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 the VideoLAN team
   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@videolan.org>
  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., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  25  *****************************************************************************/
  26
  27 /*****************************************************************************
  28  * Preamble
  29  *****************************************************************************/
  30 #ifdef HAVE_CONFIG_H
  31 # include "config.h"
  32 #endif
  33
  34 #include <vlc/vlc.h>
  35 #include <vlc_plugin.h>
  36 #include <vlc_codec.h>
  37 #include <vlc_aout.h>
  38 #include <vlc_input.h>
  39
  40 #include <vlc_block_helper.h>
  41
  42 /*****************************************************************************
  43  * decoder_sys_t : decoder descriptor
  44  *****************************************************************************/
  45 struct decoder_sys_t
  46 {
  47     /* Module mode */
  48     bool b_packetizer;
  49
  50     /*
  51      * Input properties
  52      */
  53     int        i_state;
  54
  55     block_bytestream_t bytestream;
  56
  57     /*
  58      * Common properties
  59      */
  60     audio_date_t          end_date;
  61     unsigned int          i_current_layer;
  62
  63     mtime_t i_pts;
  64
  65     int i_frame_size, i_free_frame_size;
  66     unsigned int i_channels_conf, i_channels;
  67     unsigned int i_rate, i_max_frame_size, i_frame_length;
  68     unsigned int i_layer, i_bit_rate;
  69
  70     bool   b_discontinuity;
  71
  72     int i_input_rate;
  73 };
  74
  75 enum {
  76
  77     STATE_NOSYNC,
  78     STATE_SYNC,
  79     STATE_HEADER,
  80     STATE_NEXT_SYNC,
  81     STATE_GET_DATA,
  82     STATE_SEND_DATA
  83 };
  84
  85 /* This isn't the place to put mad-specific stuff. However, it makes the
  86  * mad plug-in's life much easier if we put 8 extra bytes at the end of the
  87  * buffer, because that way it doesn't have to copy the aout_buffer_t to a
  88  * bigger buffer. This has no implication on other plug-ins, and we only
  89  * lose 8 bytes per frame. --Meuuh */
  90 #define MAD_BUFFER_GUARD 8
  91 #define MPGA_HEADER_SIZE 4
  92
  93 /****************************************************************************
  94  * Local prototypes
  95  ****************************************************************************/
  96 static int  OpenDecoder   ( vlc_object_t * );
  97 static int  OpenPacketizer( vlc_object_t * );
  98 static void CloseDecoder  ( vlc_object_t * );
  99 static void *DecodeBlock  ( decoder_t *, block_t ** );
 100
 101 static uint8_t       *GetOutBuffer ( decoder_t *, void ** );
 102 static aout_buffer_t *GetAoutBuffer( decoder_t * );
 103 static block_t       *GetSoutBuffer( decoder_t * );
 104
 105 static int SyncInfo( uint32_t i_header, unsigned int * pi_channels,
 106                      unsigned int * pi_channels_conf,
 107                      unsigned int * pi_sample_rate, unsigned int * pi_bit_rate,
 108                      unsigned int * pi_frame_length,
 109                      unsigned int * pi_max_frame_size,
 110                      unsigned int * pi_layer );
 111
 112 /*****************************************************************************
 113  * Module descriptor
 114  *****************************************************************************/
 115 vlc_module_begin();
 116     set_description( _("MPEG audio layer I/II/III decoder") );
 117     set_category( CAT_INPUT );
 118     set_subcategory( SUBCAT_INPUT_ACODEC );
 119 #if defined(UNDER_CE)
 120    set_capability( "decoder", 5 );
 121 #else
 122     set_capability( "decoder", 100 );
 123 #endif
 124     set_callbacks( OpenDecoder, CloseDecoder );
 125
 126     add_submodule();
 127     set_description( _("MPEG audio layer I/II/III packetizer") );
 128     set_capability( "packetizer", 10 );
 129     set_callbacks( OpenPacketizer, CloseDecoder );
 130 vlc_module_end();
 131
 132 /*****************************************************************************
 133  * OpenDecoder: probe the decoder and return score
 134  *****************************************************************************/
 135 static int OpenDecoder( vlc_object_t *p_this )
 136 {
 137     decoder_t *p_dec = (decoder_t*)p_this;
 138     decoder_sys_t *p_sys;
 139
 140     if( p_dec->fmt_in.i_codec != VLC_FOURCC('m','p','g','a') )
 141     {
 142         return VLC_EGENERIC;
 143     }
 144
 145     /* HACK: Don't use this codec if we don't have an mpga audio filter */
 146     if( p_dec->i_object_type == VLC_OBJECT_DECODER &&
 147         !module_Exists( p_this, "mpgatofixed32" ) )
 148     {
 149         return VLC_EGENERIC;
 150     }
 151
 152     /* Allocate the memory needed to store the decoder's structure */
 153     if( ( p_dec->p_sys = p_sys =
 154           (decoder_sys_t *)malloc(sizeof(decoder_sys_t)) ) == NULL )
 155     {
 156         msg_Err( p_dec, "out of memory" );
 157         return VLC_EGENERIC;
 158     }
 159
 160     /* Misc init */
 161     p_sys->b_packetizer = false;
 162     p_sys->i_state = STATE_NOSYNC;
 163     aout_DateSet( &p_sys->end_date, 0 );
 164     p_sys->bytestream = block_BytestreamInit();
 165     p_sys->b_discontinuity = false;
 166     p_sys->i_input_rate = INPUT_RATE_DEFAULT;
 167
 168     /* Set output properties */
 169     p_dec->fmt_out.i_cat = AUDIO_ES;
 170     p_dec->fmt_out.i_codec = VLC_FOURCC('m','p','g','a');
 171     p_dec->fmt_out.audio.i_rate = 0; /* So end_date gets initialized */
 172
 173     /* Set callback */
 174     p_dec->pf_decode_audio = (aout_buffer_t *(*)(decoder_t *, block_t **))
 175         DecodeBlock;
 176     p_dec->pf_packetize    = (block_t *(*)(decoder_t *, block_t **))
 177         DecodeBlock;
 178
 179     /* Start with the minimum size for a free bitrate frame */
 180     p_sys->i_free_frame_size = MPGA_HEADER_SIZE;
 181
 182     return VLC_SUCCESS;
 183 }
 184
 185 static int OpenPacketizer( vlc_object_t *p_this )
 186 {
 187     decoder_t *p_dec = (decoder_t*)p_this;
 188
 189     int i_ret = OpenDecoder( p_this );
 190
 191     if( i_ret == VLC_SUCCESS ) p_dec->p_sys->b_packetizer = true;
 192
 193     return i_ret;
 194 }
 195
 196 /****************************************************************************
 197  * DecodeBlock: the whole thing
 198  ****************************************************************************
 199  * This function is called just after the thread is launched.
 200  ****************************************************************************/
 201 static void *DecodeBlock( decoder_t *p_dec, block_t **pp_block )
 202 {
 203     decoder_sys_t *p_sys = p_dec->p_sys;
 204     uint8_t p_header[MAD_BUFFER_GUARD];
 205     uint32_t i_header;
 206     uint8_t *p_buf;
 207     void *p_out_buffer;
 208
 209     if( !pp_block || !*pp_block ) return NULL;
 210
 211     if( (*pp_block)->i_flags&(BLOCK_FLAG_DISCONTINUITY|BLOCK_FLAG_CORRUPTED) )
 212     {
 213         if( (*pp_block)->i_flags&BLOCK_FLAG_CORRUPTED )
 214         {
 215             p_sys->i_state = STATE_NOSYNC;
 216             block_BytestreamFlush( &p_sys->bytestream );
 217         }
 218 //        aout_DateSet( &p_sys->end_date, 0 );
 219         block_Release( *pp_block );
 220         p_sys->b_discontinuity = true;
 221         return NULL;
 222     }
 223
 224     if( !aout_DateGet( &p_sys->end_date ) && !(*pp_block)->i_pts )
 225     {
 226         /* We've just started the stream, wait for the first PTS. */
 227         msg_Dbg( p_dec, "waiting for PTS" );
 228         block_Release( *pp_block );
 229         return NULL;
 230     }
 231
 232     if( (*pp_block)->i_rate > 0 )
 233         p_sys->i_input_rate = (*pp_block)->i_rate;
 234
 235     block_BytestreamPush( &p_sys->bytestream, *pp_block );
 236
 237     while( 1 )
 238     {
 239         switch( p_sys->i_state )
 240         {
 241
 242         case STATE_NOSYNC:
 243             while( block_PeekBytes( &p_sys->bytestream, p_header, 2 )
 244                    == VLC_SUCCESS )
 245             {
 246                 /* Look for sync word - should be 0xffe */
 247                 if( p_header[0] == 0xff && (p_header[1] & 0xe0) == 0xe0 )
 248                 {
 249                     p_sys->i_state = STATE_SYNC;
 250                     break;
 251                 }
 252                 block_SkipByte( &p_sys->bytestream );
 253             }
 254             if( p_sys->i_state != STATE_SYNC )
 255             {
 256                 block_BytestreamFlush( &p_sys->bytestream );
 257
 258                 /* Need more data */
 259                 return NULL;
 260             }
 261
 262         case STATE_SYNC:
 263             /* New frame, set the Presentation Time Stamp */
 264             p_sys->i_pts = p_sys->bytestream.p_block->i_pts;
 265             if( p_sys->i_pts != 0 &&
 266                 p_sys->i_pts != aout_DateGet( &p_sys->end_date ) )
 267             {
 268                 aout_DateSet( &p_sys->end_date, p_sys->i_pts );
 269             }
 270             p_sys->i_state = STATE_HEADER;
 271
 272         case STATE_HEADER:
 273             /* Get MPGA frame header (MPGA_HEADER_SIZE bytes) */
 274             if( block_PeekBytes( &p_sys->bytestream, p_header,
 275                                  MPGA_HEADER_SIZE ) != VLC_SUCCESS )
 276             {
 277                 /* Need more data */
 278                 return NULL;
 279             }
 280
 281             /* Build frame header */
 282             i_header = (p_header[0]<<24)|(p_header[1]<<16)|(p_header[2]<<8)
 283                        |p_header[3];
 284
 285             /* Check if frame is valid and get frame info */
 286             p_sys->i_frame_size = SyncInfo( i_header,
 287                                             &p_sys->i_channels,
 288                                             &p_sys->i_channels_conf,
 289                                             &p_sys->i_rate,
 290                                             &p_sys->i_bit_rate,
 291                                             &p_sys->i_frame_length,
 292                                             &p_sys->i_max_frame_size,
 293                                             &p_sys->i_layer );
 294
 295             if( p_sys->i_frame_size == -1 )
 296             {
 297                 msg_Dbg( p_dec, "emulated startcode" );
 298                 block_SkipByte( &p_sys->bytestream );
 299                 p_sys->i_state = STATE_NOSYNC;
 300                 p_sys->b_discontinuity = true;
 301                 break;
 302             }
 303
 304             if( p_sys->i_bit_rate == 0 )
 305             {
 306                 /* Free bitrate, but 99% emulated startcode :( */
 307                 if( p_dec->p_sys->i_free_frame_size == MPGA_HEADER_SIZE )
 308                 {
 309                     msg_Dbg( p_dec, "free bitrate mode");
 310                 }
 311                 /* The -1 below is to account for the frame padding */
 312                 p_sys->i_frame_size = p_sys->i_free_frame_size - 1;
 313             }
 314
 315             p_sys->i_state = STATE_NEXT_SYNC;
 316
 317         case STATE_NEXT_SYNC:
 318             /* TODO: If p_block == NULL, flush the buffer without checking the
 319              * next sync word */
 320
 321             /* Check if next expected frame contains the sync word */
 322             if( block_PeekOffsetBytes( &p_sys->bytestream,
 323                                        p_sys->i_frame_size, p_header,
 324                                        MAD_BUFFER_GUARD ) != VLC_SUCCESS )
 325             {
 326                 /* Need more data */
 327                 return NULL;
 328             }
 329
 330             if( p_header[0] == 0xff && (p_header[1] & 0xe0) == 0xe0 )
 331             {
 332                 /* Startcode is fine, let's try the header as an extra check */
 333                 int i_next_frame_size;
 334                 unsigned int i_next_channels, i_next_channels_conf;
 335                 unsigned int i_next_rate, i_next_bit_rate;
 336                 unsigned int i_next_frame_length, i_next_max_frame_size;
 337                 unsigned int i_next_layer;
 338
 339                 /* Build frame header */
 340                 i_header = (p_header[0]<<24)|(p_header[1]<<16)|(p_header[2]<<8)
 341                            |p_header[3];
 342
 343                 i_next_frame_size = SyncInfo( i_header,
 344                                               &i_next_channels,
 345                                               &i_next_channels_conf,
 346                                               &i_next_rate,
 347                                               &i_next_bit_rate,
 348                                               &i_next_frame_length,
 349                                               &i_next_max_frame_size,
 350                                               &i_next_layer );
 351
 352                 /* Free bitrate only */
 353                 if( p_sys->i_bit_rate == 0 && i_next_frame_size == -1 )
 354                 {
 355                     if( (unsigned int)p_sys->i_frame_size >
 356                         p_sys->i_max_frame_size )
 357                     {
 358                         msg_Dbg( p_dec, "frame too big %d > %d "
 359                                  "(emulated startcode ?)", p_sys->i_frame_size,
 360                                  p_sys->i_max_frame_size );
 361                         block_SkipByte( &p_sys->bytestream );
 362                         p_sys->i_state = STATE_NOSYNC;
 363                         p_sys->i_free_frame_size = MPGA_HEADER_SIZE;
 364                         break;
 365                     }
 366
 367                     p_sys->i_frame_size++;
 368                     break;
 369                 }
 370
 371                 if( i_next_frame_size == -1 )
 372                 {
 373                     msg_Dbg( p_dec, "emulated startcode on next frame" );
 374                     block_SkipByte( &p_sys->bytestream );
 375                     p_sys->i_state = STATE_NOSYNC;
 376                     p_sys->b_discontinuity = true;
 377                     break;
 378                 }
 379
 380                 /* Check info is in sync with previous one */
 381                 if( i_next_channels_conf != p_sys->i_channels_conf ||
 382                     i_next_rate != p_sys->i_rate ||
 383                     i_next_layer != p_sys->i_layer ||
 384                     i_next_frame_length != p_sys->i_frame_length )
 385                 {
 386                     /* Free bitrate only */
 387                     if( p_sys->i_bit_rate == 0 )
 388                     {
 389                         p_sys->i_frame_size++;
 390                         break;
 391                     }
 392
 393                     msg_Dbg( p_dec, "parameters changed unexpectedly "
 394                              "(emulated startcode ?)" );
 395                     block_SkipByte( &p_sys->bytestream );
 396                     p_sys->i_state = STATE_NOSYNC;
 397                     break;
 398                 }
 399
 400                 /* Free bitrate only */
 401                 if( p_sys->i_bit_rate == 0 )
 402                 {
 403                     if( i_next_bit_rate != 0 )
 404                     {
 405                         p_sys->i_frame_size++;
 406                         break;
 407                     }
 408                 }
 409
 410             }
 411             else
 412             {
 413                 /* Free bitrate only */
 414                 if( p_sys->i_bit_rate == 0 )
 415                 {
 416                     if( (unsigned int)p_sys->i_frame_size >
 417                         p_sys->i_max_frame_size )
 418                     {
 419                         msg_Dbg( p_dec, "frame too big %d > %d "
 420                                  "(emulated startcode ?)", p_sys->i_frame_size,
 421                                  p_sys->i_max_frame_size );
 422                         block_SkipByte( &p_sys->bytestream );
 423                         p_sys->i_state = STATE_NOSYNC;
 424                         p_sys->i_free_frame_size = MPGA_HEADER_SIZE;
 425                         break;
 426                     }
 427
 428                     p_sys->i_frame_size++;
 429                     break;
 430                 }
 431
 432                 msg_Dbg( p_dec, "emulated startcode "
 433                          "(no startcode on following frame)" );
 434                 p_sys->i_state = STATE_NOSYNC;
 435                 block_SkipByte( &p_sys->bytestream );
 436                 break;
 437             }
 438
 439             p_sys->i_state = STATE_SEND_DATA;
 440             break;
 441
 442         case STATE_GET_DATA:
 443             /* Make sure we have enough data.
 444              * (Not useful if we went through NEXT_SYNC) */
 445             if( block_WaitBytes( &p_sys->bytestream,
 446                                  p_sys->i_frame_size ) != VLC_SUCCESS )
 447             {
 448                 /* Need more data */
 449                 return NULL;
 450             }
 451             p_sys->i_state = STATE_SEND_DATA;
 452
 453         case STATE_SEND_DATA:
 454             if( !(p_buf = GetOutBuffer( p_dec, &p_out_buffer )) )
 455             {
 456                 //p_dec->b_error = true;
 457                 return NULL;
 458             }
 459
 460             /* Free bitrate only */
 461             if( p_sys->i_bit_rate == 0 )
 462             {
 463                 p_sys->i_free_frame_size = p_sys->i_frame_size;
 464             }
 465
 466             /* Copy the whole frame into the buffer. When we reach this point
 467              * we already know we have enough data available. */
 468             block_GetBytes( &p_sys->bytestream, p_buf, p_sys->i_frame_size );
 469
 470             /* Get beginning of next frame for libmad */
 471             if( !p_sys->b_packetizer )
 472             {
 473                 memcpy( p_buf + p_sys->i_frame_size,
 474                         p_header, MAD_BUFFER_GUARD );
 475             }
 476
 477             p_sys->i_state = STATE_NOSYNC;
 478
 479             /* Make sure we don't reuse the same pts twice */
 480             if( p_sys->i_pts == p_sys->bytestream.p_block->i_pts )
 481                 p_sys->i_pts = p_sys->bytestream.p_block->i_pts = 0;
 482
 483             /* So p_block doesn't get re-added several times */
 484             *pp_block = block_BytestreamPop( &p_sys->bytestream );
 485
 486             return p_out_buffer;
 487         }
 488     }
 489
 490     return NULL;
 491 }
 492
 493 /*****************************************************************************
 494  * GetOutBuffer:
 495  *****************************************************************************/
 496 static uint8_t *GetOutBuffer( decoder_t *p_dec, void **pp_out_buffer )
 497 {
 498     decoder_sys_t *p_sys = p_dec->p_sys;
 499     uint8_t *p_buf;
 500
 501     if( p_dec->fmt_out.audio.i_rate != p_sys->i_rate )
 502     {
 503         msg_Dbg( p_dec, "MPGA channels:%d samplerate:%d bitrate:%d",
 504                   p_sys->i_channels, p_sys->i_rate, p_sys->i_bit_rate );
 505
 506         aout_DateInit( &p_sys->end_date, p_sys->i_rate );
 507         aout_DateSet( &p_sys->end_date, p_sys->i_pts );
 508     }
 509
 510     p_dec->fmt_out.audio.i_rate     = p_sys->i_rate;
 511     p_dec->fmt_out.audio.i_channels = p_sys->i_channels;
 512     p_dec->fmt_out.audio.i_frame_length = p_sys->i_frame_length;
 513     p_dec->fmt_out.audio.i_bytes_per_frame =
 514         p_sys->i_max_frame_size + MAD_BUFFER_GUARD;
 515
 516     p_dec->fmt_out.audio.i_original_channels = p_sys->i_channels_conf;
 517     p_dec->fmt_out.audio.i_physical_channels =
 518         p_sys->i_channels_conf & AOUT_CHAN_PHYSMASK;
 519
 520     p_dec->fmt_out.i_bitrate = p_sys->i_bit_rate * 1000;
 521
 522     if( p_sys->b_packetizer )
 523     {
 524         block_t *p_sout_buffer = GetSoutBuffer( p_dec );
 525         p_buf = p_sout_buffer ? p_sout_buffer->p_buffer : NULL;
 526         *pp_out_buffer = p_sout_buffer;
 527     }
 528     else
 529     {
 530         aout_buffer_t *p_aout_buffer = GetAoutBuffer( p_dec );
 531         p_buf = p_aout_buffer ? p_aout_buffer->p_buffer : NULL;
 532         *pp_out_buffer = p_aout_buffer;
 533     }
 534
 535     return p_buf;
 536 }
 537
 538 /*****************************************************************************
 539  * GetAoutBuffer:
 540  *****************************************************************************/
 541 static aout_buffer_t *GetAoutBuffer( decoder_t *p_dec )
 542 {
 543     decoder_sys_t *p_sys = p_dec->p_sys;
 544     aout_buffer_t *p_buf;
 545
 546     p_buf = p_dec->pf_aout_buffer_new( p_dec, p_sys->i_frame_length );
 547     if( p_buf == NULL ) return NULL;
 548
 549     p_buf->start_date = aout_DateGet( &p_sys->end_date );
 550     p_buf->end_date =
 551         aout_DateIncrement( &p_sys->end_date,
 552                             p_sys->i_frame_length * p_sys->i_input_rate / INPUT_RATE_DEFAULT );
 553     p_buf->b_discontinuity = p_sys->b_discontinuity;
 554     p_sys->b_discontinuity = false;
 555
 556     /* Hack for libmad filter */
 557     p_buf->i_nb_bytes = p_sys->i_frame_size + MAD_BUFFER_GUARD;
 558
 559     return p_buf;
 560 }
 561
 562 /*****************************************************************************
 563  * GetSoutBuffer:
 564  *****************************************************************************/
 565 static block_t *GetSoutBuffer( decoder_t *p_dec )
 566 {
 567     decoder_sys_t *p_sys = p_dec->p_sys;
 568     block_t *p_block;
 569
 570     p_block = block_New( p_dec, p_sys->i_frame_size );
 571     if( p_block == NULL ) return NULL;
 572
 573     p_block->i_pts = p_block->i_dts = aout_DateGet( &p_sys->end_date );
 574
 575     p_block->i_length =
 576         aout_DateIncrement( &p_sys->end_date,
 577                             p_sys->i_frame_length * p_sys->i_input_rate / INPUT_RATE_DEFAULT ) -
 578                                 p_block->i_pts;
 579
 580     return p_block;
 581 }
 582
 583 /*****************************************************************************
 584  * CloseDecoder: clean up the decoder
 585  *****************************************************************************/
 586 static void CloseDecoder( vlc_object_t *p_this )
 587 {
 588     decoder_t *p_dec = (decoder_t *)p_this;
 589     decoder_sys_t *p_sys = p_dec->p_sys;
 590
 591     block_BytestreamRelease( &p_sys->bytestream );
 592
 593     free( p_sys );
 594 }
 595
 596 /*****************************************************************************
 597  * SyncInfo: parse MPEG audio sync info
 598  *****************************************************************************/
 599 static int SyncInfo( uint32_t i_header, unsigned int * pi_channels,
 600                      unsigned int * pi_channels_conf,
 601                      unsigned int * pi_sample_rate, unsigned int * pi_bit_rate,
 602                      unsigned int * pi_frame_length,
 603                      unsigned int * pi_max_frame_size, unsigned int * pi_layer)
 604 {
 605     static const int ppi_bitrate[2][3][16] =
 606     {
 607         {
 608             /* v1 l1 */
 609             { 0, 32, 64, 96, 128, 160, 192, 224, 256, 288, 320, 352, 384,
 610               416, 448, 0},
 611             /* v1 l2 */
 612             { 0, 32, 48, 56,  64,  80,  96, 112, 128, 160, 192, 224, 256,
 613               320, 384, 0},
 614             /* v1 l3 */
 615             { 0, 32, 40, 48,  56,  64,  80,  96, 112, 128, 160, 192, 224,
 616               256, 320, 0}
 617         },
 618
 619         {
 620             /* v2 l1 */
 621             { 0, 32, 48, 56,  64,  80,  96, 112, 128, 144, 160, 176, 192,
 622               224, 256, 0},
 623             /* v2 l2 */
 624             { 0,  8, 16, 24,  32,  40,  48,  56,  64,  80,  96, 112, 128,
 625               144, 160, 0},
 626             /* v2 l3 */
 627             { 0,  8, 16, 24,  32,  40,  48,  56,  64,  80,  96, 112, 128,
 628               144, 160, 0}
 629         }
 630     };
 631
 632     static const int ppi_samplerate[2][4] = /* version 1 then 2 */
 633     {
 634         { 44100, 48000, 32000, 0 },
 635         { 22050, 24000, 16000, 0 }
 636     };
 637
 638     int i_version, i_mode, i_emphasis;
 639     bool b_padding, b_mpeg_2_5, b_crc;
 640     int i_frame_size = 0;
 641     int i_bitrate_index, i_samplerate_index;
 642     int i_max_bit_rate;
 643
 644     b_mpeg_2_5  = 1 - ((i_header & 0x100000) >> 20);
 645     i_version   = 1 - ((i_header & 0x80000) >> 19);
 646     *pi_layer   = 4 - ((i_header & 0x60000) >> 17);
 647     b_crc = !((i_header >> 16) & 0x01);
 648     i_bitrate_index = (i_header & 0xf000) >> 12;
 649     i_samplerate_index = (i_header & 0xc00) >> 10;
 650     b_padding   = (i_header & 0x200) >> 9;
 651     /* Extension */
 652     i_mode      = (i_header & 0xc0) >> 6;
 653     /* Modeext, copyright & original */
 654     i_emphasis  = i_header & 0x3;
 655
 656     if( *pi_layer != 4 &&
 657         i_bitrate_index < 0x0f &&
 658         i_samplerate_index != 0x03 &&
 659         i_emphasis != 0x02 )
 660     {
 661         switch ( i_mode )
 662         {
 663         case 0: /* stereo */
 664         case 1: /* joint stereo */
 665             *pi_channels = 2;
 666             *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT;
 667             break;
 668         case 2: /* dual-mono */
 669             *pi_channels = 2;
 670             *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 671                                 | AOUT_CHAN_DUALMONO;
 672             break;
 673         case 3: /* mono */
 674             *pi_channels = 1;
 675             *pi_channels_conf = AOUT_CHAN_CENTER;
 676             break;
 677         }
 678         *pi_bit_rate = ppi_bitrate[i_version][*pi_layer-1][i_bitrate_index];
 679         i_max_bit_rate = ppi_bitrate[i_version][*pi_layer-1][14];
 680         *pi_sample_rate = ppi_samplerate[i_version][i_samplerate_index];
 681
 682         if ( b_mpeg_2_5 )
 683         {
 684             *pi_sample_rate >>= 1;
 685         }
 686
 687         switch( *pi_layer )
 688         {
 689         case 1:
 690             i_frame_size = ( 12000 * *pi_bit_rate / *pi_sample_rate +
 691                            b_padding ) * 4;
 692             *pi_max_frame_size = ( 12000 * i_max_bit_rate /
 693                                  *pi_sample_rate + 1 ) * 4;
 694             *pi_frame_length = 384;
 695             break;
 696
 697         case 2:
 698             i_frame_size = 144000 * *pi_bit_rate / *pi_sample_rate + b_padding;
 699             *pi_max_frame_size = 144000 * i_max_bit_rate / *pi_sample_rate + 1;
 700             *pi_frame_length = 1152;
 701             break;
 702
 703         case 3:
 704             i_frame_size = ( i_version ? 72000 : 144000 ) *
 705                            *pi_bit_rate / *pi_sample_rate + b_padding;
 706             *pi_max_frame_size = ( i_version ? 72000 : 144000 ) *
 707                                  i_max_bit_rate / *pi_sample_rate + 1;
 708             *pi_frame_length = i_version ? 576 : 1152;
 709             break;
 710
 711         default:
 712             break;
 713         }
 714
 715         /* Free bitrate mode can support higher bitrates */
 716         if( !*pi_bit_rate ) *pi_max_frame_size *= 2;
 717     }
 718     else
 719     {
 720         return -1;
 721     }
 722
 723     return i_frame_size;
 724 }