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# ms.c

    00001 /*
    00002 ** FAAD2 - Freeware Advanced Audio (AAC) Decoder including SBR decoding
    00003 ** Copyright (C) 2003-2005 M. Bakker, Ahead Software AG, http://www.nero.com
    00004 **
    00005 ** This program is free software; you can redistribute it and/or modify
    00006 ** it under the terms of the GNU General Public License as published by
    00007 ** the Free Software Foundation; either version 2 of the License, or
    00008 ** (at your option) any later version.
    00009 **
    00010 ** This program is distributed in the hope that it will be useful,
    00011 ** but WITHOUT ANY WARRANTY; without even the implied warranty of
    00012 ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    00013 ** GNU General Public License for more details.
    00014 **
    00015 ** You should have received a copy of the GNU General Public License
    00016 ** along with this program; if not, write to the Free Software
    00017 ** Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
    00018 **
    00019 ** Any non-GPL usage of this software or parts of this software is strictly
    00020 ** forbidden.
    00021 **
    00022 ** Software using this code must display the following message visibly in the
    00023 ** software:
    00024 ** "FAAD2 AAC/HE-AAC/HE-AACv2/DRM decoder (c) Ahead Software, www.nero.com"
    00025 ** in, for example, the about-box or help/startup screen.
    00026 **
    00027 ** Commercial non-GPL licensing of this software is possible.
    00028 ** For more info contact Ahead Software through Mpeg4AAClicense@nero.com.
    00029 **
    00030 ** $Id: ms.c,v 1.2 2005/11/01 21:41:43 gabest Exp $
    00031 **/
    00032
    00033 #include "common.h"
    00034 #include "structs.h"
    00035
    00036 #include "syntax.h"
    00037 #include "ms.h"
    00038 #include "is.h"
    00039 #include "pns.h"
    00040
    00041 void ms_decode(ic_stream *ics, ic_stream *icsr, real_t *l_spec, real_t *r_spec,
    00042                uint16_t frame_len)
    00043 {
    00044     uint8_t g, b, sfb;
    00045     uint8_t group = 0;
    00046     uint16_t nshort = frame_len/8;
    00047
    00048     uint16_t i, k;
    00049     real_t tmp;
    00050
    00051     if (ics->ms_mask_present >= 1)
    00052     {
    00053         for (g = 0; g < ics->num_window_groups; g++)
    00054         {
    00055             for (b = 0; b < ics->window_group_length[g]; b++)
    00056             {
    00057                 for (sfb = 0; sfb < ics->max_sfb; sfb++)
    00058                 {
    00059                     /* If intensity stereo coding or noise substitution is on
    00060                        for a particular scalefactor band, no M/S stereo decoding
    00061                        is carried out.
    00062                      */
    00063                     if ((ics->ms_used[g][sfb] || ics->ms_mask_present == 2) &&
    00064                         !is_intensity(icsr, g, sfb) && !is_noise(ics, g, sfb))
    00065                     {
    00066                         for (i = ics->swb_offset[sfb]; i < ics->swb_offset[sfb+1]; i++)
    00067                         {
    00068                             k = (group*nshort) + i;
    00069                             tmp = l_spec[k] - r_spec[k];
    00070                             l_spec[k] = l_spec[k] + r_spec[k];
    00071                             r_spec[k] = tmp;
    00072                         }
    00073                     }
    00074                 }
    00075                 group++;
    00076             }
    00077         }
    00078     }
    00079 }