modules/packetizer/mpegaudio.c

   1 /*****************************************************************************
   2  * mpegaudio.c: parse MPEG audio sync info and packetize the stream
   3  *****************************************************************************
   4  * Copyright (C) 2001-2016 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_helper.h"
  44
  45 /*****************************************************************************
  46  * decoder_sys_t : decoder descriptor
  47  *****************************************************************************/
  48 struct decoder_sys_t
  49 {
  50     /*
  51      * Input properties
  52      */
  53     int        i_state;
  54
  55     block_bytestream_t bytestream;
  56
  57     /*
  58      * Common properties
  59      */
  60     date_t          end_date;
  61
  62     mtime_t i_pts;
  63
  64     int i_frame_size, i_free_frame_size;
  65     unsigned int i_channels_conf, i_chan_mode, i_channels;
  66     unsigned int i_rate, i_max_frame_size, i_frame_length;
  67     unsigned int i_layer, i_bit_rate;
  68
  69     bool   b_discontinuity;
  70 };
  71
  72 #define MAD_BUFFER_GUARD 8
  73 #define MPGA_HEADER_SIZE 4
  74
  75 /****************************************************************************
  76  * Local prototypes
  77  ****************************************************************************/
  78
  79 static int  Open( vlc_object_t * );
  80 static void Close(  vlc_object_t * );
  81
  82 /*****************************************************************************
  83  * Module descriptor
  84  *****************************************************************************/
  85 vlc_module_begin ()
  86     set_category( CAT_INPUT )
  87     set_subcategory( SUBCAT_INPUT_ACODEC )
  88     set_description( N_("MPEG audio layer I/II/III packetizer") )
  89     set_capability( "packetizer", 10 )
  90     set_callbacks( Open, Close )
  91 vlc_module_end ()
  92
  93 /*****************************************************************************
  94  * Flush:
  95  *****************************************************************************/
  96 static void Flush( decoder_t *p_dec )
  97 {
  98     decoder_sys_t *p_sys = p_dec->p_sys;
  99
 100     date_Set( &p_sys->end_date, VLC_TS_INVALID );
 101     p_sys->i_state = STATE_NOSYNC;
 102     block_BytestreamEmpty( &p_sys->bytestream );
 103     p_sys->b_discontinuity = true;
 104 }
 105
 106 /*****************************************************************************
 107  * GetOutBuffer:
 108  *****************************************************************************/
 109 static uint8_t *GetOutBuffer( decoder_t *p_dec, block_t **pp_out_buffer )
 110 {
 111     decoder_sys_t *p_sys = p_dec->p_sys;
 112
 113     if( p_dec->fmt_out.audio.i_rate != p_sys->i_rate ||
 114         date_Get( &p_sys->end_date ) == VLC_TS_INVALID )
 115     {
 116         msg_Dbg( p_dec, "MPGA channels:%d samplerate:%d bitrate:%d",
 117                   p_sys->i_channels, p_sys->i_rate, p_sys->i_bit_rate );
 118
 119         if( p_sys->end_date.i_divider_num == 0 )
 120             date_Init( &p_sys->end_date, p_sys->i_rate, 1 );
 121         else
 122             date_Change( &p_sys->end_date, p_sys->i_rate, 1 );
 123         date_Set( &p_sys->end_date, p_sys->i_pts );
 124     }
 125
 126     p_dec->fmt_out.audio.i_rate     = p_sys->i_rate;
 127     p_dec->fmt_out.audio.i_channels = p_sys->i_channels;
 128     p_dec->fmt_out.audio.i_frame_length = p_sys->i_frame_length;
 129     p_dec->fmt_out.audio.i_bytes_per_frame = p_sys->i_max_frame_size;
 130
 131     p_dec->fmt_out.audio.i_physical_channels = p_sys->i_channels_conf;
 132     p_dec->fmt_out.audio.i_chan_mode = p_sys->i_chan_mode;
 133
 134     p_dec->fmt_out.i_bitrate = p_sys->i_bit_rate * 1000;
 135
 136     block_t *p_block = block_Alloc( p_sys->i_frame_size );
 137     if( p_block == NULL )
 138         return NULL;
 139
 140     p_block->i_pts = p_block->i_dts = date_Get( &p_sys->end_date );
 141     p_block->i_length =
 142         date_Increment( &p_sys->end_date, p_sys->i_frame_length ) - p_block->i_pts;
 143
 144     *pp_out_buffer = p_block;
 145     return p_block->p_buffer;
 146 }
 147
 148 /*****************************************************************************
 149  * SyncInfo: parse MPEG audio sync info
 150  *****************************************************************************/
 151 static int SyncInfo( uint32_t i_header, unsigned int * pi_channels,
 152                      unsigned int * pi_channels_conf,
 153                      unsigned int * pi_chan_mode,
 154                      unsigned int * pi_sample_rate, unsigned int * pi_bit_rate,
 155                      unsigned int * pi_frame_length,
 156                      unsigned int * pi_max_frame_size, unsigned int * pi_layer)
 157 {
 158     static const int ppi_bitrate[2][3][16] =
 159     {
 160         {
 161             /* v1 l1 */
 162             { 0, 32, 64, 96, 128, 160, 192, 224, 256, 288, 320, 352, 384,
 163               416, 448, 0},
 164             /* v1 l2 */
 165             { 0, 32, 48, 56,  64,  80,  96, 112, 128, 160, 192, 224, 256,
 166               320, 384, 0},
 167             /* v1 l3 */
 168             { 0, 32, 40, 48,  56,  64,  80,  96, 112, 128, 160, 192, 224,
 169               256, 320, 0}
 170         },
 171
 172         {
 173             /* v2 l1 */
 174             { 0, 32, 48, 56,  64,  80,  96, 112, 128, 144, 160, 176, 192,
 175               224, 256, 0},
 176             /* v2 l2 */
 177             { 0,  8, 16, 24,  32,  40,  48,  56,  64,  80,  96, 112, 128,
 178               144, 160, 0},
 179             /* v2 l3 */
 180             { 0,  8, 16, 24,  32,  40,  48,  56,  64,  80,  96, 112, 128,
 181               144, 160, 0}
 182         }
 183     };
 184
 185     static const int ppi_samplerate[2][4] = /* version 1 then 2 */
 186     {
 187         { 44100, 48000, 32000, 0 },
 188         { 22050, 24000, 16000, 0 }
 189     };
 190
 191     int i_version, i_mode, i_emphasis;
 192     bool b_padding, b_mpeg_2_5;
 193     int i_frame_size = 0;
 194     int i_bitrate_index, i_samplerate_index;
 195     int i_max_bit_rate;
 196
 197     b_mpeg_2_5  = 1 - ((i_header & 0x100000) >> 20);
 198     i_version   = 1 - ((i_header & 0x80000) >> 19);
 199     *pi_layer   = 4 - ((i_header & 0x60000) >> 17);
 200     //bool b_crc = !((i_header >> 16) & 0x01);
 201     i_bitrate_index = (i_header & 0xf000) >> 12;
 202     i_samplerate_index = (i_header & 0xc00) >> 10;
 203     b_padding   = (i_header & 0x200) >> 9;
 204     /* Extension */
 205     i_mode      = (i_header & 0xc0) >> 6;
 206     /* Modeext, copyright & original */
 207     i_emphasis  = i_header & 0x3;
 208     *pi_chan_mode = 0;
 209
 210     if( *pi_layer != 4 &&
 211         i_bitrate_index < 0x0f &&
 212         i_samplerate_index != 0x03 &&
 213         i_emphasis != 0x02 )
 214     {
 215         switch ( i_mode )
 216         {
 217         case 2: /* dual-mono */
 218             *pi_chan_mode = AOUT_CHANMODE_DUALMONO;
 219             /* fall through */
 220         case 0: /* stereo */
 221         case 1: /* joint stereo */
 222             *pi_channels = 2;
 223             *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT;
 224             break;
 225         case 3: /* mono */
 226             *pi_channels = 1;
 227             *pi_channels_conf = AOUT_CHAN_CENTER;
 228             break;
 229         }
 230         *pi_bit_rate = ppi_bitrate[i_version][*pi_layer-1][i_bitrate_index];
 231         i_max_bit_rate = ppi_bitrate[i_version][*pi_layer-1][14];
 232         *pi_sample_rate = ppi_samplerate[i_version][i_samplerate_index];
 233
 234         if ( b_mpeg_2_5 )
 235         {
 236             *pi_sample_rate >>= 1;
 237         }
 238
 239         switch( *pi_layer )
 240         {
 241         case 1:
 242             i_frame_size = ( 12000 * *pi_bit_rate / *pi_sample_rate +
 243                            b_padding ) * 4;
 244             *pi_max_frame_size = ( 12000 * i_max_bit_rate /
 245                                  *pi_sample_rate + 1 ) * 4;
 246             *pi_frame_length = 384;
 247             break;
 248
 249         case 2:
 250             i_frame_size = 144000 * *pi_bit_rate / *pi_sample_rate + b_padding;
 251             *pi_max_frame_size = 144000 * i_max_bit_rate / *pi_sample_rate + 1;
 252             *pi_frame_length = 1152;
 253             break;
 254
 255         case 3:
 256             i_frame_size = ( i_version ? 72000 : 144000 ) *
 257                            *pi_bit_rate / *pi_sample_rate + b_padding;
 258             *pi_max_frame_size = ( i_version ? 72000 : 144000 ) *
 259                                  i_max_bit_rate / *pi_sample_rate + 1;
 260             *pi_frame_length = i_version ? 576 : 1152;
 261             break;
 262
 263         default:
 264             break;
 265         }
 266
 267         /* Free bitrate mode can support higher bitrates */
 268         if( !*pi_bit_rate ) *pi_max_frame_size *= 2;
 269     }
 270     else
 271     {
 272         return -1;
 273     }
 274
 275     return i_frame_size;
 276 }
 277
 278 /****************************************************************************
 279  * DecodeBlock: the whole thing
 280  ****************************************************************************
 281  * This function is called just after the thread is launched.
 282  ****************************************************************************/
 283 static block_t *DecodeBlock( decoder_t *p_dec, block_t **pp_block )
 284 {
 285     decoder_sys_t *p_sys = p_dec->p_sys;
 286     uint8_t p_header[MAD_BUFFER_GUARD];
 287     uint32_t i_header;
 288     uint8_t *p_buf;
 289     block_t *p_out_buffer;
 290
 291     block_t *p_block = pp_block ? *pp_block : NULL;
 292
 293     if (p_block)
 294     {
 295         if( p_block->i_flags & (BLOCK_FLAG_DISCONTINUITY|BLOCK_FLAG_CORRUPTED) )
 296         {
 297             /* First always drain complete blocks before discontinuity */
 298             block_t *p_drain = DecodeBlock( p_dec, NULL );
 299             if( p_drain )
 300                 return p_drain;
 301
 302             Flush( p_dec );
 303
 304             if( p_block->i_flags & BLOCK_FLAG_CORRUPTED )
 305             {
 306                 block_Release( p_block );
 307                 return NULL;
 308             }
 309         }
 310
 311         if( !date_Get( &p_sys->end_date ) && p_block->i_pts <= VLC_TS_INVALID )
 312         {
 313             /* We've just started the stream, wait for the first PTS. */
 314             msg_Dbg( p_dec, "waiting for PTS" );
 315             block_Release( p_block );
 316             return NULL;
 317         }
 318
 319         block_BytestreamPush( &p_sys->bytestream, p_block );
 320     }
 321
 322     while( 1 )
 323     {
 324         switch( p_sys->i_state )
 325         {
 326
 327         case STATE_NOSYNC:
 328             while( block_PeekBytes( &p_sys->bytestream, p_header, 2 )
 329                    == VLC_SUCCESS )
 330             {
 331                 /* Look for sync word - should be 0xffe */
 332                 if( p_header[0] == 0xff && (p_header[1] & 0xe0) == 0xe0 )
 333                 {
 334                     p_sys->i_state = STATE_SYNC;
 335                     break;
 336                 }
 337                 block_SkipByte( &p_sys->bytestream );
 338             }
 339             if( p_sys->i_state != STATE_SYNC )
 340             {
 341                 block_BytestreamFlush( &p_sys->bytestream );
 342
 343                 /* Need more data */
 344                 return NULL;
 345             }
 346             /* fallthrough */
 347
 348         case STATE_SYNC:
 349             /* New frame, set the Presentation Time Stamp */
 350             p_sys->i_pts = p_sys->bytestream.p_block->i_pts;
 351             if( p_sys->i_pts > VLC_TS_INVALID &&
 352                 p_sys->i_pts != date_Get( &p_sys->end_date ) )
 353             {
 354                 if( p_dec->fmt_in.i_original_fourcc == VLC_FOURCC( 'D','V','R',' ') )
 355                 {
 356                     if( date_Get( &p_sys->end_date ) == VLC_TS_INVALID )
 357                         date_Set( &p_sys->end_date, p_sys->i_pts );
 358                 }
 359                 else if ( p_sys->i_pts != date_Get( &p_sys->end_date ) )
 360                 {
 361                     date_Set( &p_sys->end_date, p_sys->i_pts );
 362                 }
 363             }
 364             p_sys->i_state = STATE_HEADER;
 365             /* fallthrough */
 366
 367         case STATE_HEADER:
 368             /* Get MPGA frame header (MPGA_HEADER_SIZE bytes) */
 369             if( block_PeekBytes( &p_sys->bytestream, p_header,
 370                                  MPGA_HEADER_SIZE ) != VLC_SUCCESS )
 371             {
 372                 /* Need more data */
 373                 return NULL;
 374             }
 375
 376             /* Build frame header */
 377             i_header = GetDWBE(p_header);
 378
 379             /* Check if frame is valid and get frame info */
 380             p_sys->i_frame_size = SyncInfo( i_header,
 381                                             &p_sys->i_channels,
 382                                             &p_sys->i_channels_conf,
 383                                             &p_sys->i_chan_mode,
 384                                             &p_sys->i_rate,
 385                                             &p_sys->i_bit_rate,
 386                                             &p_sys->i_frame_length,
 387                                             &p_sys->i_max_frame_size,
 388                                             &p_sys->i_layer );
 389
 390             p_dec->fmt_in.i_profile = p_sys->i_layer;
 391
 392             if( p_sys->i_frame_size == -1 )
 393             {
 394                 msg_Dbg( p_dec, "emulated startcode" );
 395                 block_SkipByte( &p_sys->bytestream );
 396                 p_sys->i_state = STATE_NOSYNC;
 397                 break;
 398             }
 399
 400             if( p_sys->i_bit_rate == 0 )
 401             {
 402                 /* Free bitrate, but 99% emulated startcode :( */
 403                 if( p_dec->p_sys->i_free_frame_size == MPGA_HEADER_SIZE )
 404                 {
 405                     msg_Dbg( p_dec, "free bitrate mode");
 406                 }
 407                 /* The -1 below is to account for the frame padding */
 408                 p_sys->i_frame_size = p_sys->i_free_frame_size - 1;
 409             }
 410
 411             p_sys->i_state = STATE_NEXT_SYNC;
 412             /* fallthrough */
 413
 414         case STATE_NEXT_SYNC:
 415             /* Check if next expected frame contains the sync word */
 416             if( block_PeekOffsetBytes( &p_sys->bytestream,
 417                                        p_sys->i_frame_size, p_header,
 418                                        MAD_BUFFER_GUARD ) != VLC_SUCCESS )
 419             {
 420                 if( p_block == NULL ) /* drain */
 421                 {
 422                     p_sys->i_state = STATE_SEND_DATA;
 423                     break;
 424                 }
 425                 /* Need more data */
 426                 return NULL;
 427             }
 428
 429             if( p_header[0] == 0xff && (p_header[1] & 0xe0) == 0xe0 )
 430             {
 431                 /* Startcode is fine, let's try the header as an extra check */
 432                 int i_next_frame_size;
 433                 unsigned int i_next_channels, i_next_stereo_mode, i_next_channels_conf;
 434                 unsigned int i_next_rate, i_next_bit_rate;
 435                 unsigned int i_next_frame_length, i_next_max_frame_size;
 436                 unsigned int i_next_layer;
 437
 438                 /* Build frame header */
 439                 i_header = GetDWBE(p_header);
 440
 441                 i_next_frame_size = SyncInfo( i_header,
 442                                               &i_next_channels,
 443                                               &i_next_channels_conf,
 444                                               &i_next_stereo_mode,
 445                                               &i_next_rate,
 446                                               &i_next_bit_rate,
 447                                               &i_next_frame_length,
 448                                               &i_next_max_frame_size,
 449                                               &i_next_layer );
 450
 451                 /* Free bitrate only */
 452                 if( p_sys->i_bit_rate == 0 && i_next_frame_size == -1 )
 453                 {
 454                     if( (unsigned int)p_sys->i_frame_size >
 455                         p_sys->i_max_frame_size )
 456                     {
 457                         msg_Dbg( p_dec, "frame too big %d > %d "
 458                                  "(emulated startcode ?)", p_sys->i_frame_size,
 459                                  p_sys->i_max_frame_size );
 460                         block_SkipByte( &p_sys->bytestream );
 461                         p_sys->i_state = STATE_NOSYNC;
 462                         p_sys->i_free_frame_size = MPGA_HEADER_SIZE;
 463                         break;
 464                     }
 465
 466                     p_sys->i_frame_size++;
 467                     break;
 468                 }
 469
 470                 if( i_next_frame_size == -1 )
 471                 {
 472                     msg_Dbg( p_dec, "emulated startcode on next frame" );
 473                     block_SkipByte( &p_sys->bytestream );
 474                     p_sys->i_state = STATE_NOSYNC;
 475                     break;
 476                 }
 477
 478                 /* Check info is in sync with previous one */
 479                 if( i_next_channels_conf != p_sys->i_channels_conf ||
 480                     i_next_stereo_mode != p_sys->i_chan_mode ||
 481                     i_next_rate != p_sys->i_rate ||
 482                     i_next_layer != p_sys->i_layer ||
 483                     i_next_frame_length != p_sys->i_frame_length )
 484                 {
 485                     /* Free bitrate only */
 486                     if( p_sys->i_bit_rate == 0 )
 487                     {
 488                         p_sys->i_frame_size++;
 489                         break;
 490                     }
 491
 492                     msg_Dbg( p_dec, "parameters changed unexpectedly "
 493                              "(emulated startcode ?)" );
 494                     block_SkipByte( &p_sys->bytestream );
 495                     p_sys->i_state = STATE_NOSYNC;
 496                     break;
 497                 }
 498
 499                 /* Free bitrate only */
 500                 if( p_sys->i_bit_rate == 0 )
 501                 {
 502                     if( i_next_bit_rate != 0 )
 503                     {
 504                         p_sys->i_frame_size++;
 505                         break;
 506                     }
 507                 }
 508
 509             }
 510             else
 511             {
 512                 /* Free bitrate only */
 513                 if( p_sys->i_bit_rate == 0 )
 514                 {
 515                     if( (unsigned int)p_sys->i_frame_size >
 516                         p_sys->i_max_frame_size )
 517                     {
 518                         msg_Dbg( p_dec, "frame too big %d > %d "
 519                                  "(emulated startcode ?)", p_sys->i_frame_size,
 520                                  p_sys->i_max_frame_size );
 521                         block_SkipByte( &p_sys->bytestream );
 522                         p_sys->i_state = STATE_NOSYNC;
 523                         p_sys->i_free_frame_size = MPGA_HEADER_SIZE;
 524                         break;
 525                     }
 526
 527                     p_sys->i_frame_size++;
 528                     break;
 529                 }
 530
 531                 msg_Dbg( p_dec, "emulated startcode "
 532                          "(no startcode on following frame)" );
 533                 p_sys->i_state = STATE_NOSYNC;
 534                 block_SkipByte( &p_sys->bytestream );
 535                 break;
 536             }
 537
 538             p_sys->i_state = STATE_GET_DATA;
 539             break;
 540
 541         case STATE_GET_DATA:
 542             /* Make sure we have enough data.
 543              * (Not useful if we went through NEXT_SYNC) */
 544             if( block_WaitBytes( &p_sys->bytestream,
 545                                  p_sys->i_frame_size ) != VLC_SUCCESS )
 546             {
 547                 /* Need more data */
 548                 return NULL;
 549             }
 550             p_sys->i_state = STATE_SEND_DATA;
 551             /* fallthrough */
 552
 553         case STATE_SEND_DATA:
 554             if( !(p_buf = GetOutBuffer( p_dec, &p_out_buffer )) )
 555             {
 556                 return NULL;
 557             }
 558
 559             /* Free bitrate only */
 560             if( p_sys->i_bit_rate == 0 )
 561             {
 562                 p_sys->i_free_frame_size = p_sys->i_frame_size;
 563             }
 564
 565             /* Copy the whole frame into the buffer. */
 566             if (block_GetBytes( &p_sys->bytestream,
 567                             p_buf, __MIN( (unsigned)p_sys->i_frame_size, p_out_buffer->i_buffer ) )) {
 568                 block_Release(p_out_buffer);
 569                 return NULL;
 570             }
 571
 572             p_sys->i_state = STATE_NOSYNC;
 573
 574             /* Make sure we don't reuse the same pts twice */
 575             if( p_sys->i_pts == p_sys->bytestream.p_block->i_pts )
 576                 p_sys->i_pts = p_sys->bytestream.p_block->i_pts = VLC_TS_INVALID;
 577
 578             if( p_sys->b_discontinuity )
 579             {
 580                 p_out_buffer->i_flags |= BLOCK_FLAG_DISCONTINUITY;
 581                 p_sys->b_discontinuity = false;
 582             }
 583
 584             /* So p_block doesn't get re-added several times */
 585             p_block = block_BytestreamPop( &p_sys->bytestream );
 586             if (pp_block)
 587                 *pp_block = p_block;
 588             else if (p_block)
 589                 block_Release(p_block);
 590
 591             return p_out_buffer;
 592         }
 593     }
 594
 595     return NULL;
 596 }
 597
 598 /*****************************************************************************
 599  * Close: clean up the decoder
 600  *****************************************************************************/
 601 static void Close( vlc_object_t *p_this )
 602 {
 603     decoder_t *p_dec = (decoder_t *)p_this;
 604     decoder_sys_t *p_sys = p_dec->p_sys;
 605
 606     block_BytestreamRelease( &p_sys->bytestream );
 607
 608     free( p_sys );
 609 }
 610
 611 /*****************************************************************************
 612  * Open: probe the decoder and return score
 613  *****************************************************************************/
 614 static int Open( vlc_object_t *p_this )
 615 {
 616     decoder_t *p_dec = (decoder_t*)p_this;
 617     decoder_sys_t *p_sys;
 618
 619     if(( p_dec->fmt_in.i_codec != VLC_CODEC_MPGA ) &&
 620        ( p_dec->fmt_in.i_codec != VLC_CODEC_MP3 ) )
 621     {
 622         return VLC_EGENERIC;
 623     }
 624
 625     /* Allocate the memory needed to store the decoder's structure */
 626     if( ( p_dec->p_sys = p_sys =
 627           (decoder_sys_t *)malloc(sizeof(decoder_sys_t)) ) == NULL )
 628         return VLC_ENOMEM;
 629
 630     /* Misc init */
 631     p_sys->i_state = STATE_NOSYNC;
 632     date_Init( &p_sys->end_date, 1, 1 );
 633     date_Set( &p_sys->end_date, VLC_TS_INVALID );
 634     block_BytestreamInit( &p_sys->bytestream );
 635     p_sys->i_pts = VLC_TS_INVALID;
 636     p_sys->b_discontinuity = false;
 637     p_sys->i_frame_size = 0;
 638
 639     p_sys->i_channels_conf = p_sys->i_chan_mode = p_sys->i_channels =
 640     p_sys->i_rate = p_sys->i_max_frame_size = p_sys->i_frame_length =
 641     p_sys->i_layer = p_sys->i_bit_rate = 0;
 642
 643     /* Set output properties */
 644     p_dec->fmt_out.i_codec = VLC_CODEC_MPGA;
 645     p_dec->fmt_out.audio.i_rate = 0; /* So end_date gets initialized */
 646
 647     /* Set callback */
 648     p_dec->pf_packetize    = DecodeBlock;
 649     p_dec->pf_flush        = Flush;
 650
 651     /* Start with the minimum size for a free bitrate frame */
 652     p_sys->i_free_frame_size = MPGA_HEADER_SIZE;
 653
 654     return VLC_SUCCESS;
 655 }