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        ( p_dec->fmt_in.i_codec != VLC_CODEC_MP3 ) )
 129     {
 130         return VLC_EGENERIC;
 131     }
 132
 133     /* Allocate the memory needed to store the decoder's structure */
 134     if( ( p_dec->p_sys = p_sys =
 135           (decoder_sys_t *)malloc(sizeof(decoder_sys_t)) ) == NULL )
 136         return VLC_ENOMEM;
 137
 138     /* Misc init */
 139     p_sys->b_packetizer = false;
 140     p_sys->i_state = STATE_NOSYNC;
 141     date_Set( &p_sys->end_date, 0 );
 142     block_BytestreamInit( &p_sys->bytestream );
 143     p_sys->i_pts = VLC_TS_INVALID;
 144     p_sys->b_discontinuity = false;
 145
 146     /* Set output properties */
 147     p_dec->fmt_out.i_cat = AUDIO_ES;
 148     p_dec->fmt_out.i_codec = VLC_CODEC_MPGA;
 149     p_dec->fmt_out.audio.i_rate = 0; /* So end_date gets initialized */
 150
 151     /* Set callback */
 152     p_dec->pf_decode_audio = DecodeBlock;
 153     p_dec->pf_packetize    = DecodeBlock;
 154
 155     /* Start with the minimum size for a free bitrate frame */
 156     p_sys->i_free_frame_size = MPGA_HEADER_SIZE;
 157
 158     return VLC_SUCCESS;
 159 }
 160
 161 static int OpenDecoder( vlc_object_t *p_this )
 162 {
 163     /* HACK: Don't use this codec if we don't have an mpga audio filter */
 164     if( !module_exists( "mpgatofixed32" ) )
 165         return VLC_EGENERIC;
 166
 167     return Open( p_this );
 168 }
 169
 170 static int OpenPacketizer( vlc_object_t *p_this )
 171 {
 172     decoder_t *p_dec = (decoder_t*)p_this;
 173
 174     int i_ret = Open( p_this );
 175
 176     if( i_ret == VLC_SUCCESS ) p_dec->p_sys->b_packetizer = true;
 177
 178     return i_ret;
 179 }
 180
 181 /****************************************************************************
 182  * DecodeBlock: the whole thing
 183  ****************************************************************************
 184  * This function is called just after the thread is launched.
 185  ****************************************************************************/
 186 static block_t *DecodeBlock( decoder_t *p_dec, block_t **pp_block )
 187 {
 188     decoder_sys_t *p_sys = p_dec->p_sys;
 189     uint8_t p_header[MAD_BUFFER_GUARD];
 190     uint32_t i_header;
 191     uint8_t *p_buf;
 192     block_t *p_out_buffer;
 193
 194     block_t *p_block = pp_block ? *pp_block : NULL;
 195
 196     if (p_block) {
 197         if( p_block->i_flags&(BLOCK_FLAG_DISCONTINUITY|BLOCK_FLAG_CORRUPTED) )
 198         {
 199             if( p_block->i_flags&BLOCK_FLAG_CORRUPTED )
 200             {
 201                 p_sys->i_state = STATE_NOSYNC;
 202                 block_BytestreamEmpty( &p_sys->bytestream );
 203             }
 204             date_Set( &p_sys->end_date, 0 );
 205             block_Release( p_block );
 206             p_sys->b_discontinuity = true;
 207             return NULL;
 208         }
 209
 210         if( !date_Get( &p_sys->end_date ) && p_block->i_pts <= VLC_TS_INVALID )
 211         {
 212             /* We've just started the stream, wait for the first PTS. */
 213             msg_Dbg( p_dec, "waiting for PTS" );
 214             block_Release( p_block );
 215             return NULL;
 216         }
 217
 218         block_BytestreamPush( &p_sys->bytestream, p_block );
 219     } else
 220         p_sys->i_state = STATE_SEND_DATA; /* return all the data we have left */
 221
 222     while( 1 )
 223     {
 224         switch( p_sys->i_state )
 225         {
 226
 227         case STATE_NOSYNC:
 228             while( block_PeekBytes( &p_sys->bytestream, p_header, 2 )
 229                    == VLC_SUCCESS )
 230             {
 231                 /* Look for sync word - should be 0xffe */
 232                 if( p_header[0] == 0xff && (p_header[1] & 0xe0) == 0xe0 )
 233                 {
 234                     p_sys->i_state = STATE_SYNC;
 235                     break;
 236                 }
 237                 block_SkipByte( &p_sys->bytestream );
 238             }
 239             if( p_sys->i_state != STATE_SYNC )
 240             {
 241                 block_BytestreamFlush( &p_sys->bytestream );
 242
 243                 /* Need more data */
 244                 return NULL;
 245             }
 246
 247         case STATE_SYNC:
 248             /* New frame, set the Presentation Time Stamp */
 249             p_sys->i_pts = p_sys->bytestream.p_block->i_pts;
 250             if( p_sys->i_pts > VLC_TS_INVALID &&
 251                 p_sys->i_pts > date_Get( &p_sys->end_date ) )
 252             {
 253                 date_Set( &p_sys->end_date, p_sys->i_pts );
 254             }
 255             p_sys->i_state = STATE_HEADER;
 256
 257         case STATE_HEADER:
 258             /* Get MPGA frame header (MPGA_HEADER_SIZE bytes) */
 259             if( block_PeekBytes( &p_sys->bytestream, p_header,
 260                                  MPGA_HEADER_SIZE ) != VLC_SUCCESS )
 261             {
 262                 /* Need more data */
 263                 return NULL;
 264             }
 265
 266             /* Build frame header */
 267             i_header = GetDWBE(p_header);
 268
 269             /* Check if frame is valid and get frame info */
 270             p_sys->i_frame_size = SyncInfo( i_header,
 271                                             &p_sys->i_channels,
 272                                             &p_sys->i_channels_conf,
 273                                             &p_sys->i_rate,
 274                                             &p_sys->i_bit_rate,
 275                                             &p_sys->i_frame_length,
 276                                             &p_sys->i_max_frame_size,
 277                                             &p_sys->i_layer );
 278
 279             p_dec->fmt_in.i_profile = p_sys->i_layer;
 280
 281             if( p_sys->i_frame_size == -1 )
 282             {
 283                 msg_Dbg( p_dec, "emulated startcode" );
 284                 block_SkipByte( &p_sys->bytestream );
 285                 p_sys->i_state = STATE_NOSYNC;
 286                 p_sys->b_discontinuity = true;
 287                 break;
 288             }
 289
 290             if( p_sys->i_bit_rate == 0 )
 291             {
 292                 /* Free bitrate, but 99% emulated startcode :( */
 293                 if( p_dec->p_sys->i_free_frame_size == MPGA_HEADER_SIZE )
 294                 {
 295                     msg_Dbg( p_dec, "free bitrate mode");
 296                 }
 297                 /* The -1 below is to account for the frame padding */
 298                 p_sys->i_frame_size = p_sys->i_free_frame_size - 1;
 299             }
 300
 301             p_sys->i_state = STATE_NEXT_SYNC;
 302
 303         case STATE_NEXT_SYNC:
 304             /* TODO: If p_block == NULL, flush the buffer without checking the
 305              * next sync word */
 306
 307             /* Check if next expected frame contains the sync word */
 308             if( block_PeekOffsetBytes( &p_sys->bytestream,
 309                                        p_sys->i_frame_size, p_header,
 310                                        MAD_BUFFER_GUARD ) != VLC_SUCCESS )
 311             {
 312                 /* Need more data */
 313                 return NULL;
 314             }
 315
 316             if( p_header[0] == 0xff && (p_header[1] & 0xe0) == 0xe0 )
 317             {
 318                 /* Startcode is fine, let's try the header as an extra check */
 319                 int i_next_frame_size;
 320                 unsigned int i_next_channels, i_next_channels_conf;
 321                 unsigned int i_next_rate, i_next_bit_rate;
 322                 unsigned int i_next_frame_length, i_next_max_frame_size;
 323                 unsigned int i_next_layer;
 324
 325                 /* Build frame header */
 326                 i_header = GetDWBE(p_header);
 327
 328                 i_next_frame_size = SyncInfo( i_header,
 329                                               &i_next_channels,
 330                                               &i_next_channels_conf,
 331                                               &i_next_rate,
 332                                               &i_next_bit_rate,
 333                                               &i_next_frame_length,
 334                                               &i_next_max_frame_size,
 335                                               &i_next_layer );
 336
 337                 /* Free bitrate only */
 338                 if( p_sys->i_bit_rate == 0 && i_next_frame_size == -1 )
 339                 {
 340                     if( (unsigned int)p_sys->i_frame_size >
 341                         p_sys->i_max_frame_size )
 342                     {
 343                         msg_Dbg( p_dec, "frame too big %d > %d "
 344                                  "(emulated startcode ?)", p_sys->i_frame_size,
 345                                  p_sys->i_max_frame_size );
 346                         block_SkipByte( &p_sys->bytestream );
 347                         p_sys->i_state = STATE_NOSYNC;
 348                         p_sys->i_free_frame_size = MPGA_HEADER_SIZE;
 349                         break;
 350                     }
 351
 352                     p_sys->i_frame_size++;
 353                     break;
 354                 }
 355
 356                 if( i_next_frame_size == -1 )
 357                 {
 358                     msg_Dbg( p_dec, "emulated startcode on next frame" );
 359                     block_SkipByte( &p_sys->bytestream );
 360                     p_sys->i_state = STATE_NOSYNC;
 361                     p_sys->b_discontinuity = true;
 362                     break;
 363                 }
 364
 365                 /* Check info is in sync with previous one */
 366                 if( i_next_channels_conf != p_sys->i_channels_conf ||
 367                     i_next_rate != p_sys->i_rate ||
 368                     i_next_layer != p_sys->i_layer ||
 369                     i_next_frame_length != p_sys->i_frame_length )
 370                 {
 371                     /* Free bitrate only */
 372                     if( p_sys->i_bit_rate == 0 )
 373                     {
 374                         p_sys->i_frame_size++;
 375                         break;
 376                     }
 377
 378                     msg_Dbg( p_dec, "parameters changed unexpectedly "
 379                              "(emulated startcode ?)" );
 380                     block_SkipByte( &p_sys->bytestream );
 381                     p_sys->i_state = STATE_NOSYNC;
 382                     break;
 383                 }
 384
 385                 /* Free bitrate only */
 386                 if( p_sys->i_bit_rate == 0 )
 387                 {
 388                     if( i_next_bit_rate != 0 )
 389                     {
 390                         p_sys->i_frame_size++;
 391                         break;
 392                     }
 393                 }
 394
 395             }
 396             else
 397             {
 398                 /* Free bitrate only */
 399                 if( p_sys->i_bit_rate == 0 )
 400                 {
 401                     if( (unsigned int)p_sys->i_frame_size >
 402                         p_sys->i_max_frame_size )
 403                     {
 404                         msg_Dbg( p_dec, "frame too big %d > %d "
 405                                  "(emulated startcode ?)", p_sys->i_frame_size,
 406                                  p_sys->i_max_frame_size );
 407                         block_SkipByte( &p_sys->bytestream );
 408                         p_sys->i_state = STATE_NOSYNC;
 409                         p_sys->i_free_frame_size = MPGA_HEADER_SIZE;
 410                         break;
 411                     }
 412
 413                     p_sys->i_frame_size++;
 414                     break;
 415                 }
 416
 417                 msg_Dbg( p_dec, "emulated startcode "
 418                          "(no startcode on following frame)" );
 419                 p_sys->i_state = STATE_NOSYNC;
 420                 block_SkipByte( &p_sys->bytestream );
 421                 break;
 422             }
 423
 424             p_sys->i_state = STATE_SEND_DATA;
 425             break;
 426
 427         case STATE_GET_DATA:
 428             /* Make sure we have enough data.
 429              * (Not useful if we went through NEXT_SYNC) */
 430             if( block_WaitBytes( &p_sys->bytestream,
 431                                  p_sys->i_frame_size ) != VLC_SUCCESS )
 432             {
 433                 /* Need more data */
 434                 return NULL;
 435             }
 436             p_sys->i_state = STATE_SEND_DATA;
 437
 438         case STATE_SEND_DATA:
 439             if( !(p_buf = GetOutBuffer( p_dec, &p_out_buffer )) )
 440             {
 441                 //p_dec->b_error = true;
 442                 return NULL;
 443             }
 444
 445             /* Free bitrate only */
 446             if( p_sys->i_bit_rate == 0 )
 447             {
 448                 p_sys->i_free_frame_size = p_sys->i_frame_size;
 449             }
 450
 451             /* Copy the whole frame into the buffer. */
 452             if (block_GetBytes( &p_sys->bytestream,
 453                             p_buf, __MIN( (unsigned)p_sys->i_frame_size, p_out_buffer->i_buffer ) )) {
 454                 block_Release(p_out_buffer);
 455                 return NULL;
 456             }
 457
 458             /* Get beginning of next frame for libmad */
 459             if( !p_sys->b_packetizer )
 460             {
 461                 assert( p_out_buffer->i_buffer >= (unsigned)p_sys->i_frame_size + MAD_BUFFER_GUARD );
 462                 memcpy( p_buf + p_sys->i_frame_size,
 463                         p_header, MAD_BUFFER_GUARD );
 464             }
 465
 466             p_sys->i_state = STATE_NOSYNC;
 467
 468             /* Make sure we don't reuse the same pts twice */
 469             if( p_sys->i_pts == p_sys->bytestream.p_block->i_pts )
 470                 p_sys->i_pts = p_sys->bytestream.p_block->i_pts = VLC_TS_INVALID;
 471
 472             /* So p_block doesn't get re-added several times */
 473             p_block = block_BytestreamPop( &p_sys->bytestream );
 474             if (pp_block)
 475                 *pp_block = p_block;
 476             else if (p_block)
 477                 block_Release(p_block);
 478
 479             return p_out_buffer;
 480         }
 481     }
 482
 483     return NULL;
 484 }
 485
 486 /*****************************************************************************
 487  * GetOutBuffer:
 488  *****************************************************************************/
 489 static uint8_t *GetOutBuffer( decoder_t *p_dec, block_t **pp_out_buffer )
 490 {
 491     decoder_sys_t *p_sys = p_dec->p_sys;
 492     uint8_t *p_buf;
 493
 494     if( p_dec->fmt_out.audio.i_rate != p_sys->i_rate )
 495     {
 496         msg_Dbg( p_dec, "MPGA channels:%d samplerate:%d bitrate:%d",
 497                   p_sys->i_channels, p_sys->i_rate, p_sys->i_bit_rate );
 498
 499         date_Init( &p_sys->end_date, p_sys->i_rate, 1 );
 500         date_Set( &p_sys->end_date, p_sys->i_pts );
 501     }
 502
 503     p_dec->fmt_out.audio.i_rate     = p_sys->i_rate;
 504     p_dec->fmt_out.audio.i_channels = p_sys->i_channels;
 505     p_dec->fmt_out.audio.i_frame_length = p_sys->i_frame_length;
 506     p_dec->fmt_out.audio.i_bytes_per_frame =
 507         p_sys->i_max_frame_size + MAD_BUFFER_GUARD;
 508
 509     p_dec->fmt_out.audio.i_original_channels = p_sys->i_channels_conf;
 510     p_dec->fmt_out.audio.i_physical_channels =
 511         p_sys->i_channels_conf & AOUT_CHAN_PHYSMASK;
 512
 513     p_dec->fmt_out.i_bitrate = p_sys->i_bit_rate * 1000;
 514
 515     if( p_sys->b_packetizer )
 516     {
 517         block_t *p_sout_buffer = GetSoutBuffer( p_dec );
 518         p_buf = p_sout_buffer ? p_sout_buffer->p_buffer : NULL;
 519         *pp_out_buffer = p_sout_buffer;
 520     }
 521     else
 522     {
 523         block_t *p_aout_buffer = GetAoutBuffer( p_dec );
 524         p_buf = p_aout_buffer ? p_aout_buffer->p_buffer : NULL;
 525         *pp_out_buffer = p_aout_buffer;
 526     }
 527
 528     return p_buf;
 529 }
 530
 531 /*****************************************************************************
 532  * GetAoutBuffer:
 533  *****************************************************************************/
 534 static block_t *GetAoutBuffer( decoder_t *p_dec )
 535 {
 536     decoder_sys_t *p_sys = p_dec->p_sys;
 537     block_t *p_buf;
 538
 539     p_buf = decoder_NewAudioBuffer( p_dec, p_sys->i_frame_length );
 540     if( p_buf == NULL ) return NULL;
 541
 542     p_buf->i_pts = date_Get( &p_sys->end_date );
 543     p_buf->i_length = date_Increment( &p_sys->end_date, p_sys->i_frame_length )
 544                       - p_buf->i_pts;
 545     if( p_sys->b_discontinuity )
 546         p_buf->i_flags |= BLOCK_FLAG_DISCONTINUITY;
 547     p_sys->b_discontinuity = false;
 548
 549     /* Hack for libmad filter */
 550     p_buf = block_Realloc( p_buf, 0, p_sys->i_frame_size + MAD_BUFFER_GUARD );
 551
 552     return p_buf;
 553 }
 554
 555 /*****************************************************************************
 556  * GetSoutBuffer:
 557  *****************************************************************************/
 558 static block_t *GetSoutBuffer( decoder_t *p_dec )
 559 {
 560     decoder_sys_t *p_sys = p_dec->p_sys;
 561     block_t *p_block;
 562
 563     p_block = block_Alloc( p_sys->i_frame_size );
 564     if( p_block == NULL ) return NULL;
 565
 566     p_block->i_pts = p_block->i_dts = date_Get( &p_sys->end_date );
 567
 568     p_block->i_length =
 569         date_Increment( &p_sys->end_date, p_sys->i_frame_length ) - p_block->i_pts;
 570
 571     return p_block;
 572 }
 573
 574 /*****************************************************************************
 575  * CloseDecoder: clean up the decoder
 576  *****************************************************************************/
 577 static void CloseDecoder( vlc_object_t *p_this )
 578 {
 579     decoder_t *p_dec = (decoder_t *)p_this;
 580     decoder_sys_t *p_sys = p_dec->p_sys;
 581
 582     block_BytestreamRelease( &p_sys->bytestream );
 583
 584     free( p_sys );
 585 }
 586
 587 /*****************************************************************************
 588  * SyncInfo: parse MPEG audio sync info
 589  *****************************************************************************/
 590 static int SyncInfo( uint32_t i_header, unsigned int * pi_channels,
 591                      unsigned int * pi_channels_conf,
 592                      unsigned int * pi_sample_rate, unsigned int * pi_bit_rate,
 593                      unsigned int * pi_frame_length,
 594                      unsigned int * pi_max_frame_size, unsigned int * pi_layer)
 595 {
 596     static const int ppi_bitrate[2][3][16] =
 597     {
 598         {
 599             /* v1 l1 */
 600             { 0, 32, 64, 96, 128, 160, 192, 224, 256, 288, 320, 352, 384,
 601               416, 448, 0},
 602             /* v1 l2 */
 603             { 0, 32, 48, 56,  64,  80,  96, 112, 128, 160, 192, 224, 256,
 604               320, 384, 0},
 605             /* v1 l3 */
 606             { 0, 32, 40, 48,  56,  64,  80,  96, 112, 128, 160, 192, 224,
 607               256, 320, 0}
 608         },
 609
 610         {
 611             /* v2 l1 */
 612             { 0, 32, 48, 56,  64,  80,  96, 112, 128, 144, 160, 176, 192,
 613               224, 256, 0},
 614             /* v2 l2 */
 615             { 0,  8, 16, 24,  32,  40,  48,  56,  64,  80,  96, 112, 128,
 616               144, 160, 0},
 617             /* v2 l3 */
 618             { 0,  8, 16, 24,  32,  40,  48,  56,  64,  80,  96, 112, 128,
 619               144, 160, 0}
 620         }
 621     };
 622
 623     static const int ppi_samplerate[2][4] = /* version 1 then 2 */
 624     {
 625         { 44100, 48000, 32000, 0 },
 626         { 22050, 24000, 16000, 0 }
 627     };
 628
 629     int i_version, i_mode, i_emphasis;
 630     bool b_padding, b_mpeg_2_5;
 631     int i_frame_size = 0;
 632     int i_bitrate_index, i_samplerate_index;
 633     int i_max_bit_rate;
 634
 635     b_mpeg_2_5  = 1 - ((i_header & 0x100000) >> 20);
 636     i_version   = 1 - ((i_header & 0x80000) >> 19);
 637     *pi_layer   = 4 - ((i_header & 0x60000) >> 17);
 638     //bool b_crc = !((i_header >> 16) & 0x01);
 639     i_bitrate_index = (i_header & 0xf000) >> 12;
 640     i_samplerate_index = (i_header & 0xc00) >> 10;
 641     b_padding   = (i_header & 0x200) >> 9;
 642     /* Extension */
 643     i_mode      = (i_header & 0xc0) >> 6;
 644     /* Modeext, copyright & original */
 645     i_emphasis  = i_header & 0x3;
 646
 647     if( *pi_layer != 4 &&
 648         i_bitrate_index < 0x0f &&
 649         i_samplerate_index != 0x03 &&
 650         i_emphasis != 0x02 )
 651     {
 652         switch ( i_mode )
 653         {
 654         case 0: /* stereo */
 655         case 1: /* joint stereo */
 656             *pi_channels = 2;
 657             *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT;
 658             break;
 659         case 2: /* dual-mono */
 660             *pi_channels = 2;
 661             *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 662                                 | AOUT_CHAN_DUALMONO;
 663             break;
 664         case 3: /* mono */
 665             *pi_channels = 1;
 666             *pi_channels_conf = AOUT_CHAN_CENTER;
 667             break;
 668         }
 669         *pi_bit_rate = ppi_bitrate[i_version][*pi_layer-1][i_bitrate_index];
 670         i_max_bit_rate = ppi_bitrate[i_version][*pi_layer-1][14];
 671         *pi_sample_rate = ppi_samplerate[i_version][i_samplerate_index];
 672
 673         if ( b_mpeg_2_5 )
 674         {
 675             *pi_sample_rate >>= 1;
 676         }
 677
 678         switch( *pi_layer )
 679         {
 680         case 1:
 681             i_frame_size = ( 12000 * *pi_bit_rate / *pi_sample_rate +
 682                            b_padding ) * 4;
 683             *pi_max_frame_size = ( 12000 * i_max_bit_rate /
 684                                  *pi_sample_rate + 1 ) * 4;
 685             *pi_frame_length = 384;
 686             break;
 687
 688         case 2:
 689             i_frame_size = 144000 * *pi_bit_rate / *pi_sample_rate + b_padding;
 690             *pi_max_frame_size = 144000 * i_max_bit_rate / *pi_sample_rate + 1;
 691             *pi_frame_length = 1152;
 692             break;
 693
 694         case 3:
 695             i_frame_size = ( i_version ? 72000 : 144000 ) *
 696                            *pi_bit_rate / *pi_sample_rate + b_padding;
 697             *pi_max_frame_size = ( i_version ? 72000 : 144000 ) *
 698                                  i_max_bit_rate / *pi_sample_rate + 1;
 699             *pi_frame_length = i_version ? 576 : 1152;
 700             break;
 701
 702         default:
 703             break;
 704         }
 705
 706         /* Free bitrate mode can support higher bitrates */
 707         if( !*pi_bit_rate ) *pi_max_frame_size *= 2;
 708     }
 709     else
 710     {
 711         return -1;
 712     }
 713
 714     return i_frame_size;
 715 }