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