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