ref: d79790588cb4a863b20d8303bf4df10bfb02d11f
dir: /libfaad/lt_predict.c/
/*
** FAAD2 - Freeware Advanced Audio (AAC) Decoder including SBR decoding
** Copyright (C) 2003 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: lt_predict.c,v 1.18 2003/11/12 20:47:58 menno Exp $
**/
#include "common.h"
#include "structs.h"
#ifdef LTP_DEC
#include <stdlib.h>
#include "syntax.h"
#include "lt_predict.h"
#include "filtbank.h"
#include "tns.h"
/* check if the object type is an object type that can have LTP */
uint8_t is_ltp_ot(uint8_t object_type)
{
#ifdef LTP_DEC
if ((object_type == LTP)
#ifdef ERROR_RESILIENCE
|| (object_type == ER_LTP)
#endif
#ifdef LD_DEC
|| (object_type == LD)
#endif
)
{
return 1;
}
#endif
return 0;
}
static real_t codebook[8] =
{
REAL_CONST(0.570829),
REAL_CONST(0.696616),
REAL_CONST(0.813004),
REAL_CONST(0.911304),
REAL_CONST(0.984900),
REAL_CONST(1.067894),
REAL_CONST(1.194601),
REAL_CONST(1.369533)
};
void lt_prediction(ic_stream *ics, ltp_info *ltp, real_t *spec,
int16_t *lt_pred_stat, fb_info *fb, uint8_t win_shape,
uint8_t win_shape_prev, uint8_t sr_index,
uint8_t object_type, uint16_t frame_len)
{
uint8_t sfb;
uint16_t bin, i, num_samples;
real_t x_est[2048];
real_t X_est[2048];
if (ics->window_sequence != EIGHT_SHORT_SEQUENCE)
{
if (ltp->data_present)
{
num_samples = frame_len << 1;
for(i = 0; i < num_samples; i++)
{
/* The extra lookback M (N/2 for LD, 0 for LTP) is handled
in the buffer updating */
#if 0
x_est[i] = MUL_R_C(lt_pred_stat[num_samples + i - ltp->lag],
codebook[ltp->coef]);
#else
/* lt_pred_stat is a 16 bit int, multiplied with the fixed point real
this gives a real for x_est
*/
x_est[i] = (real_t)lt_pred_stat[num_samples + i - ltp->lag] * codebook[ltp->coef];
#endif
}
filter_bank_ltp(fb, ics->window_sequence, win_shape, win_shape_prev,
x_est, X_est, object_type, frame_len);
tns_encode_frame(ics, &(ics->tns), sr_index, object_type, X_est,
frame_len);
for (sfb = 0; sfb < ltp->last_band; sfb++)
{
if (ltp->long_used[sfb])
{
uint16_t low = ics->swb_offset[sfb];
uint16_t high = ics->swb_offset[sfb+1];
for (bin = low; bin < high; bin++)
{
spec[bin] += X_est[bin];
}
}
}
}
}
}
#ifdef FIXED_POINT
INLINE int16_t real_to_int16(real_t sig_in)
{
if (sig_in >= 0)
{
sig_in += (1 << (REAL_BITS-1));
if (sig_in > REAL_CONST(32767))
sig_in = 32767.0f;
} else {
sig_in += -(1 << (REAL_BITS-1));
if (sig_in < REAL_CONST(-32768))
sig_in = -32768.0f;
}
return (sig_in >> REAL_BITS);
}
#else
INLINE int16_t real_to_int16(real_t sig_in)
{
if (sig_in >= 0)
{
#ifndef HAS_LRINTF
sig_in += 0.5f;
#endif
if (sig_in > REAL_CONST(32767))
sig_in = 32767.0f;
} else {
#ifndef HAS_LRINTF
sig_in -= 0.5f;
#endif
if (sig_in < REAL_CONST(-32768))
sig_in = -32768.0f;
}
return lrintf(sig_in);
}
#endif
void lt_update_state(int16_t *lt_pred_stat, real_t *time, real_t *overlap,
uint16_t frame_len, uint8_t object_type)
{
uint16_t i;
/*
* The reference point for index i and the content of the buffer
* lt_pred_stat are arranged so that lt_pred_stat(0 ... N/2 - 1) contains the
* last aliased half window from the IMDCT, and lt_pred_stat(N/2 ... N-1)
* is always all zeros. The rest of lt_pred_stat (i<0) contains the previous
* fully reconstructed time domain samples, i.e., output of the decoder.
*
* These values are shifted up by N*2 to avoid (i<0)
*
* For the LD object type an extra 512 samples lookback is accomodated here.
*/
#ifdef LD_DEC
if (object_type == LD)
{
for (i = 0; i < frame_len; i++)
{
lt_pred_stat[i] /* extra 512 */ = lt_pred_stat[i + frame_len];
lt_pred_stat[frame_len + i] = lt_pred_stat[i + (frame_len * 2)];
lt_pred_stat[(frame_len * 2) + i] = real_to_int16(time[i]);
lt_pred_stat[(frame_len * 3) + i] = real_to_int16(overlap[i]);
}
} else {
#endif
for (i = 0; i < frame_len; i++)
{
lt_pred_stat[i] = lt_pred_stat[i + frame_len];
lt_pred_stat[frame_len + i] = real_to_int16(time[i]);
lt_pred_stat[(frame_len * 2) + i] = real_to_int16(overlap[i]);
#if 0 /* set to zero once upon initialisation */
lt_pred_stat[(frame_len * 3) + i] = 0;
#endif
}
#ifdef LD_DEC
}
#endif
}
#endif