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

   1 /*****************************************************************************
   2  * headphone.c : headphone virtual spatialization channel mixer module
   3  *               -> gives the feeling of a real room with a simple headphone
   4  *****************************************************************************
   5  * Copyright (C) 2002-2006 the VideoLAN team
   6  * $Id$
   7  *
   8  * Authors: Boris Dorès <babal@via.ecp.fr>
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License as published by
  12  * the Free Software Foundation; either version 2 of the License, or
  13  * (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, write to the Free Software
  22  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  23  *****************************************************************************/
  24
  25 /*****************************************************************************
  26  * Preamble
  27  *****************************************************************************/
  28 #include <math.h>                                        /* sqrt */
  29
  30 #ifdef HAVE_CONFIG_H
  31 # include "config.h"
  32 #endif
  33
  34 #include <vlc/vlc.h>
  35 #include <vlc_aout.h>
  36 #include <vlc_filter.h>
  37 #include <vlc_block.h>
  38
  39 /*****************************************************************************
  40  * Local prototypes
  41  *****************************************************************************/
  42 static int  Create    ( vlc_object_t * );
  43 static void Destroy   ( vlc_object_t * );
  44
  45 static void DoWork    ( aout_instance_t *, aout_filter_t *, aout_buffer_t *,
  46                         aout_buffer_t * );
  47
  48 /* Audio filter2 */
  49 static int  OpenFilter ( vlc_object_t * );
  50 static void CloseFilter( vlc_object_t * );
  51 static block_t *Convert( filter_t *, block_t * );
  52
  53 /*****************************************************************************
  54  * Module descriptor
  55  *****************************************************************************/
  56 #define MODULE_DESCRIPTION N_ ( \
  57      "This effect gives you the feeling that you are standing in a room " \
  58      "with a complete 7.1 speaker set when using only a headphone, " \
  59      "providing a more realistic sound experience. It should also be " \
  60      "more comfortable and less tiring when listening to music for " \
  61      "long periods of time.\nIt works with any source format from mono " \
  62      "to 7.1.")
  63
  64 #define HEADPHONE_DIM_TEXT N_("Characteristic dimension")
  65 #define HEADPHONE_DIM_LONGTEXT N_( \
  66      "Distance between front left speaker and listener in meters.")
  67
  68 #define HEADPHONE_COMPENSATE_TEXT N_("Compensate delay")
  69 #define HEADPHONE_COMPENSATE_LONGTEXT N_( \
  70      "The delay which is introduced by the physical algorithm may "\
  71      "sometimes be disturbing for the synchronization between lips-movement "\
  72      "and speech. In case, turn this on to compensate.")
  73
  74 #define HEADPHONE_DOLBY_TEXT N_("No decoding of Dolby Surround")
  75 #define HEADPHONE_DOLBY_LONGTEXT N_( \
  76      "Dolby Surround encoded streams won't be decoded before being " \
  77      "processed by this filter. Enabling this setting is not recommended.")
  78
  79 vlc_module_begin();
  80     set_description( _("Headphone virtual spatialization effect") );
  81     set_shortname( _("Headphone effect") );
  82     set_help( MODULE_DESCRIPTION );
  83     set_category( CAT_AUDIO );
  84     set_subcategory( SUBCAT_AUDIO_AFILTER );
  85
  86     add_integer( "headphone-dim", 10, NULL, HEADPHONE_DIM_TEXT,
  87                  HEADPHONE_DIM_LONGTEXT, VLC_FALSE );
  88     add_bool( "headphone-compensate", 0, NULL, HEADPHONE_COMPENSATE_TEXT,
  89               HEADPHONE_COMPENSATE_LONGTEXT, VLC_TRUE );
  90     add_bool( "headphone-dolby", 0, NULL, HEADPHONE_DOLBY_TEXT,
  91               HEADPHONE_DOLBY_LONGTEXT, VLC_TRUE );
  92
  93     set_capability( "audio filter", 0 );
  94     set_callbacks( Create, Destroy );
  95     add_shortcut( "headphone" );
  96
  97     /* Audio filter 2 */
  98     add_submodule();
  99     set_description( _("Headphone virtual spatialization effect") );
 100     set_capability( "audio filter2", 0 );
 101     set_callbacks( OpenFilter, CloseFilter );
 102 vlc_module_end();
 103
 104
 105 /*****************************************************************************
 106  * Internal data structures
 107  *****************************************************************************/
 108 struct atomic_operation_t
 109 {
 110     int i_source_channel_offset;
 111     int i_dest_channel_offset;
 112     unsigned int i_delay;/* in sample unit */
 113     double d_amplitude_factor;
 114 };
 115
 116 struct aout_filter_sys_t
 117 {
 118     size_t i_overflow_buffer_size;/* in bytes */
 119     byte_t * p_overflow_buffer;
 120     unsigned int i_nb_atomic_operations;
 121     struct atomic_operation_t * p_atomic_operations;
 122 };
 123
 124 struct filter_sys_t
 125 {
 126     size_t i_overflow_buffer_size;/* in bytes */
 127     byte_t * p_overflow_buffer;
 128     unsigned int i_nb_atomic_operations;
 129     struct atomic_operation_t * p_atomic_operations;
 130 };
 131
 132 /*****************************************************************************
 133  * Init: initialize internal data structures
 134  * and computes the needed atomic operations
 135  *****************************************************************************/
 136 /* x and z represent the coordinates of the virtual speaker
 137  *  relatively to the center of the listener's head, measured in meters :
 138  *
 139  *  left              right
 140  *Z
 141  *-
 142  *a          head
 143  *x
 144  *i
 145  *s
 146  *  rear left    rear right
 147  *
 148  *          x-axis
 149  *  */
 150 static void ComputeChannelOperations( struct aout_filter_sys_t * p_data
 151         , unsigned int i_rate, unsigned int i_next_atomic_operation
 152         , int i_source_channel_offset, double d_x, double d_z
 153         , double d_compensation_length, double d_channel_amplitude_factor )
 154 {
 155     double d_c = 340; /*sound celerity (unit: m/s)*/
 156     double d_compensation_delay = (d_compensation_length-0.1) / d_c * i_rate;
 157
 158     /* Left ear */
 159     p_data->p_atomic_operations[i_next_atomic_operation]
 160         .i_source_channel_offset = i_source_channel_offset;
 161     p_data->p_atomic_operations[i_next_atomic_operation]
 162         .i_dest_channel_offset = 0;/* left */
 163     p_data->p_atomic_operations[i_next_atomic_operation]
 164         .i_delay = (int)( sqrt( (-0.1-d_x)*(-0.1-d_x) + (0-d_z)*(0-d_z) )
 165                           / d_c * i_rate - d_compensation_delay );
 166     if( d_x < 0 )
 167     {
 168         p_data->p_atomic_operations[i_next_atomic_operation]
 169             .d_amplitude_factor = d_channel_amplitude_factor * 1.1 / 2;
 170     }
 171     else if( d_x > 0 )
 172     {
 173         p_data->p_atomic_operations[i_next_atomic_operation]
 174             .d_amplitude_factor = d_channel_amplitude_factor * 0.9 / 2;
 175     }
 176     else
 177     {
 178         p_data->p_atomic_operations[i_next_atomic_operation]
 179             .d_amplitude_factor = d_channel_amplitude_factor / 2;
 180     }
 181
 182     /* Right ear */
 183     p_data->p_atomic_operations[i_next_atomic_operation + 1]
 184         .i_source_channel_offset = i_source_channel_offset;
 185     p_data->p_atomic_operations[i_next_atomic_operation + 1]
 186         .i_dest_channel_offset = 1;/* right */
 187     p_data->p_atomic_operations[i_next_atomic_operation + 1]
 188         .i_delay = (int)( sqrt( (0.1-d_x)*(0.1-d_x) + (0-d_z)*(0-d_z) )
 189                           / d_c * i_rate - d_compensation_delay );
 190     if( d_x < 0 )
 191     {
 192         p_data->p_atomic_operations[i_next_atomic_operation + 1]
 193             .d_amplitude_factor = d_channel_amplitude_factor * 0.9 / 2;
 194     }
 195     else if( d_x > 0 )
 196     {
 197         p_data->p_atomic_operations[i_next_atomic_operation + 1]
 198             .d_amplitude_factor = d_channel_amplitude_factor * 1.1 / 2;
 199     }
 200     else
 201     {
 202         p_data->p_atomic_operations[i_next_atomic_operation + 1]
 203             .d_amplitude_factor = d_channel_amplitude_factor / 2;
 204     }
 205 }
 206
 207 static int Init( vlc_object_t *p_this, struct aout_filter_sys_t * p_data
 208         , unsigned int i_nb_channels, uint32_t i_physical_channels
 209         , unsigned int i_rate )
 210 {
 211     double d_x = config_GetInt( p_this, "headphone-dim" );
 212     double d_z = d_x;
 213     double d_z_rear = -d_x/3;
 214     double d_min = 0;
 215     unsigned int i_next_atomic_operation;
 216     int i_source_channel_offset;
 217     unsigned int i;
 218
 219     if( p_data == NULL )
 220     {
 221         msg_Dbg( p_this, "passing a null pointer as argument" );
 222         return 0;
 223     }
 224
 225     if( config_GetInt( p_this, "headphone-compensate" ) )
 226     {
 227         /* minimal distance to any speaker */
 228         if( i_physical_channels & AOUT_CHAN_REARCENTER )
 229         {
 230             d_min = d_z_rear;
 231         }
 232         else
 233         {
 234             d_min = d_z;
 235         }
 236     }
 237
 238     /* Number of elementary operations */
 239     p_data->i_nb_atomic_operations = i_nb_channels * 2;
 240     if( i_physical_channels & AOUT_CHAN_CENTER )
 241     {
 242         p_data->i_nb_atomic_operations += 2;
 243     }
 244     p_data->p_atomic_operations = malloc( sizeof(struct atomic_operation_t)
 245             * p_data->i_nb_atomic_operations );
 246     if( p_data->p_atomic_operations == NULL )
 247     {
 248         msg_Err( p_this, "out of memory" );
 249         return -1;
 250     }
 251
 252     /* For each virtual speaker, computes elementary wave propagation time
 253      * to each ear */
 254     i_next_atomic_operation = 0;
 255     i_source_channel_offset = 0;
 256     if( i_physical_channels & AOUT_CHAN_LEFT )
 257     {
 258         ComputeChannelOperations( p_data , i_rate
 259                 , i_next_atomic_operation , i_source_channel_offset
 260                 , -d_x , d_z , d_min , 2.0 / i_nb_channels );
 261         i_next_atomic_operation += 2;
 262         i_source_channel_offset++;
 263     }
 264     if( i_physical_channels & AOUT_CHAN_RIGHT )
 265     {
 266         ComputeChannelOperations( p_data , i_rate
 267                 , i_next_atomic_operation , i_source_channel_offset
 268                 , d_x , d_z , d_min , 2.0 / i_nb_channels );
 269         i_next_atomic_operation += 2;
 270         i_source_channel_offset++;
 271     }
 272     if( i_physical_channels & AOUT_CHAN_MIDDLELEFT )
 273     {
 274         ComputeChannelOperations( p_data , i_rate
 275                 , i_next_atomic_operation , i_source_channel_offset
 276                 , -d_x , 0 , d_min , 1.5 / i_nb_channels );
 277         i_next_atomic_operation += 2;
 278         i_source_channel_offset++;
 279     }
 280     if( i_physical_channels & AOUT_CHAN_MIDDLERIGHT )
 281     {
 282         ComputeChannelOperations( p_data , i_rate
 283                 , i_next_atomic_operation , i_source_channel_offset
 284                 , d_x , 0 , d_min , 1.5 / i_nb_channels );
 285         i_next_atomic_operation += 2;
 286         i_source_channel_offset++;
 287     }
 288     if( i_physical_channels & AOUT_CHAN_REARLEFT )
 289     {
 290         ComputeChannelOperations( p_data , i_rate
 291                 , i_next_atomic_operation , i_source_channel_offset
 292                 , -d_x , d_z_rear , d_min , 1.5 / i_nb_channels );
 293         i_next_atomic_operation += 2;
 294         i_source_channel_offset++;
 295     }
 296     if( i_physical_channels & AOUT_CHAN_REARRIGHT )
 297     {
 298         ComputeChannelOperations( p_data , i_rate
 299                 , i_next_atomic_operation , i_source_channel_offset
 300                 , d_x , d_z_rear , d_min , 1.5 / i_nb_channels );
 301         i_next_atomic_operation += 2;
 302         i_source_channel_offset++;
 303     }
 304     if( i_physical_channels & AOUT_CHAN_REARCENTER )
 305     {
 306         ComputeChannelOperations( p_data , i_rate
 307                 , i_next_atomic_operation , i_source_channel_offset
 308                 , 0 , -d_z , d_min , 1.5 / i_nb_channels );
 309         i_next_atomic_operation += 2;
 310         i_source_channel_offset++;
 311     }
 312     if( i_physical_channels & AOUT_CHAN_CENTER )
 313     {
 314         /* having two center channels increases the spatialization effect */
 315         ComputeChannelOperations( p_data , i_rate
 316                 , i_next_atomic_operation , i_source_channel_offset
 317                 , d_x / 5.0 , d_z , d_min , 0.75 / i_nb_channels );
 318         i_next_atomic_operation += 2;
 319         ComputeChannelOperations( p_data , i_rate
 320                 , i_next_atomic_operation , i_source_channel_offset
 321                 , -d_x / 5.0 , d_z , d_min , 0.75 / i_nb_channels );
 322         i_next_atomic_operation += 2;
 323         i_source_channel_offset++;
 324     }
 325     if( i_physical_channels & AOUT_CHAN_LFE )
 326     {
 327         ComputeChannelOperations( p_data , i_rate
 328                 , i_next_atomic_operation , i_source_channel_offset
 329                 , 0 , d_z_rear , d_min , 5.0 / i_nb_channels );
 330         i_next_atomic_operation += 2;
 331         i_source_channel_offset++;
 332     }
 333
 334     /* Initialize the overflow buffer
 335      * we need it because the process induce a delay in the samples */
 336     p_data->i_overflow_buffer_size = 0;
 337     for( i = 0 ; i < p_data->i_nb_atomic_operations ; i++ )
 338     {
 339         if( p_data->i_overflow_buffer_size
 340                 < p_data->p_atomic_operations[i].i_delay * 2 * sizeof (float) )
 341         {
 342             p_data->i_overflow_buffer_size
 343                 = p_data->p_atomic_operations[i].i_delay * 2 * sizeof (float);
 344         }
 345     }
 346     p_data->p_overflow_buffer = malloc( p_data->i_overflow_buffer_size );
 347     if( p_data->p_atomic_operations == NULL )
 348     {
 349         msg_Err( p_this, "out of memory" );
 350         return -1;
 351     }
 352     memset( p_data->p_overflow_buffer, 0 , p_data->i_overflow_buffer_size );
 353
 354     /* end */
 355     return 0;
 356 }
 357
 358 /*****************************************************************************
 359  * Create: allocate headphone downmixer
 360  *****************************************************************************/
 361 static int Create( vlc_object_t *p_this )
 362 {
 363     aout_filter_t * p_filter = (aout_filter_t *)p_this;
 364     vlc_bool_t b_fit = VLC_TRUE;
 365
 366     /* Activate this filter only with stereo devices */
 367     if( p_filter->output.i_physical_channels
 368             != (AOUT_CHAN_LEFT|AOUT_CHAN_RIGHT) )
 369     {
 370         msg_Dbg( p_filter, "filter discarded (incompatible format)" );
 371         return VLC_EGENERIC;
 372     }
 373
 374     /* Request a specific format if not already compatible */
 375     if( p_filter->input.i_original_channels
 376             != p_filter->output.i_original_channels )
 377     {
 378         b_fit = VLC_FALSE;
 379         p_filter->input.i_original_channels =
 380                                         p_filter->output.i_original_channels;
 381     }
 382     if( p_filter->input.i_format != VLC_FOURCC('f','l','3','2')
 383           || p_filter->output.i_format != VLC_FOURCC('f','l','3','2') )
 384     {
 385         b_fit = VLC_FALSE;
 386         p_filter->input.i_format = VLC_FOURCC('f','l','3','2');
 387         p_filter->output.i_format = VLC_FOURCC('f','l','3','2');
 388     }
 389     if( p_filter->input.i_rate != p_filter->output.i_rate )
 390     {
 391         b_fit = VLC_FALSE;
 392         p_filter->input.i_rate = p_filter->output.i_rate;
 393     }
 394     if( p_filter->input.i_physical_channels == (AOUT_CHAN_LEFT|AOUT_CHAN_RIGHT)
 395           && ( p_filter->input.i_original_channels & AOUT_CHAN_DOLBYSTEREO )
 396           && ! config_GetInt ( p_filter , "headphone-dolby" ) )
 397     {
 398         b_fit = VLC_FALSE;
 399         p_filter->input.i_physical_channels = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT |
 400                                               AOUT_CHAN_CENTER |
 401                                               AOUT_CHAN_REARLEFT |
 402                                               AOUT_CHAN_REARRIGHT;
 403     }
 404     if( ! b_fit )
 405     {
 406         msg_Dbg( p_filter, "requesting specific format" );
 407         return VLC_EGENERIC;
 408     }
 409
 410     /* Allocate the memory needed to store the module's structure */
 411     p_filter->p_sys = malloc( sizeof(struct aout_filter_sys_t) );
 412     if( p_filter->p_sys == NULL )
 413     {
 414         msg_Err( p_filter, "out of memory" );
 415         return VLC_EGENERIC;
 416     }
 417     p_filter->p_sys->i_overflow_buffer_size = 0;
 418     p_filter->p_sys->p_overflow_buffer = NULL;
 419     p_filter->p_sys->i_nb_atomic_operations = 0;
 420     p_filter->p_sys->p_atomic_operations = NULL;
 421
 422     if( Init( VLC_OBJECT(p_filter), p_filter->p_sys
 423                 , aout_FormatNbChannels ( &p_filter->input )
 424                 , p_filter->input.i_physical_channels
 425                 , p_filter->input.i_rate ) < 0 )
 426     {
 427         return VLC_EGENERIC;
 428     }
 429
 430     p_filter->pf_do_work = DoWork;
 431     p_filter->b_in_place = 0;
 432
 433     return VLC_SUCCESS;
 434 }
 435
 436 /*****************************************************************************
 437  * Destroy: deallocate resources associated with headphone downmixer
 438  *****************************************************************************/
 439 static void Destroy( vlc_object_t *p_this )
 440 {
 441     aout_filter_t * p_filter = (aout_filter_t *)p_this;
 442
 443     if( p_filter->p_sys != NULL )
 444     {
 445         if( p_filter->p_sys->p_overflow_buffer != NULL )
 446         {
 447             free( p_filter->p_sys->p_overflow_buffer );
 448         }
 449         if( p_filter->p_sys->p_atomic_operations != NULL )
 450         {
 451             free( p_filter->p_sys->p_atomic_operations );
 452         }
 453         free( p_filter->p_sys );
 454         p_filter->p_sys = NULL;
 455     }
 456 }
 457
 458 /*****************************************************************************
 459  * DoWork: convert a buffer
 460  *****************************************************************************/
 461 static void DoWork( aout_instance_t * p_aout, aout_filter_t * p_filter,
 462                     aout_buffer_t * p_in_buf, aout_buffer_t * p_out_buf )
 463 {
 464     int i_input_nb = aout_FormatNbChannels( &p_filter->input );
 465     int i_output_nb = aout_FormatNbChannels( &p_filter->output );
 466
 467     float * p_in = (float*) p_in_buf->p_buffer;
 468     byte_t * p_out;
 469     byte_t * p_overflow;
 470     byte_t * p_slide;
 471
 472     size_t i_overflow_size;     /* in bytes */
 473     size_t i_out_size;          /* in bytes */
 474
 475     unsigned int i, j;
 476
 477     int i_source_channel_offset;
 478     int i_dest_channel_offset;
 479     unsigned int i_delay;
 480     double d_amplitude_factor;
 481
 482     /* out buffer characterisitcs */
 483     p_out_buf->i_nb_samples = p_in_buf->i_nb_samples;
 484     p_out_buf->i_nb_bytes = p_in_buf->i_nb_bytes * i_output_nb / i_input_nb;
 485     p_out = p_out_buf->p_buffer;
 486     i_out_size = p_out_buf->i_nb_bytes;
 487
 488     if( p_filter->p_sys != NULL )
 489     {
 490         /* Slide the overflow buffer */
 491         p_overflow = p_filter->p_sys->p_overflow_buffer;
 492         i_overflow_size = p_filter->p_sys->i_overflow_buffer_size;
 493
 494         memset( p_out, 0, i_out_size );
 495         if ( i_out_size > i_overflow_size )
 496             memcpy( p_out, p_overflow, i_overflow_size );
 497         else
 498             memcpy( p_out, p_overflow, i_out_size );
 499
 500         p_slide = p_filter->p_sys->p_overflow_buffer;
 501         while( p_slide < p_overflow + i_overflow_size )
 502         {
 503             if( p_slide + i_out_size < p_overflow + i_overflow_size )
 504             {
 505                 memset( p_slide, 0, i_out_size );
 506                 if( p_slide + 2 * i_out_size < p_overflow + i_overflow_size )
 507                     memcpy( p_slide, p_slide + i_out_size, i_out_size );
 508                 else
 509                     memcpy( p_slide, p_slide + i_out_size,
 510                             p_overflow + i_overflow_size - ( p_slide + i_out_size ) );
 511             }
 512             else
 513             {
 514                 memset( p_slide, 0, p_overflow + i_overflow_size - p_slide );
 515             }
 516             p_slide += i_out_size;
 517         }
 518
 519         /* apply the atomic operations */
 520         for( i = 0; i < p_filter->p_sys->i_nb_atomic_operations; i++ )
 521         {
 522             /* shorter variable names */
 523             i_source_channel_offset
 524                 = p_filter->p_sys->p_atomic_operations[i].i_source_channel_offset;
 525             i_dest_channel_offset
 526                 = p_filter->p_sys->p_atomic_operations[i].i_dest_channel_offset;
 527             i_delay = p_filter->p_sys->p_atomic_operations[i].i_delay;
 528             d_amplitude_factor
 529                 = p_filter->p_sys->p_atomic_operations[i].d_amplitude_factor;
 530
 531             if( p_out_buf->i_nb_samples > i_delay )
 532             {
 533                 /* current buffer coefficients */
 534                 for( j = 0; j < p_out_buf->i_nb_samples - i_delay; j++ )
 535                 {
 536                     ((float*)p_out)[ (i_delay+j)*i_output_nb + i_dest_channel_offset ]
 537                         += p_in[ j * i_input_nb + i_source_channel_offset ]
 538                            * d_amplitude_factor;
 539                 }
 540
 541                 /* overflow buffer coefficients */
 542                 for( j = 0; j < i_delay; j++ )
 543                 {
 544                     ((float*)p_overflow)[ j*i_output_nb + i_dest_channel_offset ]
 545                         += p_in[ (p_out_buf->i_nb_samples - i_delay + j)
 546                            * i_input_nb + i_source_channel_offset ]
 547                            * d_amplitude_factor;
 548                 }
 549             }
 550             else
 551             {
 552                 /* overflow buffer coefficients only */
 553                 for( j = 0; j < p_out_buf->i_nb_samples; j++ )
 554                 {
 555                     ((float*)p_overflow)[ (i_delay - p_out_buf->i_nb_samples + j)
 556                         * i_output_nb + i_dest_channel_offset ]
 557                         += p_in[ j * i_input_nb + i_source_channel_offset ]
 558                            * d_amplitude_factor;
 559                 }
 560             }
 561         }
 562     }
 563     else
 564     {
 565         memset( p_out, 0, i_out_size );
 566     }
 567 }
 568
 569 /*
 570  * Audio filter 2
 571  */
 572 /*****************************************************************************
 573  * OpenFilter:
 574  *****************************************************************************/
 575 static int OpenFilter( vlc_object_t *p_this )
 576 {
 577     filter_t *p_filter = (filter_t *)p_this;
 578     vlc_bool_t b_fit = VLC_TRUE;
 579
 580     /* Activate this filter only with stereo devices */
 581     if( p_filter->fmt_out.audio.i_physical_channels
 582             != (AOUT_CHAN_LEFT|AOUT_CHAN_RIGHT) )
 583     {
 584         msg_Dbg( p_filter, "filter discarded (incompatible format)" );
 585         return VLC_EGENERIC;
 586     }
 587
 588     /* Request a specific format if not already compatible */
 589     if( p_filter->fmt_in.audio.i_original_channels
 590             != p_filter->fmt_out.audio.i_original_channels )
 591     {
 592         b_fit = VLC_FALSE;
 593         p_filter->fmt_in.audio.i_original_channels =
 594                                         p_filter->fmt_out.audio.i_original_channels;
 595     }
 596     if( p_filter->fmt_in.audio.i_format != VLC_FOURCC('f','l','3','2')
 597           || p_filter->fmt_out.audio.i_format != VLC_FOURCC('f','l','3','2') )
 598     {
 599         b_fit = VLC_FALSE;
 600         p_filter->fmt_in.audio.i_format = VLC_FOURCC('f','l','3','2');
 601         p_filter->fmt_out.audio.i_format = VLC_FOURCC('f','l','3','2');
 602     }
 603     if( p_filter->fmt_in.audio.i_rate != p_filter->fmt_out.audio.i_rate )
 604     {
 605         b_fit = VLC_FALSE;
 606         p_filter->fmt_in.audio.i_rate = p_filter->fmt_out.audio.i_rate;
 607     }
 608     if( p_filter->fmt_in.audio.i_physical_channels == (AOUT_CHAN_LEFT|AOUT_CHAN_RIGHT)
 609           && ( p_filter->fmt_in.audio.i_original_channels & AOUT_CHAN_DOLBYSTEREO )
 610           && !config_GetInt( p_filter, "headphone-dolby" ) )
 611     {
 612         b_fit = VLC_FALSE;
 613         p_filter->fmt_in.audio.i_physical_channels = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT |
 614                                               AOUT_CHAN_CENTER |
 615                                               AOUT_CHAN_REARLEFT |
 616                                               AOUT_CHAN_REARRIGHT;
 617     }
 618     if( !b_fit )
 619     {
 620         msg_Dbg( p_filter, "requesting specific format" );
 621         return VLC_EGENERIC;
 622     }
 623
 624     /* Allocate the memory needed to store the module's structure */
 625     p_filter->p_sys = malloc( sizeof(struct filter_sys_t) );
 626     if( p_filter->p_sys == NULL )
 627     {
 628         msg_Err( p_filter, "out of memory" );
 629         return VLC_EGENERIC;
 630     }
 631     p_filter->p_sys->i_overflow_buffer_size = 0;
 632     p_filter->p_sys->p_overflow_buffer = NULL;
 633     p_filter->p_sys->i_nb_atomic_operations = 0;
 634     p_filter->p_sys->p_atomic_operations = NULL;
 635
 636     if( Init( VLC_OBJECT(p_filter), (struct aout_filter_sys_t *)p_filter->p_sys
 637                 , aout_FormatNbChannels ( &(p_filter->fmt_in.audio) )
 638                 , p_filter->fmt_in.audio.i_physical_channels
 639                 , p_filter->fmt_in.audio.i_rate ) < 0 )
 640     {
 641         return VLC_EGENERIC;
 642     }
 643
 644     p_filter->pf_audio_filter = Convert;
 645     p_filter->fmt_out.audio.i_rate = p_filter->fmt_in.audio.i_rate;
 646
 647     return VLC_SUCCESS;
 648 }
 649
 650 /*****************************************************************************
 651  * CloseFilter : deallocate data structures
 652  *****************************************************************************/
 653 static void CloseFilter( vlc_object_t *p_this )
 654 {
 655     filter_t *p_filter = (filter_t *)p_this;
 656
 657     if( p_filter->p_sys != NULL )
 658     {
 659         if( p_filter->p_sys->p_overflow_buffer != NULL )
 660         {
 661             free ( p_filter->p_sys->p_overflow_buffer );
 662         }
 663         if( p_filter->p_sys->p_atomic_operations != NULL )
 664         {
 665             free ( p_filter->p_sys->p_atomic_operations );
 666         }
 667         free( p_filter->p_sys );
 668         p_filter->p_sys = NULL;
 669     }
 670 }
 671
 672 static block_t *Convert( filter_t *p_filter, block_t *p_block )
 673 {
 674     aout_filter_t aout_filter;
 675     aout_buffer_t in_buf, out_buf;
 676     block_t *p_out;
 677     int i_out_size;
 678
 679     if( !p_block || !p_block->i_samples )
 680     {
 681         if( p_block ) p_block->pf_release( p_block );
 682         return NULL;
 683     }
 684
 685     i_out_size = p_block->i_samples *
 686       p_filter->fmt_out.audio.i_bitspersample/8 *
 687         aout_FormatNbChannels( &(p_filter->fmt_out.audio) );
 688
 689     p_out = p_filter->pf_audio_buffer_new( p_filter, i_out_size );
 690     if( !p_out )
 691     {
 692         msg_Warn( p_filter, "can't get output buffer" );
 693         if( p_block ) p_block->pf_release( p_block );
 694         return NULL;
 695     }
 696
 697     p_out->i_samples = p_block->i_samples;
 698     p_out->i_dts = p_block->i_dts;
 699     p_out->i_pts = p_block->i_pts;
 700     p_out->i_length = p_block->i_length;
 701
 702     aout_filter.p_sys = (struct aout_filter_sys_t *)p_filter->p_sys;
 703     aout_filter.input = p_filter->fmt_in.audio;
 704     aout_filter.input.i_format = p_filter->fmt_in.i_codec;
 705     aout_filter.output = p_filter->fmt_out.audio;
 706     aout_filter.output.i_format = p_filter->fmt_out.i_codec;
 707     aout_filter.b_in_place = 0;
 708
 709     in_buf.p_buffer = p_block->p_buffer;
 710     in_buf.i_nb_bytes = p_block->i_buffer;
 711     in_buf.i_nb_samples = p_block->i_samples;
 712     out_buf.p_buffer = p_out->p_buffer;
 713     out_buf.i_nb_bytes = p_out->i_buffer;
 714     out_buf.i_nb_samples = p_out->i_samples;
 715
 716     DoWork( (aout_instance_t *)p_filter, &aout_filter, &in_buf, &out_buf );
 717
 718     p_out->i_buffer = out_buf.i_nb_bytes;
 719     p_out->i_samples = out_buf.i_nb_samples;
 720
 721     if( p_block ) p_block->pf_release( p_block );
 722     return p_out;
 723 }