git.sesse.net Git - vlc/blob - modules/audio_filter/channel_mixer/trivial.c

   1 /*****************************************************************************
   2  * trivial.c : trivial channel mixer plug-in (drops unwanted channels)
   3  *****************************************************************************
   4  * Copyright (C) 2002 VideoLAN
   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., 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_filter_t *, aout_buffer_t *,
  40                         aout_buffer_t * );
  41
  42 /*****************************************************************************
  43  * Module descriptor
  44  *****************************************************************************/
  45 vlc_module_begin();
  46     set_description( _("audio filter for trivial channel mixing") );
  47     set_capability( "audio filter", 1 );
  48     set_category( CAT_AUDIO );
  49     set_subcategory( SUBCAT_AUDIO_MISC );
  50     set_callbacks( Create, NULL );
  51 vlc_module_end();
  52
  53 /*****************************************************************************
  54  * Create: allocate trivial channel mixer
  55  *****************************************************************************/
  56 static int Create( vlc_object_t *p_this )
  57 {
  58     aout_filter_t * p_filter = (aout_filter_t *)p_this;
  59
  60     if ( (p_filter->input.i_physical_channels
  61            == p_filter->output.i_physical_channels
  62            && p_filter->input.i_original_channels
  63                == p_filter->output.i_original_channels)
  64           || p_filter->input.i_format != p_filter->output.i_format
  65           || p_filter->input.i_rate != p_filter->output.i_rate
  66           || (p_filter->input.i_format != VLC_FOURCC('f','l','3','2')
  67                && p_filter->input.i_format != VLC_FOURCC('f','i','3','2')) )
  68     {
  69         return -1;
  70     }
  71
  72     p_filter->pf_do_work = DoWork;
  73     if ( aout_FormatNbChannels( &p_filter->input )
  74            > aout_FormatNbChannels( &p_filter->output ) )
  75     {
  76         /* Downmixing */
  77         p_filter->b_in_place = 1;
  78     }
  79     else
  80     {
  81         /* Upmixing */
  82         p_filter->b_in_place = 0;
  83     }
  84
  85     return 0;
  86 }
  87
  88 /*****************************************************************************
  89  * SparseCopy: trivially downmix or upmix a buffer
  90  *****************************************************************************/
  91 static void SparseCopy( int32_t * p_dest, const int32_t * p_src, size_t i_len,
  92                         int i_output_stride, int i_input_stride )
  93 {
  94     int i;
  95     for ( i = i_len; i--; )
  96     {
  97         int j;
  98         for ( j = 0; j < i_output_stride; j++ )
  99         {
 100             p_dest[j] = p_src[j % i_input_stride];
 101         }
 102         p_src += i_input_stride;
 103         p_dest += i_output_stride;
 104     }
 105 }
 106
 107 /*****************************************************************************
 108  * DoWork: convert a buffer
 109  *****************************************************************************/
 110 static void DoWork( aout_instance_t * p_aout, aout_filter_t * p_filter,
 111                     aout_buffer_t * p_in_buf, aout_buffer_t * p_out_buf )
 112 {
 113     int i_input_nb = aout_FormatNbChannels( &p_filter->input );
 114     int i_output_nb = aout_FormatNbChannels( &p_filter->output );
 115     int32_t * p_dest = (int32_t *)p_out_buf->p_buffer;
 116     int32_t * p_src = (int32_t *)p_in_buf->p_buffer;
 117
 118     p_out_buf->i_nb_samples = p_in_buf->i_nb_samples;
 119     p_out_buf->i_nb_bytes = p_in_buf->i_nb_bytes * i_output_nb / i_input_nb;
 120
 121     if ( (p_filter->output.i_original_channels & AOUT_CHAN_PHYSMASK)
 122                 != (p_filter->input.i_original_channels & AOUT_CHAN_PHYSMASK)
 123            && (p_filter->input.i_original_channels & AOUT_CHAN_PHYSMASK)
 124                 == (AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT) )
 125     {
 126         int i;
 127         /* This is a bit special. */
 128         if ( !(p_filter->output.i_original_channels & AOUT_CHAN_LEFT) )
 129         {
 130             p_src++;
 131         }
 132         if ( p_filter->output.i_physical_channels == AOUT_CHAN_CENTER )
 133         {
 134             /* Mono mode */
 135             for ( i = p_in_buf->i_nb_samples; i--; )
 136             {
 137                 *p_dest = *p_src;
 138                 p_dest++;
 139                 p_src += 2;
 140             }
 141         }
 142         else
 143         {
 144             /* Fake-stereo mode */
 145             for ( i = p_in_buf->i_nb_samples; i--; )
 146             {
 147                 *p_dest = *p_src;
 148                 p_dest++;
 149                 *p_dest = *p_src;
 150                 p_dest++;
 151                 p_src += 2;
 152             }
 153         }
 154     }
 155     else if ( p_filter->output.i_original_channels
 156                                     & AOUT_CHAN_REVERSESTEREO )
 157     {
 158         /* Reverse-stereo mode */
 159         int i;
 160         for ( i = p_in_buf->i_nb_samples; i--; )
 161         {
 162             *p_dest = p_src[1];
 163             p_dest++;
 164             *p_dest = p_src[0];
 165             p_dest++;
 166             p_src += 2;
 167         }
 168     }
 169     else
 170     {
 171         SparseCopy( p_dest, p_src, p_in_buf->i_nb_samples, i_output_nb,
 172                     i_input_nb );
 173     }
 174 }
 175