ref: c44c0332357abb38513127baeb4303c2c4663e44
dir: /libfaad/tns.c/
/*
** FAAD - Freeware Advanced Audio Decoder
** Copyright (C) 2002 M. Bakker
**
** This program is free software; you can redistribute it and/or modify
** it under the terms of the GNU General Public License as published by
** the Free Software Foundation; either version 2 of the License, or
** (at your option) any later version.
**
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
** GNU General Public License for more details.
**
** You should have received a copy of the GNU General Public License
** along with this program; if not, write to the Free Software
** Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
**
** $Id: tns.c,v 1.19 2003/02/14 14:54:24 menno Exp $
**/
#include "common.h"
#include "structs.h"
#include "syntax.h"
#include "tns.h"
#ifdef FIXED_POINT
static real_t tns_coef_0_3[] =
{
0x0, 0x6F13013, 0xC8261BA, 0xF994E02,
0xF03E3A3A, 0xF224C28C, 0xF5B72457, 0xFA8715E3,
0xF90ECFED, 0xF37D9E46, 0xF066B1FE, 0xF066B1FE,
0xF03E3A3A, 0xF224C28C, 0xF5B72457, 0xFA8715E3
};
static real_t tns_coef_0_4[] =
{
0x0, 0x3539B35, 0x681FE48, 0x9679182,
0xBE3EBD4, 0xDDB3D74, 0xF378709, 0xFE98FCA,
0xF011790B, 0xF09C5CB7, 0xF1AD6942, 0xF33B524A,
0xF5388AEB, 0xF793BBDF, 0xFA385AA9, 0xFD0F5CAB
};
static real_t tns_coef_1_3[] =
{
0x0, 0x6F13013, 0xF5B72457, 0xFA8715E3,
0xF994E02, 0xC8261BA, 0xF5B72457, 0xFA8715E3,
0xF90ECFED, 0xF37D9E46, 0xF5B72457, 0xFA8715E3,
0xF37D9E46, 0xF90ECFED, 0xF5B72457, 0xFA8715E3
};
static real_t tns_coef_1_4[] =
{
0x0, 0x3539B35, 0x681FE48, 0x9679182,
0xF5388AEB, 0xF793BBDF, 0xFA385AA9, 0xFD0F5CAB,
0xFE98FCA, 0xF378709, 0xDDB3D74, 0xBE3EBD4,
0xF5388AEB, 0xF793BBDF, 0xFA385AA9, 0xFD0F5CAB
};
#else
#ifdef _MSC_VER
#pragma warning(disable:4305)
#pragma warning(disable:4244)
#endif
static real_t tns_coef_0_3[] =
{
0.0, 0.4338837391, 0.7818314825, 0.9749279122,
-0.9848077530, -0.8660254038, -0.6427876097, -0.3420201433,
-0.4338837391, -0.7818314825, -0.9749279122, -0.9749279122,
-0.9848077530, -0.8660254038, -0.6427876097, -0.3420201433
};
static real_t tns_coef_0_4[] =
{
0.0, 0.2079116908, 0.4067366431, 0.5877852523,
0.7431448255, 0.8660254038, 0.9510565163, 0.9945218954,
-0.9957341763, -0.9618256432, -0.8951632914, -0.7980172273,
-0.6736956436, -0.5264321629, -0.3612416662, -0.1837495178
};
static real_t tns_coef_1_3[] =
{
0.0, 0.4338837391, -0.6427876097, -0.3420201433,
0.9749279122, 0.7818314825, -0.6427876097, -0.3420201433,
-0.4338837391, -0.7818314825, -0.6427876097, -0.3420201433,
-0.7818314825, -0.4338837391, -0.6427876097, -0.3420201433
};
static real_t tns_coef_1_4[] =
{
0.0, 0.2079116908, 0.4067366431, 0.5877852523,
-0.6736956436, -0.5264321629, -0.3612416662, -0.1837495178,
0.9945218954, 0.9510565163, 0.8660254038, 0.7431448255,
-0.6736956436, -0.5264321629, -0.3612416662, -0.1837495178
};
#endif
/* TNS decoding for one channel and frame */
void tns_decode_frame(ic_stream *ics, tns_info *tns, uint8_t sr_index,
uint8_t object_type, real_t *spec, uint16_t frame_len)
{
uint8_t w, f, tns_order;
int8_t inc;
uint16_t bottom, top, start, end, size;
uint16_t nshort = frame_len/8;
real_t lpc[TNS_MAX_ORDER+1];
if (!ics->tns_data_present)
return;
for (w = 0; w < ics->num_windows; w++)
{
bottom = ics->num_swb;
for (f = 0; f < tns->n_filt[w]; f++)
{
top = bottom;
bottom = max(top - tns->length[w][f], 0);
tns_order = min(tns->order[w][f], TNS_MAX_ORDER);
if (!tns_order)
continue;
tns_decode_coef(tns_order, tns->coef_res[w]+3,
tns->coef_compress[w][f], tns->coef[w][f], lpc);
start = ics->swb_offset[min(bottom, ics->max_sfb)];
end = ics->swb_offset[min(top, ics->max_sfb)];
if ((size = end - start) <= 0)
continue;
if (tns->direction[w][f])
{
inc = -1;
start = end - 1;
} else {
inc = 1;
}
tns_ar_filter(&spec[(w*nshort)+start], size, inc, lpc, tns_order);
}
}
}
/* TNS encoding for one channel and frame */
void tns_encode_frame(ic_stream *ics, tns_info *tns, uint8_t sr_index,
uint8_t object_type, real_t *spec, uint16_t frame_len)
{
uint8_t w, f, tns_order;
int8_t inc;
uint16_t bottom, top, start, end, size;
uint16_t nshort = frame_len/8;
real_t lpc[TNS_MAX_ORDER+1];
if (!ics->tns_data_present)
return;
for (w = 0; w < ics->num_windows; w++)
{
bottom = ics->num_swb;
for (f = 0; f < tns->n_filt[w]; f++)
{
top = bottom;
bottom = max(top - tns->length[w][f], 0);
tns_order = min(tns->order[w][f], TNS_MAX_ORDER);
if (!tns_order)
continue;
tns_decode_coef(tns_order, tns->coef_res[w]+3,
tns->coef_compress[w][f], tns->coef[w][f], lpc);
start = ics->swb_offset[min(bottom, ics->max_sfb)];
end = ics->swb_offset[min(top, ics->max_sfb)];
if ((size = end - start) <= 0)
continue;
if (tns->direction[w][f])
{
inc = -1;
start = end - 1;
} else {
inc = 1;
}
tns_ma_filter(&spec[(w*nshort)+start], size, inc, lpc, tns_order);
}
}
}
/* Decoder transmitted coefficients for one TNS filter */
static void tns_decode_coef(uint8_t order, uint8_t coef_res_bits, uint8_t coef_compress,
uint8_t *coef, real_t *a)
{
uint8_t i, m;
real_t tmp2[TNS_MAX_ORDER+1], b[TNS_MAX_ORDER+1];
/* Conversion to signed integer */
for (i = 0; i < order; i++)
{
if (coef_compress == 0)
{
if (coef_res_bits == 3)
{
tmp2[i] = tns_coef_0_3[coef[i]];
} else {
tmp2[i] = tns_coef_0_4[coef[i]];
}
} else {
if (coef_res_bits == 3)
{
tmp2[i] = tns_coef_1_3[coef[i]];
} else {
tmp2[i] = tns_coef_1_4[coef[i]];
}
}
}
/* Conversion to LPC coefficients */
a[0] = COEF_CONST(1.0);
for (m = 1; m <= order; m++)
{
for (i = 1; i < m; i++) /* loop only while i<m */
b[i] = a[i] + MUL_C_C(tmp2[m-1], a[m-i]);
for (i = 1; i < m; i++) /* loop only while i<m */
a[i] = b[i];
a[m] = tmp2[m-1]; /* changed */
}
}
static void tns_ar_filter(real_t *spectrum, uint16_t size, int8_t inc, real_t *lpc,
uint8_t order)
{
/*
- Simple all-pole filter of order "order" defined by
y(n) = x(n) - lpc[1]*y(n-1) - ... - lpc[order]*y(n-order)
- The state variables of the filter are initialized to zero every time
- The output data is written over the input data ("in-place operation")
- An input vector of "size" samples is processed and the index increment
to the next data sample is given by "inc"
*/
uint8_t j;
uint16_t i;
real_t y, state[TNS_MAX_ORDER];
for (i = 0; i < order; i++)
state[i] = 0;
for (i = 0; i < size; i++)
{
y = *spectrum;
for (j = 0; j < order; j++)
y -= MUL_R_C(state[j], lpc[j+1]);
for (j = order-1; j > 0; j--)
state[j] = state[j-1];
state[0] = y;
*spectrum = y;
spectrum += inc;
}
}
static void tns_ma_filter(real_t *spectrum, uint16_t size, int8_t inc, real_t *lpc,
uint8_t order)
{
/*
- Simple all-zero filter of order "order" defined by
y(n) = x(n) + a(2)*x(n-1) + ... + a(order+1)*x(n-order)
- The state variables of the filter are initialized to zero every time
- The output data is written over the input data ("in-place operation")
- An input vector of "size" samples is processed and the index increment
to the next data sample is given by "inc"
*/
uint8_t j;
uint16_t i;
real_t y, state[TNS_MAX_ORDER];
for (i = 0; i < order; i++)
state[i] = REAL_CONST(0.0);
for (i = 0; i < size; i++)
{
y = *spectrum;
for (j = 0; j < order; j++)
y += MUL_R_C(state[j], lpc[j+1]);
for (j = order-1; j > 0; j--)
state[j] = state[j-1];
state[0] = *spectrum;
*spectrum = y;
spectrum += inc;
}
}