libs/mpega/filter.c

   1 /*
   2  * mad - MPEG audio decoder
   3  * Copyright (C) 2000-2003 Robert Leslie
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18  *
  19  * $Id$
  20  */
  21
  22 # ifdef HAVE_CONFIG_H
  23 #  include "config.h"
  24 # endif
  25
  26 # include "global.h"
  27
  28 # include "filter.h"
  29 # include "fixed.h"
  30 # include "frame.h"
  31
  32 /*
  33  * NAME:        gain_filter()
  34  * DESCRIPTION: perform attenuation or amplification
  35  */
  36 void gain_filter(mad_fixed_t gain, struct mad_frame *frame)
  37 {
  38   if (gain != MAD_F_ONE) {
  39     unsigned int nch, ch, ns, s, sb;
  40
  41     nch = MAD_NCHANNELS(&frame->header);
  42     ns  = MAD_NSBSAMPLES(&frame->header);
  43
  44     for (ch = 0; ch < nch; ++ch) {
  45       for (s = 0; s < ns; ++s) {
  46         for (sb = 0; sb < 32; ++sb) {
  47           frame->sbsample[ch][s][sb] =
  48             mad_f_mul(frame->sbsample[ch][s][sb], gain);
  49         }
  50       }
  51     }
  52   }
  53 }