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_common.h>
  33 #include <vlc_plugin.h>
  34 #include <vlc_aout.h>
  35
  36 /*****************************************************************************
  37  * Local prototypes
  38  *****************************************************************************/
  39 static int  Create    ( vlc_object_t * );
  40
  41 static void DoWork    ( aout_instance_t *, aout_filter_t *, aout_buffer_t *,
  42                         aout_buffer_t * );
  43
  44 /*****************************************************************************
  45  * Module descriptor
  46  *****************************************************************************/
  47 vlc_module_begin ()
  48     set_description( N_("Audio filter for trivial channel mixing") )
  49     set_capability( "audio filter", 1 )
  50     set_category( CAT_AUDIO )
  51     set_subcategory( SUBCAT_AUDIO_MISC )
  52     set_callbacks( Create, NULL )
  53 vlc_module_end ()
  54
  55 /*****************************************************************************
  56  * Create: allocate trivial channel mixer
  57  *****************************************************************************/
  58 static int Create( vlc_object_t *p_this )
  59 {
  60     aout_filter_t * p_filter = (aout_filter_t *)p_this;
  61
  62     if ( (p_filter->input.i_physical_channels
  63            == p_filter->output.i_physical_channels
  64            && p_filter->input.i_original_channels
  65                == p_filter->output.i_original_channels)
  66           || p_filter->input.i_format != p_filter->output.i_format
  67           || p_filter->input.i_rate != p_filter->output.i_rate
  68           || (p_filter->input.i_format != VLC_CODEC_FL32
  69                && p_filter->input.i_format != VLC_CODEC_FI32) )
  70     {
  71         return -1;
  72     }
  73
  74     p_filter->pf_do_work = DoWork;
  75     if ( aout_FormatNbChannels( &p_filter->input )
  76            > aout_FormatNbChannels( &p_filter->output ) )
  77     {
  78         /* Downmixing */
  79         p_filter->b_in_place = 1;
  80     }
  81     else
  82     {
  83         /* Upmixing */
  84         p_filter->b_in_place = 0;
  85     }
  86
  87     return 0;
  88 }
  89
  90 /*****************************************************************************
  91  * SparseCopy: trivially downmix or upmix a buffer
  92  *****************************************************************************/
  93 static void SparseCopy( int32_t * p_dest, const int32_t * p_src, size_t i_len,
  94                         int i_output_stride, int i_input_stride )
  95 {
  96     int i;
  97     for ( i = i_len; i--; )
  98     {
  99         int j;
 100         for ( j = 0; j < i_output_stride; j++ )
 101         {
 102             p_dest[j] = p_src[j % i_input_stride];
 103         }
 104         p_src += i_input_stride;
 105         p_dest += i_output_stride;
 106     }
 107 }
 108
 109 /*****************************************************************************
 110  * DoWork: convert a buffer
 111  *****************************************************************************/
 112 static void DoWork( aout_instance_t * p_aout, aout_filter_t * p_filter,
 113                     aout_buffer_t * p_in_buf, aout_buffer_t * p_out_buf )
 114 {
 115     VLC_UNUSED(p_aout);
 116     int i_input_nb = aout_FormatNbChannels( &p_filter->input );
 117     int i_output_nb = aout_FormatNbChannels( &p_filter->output );
 118     int32_t * p_dest = (int32_t *)p_out_buf->p_buffer;
 119     int32_t * p_src = (int32_t *)p_in_buf->p_buffer;
 120
 121     p_out_buf->i_nb_samples = p_in_buf->i_nb_samples;
 122     p_out_buf->i_nb_bytes = p_in_buf->i_nb_bytes * i_output_nb / i_input_nb;
 123
 124     if ( (p_filter->output.i_original_channels & AOUT_CHAN_PHYSMASK)
 125                 != (p_filter->input.i_original_channels & AOUT_CHAN_PHYSMASK)
 126            && (p_filter->input.i_original_channels & AOUT_CHAN_PHYSMASK)
 127                 == (AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT) )
 128     {
 129         int i;
 130         /* This is a bit special. */
 131         if ( !(p_filter->output.i_original_channels & AOUT_CHAN_LEFT) )
 132         {
 133             p_src++;
 134         }
 135         if ( p_filter->output.i_physical_channels == AOUT_CHAN_CENTER )
 136         {
 137             /* Mono mode */
 138             for ( i = p_in_buf->i_nb_samples; i--; )
 139             {
 140                 *p_dest = *p_src;
 141                 p_dest++;
 142                 p_src += 2;
 143             }
 144         }
 145         else
 146         {
 147             /* Fake-stereo mode */
 148             for ( i = p_in_buf->i_nb_samples; i--; )
 149             {
 150                 *p_dest = *p_src;
 151                 p_dest++;
 152                 *p_dest = *p_src;
 153                 p_dest++;
 154                 p_src += 2;
 155             }
 156         }
 157     }
 158     else if ( p_filter->output.i_original_channels
 159                                     & AOUT_CHAN_REVERSESTEREO )
 160     {
 161         /* Reverse-stereo mode */
 162         int i;
 163         for ( i = p_in_buf->i_nb_samples; i--; )
 164         {
 165             *p_dest = p_src[1];
 166             p_dest++;
 167             *p_dest = p_src[0];
 168             p_dest++;
 169             p_src += 2;
 170         }
 171     }
 172     else
 173     {
 174         SparseCopy( p_dest, p_src, p_in_buf->i_nb_samples, i_output_nb,
 175                     i_input_nb );
 176     }
 177 }
 178