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