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 1.10 2004/01/25 17:20:18 kuehne 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 <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_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     if ( p_aout->i_nb_inputs == 1 && p_aout->mixer.f_multiplier == 1.0 )
  63     {
  64         /* Tell the trivial mixer to go for it. */
  65         return -1;
  66     }
  67
  68     p_aout->mixer.pf_do_work = DoWork;
  69
  70     return 0;
  71 }
  72
  73 /*****************************************************************************
  74  * ScaleWords: prepare input words for averaging
  75  *****************************************************************************/
  76 static void ScaleWords( float * p_out, const float * p_in, size_t i_nb_words,
  77                         int i_nb_inputs, float f_multiplier )
  78 {
  79     int i;
  80     f_multiplier /= i_nb_inputs;
  81
  82     for ( i = i_nb_words; i--; )
  83     {
  84         *p_out++ = *p_in++ * f_multiplier;
  85     }
  86 }
  87
  88 /*****************************************************************************
  89  * MeanWords: average input words
  90  *****************************************************************************/
  91 static void MeanWords( float * p_out, const float * p_in, size_t i_nb_words,
  92                        int i_nb_inputs, float f_multiplier )
  93 {
  94     int i;
  95     f_multiplier /= i_nb_inputs;
  96
  97     for ( i = i_nb_words; i--; )
  98     {
  99         *p_out++ += *p_in++ * f_multiplier;
 100     }
 101 }
 102
 103 /*****************************************************************************
 104  * DoWork: mix a new output buffer
 105  *****************************************************************************
 106  * Terminology : in this function a word designates a single float32, eg.
 107  * a stereo sample is consituted of two words.
 108  *****************************************************************************/
 109 static void DoWork( aout_instance_t * p_aout, aout_buffer_t * p_buffer )
 110 {
 111     int i_nb_inputs = p_aout->i_nb_inputs;
 112     float f_multiplier = p_aout->mixer.f_multiplier;
 113     int i_input;
 114     int i_nb_channels = aout_FormatNbChannels( &p_aout->mixer.mixer );
 115
 116     for ( i_input = 0; i_input < i_nb_inputs; i_input++ )
 117     {
 118         int i_nb_words = p_buffer->i_nb_samples * i_nb_channels;
 119         aout_input_t * p_input = p_aout->pp_inputs[i_input];
 120         float * p_out = (float *)p_buffer->p_buffer;
 121         float * p_in = (float *)p_input->p_first_byte_to_mix;
 122
 123         if ( p_input->b_error ) continue;
 124
 125         for ( ; ; )
 126         {
 127             ptrdiff_t i_available_words = (
 128                  (float *)p_input->fifo.p_first->p_buffer - p_in)
 129                                    + p_input->fifo.p_first->i_nb_samples
 130                                    * i_nb_channels;
 131
 132             if ( i_available_words < i_nb_words )
 133             {
 134                 aout_buffer_t * p_old_buffer;
 135
 136                 if ( i_available_words > 0 )
 137                 {
 138                     if ( !i_input )
 139                     {
 140                         ScaleWords( p_out, p_in, i_available_words,
 141                                     i_nb_inputs, f_multiplier );
 142                     }
 143                     else
 144                     {
 145                         MeanWords( p_out, p_in, i_available_words,
 146                                    i_nb_inputs, f_multiplier );
 147                     }
 148                 }
 149
 150                 i_nb_words -= i_available_words;
 151                 p_out += i_available_words;
 152
 153                 /* Next buffer */
 154                 p_old_buffer = aout_FifoPop( p_aout, &p_input->fifo );
 155                 aout_BufferFree( p_old_buffer );
 156                 if ( p_input->fifo.p_first == NULL )
 157                 {
 158                     msg_Err( p_aout, "internal amix error" );
 159                     return;
 160                 }
 161                 p_in = (float *)p_input->fifo.p_first->p_buffer;
 162             }
 163             else
 164             {
 165                 if ( i_nb_words > 0 )
 166                 {
 167                     if ( !i_input )
 168                     {
 169                         ScaleWords( p_out, p_in, i_nb_words, i_nb_inputs,
 170                                     f_multiplier );
 171                     }
 172                     else
 173                     {
 174                         MeanWords( p_out, p_in, i_nb_words, i_nb_inputs,
 175                                    f_multiplier );
 176                     }
 177                 }
 178                 p_input->p_first_byte_to_mix = (void *)(p_in
 179                                             + i_nb_words);
 180                 break;
 181             }
 182         }
 183     }
 184 }
 185