git.sesse.net Git - vlc/blob - modules/audio_filter/channel_mixer/simple.c

   1 /*****************************************************************************
   2  * simple.c : simple channel mixer plug-in (only 7/7.1/5/5.1 -> Stereo for now)
   3  *****************************************************************************
   4  * Copyright (C) 2002 VideoLAN
   5  * $Id$
   6  *
   7  * Authors: Gildas Bazin <gbazin@videolan.org>
   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 simple channel mixing") );
  47     set_capability( "audio filter", 10 );
  48     set_category( CAT_AUDIO );
  49     set_subcategory( SUBCAT_AUDIO_MISC );
  50     set_callbacks( Create, NULL );
  51 vlc_module_end();
  52
  53 /*****************************************************************************
  54  * Create: allocate trivial channel mixer
  55  *****************************************************************************/
  56 static int Create( vlc_object_t *p_this )
  57 {
  58     aout_filter_t * p_filter = (aout_filter_t *)p_this;
  59
  60     if ( (p_filter->input.i_physical_channels
  61            == p_filter->output.i_physical_channels
  62            && p_filter->input.i_original_channels
  63                == p_filter->output.i_original_channels)
  64           || p_filter->input.i_format != p_filter->output.i_format
  65           || p_filter->input.i_rate != p_filter->output.i_rate
  66           || p_filter->input.i_format != VLC_FOURCC('f','l','3','2') )
  67     {
  68         return -1;
  69     }
  70
  71     /* Only conversion to Stereo right now */
  72     if( p_filter->output.i_physical_channels !=
  73         (AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT) ) return -1;
  74
  75     /* Only from 7/7.1/5/5.1 */
  76     if( (p_filter->input.i_physical_channels & ~AOUT_CHAN_LFE) !=
  77         (AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER |
  78          AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT) &&
  79         (p_filter->input.i_physical_channels & ~AOUT_CHAN_LFE) !=
  80         (AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER |
  81          AOUT_CHAN_MIDDLELEFT | AOUT_CHAN_MIDDLERIGHT |
  82          AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT) )
  83     {
  84         return -1;
  85     }
  86
  87     p_filter->pf_do_work = DoWork;
  88     p_filter->b_in_place = 0;
  89
  90     return 0;
  91 }
  92
  93 /*****************************************************************************
  94  * DoWork: convert a buffer
  95  *****************************************************************************/
  96 static void DoWork( aout_instance_t * p_aout, aout_filter_t * p_filter,
  97                     aout_buffer_t * p_in_buf, aout_buffer_t * p_out_buf )
  98 {
  99     int i_input_nb = aout_FormatNbChannels( &p_filter->input );
 100     int i_output_nb = aout_FormatNbChannels( &p_filter->output );
 101     float *p_dest = (float *)p_out_buf->p_buffer;
 102     float *p_src = (float *)p_in_buf->p_buffer;
 103     int i;
 104
 105     p_out_buf->i_nb_samples = p_in_buf->i_nb_samples;
 106     p_out_buf->i_nb_bytes = p_in_buf->i_nb_bytes * i_output_nb / i_input_nb;
 107
 108     if( p_filter->input.i_physical_channels & AOUT_CHAN_MIDDLELEFT )
 109     for( i = p_in_buf->i_nb_samples; i--; )
 110     {
 111         *p_dest = p_src[6] + 0.5 * p_src[0] + p_src[2] / 4 + p_src[4] / 4;
 112         p_dest++;
 113         *p_dest = p_src[6] + 0.5 * p_src[1] + p_src[3] / 4 + p_src[5] / 4;
 114         p_dest++;
 115
 116         p_src += 7;
 117
 118         if( p_filter->input.i_physical_channels & AOUT_CHAN_LFE ) p_src++;
 119     }
 120     else
 121     for( i = p_in_buf->i_nb_samples; i--; )
 122     {
 123         *p_dest = p_src[4] + 0.5 * p_src[0] + 0.33 * p_src[2];
 124         p_dest++;
 125         *p_dest = p_src[4] + 0.5 * p_src[1] + 0.33 * p_src[3];
 126         p_dest++;
 127
 128         p_src += 5;
 129
 130         if( p_filter->input.i_physical_channels & AOUT_CHAN_LFE ) p_src++;
 131     }
 132 }