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 = (p_header[0]<<24)|(p_header[1]<<16)|(p_header[2]<<8)
 268                        |p_header[3];
 269
 270             /* Check if frame is valid and get frame info */
 271             p_sys->i_frame_size = SyncInfo( i_header,
 272                                             &p_sys->i_channels,
 273                                             &p_sys->i_channels_conf,
 274                                             &p_sys->i_rate,
 275                                             &p_sys->i_bit_rate,
 276                                             &p_sys->i_frame_length,
 277                                             &p_sys->i_max_frame_size,
 278                                             &p_sys->i_layer );
 279
 280             p_dec->fmt_in.i_profile = p_sys->i_layer;
 281
 282             if( p_sys->i_frame_size == -1 )
 283             {
 284                 msg_Dbg( p_dec, "emulated startcode" );
 285                 block_SkipByte( &p_sys->bytestream );
 286                 p_sys->i_state = STATE_NOSYNC;
 287                 p_sys->b_discontinuity = true;
 288                 break;
 289             }
 290
 291             if( p_sys->i_bit_rate == 0 )
 292             {
 293                 /* Free bitrate, but 99% emulated startcode :( */
 294                 if( p_dec->p_sys->i_free_frame_size == MPGA_HEADER_SIZE )
 295                 {
 296                     msg_Dbg( p_dec, "free bitrate mode");
 297                 }
 298                 /* The -1 below is to account for the frame padding */
 299                 p_sys->i_frame_size = p_sys->i_free_frame_size - 1;
 300             }
 301
 302             p_sys->i_state = STATE_NEXT_SYNC;
 303
 304         case STATE_NEXT_SYNC:
 305             /* TODO: If p_block == NULL, flush the buffer without checking the
 306              * next sync word */
 307
 308             /* Check if next expected frame contains the sync word */
 309             if( block_PeekOffsetBytes( &p_sys->bytestream,
 310                                        p_sys->i_frame_size, p_header,
 311                                        MAD_BUFFER_GUARD ) != VLC_SUCCESS )
 312             {
 313                 /* Need more data */
 314                 return NULL;
 315             }
 316
 317             if( p_header[0] == 0xff && (p_header[1] & 0xe0) == 0xe0 )
 318             {
 319                 /* Startcode is fine, let's try the header as an extra check */
 320                 int i_next_frame_size;
 321                 unsigned int i_next_channels, i_next_channels_conf;
 322                 unsigned int i_next_rate, i_next_bit_rate;
 323                 unsigned int i_next_frame_length, i_next_max_frame_size;
 324                 unsigned int i_next_layer;
 325
 326                 /* Build frame header */
 327                 i_header = (p_header[0]<<24)|(p_header[1]<<16)|(p_header[2]<<8)
 328                            |p_header[3];
 329
 330                 i_next_frame_size = SyncInfo( i_header,
 331                                               &i_next_channels,
 332                                               &i_next_channels_conf,
 333                                               &i_next_rate,
 334                                               &i_next_bit_rate,
 335                                               &i_next_frame_length,
 336                                               &i_next_max_frame_size,
 337                                               &i_next_layer );
 338
 339                 /* Free bitrate only */
 340                 if( p_sys->i_bit_rate == 0 && i_next_frame_size == -1 )
 341                 {
 342                     if( (unsigned int)p_sys->i_frame_size >
 343                         p_sys->i_max_frame_size )
 344                     {
 345                         msg_Dbg( p_dec, "frame too big %d > %d "
 346                                  "(emulated startcode ?)", p_sys->i_frame_size,
 347                                  p_sys->i_max_frame_size );
 348                         block_SkipByte( &p_sys->bytestream );
 349                         p_sys->i_state = STATE_NOSYNC;
 350                         p_sys->i_free_frame_size = MPGA_HEADER_SIZE;
 351                         break;
 352                     }
 353
 354                     p_sys->i_frame_size++;
 355                     break;
 356                 }
 357
 358                 if( i_next_frame_size == -1 )
 359                 {
 360                     msg_Dbg( p_dec, "emulated startcode on next frame" );
 361                     block_SkipByte( &p_sys->bytestream );
 362                     p_sys->i_state = STATE_NOSYNC;
 363                     p_sys->b_discontinuity = true;
 364                     break;
 365                 }
 366
 367                 /* Check info is in sync with previous one */
 368                 if( i_next_channels_conf != p_sys->i_channels_conf ||
 369                     i_next_rate != p_sys->i_rate ||
 370                     i_next_layer != p_sys->i_layer ||
 371                     i_next_frame_length != p_sys->i_frame_length )
 372                 {
 373                     /* Free bitrate only */
 374                     if( p_sys->i_bit_rate == 0 )
 375                     {
 376                         p_sys->i_frame_size++;
 377                         break;
 378                     }
 379
 380                     msg_Dbg( p_dec, "parameters changed unexpectedly "
 381                              "(emulated startcode ?)" );
 382                     block_SkipByte( &p_sys->bytestream );
 383                     p_sys->i_state = STATE_NOSYNC;
 384                     break;
 385                 }
 386
 387                 /* Free bitrate only */
 388                 if( p_sys->i_bit_rate == 0 )
 389                 {
 390                     if( i_next_bit_rate != 0 )
 391                     {
 392                         p_sys->i_frame_size++;
 393                         break;
 394                     }
 395                 }
 396
 397             }
 398             else
 399             {
 400                 /* Free bitrate only */
 401                 if( p_sys->i_bit_rate == 0 )
 402                 {
 403                     if( (unsigned int)p_sys->i_frame_size >
 404                         p_sys->i_max_frame_size )
 405                     {
 406                         msg_Dbg( p_dec, "frame too big %d > %d "
 407                                  "(emulated startcode ?)", p_sys->i_frame_size,
 408                                  p_sys->i_max_frame_size );
 409                         block_SkipByte( &p_sys->bytestream );
 410                         p_sys->i_state = STATE_NOSYNC;
 411                         p_sys->i_free_frame_size = MPGA_HEADER_SIZE;
 412                         break;
 413                     }
 414
 415                     p_sys->i_frame_size++;
 416                     break;
 417                 }
 418
 419                 msg_Dbg( p_dec, "emulated startcode "
 420                          "(no startcode on following frame)" );
 421                 p_sys->i_state = STATE_NOSYNC;
 422                 block_SkipByte( &p_sys->bytestream );
 423                 break;
 424             }
 425
 426             p_sys->i_state = STATE_SEND_DATA;
 427             break;
 428
 429         case STATE_GET_DATA:
 430             /* Make sure we have enough data.
 431              * (Not useful if we went through NEXT_SYNC) */
 432             if( block_WaitBytes( &p_sys->bytestream,
 433                                  p_sys->i_frame_size ) != VLC_SUCCESS )
 434             {
 435                 /* Need more data */
 436                 return NULL;
 437             }
 438             p_sys->i_state = STATE_SEND_DATA;
 439
 440         case STATE_SEND_DATA:
 441             if( !(p_buf = GetOutBuffer( p_dec, &p_out_buffer )) )
 442             {
 443                 //p_dec->b_error = true;
 444                 return NULL;
 445             }
 446
 447             /* Free bitrate only */
 448             if( p_sys->i_bit_rate == 0 )
 449             {
 450                 p_sys->i_free_frame_size = p_sys->i_frame_size;
 451             }
 452
 453             /* Copy the whole frame into the buffer. */
 454             if (block_GetBytes( &p_sys->bytestream,
 455                             p_buf, __MIN( (unsigned)p_sys->i_frame_size, p_out_buffer->i_buffer ) )) {
 456                 block_Release(p_out_buffer);
 457                 return NULL;
 458             }
 459
 460             /* Get beginning of next frame for libmad */
 461             if( !p_sys->b_packetizer )
 462             {
 463                 assert( p_out_buffer->i_buffer >= (unsigned)p_sys->i_frame_size + MAD_BUFFER_GUARD );
 464                 memcpy( p_buf + p_sys->i_frame_size,
 465                         p_header, MAD_BUFFER_GUARD );
 466             }
 467
 468             p_sys->i_state = STATE_NOSYNC;
 469
 470             /* Make sure we don't reuse the same pts twice */
 471             if( p_sys->i_pts == p_sys->bytestream.p_block->i_pts )
 472                 p_sys->i_pts = p_sys->bytestream.p_block->i_pts = VLC_TS_INVALID;
 473
 474             /* So p_block doesn't get re-added several times */
 475             p_block = block_BytestreamPop( &p_sys->bytestream );
 476             if (pp_block)
 477                 *pp_block = p_block;
 478             else if (p_block)
 479                 block_Release(p_block);
 480
 481             return p_out_buffer;
 482         }
 483     }
 484
 485     return NULL;
 486 }
 487
 488 /*****************************************************************************
 489  * GetOutBuffer:
 490  *****************************************************************************/
 491 static uint8_t *GetOutBuffer( decoder_t *p_dec, block_t **pp_out_buffer )
 492 {
 493     decoder_sys_t *p_sys = p_dec->p_sys;
 494     uint8_t *p_buf;
 495
 496     if( p_dec->fmt_out.audio.i_rate != p_sys->i_rate )
 497     {
 498         msg_Dbg( p_dec, "MPGA channels:%d samplerate:%d bitrate:%d",
 499                   p_sys->i_channels, p_sys->i_rate, p_sys->i_bit_rate );
 500
 501         date_Init( &p_sys->end_date, p_sys->i_rate, 1 );
 502         date_Set( &p_sys->end_date, p_sys->i_pts );
 503     }
 504
 505     p_dec->fmt_out.audio.i_rate     = p_sys->i_rate;
 506     p_dec->fmt_out.audio.i_channels = p_sys->i_channels;
 507     p_dec->fmt_out.audio.i_frame_length = p_sys->i_frame_length;
 508     p_dec->fmt_out.audio.i_bytes_per_frame =
 509         p_sys->i_max_frame_size + MAD_BUFFER_GUARD;
 510
 511     p_dec->fmt_out.audio.i_original_channels = p_sys->i_channels_conf;
 512     p_dec->fmt_out.audio.i_physical_channels =
 513         p_sys->i_channels_conf & AOUT_CHAN_PHYSMASK;
 514
 515     p_dec->fmt_out.i_bitrate = p_sys->i_bit_rate * 1000;
 516
 517     if( p_sys->b_packetizer )
 518     {
 519         block_t *p_sout_buffer = GetSoutBuffer( p_dec );
 520         p_buf = p_sout_buffer ? p_sout_buffer->p_buffer : NULL;
 521         *pp_out_buffer = p_sout_buffer;
 522     }
 523     else
 524     {
 525         block_t *p_aout_buffer = GetAoutBuffer( p_dec );
 526         p_buf = p_aout_buffer ? p_aout_buffer->p_buffer : NULL;
 527         *pp_out_buffer = p_aout_buffer;
 528     }
 529
 530     return p_buf;
 531 }
 532
 533 /*****************************************************************************
 534  * GetAoutBuffer:
 535  *****************************************************************************/
 536 static block_t *GetAoutBuffer( decoder_t *p_dec )
 537 {
 538     decoder_sys_t *p_sys = p_dec->p_sys;
 539     block_t *p_buf;
 540
 541     p_buf = decoder_NewAudioBuffer( p_dec, p_sys->i_frame_length );
 542     if( p_buf == NULL ) return NULL;
 543
 544     p_buf->i_pts = date_Get( &p_sys->end_date );
 545     p_buf->i_length = date_Increment( &p_sys->end_date, p_sys->i_frame_length )
 546                       - p_buf->i_pts;
 547     if( p_sys->b_discontinuity )
 548         p_buf->i_flags |= BLOCK_FLAG_DISCONTINUITY;
 549     p_sys->b_discontinuity = false;
 550
 551     /* Hack for libmad filter */
 552     p_buf = block_Realloc( p_buf, 0, p_sys->i_frame_size + MAD_BUFFER_GUARD );
 553
 554     return p_buf;
 555 }
 556
 557 /*****************************************************************************
 558  * GetSoutBuffer:
 559  *****************************************************************************/
 560 static block_t *GetSoutBuffer( decoder_t *p_dec )
 561 {
 562     decoder_sys_t *p_sys = p_dec->p_sys;
 563     block_t *p_block;
 564
 565     p_block = block_Alloc( p_sys->i_frame_size );
 566     if( p_block == NULL ) return NULL;
 567
 568     p_block->i_pts = p_block->i_dts = date_Get( &p_sys->end_date );
 569
 570     p_block->i_length =
 571         date_Increment( &p_sys->end_date, p_sys->i_frame_length ) - p_block->i_pts;
 572
 573     return p_block;
 574 }
 575
 576 /*****************************************************************************
 577  * CloseDecoder: clean up the decoder
 578  *****************************************************************************/
 579 static void CloseDecoder( vlc_object_t *p_this )
 580 {
 581     decoder_t *p_dec = (decoder_t *)p_this;
 582     decoder_sys_t *p_sys = p_dec->p_sys;
 583
 584     block_BytestreamRelease( &p_sys->bytestream );
 585
 586     free( p_sys );
 587 }
 588
 589 /*****************************************************************************
 590  * SyncInfo: parse MPEG audio sync info
 591  *****************************************************************************/
 592 static int SyncInfo( uint32_t i_header, unsigned int * pi_channels,
 593                      unsigned int * pi_channels_conf,
 594                      unsigned int * pi_sample_rate, unsigned int * pi_bit_rate,
 595                      unsigned int * pi_frame_length,
 596                      unsigned int * pi_max_frame_size, unsigned int * pi_layer)
 597 {
 598     static const int ppi_bitrate[2][3][16] =
 599     {
 600         {
 601             /* v1 l1 */
 602             { 0, 32, 64, 96, 128, 160, 192, 224, 256, 288, 320, 352, 384,
 603               416, 448, 0},
 604             /* v1 l2 */
 605             { 0, 32, 48, 56,  64,  80,  96, 112, 128, 160, 192, 224, 256,
 606               320, 384, 0},
 607             /* v1 l3 */
 608             { 0, 32, 40, 48,  56,  64,  80,  96, 112, 128, 160, 192, 224,
 609               256, 320, 0}
 610         },
 611
 612         {
 613             /* v2 l1 */
 614             { 0, 32, 48, 56,  64,  80,  96, 112, 128, 144, 160, 176, 192,
 615               224, 256, 0},
 616             /* v2 l2 */
 617             { 0,  8, 16, 24,  32,  40,  48,  56,  64,  80,  96, 112, 128,
 618               144, 160, 0},
 619             /* v2 l3 */
 620             { 0,  8, 16, 24,  32,  40,  48,  56,  64,  80,  96, 112, 128,
 621               144, 160, 0}
 622         }
 623     };
 624
 625     static const int ppi_samplerate[2][4] = /* version 1 then 2 */
 626     {
 627         { 44100, 48000, 32000, 0 },
 628         { 22050, 24000, 16000, 0 }
 629     };
 630
 631     int i_version, i_mode, i_emphasis;
 632     bool b_padding, b_mpeg_2_5;
 633     int i_frame_size = 0;
 634     int i_bitrate_index, i_samplerate_index;
 635     int i_max_bit_rate;
 636
 637     b_mpeg_2_5  = 1 - ((i_header & 0x100000) >> 20);
 638     i_version   = 1 - ((i_header & 0x80000) >> 19);
 639     *pi_layer   = 4 - ((i_header & 0x60000) >> 17);
 640     //bool b_crc = !((i_header >> 16) & 0x01);
 641     i_bitrate_index = (i_header & 0xf000) >> 12;
 642     i_samplerate_index = (i_header & 0xc00) >> 10;
 643     b_padding   = (i_header & 0x200) >> 9;
 644     /* Extension */
 645     i_mode      = (i_header & 0xc0) >> 6;
 646     /* Modeext, copyright & original */
 647     i_emphasis  = i_header & 0x3;
 648
 649     if( *pi_layer != 4 &&
 650         i_bitrate_index < 0x0f &&
 651         i_samplerate_index != 0x03 &&
 652         i_emphasis != 0x02 )
 653     {
 654         switch ( i_mode )
 655         {
 656         case 0: /* stereo */
 657         case 1: /* joint stereo */
 658             *pi_channels = 2;
 659             *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT;
 660             break;
 661         case 2: /* dual-mono */
 662             *pi_channels = 2;
 663             *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 664                                 | AOUT_CHAN_DUALMONO;
 665             break;
 666         case 3: /* mono */
 667             *pi_channels = 1;
 668             *pi_channels_conf = AOUT_CHAN_CENTER;
 669             break;
 670         }
 671         *pi_bit_rate = ppi_bitrate[i_version][*pi_layer-1][i_bitrate_index];
 672         i_max_bit_rate = ppi_bitrate[i_version][*pi_layer-1][14];
 673         *pi_sample_rate = ppi_samplerate[i_version][i_samplerate_index];
 674
 675         if ( b_mpeg_2_5 )
 676         {
 677             *pi_sample_rate >>= 1;
 678         }
 679
 680         switch( *pi_layer )
 681         {
 682         case 1:
 683             i_frame_size = ( 12000 * *pi_bit_rate / *pi_sample_rate +
 684                            b_padding ) * 4;
 685             *pi_max_frame_size = ( 12000 * i_max_bit_rate /
 686                                  *pi_sample_rate + 1 ) * 4;
 687             *pi_frame_length = 384;
 688             break;
 689
 690         case 2:
 691             i_frame_size = 144000 * *pi_bit_rate / *pi_sample_rate + b_padding;
 692             *pi_max_frame_size = 144000 * i_max_bit_rate / *pi_sample_rate + 1;
 693             *pi_frame_length = 1152;
 694             break;
 695
 696         case 3:
 697             i_frame_size = ( i_version ? 72000 : 144000 ) *
 698                            *pi_bit_rate / *pi_sample_rate + b_padding;
 699             *pi_max_frame_size = ( i_version ? 72000 : 144000 ) *
 700                                  i_max_bit_rate / *pi_sample_rate + 1;
 701             *pi_frame_length = i_version ? 576 : 1152;
 702             break;
 703
 704         default:
 705             break;
 706         }
 707
 708         /* Free bitrate mode can support higher bitrates */
 709         if( !*pi_bit_rate ) *pi_max_frame_size *= 2;
 710     }
 711     else
 712     {
 713         return -1;
 714     }
 715
 716     return i_frame_size;
 717 }