modules/audio_mixer/float32.c

   1 /*****************************************************************************
   2  * float32.c : precise float32 audio mixer implementation
   3  *****************************************************************************
   4  * Copyright (C) 2002 the VideoLAN team
   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
  10  * it under the terms of the GNU General Public License as published by
  11  * the Free Software Foundation; either version 2 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 General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with this program; if not, write to the Free Software
  21  * Foundation, 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_mixer.h>
  37
  38 /*****************************************************************************
  39  * Local prototypes
  40  *****************************************************************************/
  41 static int Create( vlc_object_t * );
  42 static void DoWork( audio_mixer_t *, aout_buffer_t *, float );
  43
  44 /*****************************************************************************
  45  * Module descriptor
  46  *****************************************************************************/
  47 vlc_module_begin ()
  48     set_category( CAT_AUDIO )
  49     set_subcategory( SUBCAT_AUDIO_MISC )
  50     set_description( N_("Float32 audio mixer") )
  51     set_capability( "audio mixer", 10 )
  52     set_callbacks( Create, NULL )
  53 vlc_module_end ()
  54
  55 /**
  56  * Initializes the mixer
  57  */
  58 static int Create( vlc_object_t *p_this )
  59 {
  60     audio_mixer_t *p_mixer = (audio_mixer_t *)p_this;
  61
  62     if (p_mixer->format != VLC_CODEC_FL32)
  63         return -1;
  64
  65     p_mixer->mix = DoWork;
  66     return 0;
  67 }
  68
  69 /**
  70  * Mixes a new output buffer
  71  */
  72 static void DoWork( audio_mixer_t * p_mixer, aout_buffer_t *p_buffer,
  73                     float f_multiplier )
  74 {
  75     if( f_multiplier == 1.0 )
  76         return; /* nothing to do */
  77
  78     float *p = (float *)p_buffer->p_buffer;
  79     for( size_t i = p_buffer->i_buffer / sizeof(float); i > 0; i-- )
  80         *(p++) *= f_multiplier;
  81
  82     (void) p_mixer;
  83 }