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_mixer_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_mixer_t * p_mixer = (aout_mixer_t *)p_this;
  61
  62     if ( p_mixer->fmt.i_format != VLC_CODEC_FL32 )
  63         return -1;
  64
  65     /* Use the trivial mixer when we can */
  66     if ( p_mixer->input_count == 1 && p_mixer->multiplier == 1.0 )
  67     {
  68         if( p_mixer->input[0]->multiplier == 1.0 )
  69             return -1;
  70     }
  71
  72     p_mixer->mix = DoWork;
  73     return 0;
  74 }
  75
  76 /*****************************************************************************
  77  * ScaleWords: prepare input words for averaging
  78  *****************************************************************************/
  79 static void ScaleWords( float * p_out, const float * p_in, size_t i_nb_words,
  80                         int i_nb_inputs, float f_multiplier )
  81 {
  82     int i;
  83     f_multiplier /= i_nb_inputs;
  84
  85     for ( i = i_nb_words; i--; )
  86     {
  87         *p_out++ = *p_in++ * f_multiplier;
  88     }
  89 }
  90
  91 /*****************************************************************************
  92  * MeanWords: average input words
  93  *****************************************************************************/
  94 static void MeanWords( float * p_out, const float * p_in, size_t i_nb_words,
  95                        int i_nb_inputs, float f_multiplier )
  96 {
  97     int i;
  98     f_multiplier /= i_nb_inputs;
  99
 100     for ( i = i_nb_words; i--; )
 101     {
 102         *p_out++ += *p_in++ * f_multiplier;
 103     }
 104 }
 105
 106 /*****************************************************************************
 107  * DoWork: mix a new output buffer
 108  *****************************************************************************
 109  * Terminology : in this function a word designates a single float32, eg.
 110  * a stereo sample is consituted of two words.
 111  *****************************************************************************/
 112 static void DoWork( aout_mixer_t * p_mixer, aout_buffer_t * p_buffer )
 113 {
 114     const int i_nb_inputs = p_mixer->input_count;
 115     const float f_multiplier_global = p_mixer->multiplier;
 116     const int i_nb_channels = aout_FormatNbChannels( &p_mixer->fmt );
 117     int i_input;
 118
 119     for ( i_input = 0; i_input < i_nb_inputs; i_input++ )
 120     {
 121         int i_nb_words = p_buffer->i_nb_samples * i_nb_channels;
 122         aout_mixer_input_t * p_input = p_mixer->input[i_input];
 123         float f_multiplier = f_multiplier_global * p_input->multiplier;
 124
 125         float * p_out = (float *)p_buffer->p_buffer;
 126         float * p_in = (float *)p_input->begin;
 127
 128         if ( p_input->is_invalid )
 129             continue;
 130
 131         for ( ; ; )
 132         {
 133             ptrdiff_t i_available_words = (
 134                  (float *)p_input->fifo.p_first->p_buffer - p_in)
 135                                    + p_input->fifo.p_first->i_nb_samples
 136                                    * i_nb_channels;
 137
 138             if ( i_available_words < i_nb_words )
 139             {
 140                 aout_buffer_t * p_old_buffer;
 141
 142                 if ( i_available_words > 0 )
 143                 {
 144                     if ( !i_input )
 145                     {
 146                         ScaleWords( p_out, p_in, i_available_words,
 147                                     i_nb_inputs, f_multiplier );
 148                     }
 149                     else
 150                     {
 151                         MeanWords( p_out, p_in, i_available_words,
 152                                    i_nb_inputs, f_multiplier );
 153                     }
 154                 }
 155
 156                 i_nb_words -= i_available_words;
 157                 p_out += i_available_words;
 158
 159                 /* Next buffer */
 160                 p_old_buffer = aout_FifoPop( NULL, &p_input->fifo );
 161                 aout_BufferFree( p_old_buffer );
 162                 if ( p_input->fifo.p_first == NULL )
 163                 {
 164                     msg_Err( p_mixer, "internal amix error" );
 165                     return;
 166                 }
 167                 p_in = (float *)p_input->fifo.p_first->p_buffer;
 168             }
 169             else
 170             {
 171                 if ( i_nb_words > 0 )
 172                 {
 173                     if ( !i_input )
 174                     {
 175                         ScaleWords( p_out, p_in, i_nb_words, i_nb_inputs,
 176                                     f_multiplier );
 177                     }
 178                     else
 179                     {
 180                         MeanWords( p_out, p_in, i_nb_words, i_nb_inputs,
 181                                    f_multiplier );
 182                     }
 183                 }
 184                 p_input->begin = (void *)(p_in + i_nb_words);
 185                 break;
 186             }
 187         }
 188     }
 189 }
 190