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
  37 /*****************************************************************************
  38  * Local prototypes
  39  *****************************************************************************/
  40 static int  Create    ( vlc_object_t * );
  41
  42 static void DoWork    ( aout_mixer_t *, aout_buffer_t * );
  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  * Create: allocate mixer
  57  *****************************************************************************/
  58 static int Create( vlc_object_t *p_this )
  59 {
  60     aout_mixer_t * p_mixer = (aout_mixer_t *)p_this;
  61
  62     if ( p_mixer->fmt.i_format != VLC_CODEC_FL32 )
  63         return -1;
  64
  65     /* Use the trivial mixer when we can */
  66     if ( p_mixer->input_count == 1 && p_mixer->multiplier == 1.0 )
  67     {
  68         int i;
  69         for( i = 0; i < p_mixer->input_count; i++ )
  70         {
  71             if( p_mixer->input[i]->multiplier != 1.0 )
  72                 break;
  73         }
  74         if( i >= p_mixer->input_count )
  75             return -1;
  76     }
  77
  78     p_mixer->mix = DoWork;
  79     return 0;
  80 }
  81
  82 /*****************************************************************************
  83  * ScaleWords: prepare input words for averaging
  84  *****************************************************************************/
  85 static void ScaleWords( float * p_out, const float * p_in, size_t i_nb_words,
  86                         int i_nb_inputs, float f_multiplier )
  87 {
  88     int i;
  89     f_multiplier /= i_nb_inputs;
  90
  91     for ( i = i_nb_words; i--; )
  92     {
  93         *p_out++ = *p_in++ * f_multiplier;
  94     }
  95 }
  96
  97 /*****************************************************************************
  98  * MeanWords: average input words
  99  *****************************************************************************/
 100 static void MeanWords( float * p_out, const float * p_in, size_t i_nb_words,
 101                        int i_nb_inputs, float f_multiplier )
 102 {
 103     int i;
 104     f_multiplier /= i_nb_inputs;
 105
 106     for ( i = i_nb_words; i--; )
 107     {
 108         *p_out++ += *p_in++ * f_multiplier;
 109     }
 110 }
 111
 112 /*****************************************************************************
 113  * DoWork: mix a new output buffer
 114  *****************************************************************************
 115  * Terminology : in this function a word designates a single float32, eg.
 116  * a stereo sample is consituted of two words.
 117  *****************************************************************************/
 118 static void DoWork( aout_mixer_t * p_mixer, aout_buffer_t * p_buffer )
 119 {
 120     const int i_nb_inputs = p_mixer->input_count;
 121     const float f_multiplier_global = p_mixer->multiplier;
 122     const int i_nb_channels = aout_FormatNbChannels( &p_mixer->fmt );
 123     int i_input;
 124
 125     for ( i_input = 0; i_input < i_nb_inputs; i_input++ )
 126     {
 127         int i_nb_words = p_buffer->i_nb_samples * i_nb_channels;
 128         aout_mixer_input_t * p_input = p_mixer->input[i_input];
 129         float f_multiplier = f_multiplier_global * p_input->multiplier;
 130
 131         float * p_out = (float *)p_buffer->p_buffer;
 132         float * p_in = (float *)p_input->begin;
 133
 134         if ( p_input->is_invalid )
 135             continue;
 136
 137         for ( ; ; )
 138         {
 139             ptrdiff_t i_available_words = (
 140                  (float *)p_input->fifo.p_first->p_buffer - p_in)
 141                                    + p_input->fifo.p_first->i_nb_samples
 142                                    * i_nb_channels;
 143
 144             if ( i_available_words < i_nb_words )
 145             {
 146                 aout_buffer_t * p_old_buffer;
 147
 148                 if ( i_available_words > 0 )
 149                 {
 150                     if ( !i_input )
 151                     {
 152                         ScaleWords( p_out, p_in, i_available_words,
 153                                     i_nb_inputs, f_multiplier );
 154                     }
 155                     else
 156                     {
 157                         MeanWords( p_out, p_in, i_available_words,
 158                                    i_nb_inputs, f_multiplier );
 159                     }
 160                 }
 161
 162                 i_nb_words -= i_available_words;
 163                 p_out += i_available_words;
 164
 165                 /* Next buffer */
 166                 p_old_buffer = aout_FifoPop( NULL, &p_input->fifo );
 167                 aout_BufferFree( p_old_buffer );
 168                 if ( p_input->fifo.p_first == NULL )
 169                 {
 170                     msg_Err( p_mixer, "internal amix error" );
 171                     return;
 172                 }
 173                 p_in = (float *)p_input->fifo.p_first->p_buffer;
 174             }
 175             else
 176             {
 177                 if ( i_nb_words > 0 )
 178                 {
 179                     if ( !i_input )
 180                     {
 181                         ScaleWords( p_out, p_in, i_nb_words, i_nb_inputs,
 182                                     f_multiplier );
 183                     }
 184                     else
 185                     {
 186                         MeanWords( p_out, p_in, i_nb_words, i_nb_inputs,
 187                                    f_multiplier );
 188                     }
 189                 }
 190                 p_input->begin = (void *)(p_in + i_nb_words);
 191                 break;
 192             }
 193         }
 194     }
 195 }
 196