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 #include <vlc/vlc.h>
  29 #include <vlc_aout.h>
  30
  31 /*****************************************************************************
  32  * Local prototypes
  33  *****************************************************************************/
  34 static int  Create    ( vlc_object_t * );
  35
  36 static void DoWork    ( aout_instance_t *, aout_buffer_t * );
  37
  38 /*****************************************************************************
  39  * Module descriptor
  40  *****************************************************************************/
  41 vlc_module_begin();
  42     set_category( CAT_AUDIO );
  43     set_subcategory( SUBCAT_AUDIO_MISC );
  44     set_description( _("Float32 audio mixer") );
  45     set_capability( "audio mixer", 10 );
  46     set_callbacks( Create, NULL );
  47 vlc_module_end();
  48
  49 /*****************************************************************************
  50  * Create: allocate mixer
  51  *****************************************************************************/
  52 static int Create( vlc_object_t *p_this )
  53 {
  54     aout_instance_t * p_aout = (aout_instance_t *)p_this;
  55
  56     if ( p_aout->mixer.mixer.i_format != VLC_FOURCC('f','l','3','2') )
  57     {
  58         return -1;
  59     }
  60
  61     /* Use the trivial mixer when we can */
  62     if ( p_aout->i_nb_inputs == 1 && p_aout->mixer.f_multiplier == 1.0 )
  63     {
  64         int i;
  65         for( i = 0; i < p_aout->i_nb_inputs; i++ )
  66         {
  67             if( p_aout->pp_inputs[i]->f_multiplier != 1.0 )
  68                 break;
  69         }
  70         if( i >= p_aout->i_nb_inputs )
  71             return -1;
  72     }
  73
  74     p_aout->mixer.pf_do_work = DoWork;
  75     return 0;
  76 }
  77
  78 /*****************************************************************************
  79  * ScaleWords: prepare input words for averaging
  80  *****************************************************************************/
  81 static void ScaleWords( float * p_out, const float * p_in, size_t i_nb_words,
  82                         int i_nb_inputs, float f_multiplier )
  83 {
  84     int i;
  85     f_multiplier /= i_nb_inputs;
  86
  87     for ( i = i_nb_words; i--; )
  88     {
  89         *p_out++ = *p_in++ * f_multiplier;
  90     }
  91 }
  92
  93 /*****************************************************************************
  94  * MeanWords: average input words
  95  *****************************************************************************/
  96 static void MeanWords( float * p_out, const float * p_in, size_t i_nb_words,
  97                        int i_nb_inputs, float f_multiplier )
  98 {
  99     int i;
 100     f_multiplier /= i_nb_inputs;
 101
 102     for ( i = i_nb_words; i--; )
 103     {
 104         *p_out++ += *p_in++ * f_multiplier;
 105     }
 106 }
 107
 108 /*****************************************************************************
 109  * DoWork: mix a new output buffer
 110  *****************************************************************************
 111  * Terminology : in this function a word designates a single float32, eg.
 112  * a stereo sample is consituted of two words.
 113  *****************************************************************************/
 114 static void DoWork( aout_instance_t * p_aout, aout_buffer_t * p_buffer )
 115 {
 116     const int i_nb_inputs = p_aout->i_nb_inputs;
 117     const float f_multiplier_global = p_aout->mixer.f_multiplier;
 118     const int i_nb_channels = aout_FormatNbChannels( &p_aout->mixer.mixer );
 119     int i_input;
 120
 121     for ( i_input = 0; i_input < i_nb_inputs; i_input++ )
 122     {
 123         int i_nb_words = p_buffer->i_nb_samples * i_nb_channels;
 124         aout_input_t * p_input = p_aout->pp_inputs[i_input];
 125         float f_multiplier = f_multiplier_global * p_input->f_multiplier;
 126
 127         float * p_out = (float *)p_buffer->p_buffer;
 128         float * p_in = (float *)p_input->p_first_byte_to_mix;
 129
 130         if ( p_input->b_error ) continue;
 131
 132         for ( ; ; )
 133         {
 134             ptrdiff_t i_available_words = (
 135                  (float *)p_input->fifo.p_first->p_buffer - p_in)
 136                                    + p_input->fifo.p_first->i_nb_samples
 137                                    * i_nb_channels;
 138
 139             if ( i_available_words < i_nb_words )
 140             {
 141                 aout_buffer_t * p_old_buffer;
 142
 143                 if ( i_available_words > 0 )
 144                 {
 145                     if ( !i_input )
 146                     {
 147                         ScaleWords( p_out, p_in, i_available_words,
 148                                     i_nb_inputs, f_multiplier );
 149                     }
 150                     else
 151                     {
 152                         MeanWords( p_out, p_in, i_available_words,
 153                                    i_nb_inputs, f_multiplier );
 154                     }
 155                 }
 156
 157                 i_nb_words -= i_available_words;
 158                 p_out += i_available_words;
 159
 160                 /* Next buffer */
 161                 p_old_buffer = aout_FifoPop( p_aout, &p_input->fifo );
 162                 aout_BufferFree( p_old_buffer );
 163                 if ( p_input->fifo.p_first == NULL )
 164                 {
 165                     msg_Err( p_aout, "internal amix error" );
 166                     return;
 167                 }
 168                 p_in = (float *)p_input->fifo.p_first->p_buffer;
 169             }
 170             else
 171             {
 172                 if ( i_nb_words > 0 )
 173                 {
 174                     if ( !i_input )
 175                     {
 176                         ScaleWords( p_out, p_in, i_nb_words, i_nb_inputs,
 177                                     f_multiplier );
 178                     }
 179                     else
 180                     {
 181                         MeanWords( p_out, p_in, i_nb_words, i_nb_inputs,
 182                                    f_multiplier );
 183                     }
 184                 }
 185                 p_input->p_first_byte_to_mix = (void *)(p_in
 186                                             + i_nb_words);
 187                 break;
 188             }
 189         }
 190     }
 191 }
 192