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, 2006 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 <vlc_aout.h>
  32
  33 /*****************************************************************************
  34  * Local prototypes
  35  *****************************************************************************/
  36 static int  Create    ( vlc_object_t * );
  37
  38 static void DoWork    ( aout_instance_t *, aout_filter_t *, aout_buffer_t *,
  39                         aout_buffer_t * );
  40
  41 /*****************************************************************************
  42  * Module descriptor
  43  *****************************************************************************/
  44 vlc_module_begin();
  45     set_description( _("Audio filter for trivial channel mixing") );
  46     set_capability( "audio filter", 1 );
  47     set_category( CAT_AUDIO );
  48     set_subcategory( SUBCAT_AUDIO_MISC );
  49     set_callbacks( Create, NULL );
  50 vlc_module_end();
  51
  52 /*****************************************************************************
  53  * Create: allocate trivial channel mixer
  54  *****************************************************************************/
  55 static int Create( vlc_object_t *p_this )
  56 {
  57     aout_filter_t * p_filter = (aout_filter_t *)p_this;
  58
  59     if ( (p_filter->input.i_physical_channels
  60            == p_filter->output.i_physical_channels
  61            && p_filter->input.i_original_channels
  62                == p_filter->output.i_original_channels)
  63           || p_filter->input.i_format != p_filter->output.i_format
  64           || p_filter->input.i_rate != p_filter->output.i_rate
  65           || (p_filter->input.i_format != VLC_FOURCC('f','l','3','2')
  66                && p_filter->input.i_format != VLC_FOURCC('f','i','3','2')) )
  67     {
  68         return -1;
  69     }
  70
  71     p_filter->pf_do_work = DoWork;
  72     if ( aout_FormatNbChannels( &p_filter->input )
  73            > aout_FormatNbChannels( &p_filter->output ) )
  74     {
  75         /* Downmixing */
  76         p_filter->b_in_place = 1;
  77     }
  78     else
  79     {
  80         /* Upmixing */
  81         p_filter->b_in_place = 0;
  82     }
  83
  84     return 0;
  85 }
  86
  87 /*****************************************************************************
  88  * SparseCopy: trivially downmix or upmix a buffer
  89  *****************************************************************************/
  90 static void SparseCopy( int32_t * p_dest, const int32_t * p_src, size_t i_len,
  91                         int i_output_stride, int i_input_stride )
  92 {
  93     int i;
  94     for ( i = i_len; i--; )
  95     {
  96         int j;
  97         for ( j = 0; j < i_output_stride; j++ )
  98         {
  99             p_dest[j] = p_src[j % i_input_stride];
 100         }
 101         p_src += i_input_stride;
 102         p_dest += i_output_stride;
 103     }
 104 }
 105
 106 /*****************************************************************************
 107  * DoWork: convert a buffer
 108  *****************************************************************************/
 109 static void DoWork( aout_instance_t * p_aout, aout_filter_t * p_filter,
 110                     aout_buffer_t * p_in_buf, aout_buffer_t * p_out_buf )
 111 {
 112     int i_input_nb = aout_FormatNbChannels( &p_filter->input );
 113     int i_output_nb = aout_FormatNbChannels( &p_filter->output );
 114     int32_t * p_dest = (int32_t *)p_out_buf->p_buffer;
 115     int32_t * p_src = (int32_t *)p_in_buf->p_buffer;
 116
 117     p_out_buf->i_nb_samples = p_in_buf->i_nb_samples;
 118     p_out_buf->i_nb_bytes = p_in_buf->i_nb_bytes * i_output_nb / i_input_nb;
 119
 120     if ( (p_filter->output.i_original_channels & AOUT_CHAN_PHYSMASK)
 121                 != (p_filter->input.i_original_channels & AOUT_CHAN_PHYSMASK)
 122            && (p_filter->input.i_original_channels & AOUT_CHAN_PHYSMASK)
 123                 == (AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT) )
 124     {
 125         int i;
 126         /* This is a bit special. */
 127         if ( !(p_filter->output.i_original_channels & AOUT_CHAN_LEFT) )
 128         {
 129             p_src++;
 130         }
 131         if ( p_filter->output.i_physical_channels == AOUT_CHAN_CENTER )
 132         {
 133             /* Mono mode */
 134             for ( i = p_in_buf->i_nb_samples; i--; )
 135             {
 136                 *p_dest = *p_src;
 137                 p_dest++;
 138                 p_src += 2;
 139             }
 140         }
 141         else
 142         {
 143             /* Fake-stereo mode */
 144             for ( i = p_in_buf->i_nb_samples; i--; )
 145             {
 146                 *p_dest = *p_src;
 147                 p_dest++;
 148                 *p_dest = *p_src;
 149                 p_dest++;
 150                 p_src += 2;
 151             }
 152         }
 153     }
 154     else if ( p_filter->output.i_original_channels
 155                                     & AOUT_CHAN_REVERSESTEREO )
 156     {
 157         /* Reverse-stereo mode */
 158         int i;
 159         for ( i = p_in_buf->i_nb_samples; i--; )
 160         {
 161             *p_dest = p_src[1];
 162             p_dest++;
 163             *p_dest = p_src[0];
 164             p_dest++;
 165             p_src += 2;
 166         }
 167     }
 168     else
 169     {
 170         SparseCopy( p_dest, p_src, p_in_buf->i_nb_samples, i_output_nb,
 171                     i_input_nb );
 172     }
 173 }
 174