git.sesse.net Git - vlc/blob - 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/vlc.h>
  34 #include <vlc_aout.h>
  35
  36 /*****************************************************************************
  37  * Local prototypes
  38  *****************************************************************************/
  39 static int  Create    ( vlc_object_t * );
  40
  41 static void DoWork    ( aout_instance_t *, aout_buffer_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( _("Float32 audio mixer") );
  50     set_capability( "audio mixer", 10 );
  51     set_callbacks( Create, NULL );
  52 vlc_module_end();
  53
  54 /*****************************************************************************
  55  * Create: allocate mixer
  56  *****************************************************************************/
  57 static int Create( vlc_object_t *p_this )
  58 {
  59     aout_instance_t * p_aout = (aout_instance_t *)p_this;
  60
  61     if ( p_aout->mixer.mixer.i_format != VLC_FOURCC('f','l','3','2') )
  62     {
  63         return -1;
  64     }
  65
  66     /* Use the trivial mixer when we can */
  67     if ( p_aout->i_nb_inputs == 1 && p_aout->mixer.f_multiplier == 1.0 )
  68     {
  69         int i;
  70         for( i = 0; i < p_aout->i_nb_inputs; i++ )
  71         {
  72             if( p_aout->pp_inputs[i]->f_multiplier != 1.0 )
  73                 break;
  74         }
  75         if( i >= p_aout->i_nb_inputs )
  76             return -1;
  77     }
  78
  79     p_aout->mixer.pf_do_work = DoWork;
  80     return 0;
  81 }
  82
  83 /*****************************************************************************
  84  * ScaleWords: prepare input words for averaging
  85  *****************************************************************************/
  86 static void ScaleWords( float * p_out, const float * p_in, size_t i_nb_words,
  87                         int i_nb_inputs, float f_multiplier )
  88 {
  89     int i;
  90     f_multiplier /= i_nb_inputs;
  91
  92     for ( i = i_nb_words; i--; )
  93     {
  94         *p_out++ = *p_in++ * f_multiplier;
  95     }
  96 }
  97
  98 /*****************************************************************************
  99  * MeanWords: average input words
 100  *****************************************************************************/
 101 static void MeanWords( float * p_out, const float * p_in, size_t i_nb_words,
 102                        int i_nb_inputs, float f_multiplier )
 103 {
 104     int i;
 105     f_multiplier /= i_nb_inputs;
 106
 107     for ( i = i_nb_words; i--; )
 108     {
 109         *p_out++ += *p_in++ * f_multiplier;
 110     }
 111 }
 112
 113 /*****************************************************************************
 114  * DoWork: mix a new output buffer
 115  *****************************************************************************
 116  * Terminology : in this function a word designates a single float32, eg.
 117  * a stereo sample is consituted of two words.
 118  *****************************************************************************/
 119 static void DoWork( aout_instance_t * p_aout, aout_buffer_t * p_buffer )
 120 {
 121     const int i_nb_inputs = p_aout->i_nb_inputs;
 122     const float f_multiplier_global = p_aout->mixer.f_multiplier;
 123     const int i_nb_channels = aout_FormatNbChannels( &p_aout->mixer.mixer );
 124     int i_input;
 125
 126     for ( i_input = 0; i_input < i_nb_inputs; i_input++ )
 127     {
 128         int i_nb_words = p_buffer->i_nb_samples * i_nb_channels;
 129         aout_input_t * p_input = p_aout->pp_inputs[i_input];
 130         float f_multiplier = f_multiplier_global * p_input->f_multiplier;
 131
 132         float * p_out = (float *)p_buffer->p_buffer;
 133         float * p_in = (float *)p_input->p_first_byte_to_mix;
 134
 135         if ( p_input->b_error ) 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( p_aout, &p_input->fifo );
 167                 aout_BufferFree( p_old_buffer );
 168                 if ( p_input->fifo.p_first == NULL )
 169                 {
 170                     msg_Err( p_aout, "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->p_first_byte_to_mix = (void *)(p_in
 191                                             + i_nb_words);
 192                 break;
 193             }
 194         }
 195     }
 196 }
 197