modules/audio_filter/channel_mixer/dolby.c

   1 /*****************************************************************************
   2  * dolby.c : simple decoder for dolby surround encoded streams
   3  *****************************************************************************
   4  * Copyright (C) 2005-2009 the VideoLAN team
   5  *
   6  * Authors: Boris Dorès <babal@via.ecp.fr>
   7  *
   8  * This program is free software; you can redistribute it and/or modify it
   9  * under the terms of the GNU Lesser General Public License as published by
  10  * the Free Software Foundation; either version 2.1 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public License
  19  * along with this program; if not, write to the Free Software Foundation,
  20  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  21  *****************************************************************************/
  22
  23 /*****************************************************************************
  24  * Preamble
  25  *****************************************************************************/
  26
  27 #ifdef HAVE_CONFIG_H
  28 # include "config.h"
  29 #endif
  30
  31 #include <vlc_common.h>
  32 #include <vlc_plugin.h>
  33 #include <vlc_aout.h>
  34 #include <vlc_filter.h>
  35
  36 /*****************************************************************************
  37  * Local prototypes
  38  *****************************************************************************/
  39 static int  Create    ( vlc_object_t * );
  40
  41 static block_t *DoWork( filter_t *, block_t * );
  42
  43 /*****************************************************************************
  44  * Module descriptor
  45  *****************************************************************************/
  46 vlc_module_begin ()
  47     set_description( N_("Simple decoder for Dolby Surround encoded streams") )
  48     set_shortname( N_("Dolby Surround decoder") )
  49     set_category( CAT_INPUT )
  50     set_subcategory( SUBCAT_INPUT_ACODEC )
  51     set_capability( "audio converter", 5 )
  52     set_callback( Create )
  53 vlc_module_end ()
  54
  55 /*****************************************************************************
  56  * Internal data structures
  57  *****************************************************************************/
  58 typedef struct
  59 {
  60     int i_left;
  61     int i_center;
  62     int i_right;
  63     int i_rear_left;
  64     int i_rear_center;
  65     int i_rear_right;
  66 } filter_sys_t;
  67
  68 /*****************************************************************************
  69  * Create: allocate headphone downmixer
  70  *****************************************************************************/
  71 static int Create( vlc_object_t *p_this )
  72 {
  73     int i = 0;
  74     int i_offset = 0;
  75     filter_t * p_filter = (filter_t *)p_this;
  76     filter_sys_t *p_sys;
  77
  78     /* Validate audio filter format */
  79     if ( p_filter->fmt_in.audio.i_physical_channels != (AOUT_CHAN_LEFT|AOUT_CHAN_RIGHT)
  80        || ! ( p_filter->fmt_in.audio.i_chan_mode & AOUT_CHANMODE_DOLBYSTEREO )
  81        || p_filter->fmt_out.audio.i_channels <= 2
  82        || ( p_filter->fmt_in.audio.i_chan_mode & ~AOUT_CHANMODE_DOLBYSTEREO )
  83           != ( p_filter->fmt_out.audio.i_chan_mode & ~AOUT_CHANMODE_DOLBYSTEREO ) )
  84     {
  85         return VLC_EGENERIC;
  86     }
  87
  88     if ( p_filter->fmt_in.audio.i_rate != p_filter->fmt_out.audio.i_rate )
  89     {
  90         return VLC_EGENERIC;
  91     }
  92
  93     if ( p_filter->fmt_in.audio.i_format != VLC_CODEC_FL32
  94           || p_filter->fmt_out.audio.i_format != VLC_CODEC_FL32 )
  95     {
  96         return VLC_EGENERIC;
  97     }
  98
  99     /* Allocate the memory needed to store the module's structure */
 100     p_sys = p_filter->p_sys = vlc_obj_malloc( VLC_OBJECT(p_filter), sizeof(*p_sys) );
 101     if( unlikely(p_sys == NULL) )
 102         return VLC_ENOMEM;
 103     p_sys->i_left = -1;
 104     p_sys->i_center = -1;
 105     p_sys->i_right = -1;
 106     p_sys->i_rear_left = -1;
 107     p_sys->i_rear_center = -1;
 108     p_sys->i_rear_right = -1;
 109
 110     while ( pi_vlc_chan_order_wg4[i] )
 111     {
 112         if ( p_filter->fmt_out.audio.i_physical_channels & pi_vlc_chan_order_wg4[i] )
 113         {
 114             switch ( pi_vlc_chan_order_wg4[i] )
 115             {
 116                 case AOUT_CHAN_LEFT:
 117                     p_sys->i_left = i_offset;
 118                     break;
 119                 case AOUT_CHAN_CENTER:
 120                     p_sys->i_center = i_offset;
 121                     break;
 122                 case AOUT_CHAN_RIGHT:
 123                     p_sys->i_right = i_offset;
 124                     break;
 125                 case AOUT_CHAN_REARLEFT:
 126                     p_sys->i_rear_left = i_offset;
 127                     break;
 128                 case AOUT_CHAN_REARCENTER:
 129                     p_sys->i_rear_center = i_offset;
 130                     break;
 131                 case AOUT_CHAN_REARRIGHT:
 132                     p_sys->i_rear_right = i_offset;
 133                     break;
 134             }
 135             ++i_offset;
 136         }
 137         ++i;
 138     }
 139
 140     static const struct vlc_filter_operations filter_ops =
 141     {
 142         .filter_audio = DoWork,
 143     };
 144     p_filter->ops = &filter_ops;
 145
 146     return VLC_SUCCESS;
 147 }
 148
 149 /*****************************************************************************
 150  * DoWork: convert a buffer
 151  *****************************************************************************/
 152 static block_t *DoWork( filter_t * p_filter, block_t * p_in_buf )
 153 {
 154     filter_sys_t * p_sys = p_filter->p_sys;
 155     float * p_in = (float*) p_in_buf->p_buffer;
 156     size_t i_nb_samples = p_in_buf->i_nb_samples;
 157     size_t i_nb_channels = aout_FormatNbChannels( &p_filter->fmt_out.audio );
 158     size_t i_nb_rear = 0;
 159     size_t i;
 160     block_t *p_out_buf = block_Alloc(
 161                                 sizeof(float) * i_nb_samples * i_nb_channels );
 162     if( !p_out_buf )
 163         goto out;
 164
 165     float * p_out = (float*) p_out_buf->p_buffer;
 166     p_out_buf->i_nb_samples = i_nb_samples;
 167     p_out_buf->i_dts        = p_in_buf->i_dts;
 168     p_out_buf->i_pts        = p_in_buf->i_pts;
 169     p_out_buf->i_length     = p_in_buf->i_length;
 170
 171     memset( p_out, 0, p_out_buf->i_buffer );
 172
 173     if( p_sys->i_rear_left >= 0 )
 174     {
 175         ++i_nb_rear;
 176     }
 177     if( p_sys->i_rear_center >= 0 )
 178     {
 179         ++i_nb_rear;
 180     }
 181     if( p_sys->i_rear_right >= 0 )
 182     {
 183         ++i_nb_rear;
 184     }
 185
 186     for( i = 0; i < i_nb_samples; ++i )
 187     {
 188         float f_left = p_in[ i * 2 ];
 189         float f_right = p_in[ i * 2 + 1 ];
 190         float f_rear = ( f_left - f_right ) / i_nb_rear;
 191
 192         if( p_sys->i_center >= 0 )
 193         {
 194             float f_center = f_left + f_right;
 195             f_left -= f_center / 2;
 196             f_right -= f_center / 2;
 197
 198             p_out[ i * i_nb_channels + p_sys->i_center ] = f_center;
 199         }
 200
 201         if( p_sys->i_left >= 0 )
 202         {
 203             p_out[ i * i_nb_channels + p_sys->i_left ] = f_left;
 204         }
 205         if( p_sys->i_right >= 0 )
 206         {
 207             p_out[ i * i_nb_channels + p_sys->i_right ] = f_right;
 208         }
 209         if( p_sys->i_rear_left >= 0 )
 210         {
 211             p_out[ i * i_nb_channels + p_sys->i_rear_left ] = f_rear;
 212         }
 213         if( p_sys->i_rear_center >= 0 )
 214         {
 215             p_out[ i * i_nb_channels + p_sys->i_rear_center ] = f_rear;
 216         }
 217         if( p_sys->i_rear_right >= 0 )
 218         {
 219             p_out[ i * i_nb_channels + p_sys->i_rear_right ] = f_rear;
 220         }
 221     }
 222 out:
 223     block_Release( p_in_buf );
 224     return p_out_buf;
 225 }