/* ** 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: lt_predict.c,v 1.23 2004/09/04 14:56:28 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 function declarations */ static int16_t real_to_int16(real_t sig_in); /* 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 #ifdef SCALABLE_DEC || (object_type == 6) /* TODO */ #endif ) { return 1; } #endif return 0; } ALIGN static const 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; ALIGN real_t x_est[2048]; ALIGN 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 static 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(32768)) return 32767; } else { sig_in += -(1 << (REAL_BITS-1)); if (sig_in <= REAL_CONST(-32768)) return -32768; } return (sig_in >> REAL_BITS); } #else static 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 >= 32768.0f) return 32767; } else { #ifndef HAS_LRINTF sig_in += -0.5f; #endif if (sig_in <= -32768.0f) return -32768; } 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