65de1cc6af
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@7699 a1c6a512-1295-4272-9138-f99709370657
106 lines
3.7 KiB
C
106 lines
3.7 KiB
C
/*
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** FAAD2 - Freeware Advanced Audio (AAC) Decoder including SBR decoding
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** Copyright (C) 2003-2004 M. Bakker, Ahead Software AG, http://www.nero.com
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**
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** This program is free software; you can redistribute it and/or modify
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** it under the terms of the GNU General Public License as published by
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** the Free Software Foundation; either version 2 of the License, or
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** (at your option) any later version.
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**
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** This program is distributed in the hope that it will be useful,
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** but WITHOUT ANY WARRANTY; without even the implied warranty of
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** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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** GNU General Public License for more details.
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**
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** You should have received a copy of the GNU General Public License
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** along with this program; if not, write to the Free Software
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** Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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**
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** Any non-GPL usage of this software or parts of this software is strictly
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** forbidden.
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**
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** Commercial non-GPL licensing of this software is possible.
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** For more info contact Ahead Software through Mpeg4AAClicense@nero.com.
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**
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** $Id$
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**/
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#include "common.h"
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#include "structs.h"
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#include "syntax.h"
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#include "is.h"
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#ifdef FIXED_POINT
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static real_t pow05_table[] = {
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COEF_CONST(1.68179283050743), /* 0.5^(-3/4) */
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COEF_CONST(1.41421356237310), /* 0.5^(-2/4) */
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COEF_CONST(1.18920711500272), /* 0.5^(-1/4) */
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COEF_CONST(1.0), /* 0.5^( 0/4) */
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COEF_CONST(0.84089641525371), /* 0.5^(+1/4) */
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COEF_CONST(0.70710678118655), /* 0.5^(+2/4) */
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COEF_CONST(0.59460355750136) /* 0.5^(+3/4) */
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};
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#endif
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void is_decode(ic_stream *ics, ic_stream *icsr, real_t *l_spec, real_t *r_spec,
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uint16_t frame_len)
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{
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uint8_t g, sfb, b;
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uint16_t i;
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#ifndef FIXED_POINT
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real_t scale;
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#else
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int32_t exp, frac;
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#endif
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uint16_t nshort = frame_len/8;
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uint8_t group = 0;
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for (g = 0; g < icsr->num_window_groups; g++)
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{
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/* Do intensity stereo decoding */
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for (b = 0; b < icsr->window_group_length[g]; b++)
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{
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for (sfb = 0; sfb < icsr->max_sfb; sfb++)
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{
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if (is_intensity(icsr, g, sfb))
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{
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#ifdef MAIN_DEC
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/* For scalefactor bands coded in intensity stereo the
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corresponding predictors in the right channel are
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switched to "off".
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*/
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ics->pred.prediction_used[sfb] = 0;
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icsr->pred.prediction_used[sfb] = 0;
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#endif
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#ifndef FIXED_POINT
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scale = (real_t)pow(0.5, (0.25*icsr->scale_factors[g][sfb]));
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#else
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exp = icsr->scale_factors[g][sfb] >> 2;
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frac = icsr->scale_factors[g][sfb] & 3;
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#endif
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/* Scale from left to right channel,
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do not touch left channel */
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for (i = icsr->swb_offset[sfb]; i < icsr->swb_offset[sfb+1]; i++)
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{
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#ifndef FIXED_POINT
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r_spec[(group*nshort)+i] = MUL_R(l_spec[(group*nshort)+i], scale);
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#else
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if (exp < 0)
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r_spec[(group*nshort)+i] = l_spec[(group*nshort)+i] << -exp;
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else
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r_spec[(group*nshort)+i] = l_spec[(group*nshort)+i] >> exp;
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r_spec[(group*nshort)+i] = MUL_C(r_spec[(group*nshort)+i], pow05_table[frac + 3]);
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#endif
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if (is_intensity(icsr, g, sfb) != invert_intensity(ics, g, sfb))
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r_spec[(group*nshort)+i] = -r_spec[(group*nshort)+i];
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}
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}
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}
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group++;
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}
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}
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}
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