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 #ifdef HAVE_MPGA_FILTER
  51     /* Module mode */
  52     bool b_packetizer;
  53 #endif
  54     /*
  55      * Input properties
  56      */
  57     int        i_state;
  58
  59     block_bytestream_t bytestream;
  60
  61     /*
  62      * Common properties
  63      */
  64     date_t          end_date;
  65     unsigned int    i_current_layer;
  66
  67     mtime_t i_pts;
  68
  69     int i_frame_size, i_free_frame_size;
  70     unsigned int i_channels_conf, i_channels;
  71     unsigned int i_rate, i_max_frame_size, i_frame_length;
  72     unsigned int i_layer, i_bit_rate;
  73
  74     bool   b_discontinuity;
  75 };
  76
  77 /* This isn't the place to put mad-specific stuff. However, it makes the
  78  * mad plug-in's life much easier if we put 8 extra bytes at the end of the
  79  * buffer, because that way it doesn't have to copy the block_t to a bigger
  80  * buffer. This has no implication on other plug-ins, and we only lose 8 bytes
  81  * per frame. --Meuuh */
  82 #define MAD_BUFFER_GUARD 8
  83 #define MPGA_HEADER_SIZE 4
  84
  85 /****************************************************************************
  86  * Local prototypes
  87  ****************************************************************************/
  88
  89 #ifdef HAVE_MPGA_FILTER
  90 static int  OpenDecoder   ( vlc_object_t * );
  91 static block_t *GetAoutBuffer( decoder_t * );
  92 #endif
  93 static int  Open( vlc_object_t * );
  94 static block_t *DecodeBlock  ( decoder_t *, block_t ** );
  95 static uint8_t *GetOutBuffer ( decoder_t *, block_t ** );
  96 static block_t *GetSoutBuffer( decoder_t * );
  97 static void Close(  vlc_object_t * );
  98 static int SyncInfo( uint32_t i_header, unsigned int * pi_channels,
  99                      unsigned int * pi_channels_conf,
 100                      unsigned int * pi_sample_rate, unsigned int * pi_bit_rate,
 101                      unsigned int * pi_frame_length,
 102                      unsigned int * pi_max_frame_size,
 103                      unsigned int * pi_layer );
 104
 105 /*****************************************************************************
 106  * Module descriptor
 107  *****************************************************************************/
 108 vlc_module_begin ()
 109     set_category( CAT_INPUT )
 110     set_subcategory( SUBCAT_INPUT_ACODEC )
 111     set_description( N_("MPEG audio layer I/II/III packetizer") )
 112     set_capability( "packetizer", 10 )
 113     set_callbacks( Open, Close )
 114 #ifdef HAVE_MPGA_FILTER
 115     add_submodule ()
 116     set_description( N_("MPEG audio layer I/II/III decoder") )
 117     set_capability( "decoder", 100 )
 118     set_callbacks( OpenDecoder, Close )
 119 #endif
 120 vlc_module_end ()
 121
 122 /*****************************************************************************
 123  * Open: probe the decoder and return score
 124  *****************************************************************************/
 125 static int Open( vlc_object_t *p_this )
 126 {
 127     decoder_t *p_dec = (decoder_t*)p_this;
 128     decoder_sys_t *p_sys;
 129
 130     if(( p_dec->fmt_in.i_codec != VLC_CODEC_MPGA ) &&
 131        ( p_dec->fmt_in.i_codec != VLC_CODEC_MP3 ) )
 132     {
 133         return VLC_EGENERIC;
 134     }
 135
 136     /* Allocate the memory needed to store the decoder's structure */
 137     if( ( p_dec->p_sys = p_sys =
 138           (decoder_sys_t *)malloc(sizeof(decoder_sys_t)) ) == NULL )
 139         return VLC_ENOMEM;
 140
 141     /* Misc init */
 142 #ifdef HAVE_MPGA_FILTER
 143     p_sys->b_packetizer = true;
 144 #endif
 145     p_sys->i_state = STATE_NOSYNC;
 146     date_Set( &p_sys->end_date, 0 );
 147     block_BytestreamInit( &p_sys->bytestream );
 148     p_sys->i_pts = VLC_TS_INVALID;
 149     p_sys->b_discontinuity = false;
 150
 151     /* Set output properties */
 152     p_dec->fmt_out.i_cat = AUDIO_ES;
 153     p_dec->fmt_out.i_codec = VLC_CODEC_MPGA;
 154     p_dec->fmt_out.audio.i_rate = 0; /* So end_date gets initialized */
 155
 156     /* Set callback */
 157     p_dec->pf_decode_audio = DecodeBlock;
 158     p_dec->pf_packetize    = DecodeBlock;
 159
 160     /* Start with the minimum size for a free bitrate frame */
 161     p_sys->i_free_frame_size = MPGA_HEADER_SIZE;
 162
 163     return VLC_SUCCESS;
 164 }
 165
 166 #ifdef HAVE_MPGA_FILTER
 167 static int OpenDecoder( vlc_object_t *p_this )
 168 {
 169     decoder_t *p_dec = (decoder_t *)p_this;
 170
 171     /* HACK: Don't use this codec if we don't have an mpga audio filter */
 172     if( !module_exists( "mad" ) )
 173         return VLC_EGENERIC;
 174
 175     int i_ret = Open( p_this );
 176     if( i_ret != VLC_SUCCESS )
 177         return i_ret;
 178
 179     p_dec->p_sys->b_packetizer = false;
 180     return VLC_SUCCESS;
 181 }
 182 #endif
 183
 184 /****************************************************************************
 185  * DecodeBlock: the whole thing
 186  ****************************************************************************
 187  * This function is called just after the thread is launched.
 188  ****************************************************************************/
 189 static block_t *DecodeBlock( decoder_t *p_dec, block_t **pp_block )
 190 {
 191     decoder_sys_t *p_sys = p_dec->p_sys;
 192     uint8_t p_header[MAD_BUFFER_GUARD];
 193     uint32_t i_header;
 194     uint8_t *p_buf;
 195     block_t *p_out_buffer;
 196
 197     block_t *p_block = pp_block ? *pp_block : NULL;
 198
 199     if (p_block) {
 200         if( p_block->i_flags&(BLOCK_FLAG_DISCONTINUITY|BLOCK_FLAG_CORRUPTED) )
 201         {
 202             if( p_block->i_flags&BLOCK_FLAG_CORRUPTED )
 203             {
 204                 p_sys->i_state = STATE_NOSYNC;
 205                 block_BytestreamEmpty( &p_sys->bytestream );
 206             }
 207             date_Set( &p_sys->end_date, 0 );
 208             block_Release( p_block );
 209             p_sys->b_discontinuity = true;
 210             return NULL;
 211         }
 212
 213         if( !date_Get( &p_sys->end_date ) && p_block->i_pts <= VLC_TS_INVALID )
 214         {
 215             /* We've just started the stream, wait for the first PTS. */
 216             msg_Dbg( p_dec, "waiting for PTS" );
 217             block_Release( p_block );
 218             return NULL;
 219         }
 220
 221         block_BytestreamPush( &p_sys->bytestream, p_block );
 222     } else
 223         p_sys->i_state = STATE_SEND_DATA; /* return all the data we have left */
 224
 225     while( 1 )
 226     {
 227         switch( p_sys->i_state )
 228         {
 229
 230         case STATE_NOSYNC:
 231             while( block_PeekBytes( &p_sys->bytestream, p_header, 2 )
 232                    == VLC_SUCCESS )
 233             {
 234                 /* Look for sync word - should be 0xffe */
 235                 if( p_header[0] == 0xff && (p_header[1] & 0xe0) == 0xe0 )
 236                 {
 237                     p_sys->i_state = STATE_SYNC;
 238                     break;
 239                 }
 240                 block_SkipByte( &p_sys->bytestream );
 241             }
 242             if( p_sys->i_state != STATE_SYNC )
 243             {
 244                 block_BytestreamFlush( &p_sys->bytestream );
 245
 246                 /* Need more data */
 247                 return NULL;
 248             }
 249
 250         case STATE_SYNC:
 251             /* New frame, set the Presentation Time Stamp */
 252             p_sys->i_pts = p_sys->bytestream.p_block->i_pts;
 253             if( p_sys->i_pts > VLC_TS_INVALID &&
 254                 p_sys->i_pts > date_Get( &p_sys->end_date ) )
 255             {
 256                 date_Set( &p_sys->end_date, p_sys->i_pts );
 257             }
 258             p_sys->i_state = STATE_HEADER;
 259
 260         case STATE_HEADER:
 261             /* Get MPGA frame header (MPGA_HEADER_SIZE bytes) */
 262             if( block_PeekBytes( &p_sys->bytestream, p_header,
 263                                  MPGA_HEADER_SIZE ) != VLC_SUCCESS )
 264             {
 265                 /* Need more data */
 266                 return NULL;
 267             }
 268
 269             /* Build frame header */
 270             i_header = GetDWBE(p_header);
 271
 272             /* Check if frame is valid and get frame info */
 273             p_sys->i_frame_size = SyncInfo( i_header,
 274                                             &p_sys->i_channels,
 275                                             &p_sys->i_channels_conf,
 276                                             &p_sys->i_rate,
 277                                             &p_sys->i_bit_rate,
 278                                             &p_sys->i_frame_length,
 279                                             &p_sys->i_max_frame_size,
 280                                             &p_sys->i_layer );
 281
 282             p_dec->fmt_in.i_profile = p_sys->i_layer;
 283
 284             if( p_sys->i_frame_size == -1 )
 285             {
 286                 msg_Dbg( p_dec, "emulated startcode" );
 287                 block_SkipByte( &p_sys->bytestream );
 288                 p_sys->i_state = STATE_NOSYNC;
 289                 p_sys->b_discontinuity = true;
 290                 break;
 291             }
 292
 293             if( p_sys->i_bit_rate == 0 )
 294             {
 295                 /* Free bitrate, but 99% emulated startcode :( */
 296                 if( p_dec->p_sys->i_free_frame_size == MPGA_HEADER_SIZE )
 297                 {
 298                     msg_Dbg( p_dec, "free bitrate mode");
 299                 }
 300                 /* The -1 below is to account for the frame padding */
 301                 p_sys->i_frame_size = p_sys->i_free_frame_size - 1;
 302             }
 303
 304             p_sys->i_state = STATE_NEXT_SYNC;
 305
 306         case STATE_NEXT_SYNC:
 307             /* TODO: If p_block == NULL, flush the buffer without checking the
 308              * next sync word */
 309
 310             /* Check if next expected frame contains the sync word */
 311             if( block_PeekOffsetBytes( &p_sys->bytestream,
 312                                        p_sys->i_frame_size, p_header,
 313                                        MAD_BUFFER_GUARD ) != VLC_SUCCESS )
 314             {
 315                 /* Need more data */
 316                 return NULL;
 317             }
 318
 319             if( p_header[0] == 0xff && (p_header[1] & 0xe0) == 0xe0 )
 320             {
 321                 /* Startcode is fine, let's try the header as an extra check */
 322                 int i_next_frame_size;
 323                 unsigned int i_next_channels, i_next_channels_conf;
 324                 unsigned int i_next_rate, i_next_bit_rate;
 325                 unsigned int i_next_frame_length, i_next_max_frame_size;
 326                 unsigned int i_next_layer;
 327
 328                 /* Build frame header */
 329                 i_header = GetDWBE(p_header);
 330
 331                 i_next_frame_size = SyncInfo( i_header,
 332                                               &i_next_channels,
 333                                               &i_next_channels_conf,
 334                                               &i_next_rate,
 335                                               &i_next_bit_rate,
 336                                               &i_next_frame_length,
 337                                               &i_next_max_frame_size,
 338                                               &i_next_layer );
 339
 340                 /* Free bitrate only */
 341                 if( p_sys->i_bit_rate == 0 && i_next_frame_size == -1 )
 342                 {
 343                     if( (unsigned int)p_sys->i_frame_size >
 344                         p_sys->i_max_frame_size )
 345                     {
 346                         msg_Dbg( p_dec, "frame too big %d > %d "
 347                                  "(emulated startcode ?)", p_sys->i_frame_size,
 348                                  p_sys->i_max_frame_size );
 349                         block_SkipByte( &p_sys->bytestream );
 350                         p_sys->i_state = STATE_NOSYNC;
 351                         p_sys->i_free_frame_size = MPGA_HEADER_SIZE;
 352                         break;
 353                     }
 354
 355                     p_sys->i_frame_size++;
 356                     break;
 357                 }
 358
 359                 if( i_next_frame_size == -1 )
 360                 {
 361                     msg_Dbg( p_dec, "emulated startcode on next frame" );
 362                     block_SkipByte( &p_sys->bytestream );
 363                     p_sys->i_state = STATE_NOSYNC;
 364                     p_sys->b_discontinuity = true;
 365                     break;
 366                 }
 367
 368                 /* Check info is in sync with previous one */
 369                 if( i_next_channels_conf != p_sys->i_channels_conf ||
 370                     i_next_rate != p_sys->i_rate ||
 371                     i_next_layer != p_sys->i_layer ||
 372                     i_next_frame_length != p_sys->i_frame_length )
 373                 {
 374                     /* Free bitrate only */
 375                     if( p_sys->i_bit_rate == 0 )
 376                     {
 377                         p_sys->i_frame_size++;
 378                         break;
 379                     }
 380
 381                     msg_Dbg( p_dec, "parameters changed unexpectedly "
 382                              "(emulated startcode ?)" );
 383                     block_SkipByte( &p_sys->bytestream );
 384                     p_sys->i_state = STATE_NOSYNC;
 385                     break;
 386                 }
 387
 388                 /* Free bitrate only */
 389                 if( p_sys->i_bit_rate == 0 )
 390                 {
 391                     if( i_next_bit_rate != 0 )
 392                     {
 393                         p_sys->i_frame_size++;
 394                         break;
 395                     }
 396                 }
 397
 398             }
 399             else
 400             {
 401                 /* Free bitrate only */
 402                 if( p_sys->i_bit_rate == 0 )
 403                 {
 404                     if( (unsigned int)p_sys->i_frame_size >
 405                         p_sys->i_max_frame_size )
 406                     {
 407                         msg_Dbg( p_dec, "frame too big %d > %d "
 408                                  "(emulated startcode ?)", p_sys->i_frame_size,
 409                                  p_sys->i_max_frame_size );
 410                         block_SkipByte( &p_sys->bytestream );
 411                         p_sys->i_state = STATE_NOSYNC;
 412                         p_sys->i_free_frame_size = MPGA_HEADER_SIZE;
 413                         break;
 414                     }
 415
 416                     p_sys->i_frame_size++;
 417                     break;
 418                 }
 419
 420                 msg_Dbg( p_dec, "emulated startcode "
 421                          "(no startcode on following frame)" );
 422                 p_sys->i_state = STATE_NOSYNC;
 423                 block_SkipByte( &p_sys->bytestream );
 424                 break;
 425             }
 426
 427             p_sys->i_state = STATE_SEND_DATA;
 428             break;
 429
 430         case STATE_GET_DATA:
 431             /* Make sure we have enough data.
 432              * (Not useful if we went through NEXT_SYNC) */
 433             if( block_WaitBytes( &p_sys->bytestream,
 434                                  p_sys->i_frame_size ) != VLC_SUCCESS )
 435             {
 436                 /* Need more data */
 437                 return NULL;
 438             }
 439             p_sys->i_state = STATE_SEND_DATA;
 440
 441         case STATE_SEND_DATA:
 442             if( !(p_buf = GetOutBuffer( p_dec, &p_out_buffer )) )
 443             {
 444                 //p_dec->b_error = true;
 445                 return NULL;
 446             }
 447
 448             /* Free bitrate only */
 449             if( p_sys->i_bit_rate == 0 )
 450             {
 451                 p_sys->i_free_frame_size = p_sys->i_frame_size;
 452             }
 453
 454             /* Copy the whole frame into the buffer. */
 455             if (block_GetBytes( &p_sys->bytestream,
 456                             p_buf, __MIN( (unsigned)p_sys->i_frame_size, p_out_buffer->i_buffer ) )) {
 457                 block_Release(p_out_buffer);
 458                 return NULL;
 459             }
 460
 461 #ifdef HAVE_MPGA_FILTER
 462             /* Get beginning of next frame for libmad */
 463             if( !p_sys->b_packetizer )
 464             {
 465                 assert( p_out_buffer->i_buffer >= (unsigned)p_sys->i_frame_size + MAD_BUFFER_GUARD );
 466                 memcpy( p_buf + p_sys->i_frame_size,
 467                         p_header, MAD_BUFFER_GUARD );
 468             }
 469 #endif
 470             p_sys->i_state = STATE_NOSYNC;
 471
 472             /* Make sure we don't reuse the same pts twice */
 473             if( p_sys->i_pts == p_sys->bytestream.p_block->i_pts )
 474                 p_sys->i_pts = p_sys->bytestream.p_block->i_pts = VLC_TS_INVALID;
 475
 476             /* So p_block doesn't get re-added several times */
 477             p_block = block_BytestreamPop( &p_sys->bytestream );
 478             if (pp_block)
 479                 *pp_block = p_block;
 480             else if (p_block)
 481                 block_Release(p_block);
 482
 483             return p_out_buffer;
 484         }
 485     }
 486
 487     return NULL;
 488 }
 489
 490 /*****************************************************************************
 491  * GetOutBuffer:
 492  *****************************************************************************/
 493 static uint8_t *GetOutBuffer( decoder_t *p_dec, block_t **pp_out_buffer )
 494 {
 495     decoder_sys_t *p_sys = p_dec->p_sys;
 496     uint8_t *p_buf;
 497
 498     if( p_dec->fmt_out.audio.i_rate != p_sys->i_rate )
 499     {
 500         msg_Dbg( p_dec, "MPGA channels:%d samplerate:%d bitrate:%d",
 501                   p_sys->i_channels, p_sys->i_rate, p_sys->i_bit_rate );
 502
 503         date_Init( &p_sys->end_date, p_sys->i_rate, 1 );
 504         date_Set( &p_sys->end_date, p_sys->i_pts );
 505     }
 506
 507     p_dec->fmt_out.audio.i_rate     = p_sys->i_rate;
 508     p_dec->fmt_out.audio.i_channels = p_sys->i_channels;
 509     p_dec->fmt_out.audio.i_frame_length = p_sys->i_frame_length;
 510     p_dec->fmt_out.audio.i_bytes_per_frame =
 511         p_sys->i_max_frame_size + MAD_BUFFER_GUARD;
 512
 513     p_dec->fmt_out.audio.i_original_channels = p_sys->i_channels_conf;
 514     p_dec->fmt_out.audio.i_physical_channels =
 515         p_sys->i_channels_conf & AOUT_CHAN_PHYSMASK;
 516
 517     p_dec->fmt_out.i_bitrate = p_sys->i_bit_rate * 1000;
 518
 519 #ifdef HAVE_MPGA_FILTER
 520     if( !p_sys->b_packetizer )
 521     {
 522         block_t *p_aout_buffer = GetAoutBuffer( p_dec );
 523         p_buf = p_aout_buffer ? p_aout_buffer->p_buffer : NULL;
 524         *pp_out_buffer = p_aout_buffer;
 525     }
 526     else
 527 #endif
 528     {
 529         block_t *p_sout_buffer = GetSoutBuffer( p_dec );
 530         p_buf = p_sout_buffer ? p_sout_buffer->p_buffer : NULL;
 531         *pp_out_buffer = p_sout_buffer;
 532     }
 533     return p_buf;
 534 }
 535
 536 #ifdef HAVE_MPGA_FILTER
 537 /*****************************************************************************
 538  * GetAoutBuffer:
 539  *****************************************************************************/
 540 static block_t *GetAoutBuffer( decoder_t *p_dec )
 541 {
 542     decoder_sys_t *p_sys = p_dec->p_sys;
 543     block_t *p_buf;
 544
 545     p_buf = decoder_NewAudioBuffer( p_dec, p_sys->i_frame_length );
 546     if( p_buf == NULL ) return NULL;
 547
 548     p_buf->i_pts = date_Get( &p_sys->end_date );
 549     p_buf->i_length = date_Increment( &p_sys->end_date, p_sys->i_frame_length )
 550                       - p_buf->i_pts;
 551     if( p_sys->b_discontinuity )
 552         p_buf->i_flags |= BLOCK_FLAG_DISCONTINUITY;
 553     p_sys->b_discontinuity = false;
 554
 555     /* Hack for libmad filter */
 556     p_buf = block_Realloc( p_buf, 0, p_sys->i_frame_size + MAD_BUFFER_GUARD );
 557
 558     return p_buf;
 559 }
 560 #endif
 561
 562 /*****************************************************************************
 563  * GetSoutBuffer:
 564  *****************************************************************************/
 565 static block_t *GetSoutBuffer( decoder_t *p_dec )
 566 {
 567     decoder_sys_t *p_sys = p_dec->p_sys;
 568     block_t *p_block;
 569
 570     p_block = block_Alloc( p_sys->i_frame_size );
 571     if( p_block == NULL ) return NULL;
 572
 573     p_block->i_pts = p_block->i_dts = date_Get( &p_sys->end_date );
 574
 575     p_block->i_length =
 576         date_Increment( &p_sys->end_date, p_sys->i_frame_length ) - p_block->i_pts;
 577
 578     return p_block;
 579 }
 580
 581 /*****************************************************************************
 582  * Close: clean up the decoder
 583  *****************************************************************************/
 584 static void Close( vlc_object_t *p_this )
 585 {
 586     decoder_t *p_dec = (decoder_t *)p_this;
 587     decoder_sys_t *p_sys = p_dec->p_sys;
 588
 589     block_BytestreamRelease( &p_sys->bytestream );
 590
 591     free( p_sys );
 592 }
 593
 594 /*****************************************************************************
 595  * SyncInfo: parse MPEG audio sync info
 596  *****************************************************************************/
 597 static int SyncInfo( uint32_t i_header, unsigned int * pi_channels,
 598                      unsigned int * pi_channels_conf,
 599                      unsigned int * pi_sample_rate, unsigned int * pi_bit_rate,
 600                      unsigned int * pi_frame_length,
 601                      unsigned int * pi_max_frame_size, unsigned int * pi_layer)
 602 {
 603     static const int ppi_bitrate[2][3][16] =
 604     {
 605         {
 606             /* v1 l1 */
 607             { 0, 32, 64, 96, 128, 160, 192, 224, 256, 288, 320, 352, 384,
 608               416, 448, 0},
 609             /* v1 l2 */
 610             { 0, 32, 48, 56,  64,  80,  96, 112, 128, 160, 192, 224, 256,
 611               320, 384, 0},
 612             /* v1 l3 */
 613             { 0, 32, 40, 48,  56,  64,  80,  96, 112, 128, 160, 192, 224,
 614               256, 320, 0}
 615         },
 616
 617         {
 618             /* v2 l1 */
 619             { 0, 32, 48, 56,  64,  80,  96, 112, 128, 144, 160, 176, 192,
 620               224, 256, 0},
 621             /* v2 l2 */
 622             { 0,  8, 16, 24,  32,  40,  48,  56,  64,  80,  96, 112, 128,
 623               144, 160, 0},
 624             /* v2 l3 */
 625             { 0,  8, 16, 24,  32,  40,  48,  56,  64,  80,  96, 112, 128,
 626               144, 160, 0}
 627         }
 628     };
 629
 630     static const int ppi_samplerate[2][4] = /* version 1 then 2 */
 631     {
 632         { 44100, 48000, 32000, 0 },
 633         { 22050, 24000, 16000, 0 }
 634     };
 635
 636     int i_version, i_mode, i_emphasis;
 637     bool b_padding, b_mpeg_2_5;
 638     int i_frame_size = 0;
 639     int i_bitrate_index, i_samplerate_index;
 640     int i_max_bit_rate;
 641
 642     b_mpeg_2_5  = 1 - ((i_header & 0x100000) >> 20);
 643     i_version   = 1 - ((i_header & 0x80000) >> 19);
 644     *pi_layer   = 4 - ((i_header & 0x60000) >> 17);
 645     //bool b_crc = !((i_header >> 16) & 0x01);
 646     i_bitrate_index = (i_header & 0xf000) >> 12;
 647     i_samplerate_index = (i_header & 0xc00) >> 10;
 648     b_padding   = (i_header & 0x200) >> 9;
 649     /* Extension */
 650     i_mode      = (i_header & 0xc0) >> 6;
 651     /* Modeext, copyright & original */
 652     i_emphasis  = i_header & 0x3;
 653
 654     if( *pi_layer != 4 &&
 655         i_bitrate_index < 0x0f &&
 656         i_samplerate_index != 0x03 &&
 657         i_emphasis != 0x02 )
 658     {
 659         switch ( i_mode )
 660         {
 661         case 0: /* stereo */
 662         case 1: /* joint stereo */
 663             *pi_channels = 2;
 664             *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT;
 665             break;
 666         case 2: /* dual-mono */
 667             *pi_channels = 2;
 668             *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 669                                 | AOUT_CHAN_DUALMONO;
 670             break;
 671         case 3: /* mono */
 672             *pi_channels = 1;
 673             *pi_channels_conf = AOUT_CHAN_CENTER;
 674             break;
 675         }
 676         *pi_bit_rate = ppi_bitrate[i_version][*pi_layer-1][i_bitrate_index];
 677         i_max_bit_rate = ppi_bitrate[i_version][*pi_layer-1][14];
 678         *pi_sample_rate = ppi_samplerate[i_version][i_samplerate_index];
 679
 680         if ( b_mpeg_2_5 )
 681         {
 682             *pi_sample_rate >>= 1;
 683         }
 684
 685         switch( *pi_layer )
 686         {
 687         case 1:
 688             i_frame_size = ( 12000 * *pi_bit_rate / *pi_sample_rate +
 689                            b_padding ) * 4;
 690             *pi_max_frame_size = ( 12000 * i_max_bit_rate /
 691                                  *pi_sample_rate + 1 ) * 4;
 692             *pi_frame_length = 384;
 693             break;
 694
 695         case 2:
 696             i_frame_size = 144000 * *pi_bit_rate / *pi_sample_rate + b_padding;
 697             *pi_max_frame_size = 144000 * i_max_bit_rate / *pi_sample_rate + 1;
 698             *pi_frame_length = 1152;
 699             break;
 700
 701         case 3:
 702             i_frame_size = ( i_version ? 72000 : 144000 ) *
 703                            *pi_bit_rate / *pi_sample_rate + b_padding;
 704             *pi_max_frame_size = ( i_version ? 72000 : 144000 ) *
 705                                  i_max_bit_rate / *pi_sample_rate + 1;
 706             *pi_frame_length = i_version ? 576 : 1152;
 707             break;
 708
 709         default:
 710             break;
 711         }
 712
 713         /* Free bitrate mode can support higher bitrates */
 714         if( !*pi_bit_rate ) *pi_max_frame_size *= 2;
 715     }
 716     else
 717     {
 718         return -1;
 719     }
 720
 721     return i_frame_size;
 722 }