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
  28 #ifdef HAVE_CONFIG_H
  29 # include "config.h"
  30 #endif
  31
  32 #include <vlc/vlc.h>
  33 #include <vlc_aout.h>
  34
  35 /*****************************************************************************
  36  * Local prototypes
  37  *****************************************************************************/
  38 static int  Create    ( vlc_object_t * );
  39
  40 static void DoWork    ( aout_instance_t *, aout_filter_t *, aout_buffer_t *,
  41                         aout_buffer_t * );
  42
  43 /*****************************************************************************
  44  * Module descriptor
  45  *****************************************************************************/
  46 vlc_module_begin();
  47     set_description( _("Audio filter for trivial channel mixing") );
  48     set_capability( "audio filter", 1 );
  49     set_category( CAT_AUDIO );
  50     set_subcategory( SUBCAT_AUDIO_MISC );
  51     set_callbacks( Create, NULL );
  52 vlc_module_end();
  53
  54 /*****************************************************************************
  55  * Create: allocate trivial channel mixer
  56  *****************************************************************************/
  57 static int Create( vlc_object_t *p_this )
  58 {
  59     aout_filter_t * p_filter = (aout_filter_t *)p_this;
  60
  61     if ( (p_filter->input.i_physical_channels
  62            == p_filter->output.i_physical_channels
  63            && p_filter->input.i_original_channels
  64                == p_filter->output.i_original_channels)
  65           || p_filter->input.i_format != p_filter->output.i_format
  66           || p_filter->input.i_rate != p_filter->output.i_rate
  67           || (p_filter->input.i_format != VLC_FOURCC('f','l','3','2')
  68                && p_filter->input.i_format != VLC_FOURCC('f','i','3','2')) )
  69     {
  70         return -1;
  71     }
  72
  73     p_filter->pf_do_work = DoWork;
  74     if ( aout_FormatNbChannels( &p_filter->input )
  75            > aout_FormatNbChannels( &p_filter->output ) )
  76     {
  77         /* Downmixing */
  78         p_filter->b_in_place = 1;
  79     }
  80     else
  81     {
  82         /* Upmixing */
  83         p_filter->b_in_place = 0;
  84     }
  85
  86     return 0;
  87 }
  88
  89 /*****************************************************************************
  90  * SparseCopy: trivially downmix or upmix a buffer
  91  *****************************************************************************/
  92 static void SparseCopy( int32_t * p_dest, const int32_t * p_src, size_t i_len,
  93                         int i_output_stride, int i_input_stride )
  94 {
  95     int i;
  96     for ( i = i_len; i--; )
  97     {
  98         int j;
  99         for ( j = 0; j < i_output_stride; j++ )
 100         {
 101             p_dest[j] = p_src[j % i_input_stride];
 102         }
 103         p_src += i_input_stride;
 104         p_dest += i_output_stride;
 105     }
 106 }
 107
 108 /*****************************************************************************
 109  * DoWork: convert a buffer
 110  *****************************************************************************/
 111 static void DoWork( aout_instance_t * p_aout, aout_filter_t * p_filter,
 112                     aout_buffer_t * p_in_buf, aout_buffer_t * p_out_buf )
 113 {
 114     VLC_UNUSED(p_aout);
 115     int i_input_nb = aout_FormatNbChannels( &p_filter->input );
 116     int i_output_nb = aout_FormatNbChannels( &p_filter->output );
 117     int32_t * p_dest = (int32_t *)p_out_buf->p_buffer;
 118     int32_t * p_src = (int32_t *)p_in_buf->p_buffer;
 119
 120     p_out_buf->i_nb_samples = p_in_buf->i_nb_samples;
 121     p_out_buf->i_nb_bytes = p_in_buf->i_nb_bytes * i_output_nb / i_input_nb;
 122
 123     if ( (p_filter->output.i_original_channels & AOUT_CHAN_PHYSMASK)
 124                 != (p_filter->input.i_original_channels & AOUT_CHAN_PHYSMASK)
 125            && (p_filter->input.i_original_channels & AOUT_CHAN_PHYSMASK)
 126                 == (AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT) )
 127     {
 128         int i;
 129         /* This is a bit special. */
 130         if ( !(p_filter->output.i_original_channels & AOUT_CHAN_LEFT) )
 131         {
 132             p_src++;
 133         }
 134         if ( p_filter->output.i_physical_channels == AOUT_CHAN_CENTER )
 135         {
 136             /* Mono mode */
 137             for ( i = p_in_buf->i_nb_samples; i--; )
 138             {
 139                 *p_dest = *p_src;
 140                 p_dest++;
 141                 p_src += 2;
 142             }
 143         }
 144         else
 145         {
 146             /* Fake-stereo mode */
 147             for ( i = p_in_buf->i_nb_samples; i--; )
 148             {
 149                 *p_dest = *p_src;
 150                 p_dest++;
 151                 *p_dest = *p_src;
 152                 p_dest++;
 153                 p_src += 2;
 154             }
 155         }
 156     }
 157     else if ( p_filter->output.i_original_channels
 158                                     & AOUT_CHAN_REVERSESTEREO )
 159     {
 160         /* Reverse-stereo mode */
 161         int i;
 162         for ( i = p_in_buf->i_nb_samples; i--; )
 163         {
 164             *p_dest = p_src[1];
 165             p_dest++;
 166             *p_dest = p_src[0];
 167             p_dest++;
 168             p_src += 2;
 169         }
 170     }
 171     else
 172     {
 173         SparseCopy( p_dest, p_src, p_in_buf->i_nb_samples, i_output_nb,
 174                     i_input_nb );
 175     }
 176 }
 177