modules/audio_mixer/float.c

   1 /*****************************************************************************
   2  * float32.c : precise float32 audio volume implementation
   3  *****************************************************************************
   4  * Copyright (C) 2002 VLC authors and VideoLAN
   5  * $Id$
   6  *
   7  * Authors: Christophe Massiot <massiot@via.ecp.fr>
   8  *
   9  * This program is free software; you can redistribute it and/or modify it
  10  * under the terms of the GNU Lesser General Public License as published by
  11  * the Free Software Foundation; either version 2.1 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  17  * GNU Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public License
  20  * along with this program; if not, write to the Free Software Foundation,
  21  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  22  *****************************************************************************/
  23
  24 /*****************************************************************************
  25  * Preamble
  26  *****************************************************************************/
  27
  28 #ifdef HAVE_CONFIG_H
  29 # include "config.h"
  30 #endif
  31
  32 #include <stddef.h>
  33 #include <vlc_common.h>
  34 #include <vlc_plugin.h>
  35 #include <vlc_aout.h>
  36 #include <vlc_aout_volume.h>
  37
  38 /*****************************************************************************
  39  * Local prototypes
  40  *****************************************************************************/
  41 static int Create( vlc_object_t * );
  42
  43 /*****************************************************************************
  44  * Module descriptor
  45  *****************************************************************************/
  46 vlc_module_begin ()
  47     set_category( CAT_AUDIO )
  48     set_subcategory( SUBCAT_AUDIO_MISC )
  49     set_description( N_("Single precision audio volume") )
  50     set_capability( "audio volume", 10 )
  51     set_callbacks( Create, NULL )
  52 vlc_module_end ()
  53
  54 /**
  55  * Mixes a new output buffer
  56  */
  57 static void FilterFL32( audio_volume_t *p_volume, block_t *p_buffer,
  58                         float f_multiplier )
  59 {
  60     if( f_multiplier == 1.f )
  61         return; /* nothing to do */
  62
  63     float *p = (float *)p_buffer->p_buffer;
  64     for( size_t i = p_buffer->i_buffer / sizeof(*p); i > 0; i-- )
  65         *(p++) *= f_multiplier;
  66
  67     (void) p_volume;
  68 }
  69
  70 static void FilterFL64( audio_volume_t *p_volume, block_t *p_buffer,
  71                         float f_multiplier )
  72 {
  73     double *p = (double *)p_buffer->p_buffer;
  74     double mult = f_multiplier;
  75     if( mult == 1. )
  76         return; /* nothing to do */
  77
  78     for( size_t i = p_buffer->i_buffer / sizeof(*p); i > 0; i-- )
  79         *(p++) *= mult;
  80
  81     (void) p_volume;
  82 }
  83
  84 /**
  85  * Initializes the mixer
  86  */
  87 static int Create( vlc_object_t *p_this )
  88 {
  89     audio_volume_t *p_volume = (audio_volume_t *)p_this;
  90
  91     switch (p_volume->format)
  92     {
  93         case VLC_CODEC_FL32:
  94             p_volume->amplify = FilterFL32;
  95             break;
  96         case VLC_CODEC_FL64:
  97             p_volume->amplify = FilterFL64;
  98             break;
  99         default:
 100             return -1;
 101     }
 102     return 0;
 103 }