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