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_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_instance_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_instance_t * p_aout = (aout_instance_t *)p_this;
  61
  62     if ( p_aout->mixer.mixer.i_format != VLC_FOURCC('f','l','3','2') )
  63     {
  64         return -1;
  65     }
  66
  67     /* Use the trivial mixer when we can */
  68     if ( p_aout->i_nb_inputs == 1 && p_aout->mixer.f_multiplier == 1.0 )
  69     {
  70         int i;
  71         for( i = 0; i < p_aout->i_nb_inputs; i++ )
  72         {
  73             if( p_aout->pp_inputs[i]->f_multiplier != 1.0 )
  74                 break;
  75         }
  76         if( i >= p_aout->i_nb_inputs )
  77             return -1;
  78     }
  79
  80     p_aout->mixer.pf_do_work = DoWork;
  81     return 0;
  82 }
  83
  84 /*****************************************************************************
  85  * ScaleWords: prepare input words for averaging
  86  *****************************************************************************/
  87 static void ScaleWords( float * p_out, const float * p_in, size_t i_nb_words,
  88                         int i_nb_inputs, float f_multiplier )
  89 {
  90     int i;
  91     f_multiplier /= i_nb_inputs;
  92
  93     for ( i = i_nb_words; i--; )
  94     {
  95         *p_out++ = *p_in++ * f_multiplier;
  96     }
  97 }
  98
  99 /*****************************************************************************
 100  * MeanWords: average input words
 101  *****************************************************************************/
 102 static void MeanWords( float * p_out, const float * p_in, size_t i_nb_words,
 103                        int i_nb_inputs, float f_multiplier )
 104 {
 105     int i;
 106     f_multiplier /= i_nb_inputs;
 107
 108     for ( i = i_nb_words; i--; )
 109     {
 110         *p_out++ += *p_in++ * f_multiplier;
 111     }
 112 }
 113
 114 /*****************************************************************************
 115  * DoWork: mix a new output buffer
 116  *****************************************************************************
 117  * Terminology : in this function a word designates a single float32, eg.
 118  * a stereo sample is consituted of two words.
 119  *****************************************************************************/
 120 static void DoWork( aout_instance_t * p_aout, aout_buffer_t * p_buffer )
 121 {
 122     const int i_nb_inputs = p_aout->i_nb_inputs;
 123     const float f_multiplier_global = p_aout->mixer.f_multiplier;
 124     const int i_nb_channels = aout_FormatNbChannels( &p_aout->mixer.mixer );
 125     int i_input;
 126
 127     for ( i_input = 0; i_input < i_nb_inputs; i_input++ )
 128     {
 129         int i_nb_words = p_buffer->i_nb_samples * i_nb_channels;
 130         aout_input_t * p_input = p_aout->pp_inputs[i_input];
 131         float f_multiplier = f_multiplier_global * p_input->f_multiplier;
 132
 133         float * p_out = (float *)p_buffer->p_buffer;
 134         float * p_in = (float *)p_input->p_first_byte_to_mix;
 135
 136         if ( p_input->b_error || p_input->b_paused )
 137             continue;
 138
 139         for ( ; ; )
 140         {
 141             ptrdiff_t i_available_words = (
 142                  (float *)p_input->fifo.p_first->p_buffer - p_in)
 143                                    + p_input->fifo.p_first->i_nb_samples
 144                                    * i_nb_channels;
 145
 146             if ( i_available_words < i_nb_words )
 147             {
 148                 aout_buffer_t * p_old_buffer;
 149
 150                 if ( i_available_words > 0 )
 151                 {
 152                     if ( !i_input )
 153                     {
 154                         ScaleWords( p_out, p_in, i_available_words,
 155                                     i_nb_inputs, f_multiplier );
 156                     }
 157                     else
 158                     {
 159                         MeanWords( p_out, p_in, i_available_words,
 160                                    i_nb_inputs, f_multiplier );
 161                     }
 162                 }
 163
 164                 i_nb_words -= i_available_words;
 165                 p_out += i_available_words;
 166
 167                 /* Next buffer */
 168                 p_old_buffer = aout_FifoPop( p_aout, &p_input->fifo );
 169                 aout_BufferFree( p_old_buffer );
 170                 if ( p_input->fifo.p_first == NULL )
 171                 {
 172                     msg_Err( p_aout, "internal amix error" );
 173                     return;
 174                 }
 175                 p_in = (float *)p_input->fifo.p_first->p_buffer;
 176             }
 177             else
 178             {
 179                 if ( i_nb_words > 0 )
 180                 {
 181                     if ( !i_input )
 182                     {
 183                         ScaleWords( p_out, p_in, i_nb_words, i_nb_inputs,
 184                                     f_multiplier );
 185                     }
 186                     else
 187                     {
 188                         MeanWords( p_out, p_in, i_nb_words, i_nb_inputs,
 189                                    f_multiplier );
 190                     }
 191                 }
 192                 p_input->p_first_byte_to_mix = (void *)(p_in
 193                                             + i_nb_words);
 194                 break;
 195             }
 196         }
 197     }
 198 }
 199