ref: 6c93b4fdda100e449e25d57102a44d9bb63318b0
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 1.11 2003/07/29 08:20:12 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"
static real_t codebook[8] =
{
COEF_CONST(0.570829),
COEF_CONST(0.696616),
COEF_CONST(0.813004),
COEF_CONST(0.911304),
COEF_CONST(0.984900),
COEF_CONST(1.067894),
COEF_CONST(1.194601),
COEF_CONST(1.369533)
};
void lt_prediction(ic_stream *ics, ltp_info *ltp, real_t *spec,
real_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;
real_t *X_est;
if (ics->window_sequence != EIGHT_SHORT_SEQUENCE)
{
if (ltp->data_present)
{
num_samples = frame_len << 1;
x_est = (real_t*)malloc(num_samples*sizeof(real_t));
X_est = (real_t*)malloc(num_samples*sizeof(real_t));
for(i = 0; i < num_samples; i++)
{
/* The extra lookback M (N/2 for LD, 0 for LTP) is handled
in the buffer updating */
x_est[i] = MUL_R_C(lt_pred_stat[num_samples + i - ltp->lag],
codebook[ltp->coef]);
}
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];
}
}
}
free(x_est);
free(X_est);
}
}
}
void lt_update_state(real_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] = time[i];
lt_pred_stat[(frame_len * 3) + i] = 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] = time[i];
lt_pred_stat[(frame_len * 2) + i] = overlap[i];
#if 0 /* set to zero once upon initialisation */
lt_pred_stat[(frame_len * 3) + i] = 0;
#endif
}
#ifdef LD_DEC
}
#endif
}
#endif