ref: f039a4fbb81a76f531df2a7b3bf405a89072bf5e
dir: /libfaad/tns.c/
/*
** FAAD2 - Freeware Advanced Audio (AAC) Decoder including SBR decoding
** Copyright (C) 2003-2004 M. Bakker, Ahead Software AG, http://www.nero.com
**
** 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.
**
** Any non-GPL usage of this software or parts of this software is strictly
** forbidden.
**
** Commercial non-GPL licensing of this software is possible.
** For more info contact Ahead Software through Mpeg4AAClicense@nero.com.
**
** $Id: tns.c,v 1.32 2004/04/12 18:17:42 menno Exp $
**/
#include "common.h"
#include "structs.h"
#include "syntax.h"
#include "tns.h"
/* static function declarations */
static void tns_decode_coef(uint8_t order, uint8_t coef_res_bits, uint8_t coef_compress,
uint8_t *coef, real_t *a);
static void tns_ar_filter(real_t *spectrum, uint16_t size, int8_t inc, real_t *lpc,
uint8_t order);
static void tns_ma_filter(real_t *spectrum, uint16_t size, int8_t inc, real_t *lpc,
uint8_t order);
#ifdef _MSC_VER
#pragma warning(disable:4305)
#pragma warning(disable:4244)
#endif
static real_t tns_coef_0_3[] =
{
COEF_CONST(0.0), COEF_CONST(0.4338837391), COEF_CONST(0.7818314825), COEF_CONST(0.9749279122),
COEF_CONST(-0.9848077530), COEF_CONST(-0.8660254038), COEF_CONST(-0.6427876097), COEF_CONST(-0.3420201433),
COEF_CONST(-0.4338837391), COEF_CONST(-0.7818314825), COEF_CONST(-0.9749279122), COEF_CONST(-0.9749279122),
COEF_CONST(-0.9848077530), COEF_CONST(-0.8660254038), COEF_CONST(-0.6427876097), COEF_CONST(-0.3420201433)
};
static real_t tns_coef_0_4[] =
{
COEF_CONST(0.0), COEF_CONST(0.2079116908), COEF_CONST(0.4067366431), COEF_CONST(0.5877852523),
COEF_CONST(0.7431448255), COEF_CONST(0.8660254038), COEF_CONST(0.9510565163), COEF_CONST(0.9945218954),
COEF_CONST(-0.9957341763), COEF_CONST(-0.9618256432), COEF_CONST(-0.8951632914), COEF_CONST(-0.7980172273),
COEF_CONST(-0.6736956436), COEF_CONST(-0.5264321629), COEF_CONST(-0.3612416662), COEF_CONST(-0.1837495178)
};
static real_t tns_coef_1_3[] =
{
COEF_CONST(0.0), COEF_CONST(0.4338837391), COEF_CONST(-0.6427876097), COEF_CONST(-0.3420201433),
COEF_CONST(0.9749279122), COEF_CONST(0.7818314825), COEF_CONST(-0.6427876097), COEF_CONST(-0.3420201433),
COEF_CONST(-0.4338837391), COEF_CONST(-0.7818314825), COEF_CONST(-0.6427876097), COEF_CONST(-0.3420201433),
COEF_CONST(-0.7818314825), COEF_CONST(-0.4338837391), COEF_CONST(-0.6427876097), COEF_CONST(-0.3420201433)
};
static real_t tns_coef_1_4[] =
{
COEF_CONST(0.0), COEF_CONST(0.2079116908), COEF_CONST(0.4067366431), COEF_CONST(0.5877852523),
COEF_CONST(-0.6736956436), COEF_CONST(-0.5264321629), COEF_CONST(-0.3612416662), COEF_CONST(-0.1837495178),
COEF_CONST(0.9945218954), COEF_CONST(0.9510565163), COEF_CONST(0.8660254038), COEF_CONST(0.7431448255),
COEF_CONST(-0.6736956436), COEF_CONST(-0.5264321629), COEF_CONST(-0.3612416662), COEF_CONST(-0.1837495178)
};
/* 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;
int16_t size;
uint16_t bottom, top, start, end;
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 = min(bottom, max_tns_sfb(sr_index, object_type, (ics->window_sequence == EIGHT_SHORT_SEQUENCE)));
start = min(start, ics->max_sfb);
start = ics->swb_offset[start];
end = min(top, max_tns_sfb(sr_index, object_type, (ics->window_sequence == EIGHT_SHORT_SEQUENCE)));
end = min(end, ics->max_sfb);
end = ics->swb_offset[end];
size = end - start;
if (size <= 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;
int16_t size;
uint16_t bottom, top, start, end;
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 = min(bottom, max_tns_sfb(sr_index, object_type, (ics->window_sequence == EIGHT_SHORT_SEQUENCE)));
start = min(start, ics->max_sfb);
start = ics->swb_offset[start];
end = min(top, max_tns_sfb(sr_index, object_type, (ics->window_sequence == EIGHT_SHORT_SEQUENCE)));
end = min(end, ics->max_sfb);
end = ics->swb_offset[end];
size = end - start;
if (size <= 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(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 is stored as a double ringbuffer */
real_t state[2*TNS_MAX_ORDER] = {0};
int8_t state_index = 0;
for (i = 0; i < size; i++)
{
y = *spectrum;
for (j = 0; j < order; j++)
y -= MUL_C(state[state_index+j], lpc[j+1]);
/* double ringbuffer state */
state_index--;
if (state_index < 0)
state_index = order-1;
state[state_index] = state[state_index + order] = 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 is stored as a double ringbuffer */
real_t state[2*TNS_MAX_ORDER] = {0};
int8_t state_index = 0;
for (i = 0; i < size; i++)
{
y = *spectrum;
for (j = 0; j < order; j++)
y += MUL_C(state[j], lpc[j+1]);
/* double ringbuffer state */
state_index--;
if (state_index < 0)
state_index = order-1;
state[state_index] = state[state_index + order] = *spectrum;
*spectrum = y;
spectrum += inc;
}
}