ref: 9831e451d4dffcfe05f7d8d60e3c96c8f04d7eef
dir: /libfaad/lt_predict.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: lt_predict.c,v 1.10 2002/11/28 18:48:30 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