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 VideoLAN
   5  * $Id: mpeg_audio.c,v 1.17 2003/09/02 20:19:25 gbazin Exp $
   6  *
   7  * Authors: Laurent Aimar <fenrir@via.ecp.fr>
   8  *          Eric Petit <titer@videolan.org>
   9  *          Christophe Massiot <massiot@via.ecp.fr>
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation; either version 2 of the License, or
  14  * (at your option) any later version.
  15  *
  16  * This program is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  * GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with this program; if not, write to the Free Software
  23  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
  24  *****************************************************************************/
  25
  26 /*****************************************************************************
  27  * Preamble
  28  *****************************************************************************/
  29 #include <stdlib.h>                                      /* malloc(), free() */
  30 #include <string.h>                                              /* strdup() */
  31
  32 #include <vlc/vlc.h>
  33 #include <vlc/aout.h>
  34 #include <vlc/decoder.h>
  35
  36 /*****************************************************************************
  37  * dec_thread_t : decoder thread descriptor
  38  *****************************************************************************/
  39 typedef struct dec_thread_t
  40 {
  41     /*
  42      * Thread properties
  43      */
  44     vlc_thread_t        thread_id;                /* id for thread functions */
  45
  46     /*
  47      * Input properties
  48      */
  49     decoder_fifo_t *    p_fifo;                /* stores the PES stream data */
  50     bit_stream_t        bit_stream;
  51
  52     /*
  53      * Output properties
  54      */
  55     aout_instance_t *   p_aout; /* opaque */
  56     aout_input_t *      p_aout_input; /* opaque */
  57     audio_sample_format_t output_format;
  58 } dec_thread_t;
  59
  60 #define MAX_FRAME_SIZE 10000
  61 /* This isn't the place to put mad-specific stuff. However, it makes the
  62  * mad plug-in's life much easier if we put 8 extra bytes at the end of the
  63  * buffer, because that way it doesn't have to copy the aout_buffer_t to a
  64  * bigger buffer. This has no implication on other plug-ins, and we only
  65  * lose 8 bytes per frame. --Meuuh */
  66 #define MAD_BUFFER_GUARD 8
  67
  68
  69 /****************************************************************************
  70  * Local prototypes
  71  ****************************************************************************/
  72 static int  Open           ( vlc_object_t * );
  73 static int  RunDecoder     ( decoder_fifo_t * );
  74
  75 static void EndThread      ( dec_thread_t * );
  76
  77 static int SyncInfo( uint32_t i_header, unsigned int * pi_channels,
  78                      unsigned int * pi_sample_rate, unsigned int * pi_bit_rate,
  79                      unsigned int * pi_frame_length,
  80                      unsigned int * pi_current_frame_length,
  81                      unsigned int * pi_layer );
  82
  83 /*****************************************************************************
  84  * Module descriptor
  85  *****************************************************************************/
  86 vlc_module_begin();
  87     set_description( _("MPEG audio layer I/II/III parser") );
  88     set_capability( "decoder", 100 );
  89     set_callbacks( Open, NULL );
  90 vlc_module_end();
  91
  92 /*****************************************************************************
  93  * OpenDecoder: probe the decoder and return score
  94  *****************************************************************************/
  95 static int Open( vlc_object_t *p_this )
  96 {
  97     decoder_t *p_dec = (decoder_t*)p_this;
  98
  99     if( p_dec->p_fifo->i_fourcc != VLC_FOURCC( 'm', 'p', 'g', 'a') )
 100     {
 101         return VLC_EGENERIC;
 102     }
 103
 104     p_dec->pf_run = RunDecoder;
 105     return VLC_SUCCESS;
 106 }
 107
 108 /*****************************************************************************
 109  * RunDecoder: this function is called just after the thread is created
 110  *****************************************************************************/
 111 static int RunDecoder( decoder_fifo_t *p_fifo )
 112 {
 113     dec_thread_t * p_dec;
 114     audio_date_t end_date;
 115     unsigned int i_layer = 0;
 116     byte_t p_sync[MAD_BUFFER_GUARD];
 117     mtime_t pts;
 118     int i_free_frame_size = 0;
 119
 120     /* Allocate the memory needed to store the thread's structure */
 121     p_dec = malloc( sizeof(dec_thread_t) );
 122     if( p_dec == NULL )
 123     {
 124         msg_Err( p_fifo, "out of memory" );
 125         DecoderError( p_fifo );
 126         return -1;
 127     }
 128
 129     /* Initialize the thread properties */
 130     p_dec->p_aout = NULL;
 131     p_dec->p_aout_input = NULL;
 132     p_dec->p_fifo = p_fifo;
 133
 134     aout_DateSet( &end_date, 0 );
 135
 136     /* Init the bitstream */
 137     if( InitBitstream( &p_dec->bit_stream, p_dec->p_fifo,
 138                        NULL, NULL ) != VLC_SUCCESS )
 139     {
 140         msg_Err( p_fifo, "cannot initialize bitstream" );
 141         DecoderError( p_fifo );
 142         free( p_dec );
 143         return -1;
 144     }
 145
 146     /* Init sync buffer. */
 147     NextPTS( &p_dec->bit_stream, &pts, NULL );
 148     GetChunk( &p_dec->bit_stream, p_sync, MAD_BUFFER_GUARD );
 149
 150     /* Decoder thread's main loop */
 151     while ( !p_dec->p_fifo->b_die && !p_dec->p_fifo->b_error )
 152     {
 153         int i_current_frame_size;
 154         unsigned int i_rate, i_original_channels, i_frame_size, i_frame_length;
 155         unsigned int i_new_layer, i_bit_rate;
 156         uint32_t i_header;
 157         aout_buffer_t * p_buffer;
 158         int i;
 159
 160         /* Look for sync word - should be 0xffe */
 161         if ( (p_sync[0] != 0xff) || ((p_sync[1] & 0xe0) != 0xe0) )
 162         {
 163             msg_Warn( p_dec->p_fifo, "no sync - skipping" );
 164             /* Look inside the sync buffer. */
 165             for ( i = 1; i < MAD_BUFFER_GUARD - 1; i++ )
 166             {
 167                 if ( (p_sync[i] == 0xff) && ((p_sync[i + 1] & 0xe0) == 0xe0) )
 168                     break;
 169             }
 170             if ( i < MAD_BUFFER_GUARD - 1 )
 171             {
 172                 /* Found it ! */
 173                 memmove( p_sync, &p_sync[i], MAD_BUFFER_GUARD - i );
 174                 GetChunk( &p_dec->bit_stream, &p_sync[MAD_BUFFER_GUARD - i],
 175                           i );
 176             }
 177             else
 178             {
 179                 if ( p_sync[MAD_BUFFER_GUARD - 1] == 0xff
 180                       && ShowBits( &p_dec->bit_stream, 3 ) == 0x3 )
 181                 {
 182                     /* Found it ! */
 183                     p_sync[0] = p_sync[MAD_BUFFER_GUARD - 1];
 184                     GetChunk( &p_dec->bit_stream,
 185                               &p_sync[1], MAD_BUFFER_GUARD - 1 );
 186                 }
 187                 else
 188                 {
 189                     /* Scan the stream. */
 190                     while ( ShowBits( &p_dec->bit_stream, 11 ) != 0x07ff &&
 191                             (!p_dec->p_fifo->b_die) &&
 192                             (!p_dec->p_fifo->b_error) )
 193                     {
 194                         RemoveBits( &p_dec->bit_stream, 8 );
 195                     }
 196                     if ( p_dec->p_fifo->b_die || p_dec->p_fifo->b_error )
 197                         break;
 198                     NextPTS( &p_dec->bit_stream, &pts, NULL );
 199                     GetChunk( &p_dec->bit_stream,p_sync, MAD_BUFFER_GUARD );
 200                 }
 201             }
 202         }
 203         if ( p_dec->p_fifo->b_die || p_dec->p_fifo->b_error ) break;
 204
 205         /* Set the Presentation Time Stamp */
 206         if ( pts != 0 && pts != aout_DateGet( &end_date ) )
 207         {
 208             aout_DateSet( &end_date, pts );
 209         }
 210
 211         /* Get frame header */
 212         i_header = (p_sync[0] << 24) | (p_sync[1] << 16) | (p_sync[2] << 8)
 213                      | p_sync[3];
 214
 215         /* Check if frame is valid and get frame info */
 216         i_current_frame_size = SyncInfo( i_header,
 217                                          &i_original_channels, &i_rate,
 218                                          &i_bit_rate, &i_frame_length,
 219                                          &i_frame_size, &i_new_layer );
 220         if( i_current_frame_size == -1 )
 221         {
 222             msg_Warn( p_dec->p_fifo, "syncinfo failed" );
 223             /* This is probably an emulated startcode, drop the first byte
 224              * to force looking for the next startcode. */
 225             memmove( p_sync, &p_sync[1], MAD_BUFFER_GUARD - 1 );
 226             p_sync[MAD_BUFFER_GUARD - 1] = GetBits( &p_dec->bit_stream, 8 );
 227             continue;
 228         }
 229
 230         if( i_bit_rate == 0 )
 231         {
 232             /* free birate, but 99% emulated startcode :( */
 233             i_current_frame_size = i_free_frame_size;
 234         }
 235
 236         if ( (unsigned int)i_current_frame_size > i_frame_size )
 237         {
 238             msg_Warn( p_dec->p_fifo, "frame too big %d > %d",
 239                       i_current_frame_size, i_frame_size );
 240             memmove( p_sync, &p_sync[1], MAD_BUFFER_GUARD - 1 );
 241             p_sync[MAD_BUFFER_GUARD - 1] = GetBits( &p_dec->bit_stream, 8 );
 242             continue;
 243         }
 244
 245         if( (p_dec->p_aout_input != NULL) &&
 246             ( (p_dec->output_format.i_rate != i_rate)
 247                 || (p_dec->output_format.i_original_channels
 248                       != i_original_channels)
 249                 || (p_dec->output_format.i_bytes_per_frame
 250                       != i_frame_size + MAD_BUFFER_GUARD)
 251                 || (p_dec->output_format.i_frame_length != i_frame_length)
 252                 || (i_layer != i_new_layer) ) )
 253         {
 254             /* Parameters changed - this should not happen. */
 255             aout_DecDelete( p_dec->p_aout, p_dec->p_aout_input );
 256             p_dec->p_aout_input = NULL;
 257         }
 258
 259         /* Creating the audio input if not created yet. */
 260         if( p_dec->p_aout_input == NULL )
 261         {
 262             i_layer = i_new_layer;
 263             if ( i_layer == 3 )
 264             {
 265                 p_dec->output_format.i_format = VLC_FOURCC('m','p','g','3');
 266             }
 267             else
 268             {
 269                 p_dec->output_format.i_format = VLC_FOURCC('m','p','g','a');
 270             }
 271             p_dec->output_format.i_rate = i_rate;
 272             p_dec->output_format.i_original_channels = i_original_channels;
 273             p_dec->output_format.i_physical_channels
 274                        = i_original_channels & AOUT_CHAN_PHYSMASK;
 275             p_dec->output_format.i_bytes_per_frame = i_frame_size
 276                                                         + MAD_BUFFER_GUARD;
 277             p_dec->output_format.i_frame_length = i_frame_length;
 278             aout_DateInit( &end_date, i_rate );
 279             aout_DateSet( &end_date, pts );
 280             p_dec->p_aout_input = aout_DecNew( p_dec->p_fifo,
 281                                                &p_dec->p_aout,
 282                                                &p_dec->output_format );
 283
 284             if ( p_dec->p_aout_input == NULL )
 285             {
 286                 p_dec->p_fifo->b_error = 1;
 287                 break;
 288             }
 289         }
 290
 291         if ( !aout_DateGet( &end_date ) )
 292         {
 293             byte_t p_junk[MAX_FRAME_SIZE];
 294             int    i_skip = i_current_frame_size - MAD_BUFFER_GUARD;
 295
 296             /* We've just started the stream, wait for the first PTS. */
 297             while( i_skip > 0 )
 298             {
 299                 int i_read;
 300
 301                 i_read = __MIN( i_current_frame_size  - MAD_BUFFER_GUARD, MAX_FRAME_SIZE );
 302                 GetChunk( &p_dec->bit_stream, p_junk, i_read );
 303
 304                 i_skip -= i_read;
 305             }
 306             NextPTS( &p_dec->bit_stream, &pts, NULL );
 307             GetChunk( &p_dec->bit_stream, p_sync, MAD_BUFFER_GUARD );
 308             continue;
 309         }
 310
 311         p_buffer = aout_DecNewBuffer( p_dec->p_aout, p_dec->p_aout_input,
 312                                       i_frame_length );
 313         if ( p_buffer == NULL )
 314         {
 315             p_dec->p_fifo->b_error = 1;
 316             break;
 317         }
 318         p_buffer->start_date = aout_DateGet( &end_date );
 319         p_buffer->end_date = aout_DateIncrement( &end_date,
 320                                                  i_frame_length );
 321
 322         /* Get the whole frame. */
 323         memcpy( p_buffer->p_buffer, p_sync, MAD_BUFFER_GUARD );
 324         if ( i_current_frame_size )
 325         {
 326             GetChunk( &p_dec->bit_stream, p_buffer->p_buffer + MAD_BUFFER_GUARD,
 327                       i_current_frame_size - MAD_BUFFER_GUARD );
 328         }
 329         else
 330         {
 331             /* Free bit-rate stream. Peek at next frame header. */
 332             i = MAD_BUFFER_GUARD;
 333             for ( ; ; )
 334             {
 335                 int i_next_real_frame_size;
 336                 unsigned int i_next_channels, i_next_rate, i_next_bit_rate;
 337                 unsigned int i_next_frame_length, i_next_frame_size;
 338                 unsigned int i_next_layer;
 339                 while ( ShowBits( &p_dec->bit_stream, 11 ) != 0x07ff &&
 340                         (!p_dec->p_fifo->b_die) &&
 341                         (!p_dec->p_fifo->b_error) &&
 342                         i < (int)i_frame_size + MAD_BUFFER_GUARD )
 343                 {
 344                     ((uint8_t *)p_buffer->p_buffer)[i++] =
 345                                 GetBits( &p_dec->bit_stream, 8 );
 346                 }
 347                 if ( p_dec->p_fifo->b_die || p_dec->p_fifo->b_error
 348                       || i == (int)i_frame_size + MAD_BUFFER_GUARD )
 349                     break;
 350                 i_header = ShowBits( &p_dec->bit_stream, 8 );
 351                 i_next_real_frame_size = SyncInfo( i_header,
 352                                          &i_next_channels, &i_next_rate,
 353                                          &i_next_bit_rate, &i_next_frame_length,
 354                                          &i_next_frame_size, &i_next_layer );
 355                 if ( i_next_real_frame_size != 0 ||
 356                      i_next_channels != i_original_channels ||
 357                      i_next_rate != i_rate ||
 358                      i_next_bit_rate != i_bit_rate ||
 359                      i_next_frame_length != i_frame_length ||
 360                      i_next_frame_size != i_frame_size ||
 361                      i_next_layer != i_new_layer )
 362                 {
 363                     /* This is an emulated start code, try again. */
 364                     /* there is at least 1 byte free */
 365                     ((uint8_t *)p_buffer->p_buffer)[i++] =
 366                                 GetBits( &p_dec->bit_stream, 8 );
 367                     continue;
 368                 }
 369                 i_free_frame_size = i;
 370                 break;
 371             }
 372             if ( p_dec->p_fifo->b_die || p_dec->p_fifo->b_error )
 373                 break;
 374             if ( i == (int)i_frame_size + MAD_BUFFER_GUARD )
 375             {
 376                 /* Couldn't find the next start-code. This is sooo
 377                  * embarassing. */
 378                 aout_DecDeleteBuffer( p_dec->p_aout, p_dec->p_aout_input,
 379                                       p_buffer );
 380                 NextPTS( &p_dec->bit_stream, &pts, NULL );
 381                 GetChunk( &p_dec->bit_stream, p_sync, MAD_BUFFER_GUARD );
 382                 continue;
 383             }
 384         }
 385         if( p_dec->p_fifo->b_die )
 386         {
 387             aout_DecDeleteBuffer( p_dec->p_aout, p_dec->p_aout_input,
 388                                   p_buffer );
 389             break;
 390         }
 391         /* Get beginning of next frame. */
 392         NextPTS( &p_dec->bit_stream, &pts, NULL );
 393         GetChunk( &p_dec->bit_stream, p_buffer->p_buffer + i_current_frame_size,
 394                   MAD_BUFFER_GUARD );
 395         memcpy( p_sync, p_buffer->p_buffer + i_current_frame_size,
 396                 MAD_BUFFER_GUARD );
 397
 398         p_buffer->i_nb_bytes = i_current_frame_size + MAD_BUFFER_GUARD;
 399
 400         /* Send the buffer to the aout core. */
 401         aout_DecPlay( p_dec->p_aout, p_dec->p_aout_input, p_buffer );
 402     }
 403
 404     if( p_dec->p_fifo->b_error )
 405     {
 406         DecoderError( p_dec->p_fifo );
 407     }
 408
 409     EndThread( p_dec );
 410
 411     return 0;
 412 }
 413
 414 /*****************************************************************************
 415  * EndThread : thread destruction
 416  *****************************************************************************/
 417 static void EndThread( dec_thread_t * p_dec )
 418 {
 419     if ( p_dec->p_aout_input != NULL )
 420     {
 421         aout_DecDelete( p_dec->p_aout, p_dec->p_aout_input );
 422     }
 423
 424     CloseBitstream( &p_dec->bit_stream );
 425     free( p_dec );
 426 }
 427
 428 /*****************************************************************************
 429  * SyncInfo: parse MPEG audio sync info
 430  *****************************************************************************/
 431 static int SyncInfo( uint32_t i_header, unsigned int * pi_channels,
 432                      unsigned int * pi_sample_rate, unsigned int * pi_bit_rate,
 433                      unsigned int * pi_frame_length,
 434                      unsigned int * pi_frame_size, unsigned int * pi_layer )
 435 {
 436     static const int pppi_mpegaudio_bitrate[2][3][16] =
 437     {
 438         {
 439             /* v1 l1 */
 440             { 0, 32, 64, 96, 128, 160, 192, 224, 256, 288, 320, 352, 384,
 441               416, 448, 0},
 442             /* v1 l2 */
 443             { 0, 32, 48, 56,  64,  80,  96, 112, 128, 160, 192, 224, 256,
 444               320, 384, 0},
 445             /* v1 l3 */
 446             { 0, 32, 40, 48,  56,  64,  80,  96, 112, 128, 160, 192, 224,
 447               256, 320, 0}
 448         },
 449
 450         {
 451             /* v2 l1 */
 452             { 0, 32, 48, 56,  64,  80,  96, 112, 128, 144, 160, 176, 192,
 453               224, 256, 0},
 454             /* v2 l2 */
 455             { 0,  8, 16, 24,  32,  40,  48,  56,  64,  80,  96, 112, 128,
 456               144, 160, 0},
 457             /* v2 l3 */
 458             { 0,  8, 16, 24,  32,  40,  48,  56,  64,  80,  96, 112, 128,
 459               144, 160, 0}
 460         }
 461     };
 462
 463     static const int ppi_mpegaudio_samplerate[2][4] = /* version 1 then 2 */
 464     {
 465         { 44100, 48000, 32000, 0 },
 466         { 22050, 24000, 16000, 0 }
 467     };
 468
 469     int i_version, i_mode, i_emphasis;
 470     vlc_bool_t b_padding, b_mpeg_2_5;
 471     int i_current_frame_size = 0;
 472     int i_bitrate_index, i_samplerate_index;
 473     int i_max_bit_rate;
 474
 475     b_mpeg_2_5  = 1 - ((i_header & 0x100000) >> 20);
 476     i_version   = 1 - ((i_header & 0x80000) >> 19);
 477     *pi_layer   = 4 - ((i_header & 0x60000) >> 17);
 478     /* CRC */
 479     i_bitrate_index = (i_header & 0xf000) >> 12;
 480     i_samplerate_index = (i_header & 0xc00) >> 10;
 481     b_padding   = (i_header & 0x200) >> 9;
 482     /* Extension */
 483     i_mode      = (i_header & 0xc0) >> 6;
 484     /* Modeext, copyright & original */
 485     i_emphasis  = i_header & 0x3;
 486
 487     if( *pi_layer != 4 &&
 488         i_bitrate_index < 0x0f &&
 489         i_samplerate_index != 0x03 &&
 490         i_emphasis != 0x02 )
 491     {
 492         switch ( i_mode )
 493         {
 494         case 0: /* stereo */
 495         case 1: /* joint stereo */
 496             *pi_channels = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT;
 497             break;
 498         case 2: /* dual-mono */
 499             *pi_channels = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 500                             | AOUT_CHAN_DUALMONO;
 501             break;
 502         case 3: /* mono */
 503             *pi_channels = AOUT_CHAN_CENTER;
 504             break;
 505         }
 506         *pi_bit_rate = pppi_mpegaudio_bitrate[i_version][*pi_layer-1][i_bitrate_index];
 507         i_max_bit_rate = pppi_mpegaudio_bitrate[i_version][*pi_layer-1][14];
 508         *pi_sample_rate = ppi_mpegaudio_samplerate[i_version][i_samplerate_index];
 509
 510         if ( b_mpeg_2_5 )
 511         {
 512             *pi_sample_rate >>= 1;
 513         }
 514
 515         switch( *pi_layer )
 516         {
 517         case 1:
 518             i_current_frame_size = ( 12000 *
 519                                         *pi_bit_rate / *pi_sample_rate
 520                                         + b_padding ) * 4;
 521             *pi_frame_size = ( 12000 *
 522                                   i_max_bit_rate / *pi_sample_rate + 1 ) * 4;
 523             *pi_frame_length = 384;
 524             break;
 525
 526         case 2:
 527             i_current_frame_size = 144000 *
 528                                       *pi_bit_rate / *pi_sample_rate
 529                                       + b_padding;
 530             *pi_frame_size = 144000 * i_max_bit_rate / *pi_sample_rate + 1;
 531             *pi_frame_length = 1152;
 532             break;
 533
 534         case 3:
 535             i_current_frame_size = ( i_version ? 72000 : 144000 ) *
 536                                    *pi_bit_rate / *pi_sample_rate + b_padding;
 537             *pi_frame_size = ( i_version ? 72000 : 144000 ) *
 538                                  i_max_bit_rate / *pi_sample_rate + 1;
 539             *pi_frame_length = i_version ? 576 : 1152;
 540             break;
 541
 542         default:
 543             break;
 544         }
 545     }
 546     else
 547     {
 548         return -1;
 549     }
 550
 551     return i_current_frame_size;
 552 }
 553