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 #include <stdlib.h>                                      /* malloc(), free() */
  28 #include <string.h>
  29
  30 #include <vlc/vlc.h>
  31 #include <vlc_aout.h>
  32
  33 /*****************************************************************************
  34  * Local prototypes
  35  *****************************************************************************/
  36 static int  Create    ( vlc_object_t * );
  37
  38 static void DoWork    ( aout_instance_t *, aout_buffer_t * );
  39
  40 /*****************************************************************************
  41  * Module descriptor
  42  *****************************************************************************/
  43 vlc_module_begin();
  44     set_category( CAT_AUDIO );
  45     set_subcategory( SUBCAT_AUDIO_MISC );
  46     set_description( _("Float32 audio mixer") );
  47     set_capability( "audio mixer", 10 );
  48     set_callbacks( Create, NULL );
  49 vlc_module_end();
  50
  51 /*****************************************************************************
  52  * Create: allocate mixer
  53  *****************************************************************************/
  54 static int Create( vlc_object_t *p_this )
  55 {
  56     aout_instance_t * p_aout = (aout_instance_t *)p_this;
  57
  58     if ( p_aout->mixer.mixer.i_format != VLC_FOURCC('f','l','3','2') )
  59     {
  60         return -1;
  61     }
  62
  63     /* Use the trivial mixer when we can */
  64     if ( p_aout->i_nb_inputs == 1 && p_aout->mixer.f_multiplier == 1.0 )
  65     {
  66         int i;
  67         for( i = 0; i < p_aout->i_nb_inputs; i++ )
  68         {
  69             if( p_aout->pp_inputs[i]->f_multiplier != 1.0 )
  70                 break;
  71         }
  72         if( i >= p_aout->i_nb_inputs )
  73             return -1;
  74     }
  75
  76     p_aout->mixer.pf_do_work = DoWork;
  77     return 0;
  78 }
  79
  80 /*****************************************************************************
  81  * ScaleWords: prepare input words for averaging
  82  *****************************************************************************/
  83 static void ScaleWords( float * p_out, const float * p_in, size_t i_nb_words,
  84                         int i_nb_inputs, float f_multiplier )
  85 {
  86     int i;
  87     f_multiplier /= i_nb_inputs;
  88
  89     for ( i = i_nb_words; i--; )
  90     {
  91         *p_out++ = *p_in++ * f_multiplier;
  92     }
  93 }
  94
  95 /*****************************************************************************
  96  * MeanWords: average input words
  97  *****************************************************************************/
  98 static void MeanWords( float * p_out, const float * p_in, size_t i_nb_words,
  99                        int i_nb_inputs, float f_multiplier )
 100 {
 101     int i;
 102     f_multiplier /= i_nb_inputs;
 103
 104     for ( i = i_nb_words; i--; )
 105     {
 106         *p_out++ += *p_in++ * f_multiplier;
 107     }
 108 }
 109
 110 /*****************************************************************************
 111  * DoWork: mix a new output buffer
 112  *****************************************************************************
 113  * Terminology : in this function a word designates a single float32, eg.
 114  * a stereo sample is consituted of two words.
 115  *****************************************************************************/
 116 static void DoWork( aout_instance_t * p_aout, aout_buffer_t * p_buffer )
 117 {
 118     const int i_nb_inputs = p_aout->i_nb_inputs;
 119     const float f_multiplier_global = p_aout->mixer.f_multiplier;
 120     const int i_nb_channels = aout_FormatNbChannels( &p_aout->mixer.mixer );
 121     int i_input;
 122
 123     for ( i_input = 0; i_input < i_nb_inputs; i_input++ )
 124     {
 125         int i_nb_words = p_buffer->i_nb_samples * i_nb_channels;
 126         aout_input_t * p_input = p_aout->pp_inputs[i_input];
 127         float f_multiplier = f_multiplier_global * p_input->f_multiplier;
 128
 129         float * p_out = (float *)p_buffer->p_buffer;
 130         float * p_in = (float *)p_input->p_first_byte_to_mix;
 131
 132         if ( p_input->b_error ) continue;
 133
 134         for ( ; ; )
 135         {
 136             ptrdiff_t i_available_words = (
 137                  (float *)p_input->fifo.p_first->p_buffer - p_in)
 138                                    + p_input->fifo.p_first->i_nb_samples
 139                                    * i_nb_channels;
 140
 141             if ( i_available_words < i_nb_words )
 142             {
 143                 aout_buffer_t * p_old_buffer;
 144
 145                 if ( i_available_words > 0 )
 146                 {
 147                     if ( !i_input )
 148                     {
 149                         ScaleWords( p_out, p_in, i_available_words,
 150                                     i_nb_inputs, f_multiplier );
 151                     }
 152                     else
 153                     {
 154                         MeanWords( p_out, p_in, i_available_words,
 155                                    i_nb_inputs, f_multiplier );
 156                     }
 157                 }
 158
 159                 i_nb_words -= i_available_words;
 160                 p_out += i_available_words;
 161
 162                 /* Next buffer */
 163                 p_old_buffer = aout_FifoPop( p_aout, &p_input->fifo );
 164                 aout_BufferFree( p_old_buffer );
 165                 if ( p_input->fifo.p_first == NULL )
 166                 {
 167                     msg_Err( p_aout, "internal amix error" );
 168                     return;
 169                 }
 170                 p_in = (float *)p_input->fifo.p_first->p_buffer;
 171             }
 172             else
 173             {
 174                 if ( i_nb_words > 0 )
 175                 {
 176                     if ( !i_input )
 177                     {
 178                         ScaleWords( p_out, p_in, i_nb_words, i_nb_inputs,
 179                                     f_multiplier );
 180                     }
 181                     else
 182                     {
 183                         MeanWords( p_out, p_in, i_nb_words, i_nb_inputs,
 184                                    f_multiplier );
 185                     }
 186                 }
 187                 p_input->p_first_byte_to_mix = (void *)(p_in
 188                                             + i_nb_words);
 189                 break;
 190             }
 191         }
 192     }
 193 }
 194