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: trivial.c,v 1.10 2003/01/22 18:31:47 massiot Exp $
   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_callbacks( Create, NULL );
  49 vlc_module_end();
  50
  51 /*****************************************************************************
  52  * Create: allocate trivial channel mixer
  53  *****************************************************************************/
  54 static int Create( vlc_object_t *p_this )
  55 {
  56     aout_filter_t * p_filter = (aout_filter_t *)p_this;
  57
  58     if ( (p_filter->input.i_physical_channels
  59            == p_filter->output.i_physical_channels
  60            && p_filter->input.i_original_channels
  61                == p_filter->output.i_original_channels)
  62           || p_filter->input.i_format != p_filter->output.i_format
  63           || p_filter->input.i_rate != p_filter->output.i_rate
  64           || (p_filter->input.i_format != VLC_FOURCC('f','l','3','2')
  65                && p_filter->input.i_format != VLC_FOURCC('f','i','3','2')) )
  66     {
  67         return -1;
  68     }
  69
  70     p_filter->pf_do_work = DoWork;
  71     if ( aout_FormatNbChannels( &p_filter->input )
  72            > aout_FormatNbChannels( &p_filter->output ) )
  73     {
  74         /* Downmixing */
  75         p_filter->b_in_place = 1;
  76     }
  77     else
  78     {
  79         /* Upmixing */
  80         p_filter->b_in_place = 0;
  81     }
  82
  83     return 0;
  84 }
  85
  86 /*****************************************************************************
  87  * SparseCopy: trivially downmix or upmix a buffer
  88  *****************************************************************************/
  89 static void SparseCopy( s32 * p_dest, const s32 * p_src, size_t i_len,
  90                         int i_output_stride, int i_input_stride )
  91 {
  92     int i;
  93     for ( i = i_len; i--; )
  94     {
  95         int j;
  96         for ( j = 0; j < i_output_stride; j++ )
  97         {
  98             p_dest[j] = p_src[j % i_input_stride];
  99         }
 100         p_src += i_input_stride;
 101         p_dest += i_output_stride;
 102     }
 103 }
 104
 105 /*****************************************************************************
 106  * DoWork: convert a buffer
 107  *****************************************************************************/
 108 static void DoWork( aout_instance_t * p_aout, aout_filter_t * p_filter,
 109                     aout_buffer_t * p_in_buf, aout_buffer_t * p_out_buf )
 110 {
 111     int i_input_nb = aout_FormatNbChannels( &p_filter->input );
 112     int i_output_nb = aout_FormatNbChannels( &p_filter->output );
 113     s32 * p_dest = (s32 *)p_out_buf->p_buffer;
 114     s32 * p_src = (s32 *)p_in_buf->p_buffer;
 115
 116     if ( (p_filter->output.i_original_channels & AOUT_CHAN_PHYSMASK)
 117                 != (p_filter->input.i_original_channels & AOUT_CHAN_PHYSMASK)
 118            && (p_filter->input.i_original_channels & AOUT_CHAN_PHYSMASK)
 119                 == (AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT) )
 120     {
 121         int i;
 122         /* This is a bit special. */
 123         if ( !(p_filter->output.i_original_channels & AOUT_CHAN_LEFT) )
 124         {
 125             p_src++;
 126         }
 127         if ( p_filter->output.i_physical_channels == AOUT_CHAN_CENTER )
 128         {
 129             /* Mono mode */
 130             for ( i = p_in_buf->i_nb_samples; i--; )
 131             {
 132                 *p_dest = *p_src;
 133                 p_dest++;
 134                 p_src += 2;
 135             }
 136         }
 137         else if ( p_filter->output.i_original_channels
 138                                         & AOUT_CHAN_REVERSESTEREO )
 139         {
 140             /* Reverse-stereo mode */
 141             for ( i = p_in_buf->i_nb_samples; i -= 2; )
 142             {
 143                 *p_dest++ = p_src[1];
 144                 *p_dest++ = p_src[0];
 145                 p_src += 2;
 146             }
 147         }
 148         else
 149         {
 150             /* Fake-stereo mode */
 151             for ( i = p_in_buf->i_nb_samples; i--; )
 152             {
 153                 *p_dest = *p_src;
 154                 p_dest++;
 155                 *p_dest = *p_src;
 156                 p_dest++;
 157                 p_src += 2;
 158             }
 159         }
 160     }
 161     else
 162     {
 163         SparseCopy( p_dest, p_src, p_in_buf->i_nb_samples, i_output_nb,
 164                     i_input_nb );
 165     }
 166
 167     p_out_buf->i_nb_samples = p_in_buf->i_nb_samples;
 168     p_out_buf->i_nb_bytes = p_in_buf->i_nb_bytes * i_output_nb / i_input_nb;
 169 }
 170