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 VLC authors and 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@videolan.org>
  11  *
  12  * This program is free software; you can redistribute it and/or modify it
  13  * under the terms of the GNU Lesser General Public License as published by
  14  * the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU Lesser General Public License
  23  * along with this program; if not, write to the Free Software Foundation,
  24  * 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 <vlc_modules.h>
  39 #include <assert.h>
  40
  41 #include <vlc_block_helper.h>
  42
  43 #include "../packetizer/packetizer_helper.h"
  44
  45 /*****************************************************************************
  46  * decoder_sys_t : decoder descriptor
  47  *****************************************************************************/
  48 struct decoder_sys_t
  49 {
  50     /* Module mode */
  51     bool b_packetizer;
  52
  53     /*
  54      * Input properties
  55      */
  56     int        i_state;
  57
  58     block_bytestream_t bytestream;
  59
  60     /*
  61      * Common properties
  62      */
  63     date_t          end_date;
  64     unsigned int    i_current_layer;
  65
  66     mtime_t i_pts;
  67
  68     int i_frame_size, i_free_frame_size;
  69     unsigned int i_channels_conf, i_channels;
  70     unsigned int i_rate, i_max_frame_size, i_frame_length;
  71     unsigned int i_layer, i_bit_rate;
  72
  73     bool   b_discontinuity;
  74 };
  75
  76 /* This isn't the place to put mad-specific stuff. However, it makes the
  77  * mad plug-in's life much easier if we put 8 extra bytes at the end of the
  78  * buffer, because that way it doesn't have to copy the block_t to a bigger
  79  * buffer. This has no implication on other plug-ins, and we only lose 8 bytes
  80  * per frame. --Meuuh */
  81 #define MAD_BUFFER_GUARD 8
  82 #define MPGA_HEADER_SIZE 4
  83
  84 /****************************************************************************
  85  * Local prototypes
  86  ****************************************************************************/
  87 static int  OpenDecoder   ( vlc_object_t * );
  88 static int  OpenPacketizer( vlc_object_t * );
  89 static void CloseDecoder  ( vlc_object_t * );
  90 static block_t *DecodeBlock  ( decoder_t *, block_t ** );
  91
  92 static uint8_t *GetOutBuffer ( decoder_t *, block_t ** );
  93 static block_t *GetAoutBuffer( decoder_t * );
  94 static block_t *GetSoutBuffer( decoder_t * );
  95
  96 static int SyncInfo( uint32_t i_header, unsigned int * pi_channels,
  97                      unsigned int * pi_channels_conf,
  98                      unsigned int * pi_sample_rate, unsigned int * pi_bit_rate,
  99                      unsigned int * pi_frame_length,
 100                      unsigned int * pi_max_frame_size,
 101                      unsigned int * pi_layer );
 102
 103 /*****************************************************************************
 104  * Module descriptor
 105  *****************************************************************************/
 106 vlc_module_begin ()
 107     set_description( N_("MPEG audio layer I/II/III decoder") )
 108     set_category( CAT_INPUT )
 109     set_subcategory( SUBCAT_INPUT_ACODEC )
 110     set_capability( "decoder", 100 )
 111     set_callbacks( OpenDecoder, CloseDecoder )
 112
 113     add_submodule ()
 114     set_description( N_("MPEG audio layer I/II/III packetizer") )
 115     set_capability( "packetizer", 10 )
 116     set_callbacks( OpenPacketizer, CloseDecoder )
 117 vlc_module_end ()
 118
 119 /*****************************************************************************
 120  * Open: probe the decoder and return score
 121  *****************************************************************************/
 122 static int Open( vlc_object_t *p_this )
 123 {
 124     decoder_t *p_dec = (decoder_t*)p_this;
 125     decoder_sys_t *p_sys;
 126
 127     if( p_dec->fmt_in.i_codec != VLC_CODEC_MPGA )
 128     {
 129         return VLC_EGENERIC;
 130     }
 131
 132     /* Allocate the memory needed to store the decoder's structure */
 133     if( ( p_dec->p_sys = p_sys =
 134           (decoder_sys_t *)malloc(sizeof(decoder_sys_t)) ) == NULL )
 135         return VLC_ENOMEM;
 136
 137     /* Misc init */
 138     p_sys->b_packetizer = false;
 139     p_sys->i_state = STATE_NOSYNC;
 140     date_Set( &p_sys->end_date, 0 );
 141     block_BytestreamInit( &p_sys->bytestream );
 142     p_sys->i_pts = VLC_TS_INVALID;
 143     p_sys->b_discontinuity = false;
 144
 145     /* Set output properties */
 146     p_dec->fmt_out.i_cat = AUDIO_ES;
 147     p_dec->fmt_out.i_codec = VLC_CODEC_MPGA;
 148     p_dec->fmt_out.audio.i_rate = 0; /* So end_date gets initialized */
 149
 150     /* Set callback */
 151     p_dec->pf_decode_audio = DecodeBlock;
 152     p_dec->pf_packetize    = DecodeBlock;
 153
 154     /* Start with the minimum size for a free bitrate frame */
 155     p_sys->i_free_frame_size = MPGA_HEADER_SIZE;
 156
 157     return VLC_SUCCESS;
 158 }
 159
 160 static int OpenDecoder( vlc_object_t *p_this )
 161 {
 162     /* HACK: Don't use this codec if we don't have an mpga audio filter */
 163     if( !module_exists( "mpgatofixed32" ) )
 164         return VLC_EGENERIC;
 165
 166     return Open( p_this );
 167 }
 168
 169 static int OpenPacketizer( vlc_object_t *p_this )
 170 {
 171     decoder_t *p_dec = (decoder_t*)p_this;
 172
 173     int i_ret = Open( p_this );
 174
 175     if( i_ret == VLC_SUCCESS ) p_dec->p_sys->b_packetizer = true;
 176
 177     return i_ret;
 178 }
 179
 180 /****************************************************************************
 181  * DecodeBlock: the whole thing
 182  ****************************************************************************
 183  * This function is called just after the thread is launched.
 184  ****************************************************************************/
 185 static block_t *DecodeBlock( decoder_t *p_dec, block_t **pp_block )
 186 {
 187     decoder_sys_t *p_sys = p_dec->p_sys;
 188     uint8_t p_header[MAD_BUFFER_GUARD];
 189     uint32_t i_header;
 190     uint8_t *p_buf;
 191     block_t *p_out_buffer;
 192
 193     if( !pp_block || !*pp_block ) return NULL;
 194
 195     if( (*pp_block)->i_flags&(BLOCK_FLAG_DISCONTINUITY|BLOCK_FLAG_CORRUPTED) )
 196     {
 197         if( (*pp_block)->i_flags&BLOCK_FLAG_CORRUPTED )
 198         {
 199             p_sys->i_state = STATE_NOSYNC;
 200             block_BytestreamEmpty( &p_sys->bytestream );
 201         }
 202         date_Set( &p_sys->end_date, 0 );
 203         block_Release( *pp_block );
 204         p_sys->b_discontinuity = true;
 205         return NULL;
 206     }
 207
 208     if( !date_Get( &p_sys->end_date ) && (*pp_block)->i_pts <= VLC_TS_INVALID )
 209     {
 210         /* We've just started the stream, wait for the first PTS. */
 211         msg_Dbg( p_dec, "waiting for PTS" );
 212         block_Release( *pp_block );
 213         return NULL;
 214     }
 215
 216     block_BytestreamPush( &p_sys->bytestream, *pp_block );
 217
 218     while( 1 )
 219     {
 220         switch( p_sys->i_state )
 221         {
 222
 223         case STATE_NOSYNC:
 224             while( block_PeekBytes( &p_sys->bytestream, p_header, 2 )
 225                    == VLC_SUCCESS )
 226             {
 227                 /* Look for sync word - should be 0xffe */
 228                 if( p_header[0] == 0xff && (p_header[1] & 0xe0) == 0xe0 )
 229                 {
 230                     p_sys->i_state = STATE_SYNC;
 231                     break;
 232                 }
 233                 block_SkipByte( &p_sys->bytestream );
 234             }
 235             if( p_sys->i_state != STATE_SYNC )
 236             {
 237                 block_BytestreamFlush( &p_sys->bytestream );
 238
 239                 /* Need more data */
 240                 return NULL;
 241             }
 242
 243         case STATE_SYNC:
 244             /* New frame, set the Presentation Time Stamp */
 245             p_sys->i_pts = p_sys->bytestream.p_block->i_pts;
 246             if( p_sys->i_pts > VLC_TS_INVALID &&
 247                 p_sys->i_pts != date_Get( &p_sys->end_date ) )
 248             {
 249                 date_Set( &p_sys->end_date, p_sys->i_pts );
 250             }
 251             p_sys->i_state = STATE_HEADER;
 252
 253         case STATE_HEADER:
 254             /* Get MPGA frame header (MPGA_HEADER_SIZE bytes) */
 255             if( block_PeekBytes( &p_sys->bytestream, p_header,
 256                                  MPGA_HEADER_SIZE ) != VLC_SUCCESS )
 257             {
 258                 /* Need more data */
 259                 return NULL;
 260             }
 261
 262             /* Build frame header */
 263             i_header = (p_header[0]<<24)|(p_header[1]<<16)|(p_header[2]<<8)
 264                        |p_header[3];
 265
 266             /* Check if frame is valid and get frame info */
 267             p_sys->i_frame_size = SyncInfo( i_header,
 268                                             &p_sys->i_channels,
 269                                             &p_sys->i_channels_conf,
 270                                             &p_sys->i_rate,
 271                                             &p_sys->i_bit_rate,
 272                                             &p_sys->i_frame_length,
 273                                             &p_sys->i_max_frame_size,
 274                                             &p_sys->i_layer );
 275
 276             p_dec->fmt_in.i_profile = p_sys->i_layer;
 277
 278             if( p_sys->i_frame_size == -1 )
 279             {
 280                 msg_Dbg( p_dec, "emulated startcode" );
 281                 block_SkipByte( &p_sys->bytestream );
 282                 p_sys->i_state = STATE_NOSYNC;
 283                 p_sys->b_discontinuity = true;
 284                 break;
 285             }
 286
 287             if( p_sys->i_bit_rate == 0 )
 288             {
 289                 /* Free bitrate, but 99% emulated startcode :( */
 290                 if( p_dec->p_sys->i_free_frame_size == MPGA_HEADER_SIZE )
 291                 {
 292                     msg_Dbg( p_dec, "free bitrate mode");
 293                 }
 294                 /* The -1 below is to account for the frame padding */
 295                 p_sys->i_frame_size = p_sys->i_free_frame_size - 1;
 296             }
 297
 298             p_sys->i_state = STATE_NEXT_SYNC;
 299
 300         case STATE_NEXT_SYNC:
 301             /* TODO: If p_block == NULL, flush the buffer without checking the
 302              * next sync word */
 303
 304             /* Check if next expected frame contains the sync word */
 305             if( block_PeekOffsetBytes( &p_sys->bytestream,
 306                                        p_sys->i_frame_size, p_header,
 307                                        MAD_BUFFER_GUARD ) != VLC_SUCCESS )
 308             {
 309                 /* Need more data */
 310                 return NULL;
 311             }
 312
 313             if( p_header[0] == 0xff && (p_header[1] & 0xe0) == 0xe0 )
 314             {
 315                 /* Startcode is fine, let's try the header as an extra check */
 316                 int i_next_frame_size;
 317                 unsigned int i_next_channels, i_next_channels_conf;
 318                 unsigned int i_next_rate, i_next_bit_rate;
 319                 unsigned int i_next_frame_length, i_next_max_frame_size;
 320                 unsigned int i_next_layer;
 321
 322                 /* Build frame header */
 323                 i_header = (p_header[0]<<24)|(p_header[1]<<16)|(p_header[2]<<8)
 324                            |p_header[3];
 325
 326                 i_next_frame_size = SyncInfo( i_header,
 327                                               &i_next_channels,
 328                                               &i_next_channels_conf,
 329                                               &i_next_rate,
 330                                               &i_next_bit_rate,
 331                                               &i_next_frame_length,
 332                                               &i_next_max_frame_size,
 333                                               &i_next_layer );
 334
 335                 /* Free bitrate only */
 336                 if( p_sys->i_bit_rate == 0 && i_next_frame_size == -1 )
 337                 {
 338                     if( (unsigned int)p_sys->i_frame_size >
 339                         p_sys->i_max_frame_size )
 340                     {
 341                         msg_Dbg( p_dec, "frame too big %d > %d "
 342                                  "(emulated startcode ?)", p_sys->i_frame_size,
 343                                  p_sys->i_max_frame_size );
 344                         block_SkipByte( &p_sys->bytestream );
 345                         p_sys->i_state = STATE_NOSYNC;
 346                         p_sys->i_free_frame_size = MPGA_HEADER_SIZE;
 347                         break;
 348                     }
 349
 350                     p_sys->i_frame_size++;
 351                     break;
 352                 }
 353
 354                 if( i_next_frame_size == -1 )
 355                 {
 356                     msg_Dbg( p_dec, "emulated startcode on next frame" );
 357                     block_SkipByte( &p_sys->bytestream );
 358                     p_sys->i_state = STATE_NOSYNC;
 359                     p_sys->b_discontinuity = true;
 360                     break;
 361                 }
 362
 363                 /* Check info is in sync with previous one */
 364                 if( i_next_channels_conf != p_sys->i_channels_conf ||
 365                     i_next_rate != p_sys->i_rate ||
 366                     i_next_layer != p_sys->i_layer ||
 367                     i_next_frame_length != p_sys->i_frame_length )
 368                 {
 369                     /* Free bitrate only */
 370                     if( p_sys->i_bit_rate == 0 )
 371                     {
 372                         p_sys->i_frame_size++;
 373                         break;
 374                     }
 375
 376                     msg_Dbg( p_dec, "parameters changed unexpectedly "
 377                              "(emulated startcode ?)" );
 378                     block_SkipByte( &p_sys->bytestream );
 379                     p_sys->i_state = STATE_NOSYNC;
 380                     break;
 381                 }
 382
 383                 /* Free bitrate only */
 384                 if( p_sys->i_bit_rate == 0 )
 385                 {
 386                     if( i_next_bit_rate != 0 )
 387                     {
 388                         p_sys->i_frame_size++;
 389                         break;
 390                     }
 391                 }
 392
 393             }
 394             else
 395             {
 396                 /* Free bitrate only */
 397                 if( p_sys->i_bit_rate == 0 )
 398                 {
 399                     if( (unsigned int)p_sys->i_frame_size >
 400                         p_sys->i_max_frame_size )
 401                     {
 402                         msg_Dbg( p_dec, "frame too big %d > %d "
 403                                  "(emulated startcode ?)", p_sys->i_frame_size,
 404                                  p_sys->i_max_frame_size );
 405                         block_SkipByte( &p_sys->bytestream );
 406                         p_sys->i_state = STATE_NOSYNC;
 407                         p_sys->i_free_frame_size = MPGA_HEADER_SIZE;
 408                         break;
 409                     }
 410
 411                     p_sys->i_frame_size++;
 412                     break;
 413                 }
 414
 415                 msg_Dbg( p_dec, "emulated startcode "
 416                          "(no startcode on following frame)" );
 417                 p_sys->i_state = STATE_NOSYNC;
 418                 block_SkipByte( &p_sys->bytestream );
 419                 break;
 420             }
 421
 422             p_sys->i_state = STATE_SEND_DATA;
 423             break;
 424
 425         case STATE_GET_DATA:
 426             /* Make sure we have enough data.
 427              * (Not useful if we went through NEXT_SYNC) */
 428             if( block_WaitBytes( &p_sys->bytestream,
 429                                  p_sys->i_frame_size ) != VLC_SUCCESS )
 430             {
 431                 /* Need more data */
 432                 return NULL;
 433             }
 434             p_sys->i_state = STATE_SEND_DATA;
 435
 436         case STATE_SEND_DATA:
 437             if( !(p_buf = GetOutBuffer( p_dec, &p_out_buffer )) )
 438             {
 439                 //p_dec->b_error = true;
 440                 return NULL;
 441             }
 442
 443             /* Free bitrate only */
 444             if( p_sys->i_bit_rate == 0 )
 445             {
 446                 p_sys->i_free_frame_size = p_sys->i_frame_size;
 447             }
 448
 449             /* Copy the whole frame into the buffer. When we reach this point
 450              * we already know we have enough data available. */
 451             block_GetBytes( &p_sys->bytestream,
 452                             p_buf, __MIN( (unsigned)p_sys->i_frame_size, p_out_buffer->i_buffer ) );
 453
 454             /* Get beginning of next frame for libmad */
 455             if( !p_sys->b_packetizer )
 456             {
 457                 assert( p_out_buffer->i_buffer >= (unsigned)p_sys->i_frame_size + MAD_BUFFER_GUARD );
 458                 memcpy( p_buf + p_sys->i_frame_size,
 459                         p_header, MAD_BUFFER_GUARD );
 460             }
 461
 462             p_sys->i_state = STATE_NOSYNC;
 463
 464             /* Make sure we don't reuse the same pts twice */
 465             if( p_sys->i_pts == p_sys->bytestream.p_block->i_pts )
 466                 p_sys->i_pts = p_sys->bytestream.p_block->i_pts = VLC_TS_INVALID;
 467
 468             /* So p_block doesn't get re-added several times */
 469             *pp_block = block_BytestreamPop( &p_sys->bytestream );
 470
 471             return p_out_buffer;
 472         }
 473     }
 474
 475     return NULL;
 476 }
 477
 478 /*****************************************************************************
 479  * GetOutBuffer:
 480  *****************************************************************************/
 481 static uint8_t *GetOutBuffer( decoder_t *p_dec, block_t **pp_out_buffer )
 482 {
 483     decoder_sys_t *p_sys = p_dec->p_sys;
 484     uint8_t *p_buf;
 485
 486     if( p_dec->fmt_out.audio.i_rate != p_sys->i_rate )
 487     {
 488         msg_Dbg( p_dec, "MPGA channels:%d samplerate:%d bitrate:%d",
 489                   p_sys->i_channels, p_sys->i_rate, p_sys->i_bit_rate );
 490
 491         date_Init( &p_sys->end_date, p_sys->i_rate, 1 );
 492         date_Set( &p_sys->end_date, p_sys->i_pts );
 493     }
 494
 495     p_dec->fmt_out.audio.i_rate     = p_sys->i_rate;
 496     p_dec->fmt_out.audio.i_channels = p_sys->i_channels;
 497     p_dec->fmt_out.audio.i_frame_length = p_sys->i_frame_length;
 498     p_dec->fmt_out.audio.i_bytes_per_frame =
 499         p_sys->i_max_frame_size + MAD_BUFFER_GUARD;
 500
 501     p_dec->fmt_out.audio.i_original_channels = p_sys->i_channels_conf;
 502     p_dec->fmt_out.audio.i_physical_channels =
 503         p_sys->i_channels_conf & AOUT_CHAN_PHYSMASK;
 504
 505     p_dec->fmt_out.i_bitrate = p_sys->i_bit_rate * 1000;
 506
 507     if( p_sys->b_packetizer )
 508     {
 509         block_t *p_sout_buffer = GetSoutBuffer( p_dec );
 510         p_buf = p_sout_buffer ? p_sout_buffer->p_buffer : NULL;
 511         *pp_out_buffer = p_sout_buffer;
 512     }
 513     else
 514     {
 515         block_t *p_aout_buffer = GetAoutBuffer( p_dec );
 516         p_buf = p_aout_buffer ? p_aout_buffer->p_buffer : NULL;
 517         *pp_out_buffer = p_aout_buffer;
 518     }
 519
 520     return p_buf;
 521 }
 522
 523 /*****************************************************************************
 524  * GetAoutBuffer:
 525  *****************************************************************************/
 526 static block_t *GetAoutBuffer( decoder_t *p_dec )
 527 {
 528     decoder_sys_t *p_sys = p_dec->p_sys;
 529     block_t *p_buf;
 530
 531     p_buf = decoder_NewAudioBuffer( p_dec, p_sys->i_frame_length );
 532     if( p_buf == NULL ) return NULL;
 533
 534     p_buf->i_pts = date_Get( &p_sys->end_date );
 535     p_buf->i_length = date_Increment( &p_sys->end_date, p_sys->i_frame_length )
 536                       - p_buf->i_pts;
 537     if( p_sys->b_discontinuity )
 538         p_buf->i_flags |= BLOCK_FLAG_DISCONTINUITY;
 539     p_sys->b_discontinuity = false;
 540
 541     /* Hack for libmad filter */
 542     p_buf = block_Realloc( p_buf, 0, p_sys->i_frame_size + MAD_BUFFER_GUARD );
 543
 544     return p_buf;
 545 }
 546
 547 /*****************************************************************************
 548  * GetSoutBuffer:
 549  *****************************************************************************/
 550 static block_t *GetSoutBuffer( decoder_t *p_dec )
 551 {
 552     decoder_sys_t *p_sys = p_dec->p_sys;
 553     block_t *p_block;
 554
 555     p_block = block_Alloc( p_sys->i_frame_size );
 556     if( p_block == NULL ) return NULL;
 557
 558     p_block->i_pts = p_block->i_dts = date_Get( &p_sys->end_date );
 559
 560     p_block->i_length =
 561         date_Increment( &p_sys->end_date, p_sys->i_frame_length ) - p_block->i_pts;
 562
 563     return p_block;
 564 }
 565
 566 /*****************************************************************************
 567  * CloseDecoder: clean up the decoder
 568  *****************************************************************************/
 569 static void CloseDecoder( vlc_object_t *p_this )
 570 {
 571     decoder_t *p_dec = (decoder_t *)p_this;
 572     decoder_sys_t *p_sys = p_dec->p_sys;
 573
 574     block_BytestreamRelease( &p_sys->bytestream );
 575
 576     free( p_sys );
 577 }
 578
 579 /*****************************************************************************
 580  * SyncInfo: parse MPEG audio sync info
 581  *****************************************************************************/
 582 static int SyncInfo( uint32_t i_header, unsigned int * pi_channels,
 583                      unsigned int * pi_channels_conf,
 584                      unsigned int * pi_sample_rate, unsigned int * pi_bit_rate,
 585                      unsigned int * pi_frame_length,
 586                      unsigned int * pi_max_frame_size, unsigned int * pi_layer)
 587 {
 588     static const int ppi_bitrate[2][3][16] =
 589     {
 590         {
 591             /* v1 l1 */
 592             { 0, 32, 64, 96, 128, 160, 192, 224, 256, 288, 320, 352, 384,
 593               416, 448, 0},
 594             /* v1 l2 */
 595             { 0, 32, 48, 56,  64,  80,  96, 112, 128, 160, 192, 224, 256,
 596               320, 384, 0},
 597             /* v1 l3 */
 598             { 0, 32, 40, 48,  56,  64,  80,  96, 112, 128, 160, 192, 224,
 599               256, 320, 0}
 600         },
 601
 602         {
 603             /* v2 l1 */
 604             { 0, 32, 48, 56,  64,  80,  96, 112, 128, 144, 160, 176, 192,
 605               224, 256, 0},
 606             /* v2 l2 */
 607             { 0,  8, 16, 24,  32,  40,  48,  56,  64,  80,  96, 112, 128,
 608               144, 160, 0},
 609             /* v2 l3 */
 610             { 0,  8, 16, 24,  32,  40,  48,  56,  64,  80,  96, 112, 128,
 611               144, 160, 0}
 612         }
 613     };
 614
 615     static const int ppi_samplerate[2][4] = /* version 1 then 2 */
 616     {
 617         { 44100, 48000, 32000, 0 },
 618         { 22050, 24000, 16000, 0 }
 619     };
 620
 621     int i_version, i_mode, i_emphasis;
 622     bool b_padding, b_mpeg_2_5;
 623     int i_frame_size = 0;
 624     int i_bitrate_index, i_samplerate_index;
 625     int i_max_bit_rate;
 626
 627     b_mpeg_2_5  = 1 - ((i_header & 0x100000) >> 20);
 628     i_version   = 1 - ((i_header & 0x80000) >> 19);
 629     *pi_layer   = 4 - ((i_header & 0x60000) >> 17);
 630     //bool b_crc = !((i_header >> 16) & 0x01);
 631     i_bitrate_index = (i_header & 0xf000) >> 12;
 632     i_samplerate_index = (i_header & 0xc00) >> 10;
 633     b_padding   = (i_header & 0x200) >> 9;
 634     /* Extension */
 635     i_mode      = (i_header & 0xc0) >> 6;
 636     /* Modeext, copyright & original */
 637     i_emphasis  = i_header & 0x3;
 638
 639     if( *pi_layer != 4 &&
 640         i_bitrate_index < 0x0f &&
 641         i_samplerate_index != 0x03 &&
 642         i_emphasis != 0x02 )
 643     {
 644         switch ( i_mode )
 645         {
 646         case 0: /* stereo */
 647         case 1: /* joint stereo */
 648             *pi_channels = 2;
 649             *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT;
 650             break;
 651         case 2: /* dual-mono */
 652             *pi_channels = 2;
 653             *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 654                                 | AOUT_CHAN_DUALMONO;
 655             break;
 656         case 3: /* mono */
 657             *pi_channels = 1;
 658             *pi_channels_conf = AOUT_CHAN_CENTER;
 659             break;
 660         }
 661         *pi_bit_rate = ppi_bitrate[i_version][*pi_layer-1][i_bitrate_index];
 662         i_max_bit_rate = ppi_bitrate[i_version][*pi_layer-1][14];
 663         *pi_sample_rate = ppi_samplerate[i_version][i_samplerate_index];
 664
 665         if ( b_mpeg_2_5 )
 666         {
 667             *pi_sample_rate >>= 1;
 668         }
 669
 670         switch( *pi_layer )
 671         {
 672         case 1:
 673             i_frame_size = ( 12000 * *pi_bit_rate / *pi_sample_rate +
 674                            b_padding ) * 4;
 675             *pi_max_frame_size = ( 12000 * i_max_bit_rate /
 676                                  *pi_sample_rate + 1 ) * 4;
 677             *pi_frame_length = 384;
 678             break;
 679
 680         case 2:
 681             i_frame_size = 144000 * *pi_bit_rate / *pi_sample_rate + b_padding;
 682             *pi_max_frame_size = 144000 * i_max_bit_rate / *pi_sample_rate + 1;
 683             *pi_frame_length = 1152;
 684             break;
 685
 686         case 3:
 687             i_frame_size = ( i_version ? 72000 : 144000 ) *
 688                            *pi_bit_rate / *pi_sample_rate + b_padding;
 689             *pi_max_frame_size = ( i_version ? 72000 : 144000 ) *
 690                                  i_max_bit_rate / *pi_sample_rate + 1;
 691             *pi_frame_length = i_version ? 576 : 1152;
 692             break;
 693
 694         default:
 695             break;
 696         }
 697
 698         /* Free bitrate mode can support higher bitrates */
 699         if( !*pi_bit_rate ) *pi_max_frame_size *= 2;
 700     }
 701     else
 702     {
 703         return -1;
 704     }
 705
 706     return i_frame_size;
 707 }