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 <vlc/vlc.h>
  33 #include <vlc_aout.h>
  34
  35 /*****************************************************************************
  36  * Local prototypes
  37  *****************************************************************************/
  38 static int  Create    ( vlc_object_t * );
  39
  40 static void DoWork    ( aout_instance_t *, aout_buffer_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( _("Float32 audio mixer") );
  49     set_capability( "audio mixer", 10 );
  50     set_callbacks( Create, NULL );
  51 vlc_module_end();
  52
  53 /*****************************************************************************
  54  * Create: allocate mixer
  55  *****************************************************************************/
  56 static int Create( vlc_object_t *p_this )
  57 {
  58     aout_instance_t * p_aout = (aout_instance_t *)p_this;
  59
  60     if ( p_aout->mixer.mixer.i_format != VLC_FOURCC('f','l','3','2') )
  61     {
  62         return -1;
  63     }
  64
  65     /* Use the trivial mixer when we can */
  66     if ( p_aout->i_nb_inputs == 1 && p_aout->mixer.f_multiplier == 1.0 )
  67     {
  68         int i;
  69         for( i = 0; i < p_aout->i_nb_inputs; i++ )
  70         {
  71             if( p_aout->pp_inputs[i]->f_multiplier != 1.0 )
  72                 break;
  73         }
  74         if( i >= p_aout->i_nb_inputs )
  75             return -1;
  76     }
  77
  78     p_aout->mixer.pf_do_work = 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_instance_t * p_aout, aout_buffer_t * p_buffer )
 119 {
 120     const int i_nb_inputs = p_aout->i_nb_inputs;
 121     const float f_multiplier_global = p_aout->mixer.f_multiplier;
 122     const int i_nb_channels = aout_FormatNbChannels( &p_aout->mixer.mixer );
 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_input_t * p_input = p_aout->pp_inputs[i_input];
 129         float f_multiplier = f_multiplier_global * p_input->f_multiplier;
 130
 131         float * p_out = (float *)p_buffer->p_buffer;
 132         float * p_in = (float *)p_input->p_first_byte_to_mix;
 133
 134         if ( p_input->b_error ) continue;
 135
 136         for ( ; ; )
 137         {
 138             ptrdiff_t i_available_words = (
 139                  (float *)p_input->fifo.p_first->p_buffer - p_in)
 140                                    + p_input->fifo.p_first->i_nb_samples
 141                                    * i_nb_channels;
 142
 143             if ( i_available_words < i_nb_words )
 144             {
 145                 aout_buffer_t * p_old_buffer;
 146
 147                 if ( i_available_words > 0 )
 148                 {
 149                     if ( !i_input )
 150                     {
 151                         ScaleWords( p_out, p_in, i_available_words,
 152                                     i_nb_inputs, f_multiplier );
 153                     }
 154                     else
 155                     {
 156                         MeanWords( p_out, p_in, i_available_words,
 157                                    i_nb_inputs, f_multiplier );
 158                     }
 159                 }
 160
 161                 i_nb_words -= i_available_words;
 162                 p_out += i_available_words;
 163
 164                 /* Next buffer */
 165                 p_old_buffer = aout_FifoPop( p_aout, &p_input->fifo );
 166                 aout_BufferFree( p_old_buffer );
 167                 if ( p_input->fifo.p_first == NULL )
 168                 {
 169                     msg_Err( p_aout, "internal amix error" );
 170                     return;
 171                 }
 172                 p_in = (float *)p_input->fifo.p_first->p_buffer;
 173             }
 174             else
 175             {
 176                 if ( i_nb_words > 0 )
 177                 {
 178                     if ( !i_input )
 179                     {
 180                         ScaleWords( p_out, p_in, i_nb_words, i_nb_inputs,
 181                                     f_multiplier );
 182                     }
 183                     else
 184                     {
 185                         MeanWords( p_out, p_in, i_nb_words, i_nb_inputs,
 186                                    f_multiplier );
 187                     }
 188                 }
 189                 p_input->p_first_byte_to_mix = (void *)(p_in
 190                                             + i_nb_words);
 191                 break;
 192             }
 193         }
 194     }
 195 }
 196