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 VideoLAN
   5  * $Id: float32.c,v 1.3 2002/09/19 21:56:39 massiot Exp $
   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., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
  22  *****************************************************************************/
  23
  24 /*****************************************************************************
  25  * Preamble
  26  *****************************************************************************/
  27 #include <errno.h>
  28 #include <stdlib.h>                                      /* malloc(), free() */
  29 #include <string.h>
  30
  31 #include <vlc/vlc.h>
  32 #include "audio_output.h"
  33 #include "aout_internal.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_description( _("float32 audio mixer module") );
  47     set_capability( "audio mixer", 10 );
  48     set_callbacks( Create, NULL );
  49 vlc_module_end();
  50
  51 /*****************************************************************************
  52  * Create: allocate trivial 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 != AOUT_FMT_FLOAT32 )
  59     {
  60         return -1;
  61     }
  62
  63     if ( p_aout->i_nb_inputs == 1 && p_aout->mixer.f_multiplier == 1.0 )
  64     {
  65         /* Tell the trivial mixer to go for it. */
  66         return -1;
  67     }
  68
  69     p_aout->mixer.pf_do_work = DoWork;
  70
  71     return 0;
  72 }
  73
  74 /*****************************************************************************
  75  * ScaleWords: prepare input words for averaging
  76  *****************************************************************************/
  77 static void ScaleWords( float * p_out, const float * p_in, size_t i_nb_words,
  78                         int i_nb_inputs, float f_multiplier )
  79 {
  80     int i;
  81     f_multiplier /= i_nb_inputs;
  82
  83     for ( i = i_nb_words; i--; )
  84     {
  85         *p_out++ = *p_in++ * f_multiplier;
  86     }
  87 }
  88
  89 /*****************************************************************************
  90  * MeanWords: average input words
  91  *****************************************************************************/
  92 static void MeanWords( float * p_out, const float * p_in, size_t i_nb_words,
  93                        int i_nb_inputs, float f_multiplier )
  94 {
  95     int i;
  96     f_multiplier /= i_nb_inputs;
  97
  98     for ( i = i_nb_words; i--; )
  99     {
 100         *p_out++ += *p_in++ * f_multiplier;
 101     }
 102 }
 103
 104 /*****************************************************************************
 105  * DoWork: mix a new output buffer
 106  *****************************************************************************
 107  * Terminology : in this function a word designates a single float32, eg.
 108  * a stereo sample is consituted of two words.
 109  *****************************************************************************/
 110 static void DoWork( aout_instance_t * p_aout, aout_buffer_t * p_buffer )
 111 {
 112     int i_nb_inputs = p_aout->i_nb_inputs;
 113     float f_multiplier = p_aout->mixer.f_multiplier;
 114     int i_input;
 115
 116     for ( i_input = 0; i_input < i_nb_inputs; i_input++ )
 117     {
 118         int i_nb_words = p_buffer->i_nb_samples
 119                           * p_aout->mixer.mixer.i_channels;
 120         aout_input_t * p_input = p_aout->pp_inputs[i_input];
 121         float * p_out = (float *)p_buffer->p_buffer;
 122         float * p_in = (float *)p_input->p_first_byte_to_mix;
 123
 124         for ( ; ; )
 125         {
 126             ptrdiff_t i_available_words = (
 127                  (float *)p_input->fifo.p_first->p_buffer - p_in)
 128                                    + p_input->fifo.p_first->i_nb_samples
 129                                    * p_aout->mixer.mixer.i_channels;
 130
 131             if ( i_available_words < i_nb_words )
 132             {
 133                 aout_buffer_t * p_old_buffer;
 134
 135                 if ( i_available_words > 0 )
 136                 {
 137                     if ( !i_input )
 138                     {
 139                         ScaleWords( p_out, p_in, i_available_words,
 140                                     i_nb_inputs, f_multiplier );
 141                     }
 142                     else
 143                     {
 144                         MeanWords( p_out, p_in, i_available_words,
 145                                    i_nb_inputs, f_multiplier );
 146                     }
 147                 }
 148
 149                 i_nb_words -= i_available_words;
 150                 p_out += i_available_words;
 151
 152                 /* Next buffer */
 153                 p_old_buffer = aout_FifoPop( p_aout, &p_input->fifo );
 154                 aout_BufferFree( p_old_buffer );
 155                 if ( p_input->fifo.p_first == NULL )
 156                 {
 157                     msg_Err( p_aout, "internal amix error" );
 158                     return;
 159                 }
 160                 p_in = (float *)p_input->fifo.p_first->p_buffer;
 161             }
 162             else
 163             {
 164                 if ( i_nb_words > 0 )
 165                 {
 166                     if ( !i_input )
 167                     {
 168                         ScaleWords( p_out, p_in, i_nb_words, i_nb_inputs,
 169                                     f_multiplier );
 170                     }
 171                     else
 172                     {
 173                         MeanWords( p_out, p_in, i_nb_words, i_nb_inputs,
 174                                    f_multiplier );
 175                     }
 176                 }
 177                 p_input->p_first_byte_to_mix = (void *)(p_in
 178                                             + i_nb_words);
 179                 break;
 180             }
 181         }
 182     }
 183 }
 184