FAC), 1);
Up_samp(signal + NB_COEF_UP, sig16k, lg_up);
Copy(signal + lg, mem, 2 * NB_COEF_UP);
return;
}
static void Down_samp(
Word16 * sig, /* input: signal to downsampling */
Word16 * sig_d, /* output: downsampled signal */
Word16 L_frame_d /* input: length of output */
)
{
Word16 i, j, frac, pos;
pos = 0; move16(); /* position is in Q2 -> 1/4 resolution */
for (j = 0; j < L_frame_d; j++)
{
i = shr(pos, 2); /* integer part */
frac = (Word16) (pos & 3); logic16(); /* fractional part */
sig_d[j] = Interpol(&sig[i], fir_down, frac, FAC4, NB_COEF_DOWN); move16();
pos = add(pos, FAC5); /* pos + 5/4 */
}
return;
}
static void Up_samp(
Word16 * sig_d, /* input: signal to oversampling */
Word16 * sig_u, /* output: oversampled signal */
Word16 L_frame /* input: length of output */
)
{
Word16 i, j, pos, frac;
pos = 0; move16(); /* position with 1/5 resolution */
for (j = 0; j < L_frame; j++)
{
i = mult(pos, INV_FAC5); /* integer part = pos * 1/5 */
frac = sub(pos, add(shl(i, 2), i));/* frac = pos - (pos/5)*5 */
sig_u[j] = Interpol(&sig_d[i], fir_up, frac, FAC5, NB_COEF_UP); move16();
pos = add(pos, FAC4); /* position + 4/5 */
}
return;
}
/* Fractional interpolation of signal at position (frac/resol) */
static Word16 Interpol( /* return result of interpolation */
Word16 * x, /* input vector */
Word16 * fir, /* filter coefficient */
Word16 frac, /* fraction (0..resol) */
Word16 resol, /* resolution */
Word16 nb_coef /* number of coefficients */
)
{
Word16 i, k;
Word32 L_sum;
x = x - nb_coef + 1; move16();
L_sum = 0L; move32();
for (i = 0, k = sub(sub(resol, 1), frac); i < 2 * nb_coef; i++, k = (Word16) (k + resol))
{
L_sum = L_mac(L_sum, x[i], fir[k]);
}
L_sum = L_shl(L_sum, 1); /* saturation can occur here */
return (roundL(L_sum));
}