git.sesse.net Git - vlc/blob - modules/codec/mpeg_audio.c

   1 /*****************************************************************************
   2  * mpeg_audio.c: parse MPEG audio sync info and packetize the stream
   3  *****************************************************************************
   4  * Copyright (C) 2001-2003 VideoLAN
   5  * $Id$
   6  *
   7  * Authors: Laurent Aimar <fenrir@via.ecp.fr>
   8  *          Eric Petit <titer@videolan.org>
   9  *          Christophe Massiot <massiot@via.ecp.fr>
  10  *          Gildas Bazin <gbazin@netcourrier.com>
  11  *
  12  * This program is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License as published by
  14  * the Free Software Foundation; either version 2 of the License, or
  15  * (at your option) any later version.
  16  *
  17  * This program is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with this program; if not, write to the Free Software
  24  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
  25  *****************************************************************************/
  26
  27 /*****************************************************************************
  28  * Preamble
  29  *****************************************************************************/
  30 #include <vlc/vlc.h>
  31 #include <vlc/decoder.h>
  32 #include <vlc/aout.h>
  33
  34 #include "vlc_block_helper.h"
  35
  36 /*****************************************************************************
  37  * decoder_sys_t : decoder descriptor
  38  *****************************************************************************/
  39 struct decoder_sys_t
  40 {
  41     /* Module mode */
  42     vlc_bool_t b_packetizer;
  43
  44     /*
  45      * Input properties
  46      */
  47     int        i_state;
  48
  49     block_bytestream_t bytestream;
  50
  51     /*
  52      * Common properties
  53      */
  54     audio_date_t          end_date;
  55     unsigned int          i_current_layer;
  56
  57     mtime_t i_pts;
  58
  59     int i_frame_size, i_free_frame_size;
  60     unsigned int i_channels_conf, i_channels;
  61     unsigned int i_rate, i_max_frame_size, i_frame_length;
  62     unsigned int i_layer, i_bit_rate;
  63 };
  64
  65 enum {
  66
  67     STATE_NOSYNC,
  68     STATE_SYNC,
  69     STATE_HEADER,
  70     STATE_NEXT_SYNC,
  71     STATE_GET_DATA,
  72     STATE_SEND_DATA
  73 };
  74
  75 /* This isn't the place to put mad-specific stuff. However, it makes the
  76  * mad plug-in's life much easier if we put 8 extra bytes at the end of the
  77  * buffer, because that way it doesn't have to copy the aout_buffer_t to a
  78  * bigger buffer. This has no implication on other plug-ins, and we only
  79  * lose 8 bytes per frame. --Meuuh */
  80 #define MAD_BUFFER_GUARD 8
  81 #define MPGA_HEADER_SIZE 4
  82
  83 /****************************************************************************
  84  * Local prototypes
  85  ****************************************************************************/
  86 static int  OpenDecoder   ( vlc_object_t * );
  87 static int  OpenPacketizer( vlc_object_t * );
  88 static void CloseDecoder  ( vlc_object_t * );
  89 static void *DecodeBlock  ( decoder_t *, block_t ** );
  90
  91 static uint8_t       *GetOutBuffer ( decoder_t *, void ** );
  92 static aout_buffer_t *GetAoutBuffer( decoder_t * );
  93 static block_t       *GetSoutBuffer( decoder_t * );
  94
  95 static int SyncInfo( uint32_t i_header, unsigned int * pi_channels,
  96                      unsigned int * pi_channels_conf,
  97                      unsigned int * pi_sample_rate, unsigned int * pi_bit_rate,
  98                      unsigned int * pi_frame_length,
  99                      unsigned int * pi_max_frame_size,
 100                      unsigned int * pi_layer );
 101
 102 /*****************************************************************************
 103  * Module descriptor
 104  *****************************************************************************/
 105 vlc_module_begin();
 106     set_description( _("MPEG audio layer I/II/III parser") );
 107 #if defined(SYS_DARWIN)
 108     set_capability( "decoder", 5 );
 109 #else
 110     set_capability( "decoder", 100 );
 111 #endif
 112     set_callbacks( OpenDecoder, CloseDecoder );
 113
 114     add_submodule();
 115     set_description( _("MPEG audio layer I/II/III packetizer") );
 116     set_capability( "packetizer", 10 );
 117     set_callbacks( OpenPacketizer, CloseDecoder );
 118 vlc_module_end();
 119
 120 /*****************************************************************************
 121  * OpenDecoder: probe the decoder and return score
 122  *****************************************************************************/
 123 static int OpenDecoder( vlc_object_t *p_this )
 124 {
 125     decoder_t *p_dec = (decoder_t*)p_this;
 126     decoder_sys_t *p_sys;
 127
 128     if( p_dec->fmt_in.i_codec != VLC_FOURCC('m','p','g','a') )
 129     {
 130         return VLC_EGENERIC;
 131     }
 132
 133     /* Allocate the memory needed to store the decoder's structure */
 134     if( ( p_dec->p_sys = p_sys =
 135           (decoder_sys_t *)malloc(sizeof(decoder_sys_t)) ) == NULL )
 136     {
 137         msg_Err( p_dec, "out of memory" );
 138         return VLC_EGENERIC;
 139     }
 140
 141     /* Misc init */
 142     p_sys->b_packetizer = VLC_FALSE;
 143     p_sys->i_state = STATE_NOSYNC;
 144     aout_DateSet( &p_sys->end_date, 0 );
 145     p_sys->bytestream = block_BytestreamInit( p_dec );
 146
 147     /* Set output properties */
 148     p_dec->fmt_out.i_cat = AUDIO_ES;
 149     p_dec->fmt_out.i_codec = VLC_FOURCC('m','p','g','a');
 150
 151     /* Set callback */
 152     p_dec->pf_decode_audio = (aout_buffer_t *(*)(decoder_t *, block_t **))
 153         DecodeBlock;
 154     p_dec->pf_packetize    = (block_t *(*)(decoder_t *, block_t **))
 155         DecodeBlock;
 156
 157     /* Start with the minimum size for a free bitrate frame */
 158     p_sys->i_free_frame_size = MPGA_HEADER_SIZE;
 159
 160     return VLC_SUCCESS;
 161 }
 162
 163 static int OpenPacketizer( vlc_object_t *p_this )
 164 {
 165     decoder_t *p_dec = (decoder_t*)p_this;
 166
 167     int i_ret = OpenDecoder( p_this );
 168
 169     if( i_ret == VLC_SUCCESS ) p_dec->p_sys->b_packetizer = VLC_TRUE;
 170
 171     return i_ret;
 172 }
 173
 174 /****************************************************************************
 175  * DecodeBlock: the whole thing
 176  ****************************************************************************
 177  * This function is called just after the thread is launched.
 178  ****************************************************************************/
 179 static void *DecodeBlock( decoder_t *p_dec, block_t **pp_block )
 180 {
 181     decoder_sys_t *p_sys = p_dec->p_sys;
 182     uint8_t p_header[MAD_BUFFER_GUARD];
 183     uint32_t i_header;
 184     uint8_t *p_buf;
 185     void *p_out_buffer;
 186
 187     if( !pp_block || !*pp_block ) return NULL;
 188
 189     if( !aout_DateGet( &p_sys->end_date ) && !(*pp_block)->i_pts )
 190     {
 191         /* We've just started the stream, wait for the first PTS. */
 192         block_Release( *pp_block );
 193         return NULL;
 194     }
 195
 196     if( (*pp_block)->i_flags&BLOCK_FLAG_DISCONTINUITY )
 197     {
 198         p_sys->i_state = STATE_NOSYNC;
 199     }
 200
 201     block_BytestreamPush( &p_sys->bytestream, *pp_block );
 202
 203     while( 1 )
 204     {
 205         switch( p_sys->i_state )
 206         {
 207
 208         case STATE_NOSYNC:
 209             while( block_PeekBytes( &p_sys->bytestream, p_header, 2 )
 210                    == VLC_SUCCESS )
 211             {
 212                 /* Look for sync word - should be 0xffe */
 213                 if( p_header[0] == 0xff && (p_header[1] & 0xe0) == 0xe0 )
 214                 {
 215                     p_sys->i_state = STATE_SYNC;
 216                     break;
 217                 }
 218                 block_SkipByte( &p_sys->bytestream );
 219             }
 220             if( p_sys->i_state != STATE_SYNC )
 221             {
 222                 block_BytestreamFlush( &p_sys->bytestream );
 223
 224                 /* Need more data */
 225                 return NULL;
 226             }
 227
 228         case STATE_SYNC:
 229             /* New frame, set the Presentation Time Stamp */
 230             p_sys->i_pts = p_sys->bytestream.p_block->i_pts;
 231             if( p_sys->i_pts != 0 &&
 232                 p_sys->i_pts != aout_DateGet( &p_sys->end_date ) )
 233             {
 234                 aout_DateSet( &p_sys->end_date, p_sys->i_pts );
 235             }
 236             p_sys->i_state = STATE_HEADER;
 237
 238         case STATE_HEADER:
 239             /* Get MPGA frame header (MPGA_HEADER_SIZE bytes) */
 240             if( block_PeekBytes( &p_sys->bytestream, p_header,
 241                                  MPGA_HEADER_SIZE ) != VLC_SUCCESS )
 242             {
 243                 /* Need more data */
 244                 return NULL;
 245             }
 246
 247             /* Build frame header */
 248             i_header = (p_header[0]<<24)|(p_header[1]<<16)|(p_header[2]<<8)
 249                        |p_header[3];
 250
 251             /* Check if frame is valid and get frame info */
 252             p_sys->i_frame_size = SyncInfo( i_header,
 253                                             &p_sys->i_channels,
 254                                             &p_sys->i_channels_conf,
 255                                             &p_sys->i_rate,
 256                                             &p_sys->i_bit_rate,
 257                                             &p_sys->i_frame_length,
 258                                             &p_sys->i_max_frame_size,
 259                                             &p_sys->i_layer );
 260
 261             if( p_sys->i_frame_size == -1 )
 262             {
 263                 msg_Dbg( p_dec, "emulated startcode" );
 264                 block_SkipByte( &p_sys->bytestream );
 265                 p_sys->i_state = STATE_NOSYNC;
 266                 break;
 267             }
 268
 269             if( p_sys->i_bit_rate == 0 )
 270             {
 271                 /* Free birate, but 99% emulated startcode :( */
 272                 if( p_dec->p_sys->i_free_frame_size == MPGA_HEADER_SIZE )
 273                 {
 274                     msg_Dbg( p_dec, "free bitrate mode");
 275                 }
 276                 p_sys->i_frame_size = p_sys->i_free_frame_size;
 277             }
 278
 279             p_sys->i_state = STATE_NEXT_SYNC;
 280
 281         case STATE_NEXT_SYNC:
 282             /* TODO: If p_block == NULL, flush the buffer without checking the
 283              * next sync word */
 284
 285             /* Check if next expected frame contains the sync word */
 286             if( block_PeekOffsetBytes( &p_sys->bytestream,
 287                                        p_sys->i_frame_size, p_header,
 288                                        MAD_BUFFER_GUARD ) != VLC_SUCCESS )
 289             {
 290                 /* Need more data */
 291                 return NULL;
 292             }
 293
 294             if( p_header[0] == 0xff && (p_header[1] & 0xe0) == 0xe0 )
 295             {
 296                 /* Startcode is fine, let's try the header as an extra check */
 297                 int i_next_frame_size;
 298                 unsigned int i_next_channels, i_next_channels_conf;
 299                 unsigned int i_next_rate, i_next_bit_rate;
 300                 unsigned int i_next_frame_length, i_next_max_frame_size;
 301                 unsigned int i_next_layer;
 302
 303                 /* Build frame header */
 304                 i_header = (p_header[0]<<24)|(p_header[1]<<16)|(p_header[2]<<8)
 305                            |p_header[3];
 306
 307                 i_next_frame_size = SyncInfo( i_header,
 308                                               &i_next_channels,
 309                                               &i_next_channels_conf,
 310                                               &i_next_rate,
 311                                               &i_next_bit_rate,
 312                                               &i_next_frame_length,
 313                                               &i_next_max_frame_size,
 314                                               &i_next_layer );
 315
 316                 /* Free bitrate only */
 317                 if( p_sys->i_bit_rate == 0 && i_next_frame_size == -1 )
 318                 {
 319                     if( (unsigned int)p_sys->i_frame_size >
 320                         p_sys->i_max_frame_size )
 321                     {
 322                         msg_Dbg( p_dec, "frame too big %d > %d "
 323                                  "(emulated startcode ?)", p_sys->i_frame_size,
 324                                  p_sys->i_max_frame_size );
 325                         block_SkipByte( &p_sys->bytestream );
 326                         p_sys->i_state = STATE_NOSYNC;
 327                         p_sys->i_free_frame_size = MPGA_HEADER_SIZE;
 328                         break;
 329                     }
 330
 331                     p_sys->i_frame_size++;
 332                     break;
 333                 }
 334
 335                 if( i_next_frame_size == -1 )
 336                 {
 337                     msg_Dbg( p_dec, "emulated startcode on next frame" );
 338                     block_SkipByte( &p_sys->bytestream );
 339                     p_sys->i_state = STATE_NOSYNC;
 340                     break;
 341                 }
 342
 343                 /* Check info is in sync with previous one */
 344                 if( i_next_channels_conf != p_sys->i_channels_conf ||
 345                     i_next_rate != p_sys->i_rate ||
 346                     i_next_layer != p_sys->i_layer ||
 347                     i_next_frame_length != p_sys->i_frame_length )
 348                 {
 349                     /* Free bitrate only */
 350                     if( p_sys->i_bit_rate == 0 )
 351                     {
 352                         p_sys->i_frame_size++;
 353                         break;
 354                     }
 355
 356                     msg_Dbg( p_dec, "parameters changed unexpectedly "
 357                              "(emulated startcode ?)" );
 358                     block_SkipByte( &p_sys->bytestream );
 359                     p_sys->i_state = STATE_NOSYNC;
 360                     break;
 361                 }
 362
 363                 /* Free bitrate only */
 364                 if( p_sys->i_bit_rate == 0 )
 365                 {
 366                     if( i_next_bit_rate != 0 )
 367                     {
 368                         p_sys->i_frame_size++;
 369                         break;
 370                     }
 371                 }
 372
 373             }
 374             else
 375             {
 376                 /* Free bitrate only */
 377                 if( p_sys->i_bit_rate == 0 )
 378                 {
 379                     if( (unsigned int)p_sys->i_frame_size >
 380                         p_sys->i_max_frame_size )
 381                     {
 382                         msg_Dbg( p_dec, "frame too big %d > %d "
 383                                  "(emulated startcode ?)", p_sys->i_frame_size,
 384                                  p_sys->i_max_frame_size );
 385                         block_SkipByte( &p_sys->bytestream );
 386                         p_sys->i_state = STATE_NOSYNC;
 387                         p_sys->i_free_frame_size = MPGA_HEADER_SIZE;
 388                         break;
 389                     }
 390
 391                     p_sys->i_frame_size++;
 392                     break;
 393                 }
 394
 395                 msg_Dbg( p_dec, "emulated startcode "
 396                          "(no startcode on following frame)" );
 397                 p_sys->i_state = STATE_NOSYNC;
 398                 block_SkipByte( &p_sys->bytestream );
 399                 break;
 400             }
 401
 402             p_sys->i_state = STATE_SEND_DATA;
 403             break;
 404
 405         case STATE_GET_DATA:
 406             /* Make sure we have enough data.
 407              * (Not useful if we went through NEXT_SYNC) */
 408             if( block_WaitBytes( &p_sys->bytestream,
 409                                  p_sys->i_frame_size ) != VLC_SUCCESS )
 410             {
 411                 /* Need more data */
 412                 return NULL;
 413             }
 414             p_sys->i_state = STATE_SEND_DATA;
 415
 416         case STATE_SEND_DATA:
 417             if( !(p_buf = GetOutBuffer( p_dec, &p_out_buffer )) )
 418             {
 419                 //p_dec->b_error = VLC_TRUE;
 420                 return NULL;
 421             }
 422
 423             /* Free bitrate only */
 424             if( p_sys->i_bit_rate == 0 )
 425             {
 426                 p_sys->i_free_frame_size = p_sys->i_frame_size;
 427             }
 428
 429             /* Copy the whole frame into the buffer. When we reach this point
 430              * we already know we have enough data available. */
 431             block_GetBytes( &p_sys->bytestream, p_buf, p_sys->i_frame_size );
 432
 433             /* Get beginning of next frame for libmad */
 434             if( !p_sys->b_packetizer )
 435             {
 436                 memcpy( p_buf + p_sys->i_frame_size,
 437                         p_header, MAD_BUFFER_GUARD );
 438             }
 439
 440             p_sys->i_state = STATE_NOSYNC;
 441
 442             /* Make sure we don't reuse the same pts twice */
 443             if( p_sys->i_pts == p_sys->bytestream.p_block->i_pts )
 444                 p_sys->i_pts = p_sys->bytestream.p_block->i_pts = 0;
 445
 446             /* So p_block doesn't get re-added several times */
 447             *pp_block = block_BytestreamPop( &p_sys->bytestream );
 448
 449             return p_out_buffer;
 450         }
 451     }
 452
 453     return NULL;
 454 }
 455
 456 /*****************************************************************************
 457  * GetOutBuffer:
 458  *****************************************************************************/
 459 static uint8_t *GetOutBuffer( decoder_t *p_dec, void **pp_out_buffer )
 460 {
 461     decoder_sys_t *p_sys = p_dec->p_sys;
 462     uint8_t *p_buf;
 463
 464     if( p_dec->fmt_out.audio.i_rate != p_sys->i_rate )
 465     {
 466         msg_Info( p_dec, "MPGA channels:%d samplerate:%d bitrate:%d",
 467                   p_sys->i_channels, p_sys->i_rate, p_sys->i_bit_rate );
 468
 469         aout_DateInit( &p_sys->end_date, p_sys->i_rate );
 470         aout_DateSet( &p_sys->end_date, p_sys->i_pts );
 471     }
 472
 473     p_dec->fmt_out.audio.i_rate     = p_sys->i_rate;
 474     p_dec->fmt_out.audio.i_channels = p_sys->i_channels;
 475     p_dec->fmt_out.audio.i_frame_length = p_sys->i_frame_length;
 476     p_dec->fmt_out.audio.i_bytes_per_frame =
 477         p_sys->i_max_frame_size + MAD_BUFFER_GUARD;
 478
 479     p_dec->fmt_out.audio.i_original_channels = p_sys->i_channels_conf;
 480     p_dec->fmt_out.audio.i_physical_channels =
 481         p_sys->i_channels_conf & AOUT_CHAN_PHYSMASK;
 482
 483     p_dec->fmt_out.i_bitrate = p_sys->i_bit_rate;
 484
 485     if( p_sys->b_packetizer )
 486     {
 487         block_t *p_sout_buffer = GetSoutBuffer( p_dec );
 488         p_buf = p_sout_buffer ? p_sout_buffer->p_buffer : NULL;
 489         *pp_out_buffer = p_sout_buffer;
 490     }
 491     else
 492     {
 493         aout_buffer_t *p_aout_buffer = GetAoutBuffer( p_dec );
 494         p_buf = p_aout_buffer ? p_aout_buffer->p_buffer : NULL;
 495         *pp_out_buffer = p_aout_buffer;
 496     }
 497
 498     return p_buf;
 499 }
 500
 501 /*****************************************************************************
 502  * GetAoutBuffer:
 503  *****************************************************************************/
 504 static aout_buffer_t *GetAoutBuffer( decoder_t *p_dec )
 505 {
 506     decoder_sys_t *p_sys = p_dec->p_sys;
 507     aout_buffer_t *p_buf;
 508
 509     p_buf = p_dec->pf_aout_buffer_new( p_dec, p_sys->i_frame_length );
 510     if( p_buf == NULL ) return NULL;
 511
 512     p_buf->start_date = aout_DateGet( &p_sys->end_date );
 513     p_buf->end_date =
 514         aout_DateIncrement( &p_sys->end_date, p_sys->i_frame_length );
 515
 516     /* Hack for libmad filter */
 517     p_buf->i_nb_bytes = p_sys->i_frame_size + MAD_BUFFER_GUARD;
 518
 519     return p_buf;
 520 }
 521
 522 /*****************************************************************************
 523  * GetSoutBuffer:
 524  *****************************************************************************/
 525 static block_t *GetSoutBuffer( decoder_t *p_dec )
 526 {
 527     decoder_sys_t *p_sys = p_dec->p_sys;
 528     block_t *p_block;
 529
 530     p_block = block_New( p_dec, p_sys->i_frame_size );
 531     if( p_block == NULL ) return NULL;
 532
 533     p_block->i_pts = p_block->i_dts = aout_DateGet( &p_sys->end_date );
 534
 535     p_block->i_length =
 536         aout_DateIncrement( &p_sys->end_date, p_sys->i_frame_length ) -
 537             p_block->i_pts;
 538
 539     return p_block;
 540 }
 541
 542 /*****************************************************************************
 543  * CloseDecoder: clean up the decoder
 544  *****************************************************************************/
 545 static void CloseDecoder( vlc_object_t *p_this )
 546 {
 547     decoder_t *p_dec = (decoder_t *)p_this;
 548     decoder_sys_t *p_sys = p_dec->p_sys;
 549
 550     block_BytestreamRelease( &p_sys->bytestream );
 551
 552     free( p_sys );
 553 }
 554
 555 /*****************************************************************************
 556  * SyncInfo: parse MPEG audio sync info
 557  *****************************************************************************/
 558 static int SyncInfo( uint32_t i_header, unsigned int * pi_channels,
 559                      unsigned int * pi_channels_conf,
 560                      unsigned int * pi_sample_rate, unsigned int * pi_bit_rate,
 561                      unsigned int * pi_frame_length,
 562                      unsigned int * pi_max_frame_size, unsigned int * pi_layer)
 563 {
 564     static const int ppi_bitrate[2][3][16] =
 565     {
 566         {
 567             /* v1 l1 */
 568             { 0, 32, 64, 96, 128, 160, 192, 224, 256, 288, 320, 352, 384,
 569               416, 448, 0},
 570             /* v1 l2 */
 571             { 0, 32, 48, 56,  64,  80,  96, 112, 128, 160, 192, 224, 256,
 572               320, 384, 0},
 573             /* v1 l3 */
 574             { 0, 32, 40, 48,  56,  64,  80,  96, 112, 128, 160, 192, 224,
 575               256, 320, 0}
 576         },
 577
 578         {
 579             /* v2 l1 */
 580             { 0, 32, 48, 56,  64,  80,  96, 112, 128, 144, 160, 176, 192,
 581               224, 256, 0},
 582             /* v2 l2 */
 583             { 0,  8, 16, 24,  32,  40,  48,  56,  64,  80,  96, 112, 128,
 584               144, 160, 0},
 585             /* v2 l3 */
 586             { 0,  8, 16, 24,  32,  40,  48,  56,  64,  80,  96, 112, 128,
 587               144, 160, 0}
 588         }
 589     };
 590
 591     static const int ppi_samplerate[2][4] = /* version 1 then 2 */
 592     {
 593         { 44100, 48000, 32000, 0 },
 594         { 22050, 24000, 16000, 0 }
 595     };
 596
 597     int i_version, i_mode, i_emphasis;
 598     vlc_bool_t b_padding, b_mpeg_2_5, b_crc;
 599     int i_frame_size = 0;
 600     int i_bitrate_index, i_samplerate_index;
 601     int i_max_bit_rate;
 602
 603     b_mpeg_2_5  = 1 - ((i_header & 0x100000) >> 20);
 604     i_version   = 1 - ((i_header & 0x80000) >> 19);
 605     *pi_layer   = 4 - ((i_header & 0x60000) >> 17);
 606     b_crc = !((i_header >> 16) & 0x01);
 607     i_bitrate_index = (i_header & 0xf000) >> 12;
 608     i_samplerate_index = (i_header & 0xc00) >> 10;
 609     b_padding   = (i_header & 0x200) >> 9;
 610     /* Extension */
 611     i_mode      = (i_header & 0xc0) >> 6;
 612     /* Modeext, copyright & original */
 613     i_emphasis  = i_header & 0x3;
 614
 615     if( *pi_layer != 4 &&
 616         i_bitrate_index < 0x0f &&
 617         i_samplerate_index != 0x03 &&
 618         i_emphasis != 0x02 )
 619     {
 620         switch ( i_mode )
 621         {
 622         case 0: /* stereo */
 623         case 1: /* joint stereo */
 624             *pi_channels = 2;
 625             *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT;
 626             break;
 627         case 2: /* dual-mono */
 628             *pi_channels = 2;
 629             *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 630                                 | AOUT_CHAN_DUALMONO;
 631             break;
 632         case 3: /* mono */
 633             *pi_channels = 1;
 634             *pi_channels_conf = AOUT_CHAN_CENTER;
 635             break;
 636         }
 637         *pi_bit_rate = ppi_bitrate[i_version][*pi_layer-1][i_bitrate_index];
 638         i_max_bit_rate = ppi_bitrate[i_version][*pi_layer-1][14];
 639         *pi_sample_rate = ppi_samplerate[i_version][i_samplerate_index];
 640
 641         if ( b_mpeg_2_5 )
 642         {
 643             *pi_sample_rate >>= 1;
 644         }
 645
 646         switch( *pi_layer )
 647         {
 648         case 1:
 649             i_frame_size = ( 12000 * *pi_bit_rate / *pi_sample_rate +
 650                            b_padding ) * 4;
 651             *pi_max_frame_size = ( 12000 * i_max_bit_rate /
 652                                  *pi_sample_rate + 1 ) * 4;
 653             *pi_frame_length = 384;
 654             break;
 655
 656         case 2:
 657             i_frame_size = 144000 * *pi_bit_rate / *pi_sample_rate + b_padding;
 658             *pi_max_frame_size = 144000 * i_max_bit_rate / *pi_sample_rate + 1;
 659             *pi_frame_length = 1152;
 660             break;
 661
 662         case 3:
 663             i_frame_size = ( i_version ? 72000 : 144000 ) *
 664                            *pi_bit_rate / *pi_sample_rate + b_padding;
 665             *pi_max_frame_size = ( i_version ? 72000 : 144000 ) *
 666                                  i_max_bit_rate / *pi_sample_rate + 1;
 667             *pi_frame_length = i_version ? 576 : 1152;
 668             break;
 669
 670         default:
 671             break;
 672         }
 673     }
 674     else
 675     {
 676         return -1;
 677     }
 678
 679     return i_frame_size;
 680 }