src/audio_output/common.c

   1 /*****************************************************************************
   2  * common.c : audio output management of common data structures
   3  *****************************************************************************
   4  * Copyright (C) 2002-2007 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 #ifdef HAVE_CONFIG_H
  28 # include "config.h"
  29 #endif
  30
  31 #include <vlc_common.h>
  32 #include <vlc_aout.h>
  33 #include "aout_internal.h"
  34
  35 /*
  36  * Instances management (internal and external)
  37  */
  38
  39 /* Local functions */
  40 static void aout_Destructor( vlc_object_t * p_this );
  41
  42 /*****************************************************************************
  43  * aout_New: initialize aout structure
  44  *****************************************************************************/
  45 aout_instance_t * __aout_New( vlc_object_t * p_parent )
  46 {
  47     aout_instance_t * p_aout;
  48     vlc_value_t val;
  49
  50     /* Allocate descriptor. */
  51     p_aout = vlc_object_create( p_parent, VLC_OBJECT_AOUT );
  52     if( p_aout == NULL )
  53     {
  54         return NULL;
  55     }
  56
  57     /* Initialize members. */
  58     vlc_mutex_init( &p_aout->input_fifos_lock );
  59     vlc_mutex_init( &p_aout->mixer_lock );
  60     vlc_mutex_init( &p_aout->output_fifo_lock );
  61     p_aout->i_nb_inputs = 0;
  62     p_aout->mixer.f_multiplier = 1.0;
  63     p_aout->mixer.b_error = 1;
  64     p_aout->output.b_error = 1;
  65     p_aout->output.b_starving = 1;
  66
  67     var_Create( p_aout, "intf-change", VLC_VAR_BOOL );
  68     val.b_bool = true;
  69     var_Set( p_aout, "intf-change", val );
  70
  71     vlc_object_set_destructor( p_aout, aout_Destructor );
  72
  73     return p_aout;
  74 }
  75
  76 /*****************************************************************************
  77  * aout_Destructor: destroy aout structure
  78  *****************************************************************************/
  79 static void aout_Destructor( vlc_object_t * p_this )
  80 {
  81     aout_instance_t * p_aout = (aout_instance_t *)p_this;
  82     vlc_mutex_destroy( &p_aout->input_fifos_lock );
  83     vlc_mutex_destroy( &p_aout->mixer_lock );
  84     vlc_mutex_destroy( &p_aout->output_fifo_lock );
  85 }
  86
  87
  88 /*
  89  * Formats management (internal and external)
  90  */
  91
  92 /*****************************************************************************
  93  * aout_FormatNbChannels : return the number of channels
  94  *****************************************************************************/
  95 unsigned int aout_FormatNbChannels( const audio_sample_format_t * p_format )
  96 {
  97     static const uint32_t pi_channels[] =
  98         { AOUT_CHAN_CENTER, AOUT_CHAN_LEFT, AOUT_CHAN_RIGHT,
  99           AOUT_CHAN_REARCENTER, AOUT_CHAN_REARLEFT, AOUT_CHAN_REARRIGHT,
 100           AOUT_CHAN_MIDDLELEFT, AOUT_CHAN_MIDDLERIGHT, AOUT_CHAN_LFE };
 101     unsigned int i_nb = 0, i;
 102
 103     for ( i = 0; i < sizeof(pi_channels)/sizeof(uint32_t); i++ )
 104     {
 105         if ( p_format->i_physical_channels & pi_channels[i] ) i_nb++;
 106     }
 107
 108     return i_nb;
 109 }
 110
 111 /*****************************************************************************
 112  * aout_BitsPerSample : get the number of bits per sample
 113  *****************************************************************************/
 114 unsigned int aout_BitsPerSample( vlc_fourcc_t i_format )
 115 {
 116     switch( i_format )
 117     {
 118     case VLC_FOURCC('u','8',' ',' '):
 119     case VLC_FOURCC('s','8',' ',' '):
 120         return 8;
 121
 122     case VLC_FOURCC('u','1','6','l'):
 123     case VLC_FOURCC('s','1','6','l'):
 124     case VLC_FOURCC('u','1','6','b'):
 125     case VLC_FOURCC('s','1','6','b'):
 126         return 16;
 127
 128     case VLC_FOURCC('u','2','4','l'):
 129     case VLC_FOURCC('s','2','4','l'):
 130     case VLC_FOURCC('u','2','4','b'):
 131     case VLC_FOURCC('s','2','4','b'):
 132         return 24;
 133
 134     case VLC_FOURCC('f','l','3','2'):
 135     case VLC_FOURCC('f','i','3','2'):
 136         return 32;
 137
 138     case VLC_FOURCC('f','l','6','4'):
 139         return 64;
 140
 141     default:
 142         /* For these formats the caller has to indicate the parameters
 143          * by hand. */
 144         return 0;
 145     }
 146 }
 147
 148 /*****************************************************************************
 149  * aout_FormatPrepare : compute the number of bytes per frame & frame length
 150  *****************************************************************************/
 151 void aout_FormatPrepare( audio_sample_format_t * p_format )
 152 {
 153     p_format->i_bitspersample = aout_BitsPerSample( p_format->i_format );
 154     if( p_format->i_bitspersample > 0 )
 155     {
 156         p_format->i_bytes_per_frame = ( p_format->i_bitspersample / 8 )
 157                                     * aout_FormatNbChannels( p_format );
 158         p_format->i_frame_length = 1;
 159     }
 160 }
 161
 162 /*****************************************************************************
 163  * aout_FormatPrintChannels : print a channel in a human-readable form
 164  *****************************************************************************/
 165 const char * aout_FormatPrintChannels( const audio_sample_format_t * p_format )
 166 {
 167     switch ( p_format->i_physical_channels & AOUT_CHAN_PHYSMASK )
 168     {
 169     case AOUT_CHAN_CENTER:
 170         if ( (p_format->i_original_channels & AOUT_CHAN_CENTER)
 171               || (p_format->i_original_channels
 172                    & (AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT)) )
 173             return "Mono";
 174         else if ( p_format->i_original_channels & AOUT_CHAN_LEFT )
 175             return "Left";
 176         return "Right";
 177     case AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT:
 178         if ( p_format->i_original_channels & AOUT_CHAN_REVERSESTEREO )
 179         {
 180             if ( p_format->i_original_channels & AOUT_CHAN_DOLBYSTEREO )
 181                 return "Dolby/Reverse";
 182             return "Stereo/Reverse";
 183         }
 184         else
 185         {
 186             if ( p_format->i_original_channels & AOUT_CHAN_DOLBYSTEREO )
 187                 return "Dolby";
 188             else if ( p_format->i_original_channels & AOUT_CHAN_DUALMONO )
 189                 return "Dual-mono";
 190             else if ( p_format->i_original_channels == AOUT_CHAN_CENTER )
 191                 return "Stereo/Mono";
 192             else if ( !(p_format->i_original_channels & AOUT_CHAN_RIGHT) )
 193                 return "Stereo/Left";
 194             else if ( !(p_format->i_original_channels & AOUT_CHAN_LEFT) )
 195                 return "Stereo/Right";
 196             return "Stereo";
 197         }
 198     case AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER:
 199         return "3F";
 200     case AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_REARCENTER:
 201         return "2F1R";
 202     case AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER
 203           | AOUT_CHAN_REARCENTER:
 204         return "3F1R";
 205     case AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 206           | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT:
 207         return "2F2R";
 208     case AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER
 209           | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT:
 210         return "3F2R";
 211
 212     case AOUT_CHAN_CENTER | AOUT_CHAN_LFE:
 213         if ( (p_format->i_original_channels & AOUT_CHAN_CENTER)
 214               || (p_format->i_original_channels
 215                    & (AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT)) )
 216             return "Mono/LFE";
 217         else if ( p_format->i_original_channels & AOUT_CHAN_LEFT )
 218             return "Left/LFE";
 219         return "Right/LFE";
 220     case AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_LFE:
 221         if ( p_format->i_original_channels & AOUT_CHAN_DOLBYSTEREO )
 222             return "Dolby/LFE";
 223         else if ( p_format->i_original_channels & AOUT_CHAN_DUALMONO )
 224             return "Dual-mono/LFE";
 225         else if ( p_format->i_original_channels == AOUT_CHAN_CENTER )
 226             return "Mono/LFE";
 227         else if ( !(p_format->i_original_channels & AOUT_CHAN_RIGHT) )
 228             return "Stereo/Left/LFE";
 229         else if ( !(p_format->i_original_channels & AOUT_CHAN_LEFT) )
 230             return "Stereo/Right/LFE";
 231          return "Stereo/LFE";
 232     case AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER | AOUT_CHAN_LFE:
 233         return "3F/LFE";
 234     case AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_REARCENTER
 235           | AOUT_CHAN_LFE:
 236         return "2F1R/LFE";
 237     case AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER
 238           | AOUT_CHAN_REARCENTER | AOUT_CHAN_LFE:
 239         return "3F1R/LFE";
 240     case AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 241           | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT | AOUT_CHAN_LFE:
 242         return "2F2R/LFE";
 243     case AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER
 244           | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT | AOUT_CHAN_LFE:
 245         return "3F2R/LFE";
 246     case AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER
 247           | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT | AOUT_CHAN_MIDDLELEFT
 248           | AOUT_CHAN_MIDDLERIGHT:
 249         return "3F2M2R";
 250     case AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER
 251           | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT | AOUT_CHAN_MIDDLELEFT
 252           | AOUT_CHAN_MIDDLERIGHT | AOUT_CHAN_LFE:
 253         return "3F2M2R/LFE";
 254     }
 255
 256     return "ERROR";
 257 }
 258
 259 /*****************************************************************************
 260  * aout_FormatPrint : print a format in a human-readable form
 261  *****************************************************************************/
 262 void aout_FormatPrint( aout_instance_t * p_aout, const char * psz_text,
 263                        const audio_sample_format_t * p_format )
 264 {
 265     msg_Dbg( p_aout, "%s '%4.4s' %d Hz %s frame=%d samples/%d bytes", psz_text,
 266              (char *)&p_format->i_format, p_format->i_rate,
 267              aout_FormatPrintChannels( p_format ),
 268              p_format->i_frame_length, p_format->i_bytes_per_frame );
 269 }
 270
 271 /*****************************************************************************
 272  * aout_FormatsPrint : print two formats in a human-readable form
 273  *****************************************************************************/
 274 void aout_FormatsPrint( aout_instance_t * p_aout, const char * psz_text,
 275                         const audio_sample_format_t * p_format1,
 276                         const audio_sample_format_t * p_format2 )
 277 {
 278     msg_Dbg( p_aout, "%s '%4.4s'->'%4.4s' %d Hz->%d Hz %s->%s",
 279              psz_text,
 280              (char *)&p_format1->i_format, (char *)&p_format2->i_format,
 281              p_format1->i_rate, p_format2->i_rate,
 282              aout_FormatPrintChannels( p_format1 ),
 283              aout_FormatPrintChannels( p_format2 ) );
 284 }
 285
 286
 287 /*
 288  * FIFO management (internal) - please understand that solving race conditions
 289  * is _your_ job, ie. in the audio output you should own the mixer lock
 290  * before calling any of these functions.
 291  */
 292
 293 /*****************************************************************************
 294  * aout_FifoInit : initialize the members of a FIFO
 295  *****************************************************************************/
 296 void aout_FifoInit( aout_instance_t * p_aout, aout_fifo_t * p_fifo,
 297                     uint32_t i_rate )
 298 {
 299     if( i_rate == 0 )
 300     {
 301         msg_Err( p_aout, "initialising fifo with zero divider" );
 302     }
 303
 304     p_fifo->p_first = NULL;
 305     p_fifo->pp_last = &p_fifo->p_first;
 306     aout_DateInit( &p_fifo->end_date, i_rate );
 307 }
 308
 309 /*****************************************************************************
 310  * aout_FifoPush : push a packet into the FIFO
 311  *****************************************************************************/
 312 void aout_FifoPush( aout_instance_t * p_aout, aout_fifo_t * p_fifo,
 313                     aout_buffer_t * p_buffer )
 314 {
 315     (void)p_aout;
 316     *p_fifo->pp_last = p_buffer;
 317     p_fifo->pp_last = &p_buffer->p_next;
 318     *p_fifo->pp_last = NULL;
 319     /* Enforce the continuity of the stream. */
 320     if ( aout_DateGet( &p_fifo->end_date ) )
 321     {
 322         p_buffer->start_date = aout_DateGet( &p_fifo->end_date );
 323         p_buffer->end_date = aout_DateIncrement( &p_fifo->end_date,
 324                                                  p_buffer->i_nb_samples );
 325     }
 326     else
 327     {
 328         aout_DateSet( &p_fifo->end_date, p_buffer->end_date );
 329     }
 330 }
 331
 332 /*****************************************************************************
 333  * aout_FifoSet : set end_date and trash all buffers (because they aren't
 334  * properly dated)
 335  *****************************************************************************/
 336 void aout_FifoSet( aout_instance_t * p_aout, aout_fifo_t * p_fifo,
 337                    mtime_t date )
 338 {
 339     aout_buffer_t * p_buffer;
 340     (void)p_aout;
 341
 342     aout_DateSet( &p_fifo->end_date, date );
 343     p_buffer = p_fifo->p_first;
 344     while ( p_buffer != NULL )
 345     {
 346         aout_buffer_t * p_next = p_buffer->p_next;
 347         aout_BufferFree( p_buffer );
 348         p_buffer = p_next;
 349     }
 350     p_fifo->p_first = NULL;
 351     p_fifo->pp_last = &p_fifo->p_first;
 352 }
 353
 354 /*****************************************************************************
 355  * aout_FifoMoveDates : Move forwards or backwards all dates in the FIFO
 356  *****************************************************************************/
 357 void aout_FifoMoveDates( aout_instance_t * p_aout, aout_fifo_t * p_fifo,
 358                          mtime_t difference )
 359 {
 360     aout_buffer_t * p_buffer;
 361     (void)p_aout;
 362
 363     aout_DateMove( &p_fifo->end_date, difference );
 364     p_buffer = p_fifo->p_first;
 365     while ( p_buffer != NULL )
 366     {
 367         p_buffer->start_date += difference;
 368         p_buffer->end_date += difference;
 369         p_buffer = p_buffer->p_next;
 370     }
 371 }
 372
 373 /*****************************************************************************
 374  * aout_FifoNextStart : return the current end_date
 375  *****************************************************************************/
 376 mtime_t aout_FifoNextStart( aout_instance_t * p_aout, aout_fifo_t * p_fifo )
 377 {
 378     (void)p_aout;
 379     return aout_DateGet( &p_fifo->end_date );
 380 }
 381
 382 /*****************************************************************************
 383  * aout_FifoFirstDate : return the playing date of the first buffer in the
 384  * FIFO
 385  *****************************************************************************/
 386 mtime_t aout_FifoFirstDate( aout_instance_t * p_aout, aout_fifo_t * p_fifo )
 387 {
 388     (void)p_aout;
 389     return p_fifo->p_first ?  p_fifo->p_first->start_date : 0;
 390 }
 391
 392 /*****************************************************************************
 393  * aout_FifoPop : get the next buffer out of the FIFO
 394  *****************************************************************************/
 395 aout_buffer_t * aout_FifoPop( aout_instance_t * p_aout, aout_fifo_t * p_fifo )
 396 {
 397     aout_buffer_t * p_buffer;
 398     (void)p_aout;
 399
 400     p_buffer = p_fifo->p_first;
 401     if ( p_buffer == NULL ) return NULL;
 402     p_fifo->p_first = p_buffer->p_next;
 403     if ( p_fifo->p_first == NULL )
 404     {
 405         p_fifo->pp_last = &p_fifo->p_first;
 406     }
 407
 408     return p_buffer;
 409 }
 410
 411 /*****************************************************************************
 412  * aout_FifoDestroy : destroy a FIFO and its buffers
 413  *****************************************************************************/
 414 void aout_FifoDestroy( aout_instance_t * p_aout, aout_fifo_t * p_fifo )
 415 {
 416     aout_buffer_t * p_buffer;
 417     (void)p_aout;
 418
 419     p_buffer = p_fifo->p_first;
 420     while ( p_buffer != NULL )
 421     {
 422         aout_buffer_t * p_next = p_buffer->p_next;
 423         aout_BufferFree( p_buffer );
 424         p_buffer = p_next;
 425     }
 426
 427     p_fifo->p_first = NULL;
 428     p_fifo->pp_last = &p_fifo->p_first;
 429 }
 430
 431
 432 /*
 433  * Date management (internal and external)
 434  */
 435
 436 /*****************************************************************************
 437  * aout_DateInit : set the divider of an audio_date_t
 438  *****************************************************************************/
 439 void aout_DateInit( audio_date_t * p_date, uint32_t i_divider )
 440 {
 441     p_date->date = 0;
 442     p_date->i_divider = i_divider;
 443     p_date->i_remainder = 0;
 444 }
 445
 446 /*****************************************************************************
 447  * aout_DateSet : set the date of an audio_date_t
 448  *****************************************************************************/
 449 void aout_DateSet( audio_date_t * p_date, mtime_t new_date )
 450 {
 451     p_date->date = new_date;
 452     p_date->i_remainder = 0;
 453 }
 454
 455 /*****************************************************************************
 456  * aout_DateMove : move forwards or backwards the date of an audio_date_t
 457  *****************************************************************************/
 458 void aout_DateMove( audio_date_t * p_date, mtime_t difference )
 459 {
 460     p_date->date += difference;
 461 }
 462
 463 /*****************************************************************************
 464  * aout_DateGet : get the date of an audio_date_t
 465  *****************************************************************************/
 466 mtime_t aout_DateGet( const audio_date_t * p_date )
 467 {
 468     return p_date->date;
 469 }
 470
 471 /*****************************************************************************
 472  * aout_DateIncrement : increment the date and return the result, taking
 473  * into account rounding errors
 474  *****************************************************************************/
 475 mtime_t aout_DateIncrement( audio_date_t * p_date, uint32_t i_nb_samples )
 476 {
 477     mtime_t i_dividend = (mtime_t)i_nb_samples * 1000000;
 478     p_date->date += i_dividend / p_date->i_divider;
 479     p_date->i_remainder += (int)(i_dividend % p_date->i_divider);
 480     if ( p_date->i_remainder >= p_date->i_divider )
 481     {
 482         /* This is Bresenham algorithm. */
 483         p_date->date++;
 484         p_date->i_remainder -= p_date->i_divider;
 485     }
 486     return p_date->date;
 487 }
 488
 489 /*****************************************************************************
 490  * aout_CheckChannelReorder : Check if we need to do some channel re-ordering
 491  *****************************************************************************/
 492 int aout_CheckChannelReorder( const uint32_t *pi_chan_order_in,
 493                               const uint32_t *pi_chan_order_out,
 494                               uint32_t i_channel_mask,
 495                               int i_channels, int *pi_chan_table )
 496 {
 497     bool b_chan_reorder = false;
 498     int i, j, k, l;
 499
 500     if( i_channels > AOUT_CHAN_MAX ) return false;
 501
 502     for( i = 0, j = 0; pi_chan_order_in[i]; i++ )
 503     {
 504         if( !(i_channel_mask & pi_chan_order_in[i]) ) continue;
 505
 506         for( k = 0, l = 0; pi_chan_order_in[i] != pi_chan_order_out[k]; k++ )
 507         {
 508             if( i_channel_mask & pi_chan_order_out[k] ) l++;
 509         }
 510
 511         pi_chan_table[j++] = l;
 512     }
 513
 514     for( i = 0; i < i_channels; i++ )
 515     {
 516         if( pi_chan_table[i] != i ) b_chan_reorder = true;
 517     }
 518
 519     return b_chan_reorder;
 520 }
 521
 522 /*****************************************************************************
 523  * aout_ChannelReorder :
 524  *****************************************************************************/
 525 void aout_ChannelReorder( uint8_t *p_buf, int i_buffer,
 526                           int i_channels, const int *pi_chan_table,
 527                           int i_bits_per_sample )
 528 {
 529     uint8_t p_tmp[AOUT_CHAN_MAX * 4];
 530     int i, j;
 531
 532     if( i_bits_per_sample == 8 )
 533     {
 534         for( i = 0; i < i_buffer / i_channels; i++ )
 535         {
 536             for( j = 0; j < i_channels; j++ )
 537             {
 538                 p_tmp[pi_chan_table[j]] = p_buf[j];
 539             }
 540
 541             memcpy( p_buf, p_tmp, i_channels );
 542             p_buf += i_channels;
 543         }
 544     }
 545     else if( i_bits_per_sample == 16 )
 546     {
 547         for( i = 0; i < i_buffer / i_channels / 2; i++ )
 548         {
 549             for( j = 0; j < i_channels; j++ )
 550             {
 551                 p_tmp[2 * pi_chan_table[j]]     = p_buf[2 * j];
 552                 p_tmp[2 * pi_chan_table[j] + 1] = p_buf[2 * j + 1];
 553             }
 554
 555             memcpy( p_buf, p_tmp, 2 * i_channels );
 556             p_buf += 2 * i_channels;
 557         }
 558     }
 559     else if( i_bits_per_sample == 24 )
 560     {
 561         for( i = 0; i < i_buffer / i_channels / 3; i++ )
 562         {
 563             for( j = 0; j < i_channels; j++ )
 564             {
 565                 p_tmp[3 * pi_chan_table[j]]     = p_buf[3 * j];
 566                 p_tmp[3 * pi_chan_table[j] + 1] = p_buf[3 * j + 1];
 567                 p_tmp[3 * pi_chan_table[j] + 2] = p_buf[3 * j + 2];
 568             }
 569
 570             memcpy( p_buf, p_tmp, 3 * i_channels );
 571             p_buf += 3 * i_channels;
 572         }
 573     }
 574     else if( i_bits_per_sample == 32 )
 575     {
 576         for( i = 0; i < i_buffer / i_channels / 4; i++ )
 577         {
 578             for( j = 0; j < i_channels; j++ )
 579             {
 580                 p_tmp[4 * pi_chan_table[j]]     = p_buf[4 * j];
 581                 p_tmp[4 * pi_chan_table[j] + 1] = p_buf[4 * j + 1];
 582                 p_tmp[4 * pi_chan_table[j] + 2] = p_buf[4 * j + 2];
 583                 p_tmp[4 * pi_chan_table[j] + 3] = p_buf[4 * j + 3];
 584             }
 585
 586             memcpy( p_buf, p_tmp, 4 * i_channels );
 587             p_buf += 4 * i_channels;
 588         }
 589     }
 590 }