modules/audio_mixer/float.c

   1 /*****************************************************************************
   2  * float32.c : precise float32 audio volume implementation
   3  *****************************************************************************
   4  * Copyright (C) 2002 VLC authors and VideoLAN
   5  *
   6  * Authors: Christophe Massiot <massiot@via.ecp.fr>
   7  *
   8  * This program is free software; you can redistribute it and/or modify it
   9  * under the terms of the GNU Lesser General Public License as published by
  10  * the Free Software Foundation; either version 2.1 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public License
  19  * along with this program; if not, write to the Free Software Foundation,
  20  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  21  *****************************************************************************/
  22
  23 /*****************************************************************************
  24  * Preamble
  25  *****************************************************************************/
  26
  27 #ifdef HAVE_CONFIG_H
  28 # include "config.h"
  29 #endif
  30
  31 #include <stddef.h>
  32 #include <vlc_common.h>
  33 #include <vlc_plugin.h>
  34 #include <vlc_aout.h>
  35 #include <vlc_aout_volume.h>
  36
  37 /*****************************************************************************
  38  * Local prototypes
  39  *****************************************************************************/
  40 static int Create( vlc_object_t * );
  41
  42 /*****************************************************************************
  43  * Module descriptor
  44  *****************************************************************************/
  45 vlc_module_begin ()
  46     set_category( CAT_AUDIO )
  47     set_subcategory( SUBCAT_AUDIO_MISC )
  48     set_description( N_("Single precision audio volume") )
  49     set_capability( "audio volume", 10 )
  50     set_callback( Create )
  51 vlc_module_end ()
  52
  53 /**
  54  * Mixes a new output buffer
  55  */
  56 static void FilterFL32( audio_volume_t *p_volume, block_t *p_buffer,
  57                         float f_multiplier )
  58 {
  59     if( f_multiplier == 1.f )
  60         return; /* nothing to do */
  61
  62     float *p = (float *)p_buffer->p_buffer;
  63     for( size_t i = p_buffer->i_buffer / sizeof(*p); i > 0; i-- )
  64         *(p++) *= f_multiplier;
  65
  66     (void) p_volume;
  67 }
  68
  69 static void FilterFL64( audio_volume_t *p_volume, block_t *p_buffer,
  70                         float f_multiplier )
  71 {
  72     double *p = (double *)p_buffer->p_buffer;
  73     double mult = f_multiplier;
  74     if( mult == 1. )
  75         return; /* nothing to do */
  76
  77     for( size_t i = p_buffer->i_buffer / sizeof(*p); i > 0; i-- )
  78         *(p++) *= mult;
  79
  80     (void) p_volume;
  81 }
  82
  83 /**
  84  * Initializes the mixer
  85  */
  86 static int Create( vlc_object_t *p_this )
  87 {
  88     audio_volume_t *p_volume = (audio_volume_t *)p_this;
  89
  90     switch (p_volume->format)
  91     {
  92         case VLC_CODEC_FL32:
  93             p_volume->amplify = FilterFL32;
  94             break;
  95         case VLC_CODEC_FL64:
  96             p_volume->amplify = FilterFL64;
  97             break;
  98         default:
  99             return -1;
 100     }
 101     return 0;
 102 }