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