git.sesse.net Git - vlc/blob - modules/codec/a52.c

   1 /*****************************************************************************
   2  * a52.c: parse A/52 audio sync info and packetize the stream
   3  *****************************************************************************
   4  * Copyright (C) 2001-2002 VideoLAN
   5  * $Id$
   6  *
   7  * Authors: Stéphane Borel <stef@via.ecp.fr>
   8  *          Christophe Massiot <massiot@via.ecp.fr>
   9  *          Gildas Bazin <gbazin@videolan.org>
  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 <vlc/vlc.h>
  30 #include <vlc/decoder.h>
  31
  32 #include "vlc_block_helper.h"
  33
  34 #define A52_HEADER_SIZE 7
  35
  36 /*****************************************************************************
  37  * decoder_sys_t : decoder descriptor
  38  *****************************************************************************/
  39 struct decoder_sys_t
  40 {
  41     /* Module mode */
  42     vlc_bool_t b_packetizer;
  43
  44     /*
  45      * Input properties
  46      */
  47     int i_state;
  48
  49     block_bytestream_t bytestream;
  50
  51     /*
  52      * Common properties
  53      */
  54     audio_date_t   end_date;
  55
  56     mtime_t i_pts;
  57     int i_frame_size, i_bit_rate;
  58     unsigned int i_rate, i_channels, i_channels_conf;
  59
  60 };
  61
  62 enum {
  63
  64     STATE_NOSYNC,
  65     STATE_SYNC,
  66     STATE_HEADER,
  67     STATE_NEXT_SYNC,
  68     STATE_GET_DATA,
  69     STATE_SEND_DATA
  70 };
  71
  72 /****************************************************************************
  73  * Local prototypes
  74  ****************************************************************************/
  75 static int  OpenDecoder   ( vlc_object_t * );
  76 static int  OpenPacketizer( vlc_object_t * );
  77 static void CloseDecoder  ( vlc_object_t * );
  78 static void *DecodeBlock  ( decoder_t *, block_t ** );
  79
  80 static int  SyncInfo      ( const byte_t *, int *, int *, int *,int * );
  81
  82 static uint8_t       *GetOutBuffer ( decoder_t *, void ** );
  83 static aout_buffer_t *GetAoutBuffer( decoder_t * );
  84 static block_t       *GetSoutBuffer( decoder_t * );
  85
  86 /*****************************************************************************
  87  * Module descriptor
  88  *****************************************************************************/
  89 vlc_module_begin();
  90     set_description( _("A/52 parser") );
  91     set_capability( "decoder", 100 );
  92     set_callbacks( OpenDecoder, CloseDecoder );
  93     set_category( CAT_INPUT );
  94     set_subcategory( SUBCAT_INPUT_ACODEC );
  95
  96     add_submodule();
  97     set_description( _("A/52 audio packetizer") );
  98     set_capability( "packetizer", 10 );
  99     set_callbacks( OpenPacketizer, CloseDecoder );
 100 vlc_module_end();
 101
 102 /*****************************************************************************
 103  * OpenDecoder: probe the decoder and return score
 104  *****************************************************************************/
 105 static int OpenDecoder( vlc_object_t *p_this )
 106 {
 107     decoder_t *p_dec = (decoder_t*)p_this;
 108     decoder_sys_t *p_sys;
 109
 110     if( p_dec->fmt_in.i_codec != VLC_FOURCC('a','5','2',' ')
 111           && p_dec->fmt_in.i_codec != VLC_FOURCC('a','5','2','b') )
 112     {
 113         return VLC_EGENERIC;
 114     }
 115
 116     /* Allocate the memory needed to store the decoder's structure */
 117     if( ( p_dec->p_sys = p_sys =
 118           (decoder_sys_t *)malloc(sizeof(decoder_sys_t)) ) == NULL )
 119     {
 120         msg_Err( p_dec, "out of memory" );
 121         return VLC_EGENERIC;
 122     }
 123
 124     /* Misc init */
 125     p_sys->b_packetizer = VLC_FALSE;
 126     p_sys->i_state = STATE_NOSYNC;
 127     aout_DateSet( &p_sys->end_date, 0 );
 128
 129     p_sys->bytestream = block_BytestreamInit( p_dec );
 130
 131     /* Set output properties */
 132     p_dec->fmt_out.i_cat = AUDIO_ES;
 133     p_dec->fmt_out.i_codec = VLC_FOURCC('a','5','2',' ');
 134     p_dec->fmt_out.audio.i_rate = 0; /* So end_date gets initialized */
 135
 136     /* Set callback */
 137     p_dec->pf_decode_audio = (aout_buffer_t *(*)(decoder_t *, block_t **))
 138         DecodeBlock;
 139     p_dec->pf_packetize    = (block_t *(*)(decoder_t *, block_t **))
 140         DecodeBlock;
 141
 142     return VLC_SUCCESS;
 143 }
 144
 145 static int OpenPacketizer( vlc_object_t *p_this )
 146 {
 147     decoder_t *p_dec = (decoder_t*)p_this;
 148
 149     int i_ret = OpenDecoder( p_this );
 150
 151     if( i_ret == VLC_SUCCESS ) p_dec->p_sys->b_packetizer = VLC_TRUE;
 152
 153     return i_ret;
 154 }
 155
 156 /****************************************************************************
 157  * DecodeBlock: the whole thing
 158  ****************************************************************************
 159  * This function is called just after the thread is launched.
 160  ****************************************************************************/
 161 static void *DecodeBlock( decoder_t *p_dec, block_t **pp_block )
 162 {
 163     decoder_sys_t *p_sys = p_dec->p_sys;
 164     uint8_t p_header[A52_HEADER_SIZE];
 165     uint8_t *p_buf;
 166     void *p_out_buffer;
 167
 168     if( !pp_block || !*pp_block ) return NULL;
 169
 170     if( !aout_DateGet( &p_sys->end_date ) && !(*pp_block)->i_pts )
 171     {
 172         /* We've just started the stream, wait for the first PTS. */
 173         block_Release( *pp_block );
 174         return NULL;
 175     }
 176
 177     if( (*pp_block)->i_flags&(BLOCK_FLAG_DISCONTINUITY|BLOCK_FLAG_CORRUPTED) )
 178     {
 179         p_sys->i_state = STATE_NOSYNC;
 180     }
 181
 182     block_BytestreamPush( &p_sys->bytestream, *pp_block );
 183
 184     while( 1 )
 185     {
 186         switch( p_sys->i_state )
 187         {
 188         case STATE_NOSYNC:
 189             while( block_PeekBytes( &p_sys->bytestream, p_header, 2 )
 190                    == VLC_SUCCESS )
 191             {
 192                 if( p_header[0] == 0x0b && p_header[1] == 0x77 )
 193                 {
 194                     p_sys->i_state = STATE_SYNC;
 195                     break;
 196                 }
 197                 block_SkipByte( &p_sys->bytestream );
 198             }
 199             if( p_sys->i_state != STATE_SYNC )
 200             {
 201                 block_BytestreamFlush( &p_sys->bytestream );
 202
 203                 /* Need more data */
 204                 return NULL;
 205             }
 206
 207         case STATE_SYNC:
 208             /* New frame, set the Presentation Time Stamp */
 209             p_sys->i_pts = p_sys->bytestream.p_block->i_pts;
 210             if( p_sys->i_pts != 0 &&
 211                 p_sys->i_pts != aout_DateGet( &p_sys->end_date ) )
 212             {
 213                 aout_DateSet( &p_sys->end_date, p_sys->i_pts );
 214             }
 215             p_sys->i_state = STATE_HEADER;
 216
 217         case STATE_HEADER:
 218             /* Get A/52 frame header (A52_HEADER_SIZE bytes) */
 219             if( block_PeekBytes( &p_sys->bytestream, p_header,
 220                                  A52_HEADER_SIZE ) != VLC_SUCCESS )
 221             {
 222                 /* Need more data */
 223                 return NULL;
 224             }
 225
 226             /* Check if frame is valid and get frame info */
 227             p_sys->i_frame_size = SyncInfo( p_header,
 228                                             &p_sys->i_channels,
 229                                             &p_sys->i_channels_conf,
 230                                             &p_sys->i_rate,
 231                                             &p_sys->i_bit_rate );
 232             if( !p_sys->i_frame_size )
 233             {
 234                 msg_Dbg( p_dec, "emulated sync word" );
 235                 block_SkipByte( &p_sys->bytestream );
 236                 p_sys->i_state = STATE_NOSYNC;
 237                 break;
 238             }
 239             p_sys->i_state = STATE_NEXT_SYNC;
 240
 241         case STATE_NEXT_SYNC:
 242             /* TODO: If pp_block == NULL, flush the buffer without checking the
 243              * next sync word */
 244
 245             /* Check if next expected frame contains the sync word */
 246             if( block_PeekOffsetBytes( &p_sys->bytestream,
 247                                        p_sys->i_frame_size, p_header, 2 )
 248                 != VLC_SUCCESS )
 249             {
 250                 /* Need more data */
 251                 return NULL;
 252             }
 253
 254             if( p_sys->b_packetizer &&
 255                 p_header[0] == 0 && p_header[1] == 0 )
 256             {
 257                 /* A52 wav files and audio CD's use stuffing */
 258                 p_sys->i_state = STATE_GET_DATA;
 259                 break;
 260             }
 261
 262             if( p_header[0] != 0x0b || p_header[1] != 0x77 )
 263             {
 264                 msg_Dbg( p_dec, "emulated sync word "
 265                          "(no sync on following frame)" );
 266                 p_sys->i_state = STATE_NOSYNC;
 267                 block_SkipByte( &p_sys->bytestream );
 268                 break;
 269             }
 270             p_sys->i_state = STATE_SEND_DATA;
 271             break;
 272
 273         case STATE_GET_DATA:
 274             /* Make sure we have enough data.
 275              * (Not useful if we went through NEXT_SYNC) */
 276             if( block_WaitBytes( &p_sys->bytestream,
 277                                  p_sys->i_frame_size ) != VLC_SUCCESS )
 278             {
 279                 /* Need more data */
 280                 return NULL;
 281             }
 282             p_sys->i_state = STATE_SEND_DATA;
 283
 284         case STATE_SEND_DATA:
 285             if( !(p_buf = GetOutBuffer( p_dec, &p_out_buffer )) )
 286             {
 287                 //p_dec->b_error = VLC_TRUE;
 288                 return NULL;
 289             }
 290
 291             /* Copy the whole frame into the buffer. When we reach this point
 292              * we already know we have enough data available. */
 293             block_GetBytes( &p_sys->bytestream, p_buf, p_sys->i_frame_size );
 294
 295             /* Make sure we don't reuse the same pts twice */
 296             if( p_sys->i_pts == p_sys->bytestream.p_block->i_pts )
 297                 p_sys->i_pts = p_sys->bytestream.p_block->i_pts = 0;
 298
 299             /* So p_block doesn't get re-added several times */
 300             *pp_block = block_BytestreamPop( &p_sys->bytestream );
 301
 302             p_sys->i_state = STATE_NOSYNC;
 303
 304             return p_out_buffer;
 305         }
 306     }
 307
 308     return NULL;
 309 }
 310
 311 /*****************************************************************************
 312  * CloseDecoder: clean up the decoder
 313  *****************************************************************************/
 314 static void CloseDecoder( vlc_object_t *p_this )
 315 {
 316     decoder_t *p_dec = (decoder_t*)p_this;
 317     decoder_sys_t *p_sys = p_dec->p_sys;
 318
 319     block_BytestreamRelease( &p_sys->bytestream );
 320
 321     free( p_sys );
 322 }
 323
 324 /*****************************************************************************
 325  * GetOutBuffer:
 326  *****************************************************************************/
 327 static uint8_t *GetOutBuffer( decoder_t *p_dec, void **pp_out_buffer )
 328 {
 329     decoder_sys_t *p_sys = p_dec->p_sys;
 330     uint8_t *p_buf;
 331
 332     if( p_dec->fmt_out.audio.i_rate != p_sys->i_rate )
 333     {
 334         msg_Info( p_dec, "A/52 channels:%d samplerate:%d bitrate:%d",
 335                   p_sys->i_channels, p_sys->i_rate, p_sys->i_bit_rate );
 336
 337         aout_DateInit( &p_sys->end_date, p_sys->i_rate );
 338         aout_DateSet( &p_sys->end_date, p_sys->i_pts );
 339     }
 340
 341     p_dec->fmt_out.audio.i_rate     = p_sys->i_rate;
 342     p_dec->fmt_out.audio.i_channels = p_sys->i_channels;
 343     p_dec->fmt_out.audio.i_bytes_per_frame = p_sys->i_frame_size;
 344     p_dec->fmt_out.audio.i_frame_length = A52_FRAME_NB;
 345
 346     p_dec->fmt_out.audio.i_original_channels = p_sys->i_channels_conf;
 347     p_dec->fmt_out.audio.i_physical_channels =
 348         p_sys->i_channels_conf & AOUT_CHAN_PHYSMASK;
 349
 350     p_dec->fmt_out.i_bitrate = p_sys->i_bit_rate;
 351
 352     if( p_sys->b_packetizer )
 353     {
 354         block_t *p_sout_buffer = GetSoutBuffer( p_dec );
 355         p_buf = p_sout_buffer ? p_sout_buffer->p_buffer : NULL;
 356         *pp_out_buffer = p_sout_buffer;
 357     }
 358     else
 359     {
 360         aout_buffer_t *p_aout_buffer = GetAoutBuffer( p_dec );
 361         p_buf = p_aout_buffer ? p_aout_buffer->p_buffer : NULL;
 362         *pp_out_buffer = p_aout_buffer;
 363     }
 364
 365     return p_buf;
 366 }
 367
 368 /*****************************************************************************
 369  * GetAoutBuffer:
 370  *****************************************************************************/
 371 static aout_buffer_t *GetAoutBuffer( decoder_t *p_dec )
 372 {
 373     decoder_sys_t *p_sys = p_dec->p_sys;
 374     aout_buffer_t *p_buf;
 375
 376     p_buf = p_dec->pf_aout_buffer_new( p_dec, A52_FRAME_NB  );
 377     if( p_buf == NULL ) return NULL;
 378
 379     p_buf->start_date = aout_DateGet( &p_sys->end_date );
 380     p_buf->end_date = aout_DateIncrement( &p_sys->end_date, A52_FRAME_NB );
 381
 382     return p_buf;
 383 }
 384
 385 /*****************************************************************************
 386  * GetSoutBuffer:
 387  *****************************************************************************/
 388 static block_t *GetSoutBuffer( decoder_t *p_dec )
 389 {
 390     decoder_sys_t *p_sys = p_dec->p_sys;
 391     block_t *p_block;
 392
 393     p_block = block_New( p_dec, p_sys->i_frame_size );
 394     if( p_block == NULL ) return NULL;
 395
 396     p_block->i_pts = p_block->i_dts = aout_DateGet( &p_sys->end_date );
 397
 398     p_block->i_length = aout_DateIncrement( &p_sys->end_date, A52_FRAME_NB ) -
 399         p_block->i_pts;
 400
 401     return p_block;
 402 }
 403
 404 /*****************************************************************************
 405  * SyncInfo: parse A/52 sync info
 406  *****************************************************************************
 407  * This code is borrowed from liba52 by Aaron Holtzman & Michel Lespinasse,
 408  * since we don't want to oblige S/PDIF people to use liba52 just to get
 409  * their SyncInfo...
 410  *****************************************************************************/
 411 static int SyncInfo( const byte_t * p_buf,
 412                      int * pi_channels, int * pi_channels_conf,
 413                      int * pi_sample_rate, int * pi_bit_rate )
 414 {
 415     static const uint8_t halfrate[12] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3 };
 416     static const int rate[] = { 32,  40,  48,  56,  64,  80,  96, 112,
 417                                 128, 160, 192, 224, 256, 320, 384, 448,
 418                                 512, 576, 640 };
 419     static const uint8_t lfeon[8] = { 0x10, 0x10, 0x04, 0x04,
 420                                       0x04, 0x01, 0x04, 0x01 };
 421     int frmsizecod;
 422     int bitrate;
 423     int half;
 424     int acmod;
 425
 426     if ((p_buf[0] != 0x0b) || (p_buf[1] != 0x77))        /* syncword */
 427         return 0;
 428
 429     if (p_buf[5] >= 0x60)                /* bsid >= 12 */
 430         return 0;
 431     half = halfrate[p_buf[5] >> 3];
 432
 433     /* acmod, dsurmod and lfeon */
 434     acmod = p_buf[6] >> 5;
 435     if ( (p_buf[6] & 0xf8) == 0x50 )
 436     {
 437         /* Dolby surround = stereo + Dolby */
 438         *pi_channels = 2;
 439         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 440                             | AOUT_CHAN_DOLBYSTEREO;
 441     }
 442     else switch ( acmod )
 443     {
 444     case 0x0:
 445         /* Dual-mono = stereo + dual-mono */
 446         *pi_channels = 2;
 447         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 448                             | AOUT_CHAN_DUALMONO;
 449         break;
 450     case 0x1:
 451         /* Mono */
 452         *pi_channels = 1;
 453         *pi_channels_conf = AOUT_CHAN_CENTER;
 454         break;
 455     case 0x2:
 456         /* Stereo */
 457         *pi_channels = 2;
 458         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT;
 459         break;
 460     case 0x3:
 461         /* 3F */
 462         *pi_channels = 3;
 463         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 464                             | AOUT_CHAN_CENTER;
 465         break;
 466     case 0x4:
 467         /* 2F1R */
 468         *pi_channels = 3;
 469         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 470                             | AOUT_CHAN_REARCENTER;
 471         break;
 472     case 0x5:
 473         /* 3F1R */
 474         *pi_channels = 4;
 475         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER
 476                             | AOUT_CHAN_REARCENTER;
 477         break;
 478     case 0x6:
 479         /* 2F2R */
 480         *pi_channels = 4;
 481         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 482                             | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT;
 483         break;
 484     case 0x7:
 485         /* 3F2R */
 486         *pi_channels = 5;
 487         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER
 488                             | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT;
 489         break;
 490     default:
 491         return 0;
 492     }
 493
 494     if ( p_buf[6] & lfeon[acmod] )
 495     {
 496         (*pi_channels)++;
 497         *pi_channels_conf |= AOUT_CHAN_LFE;
 498     }
 499
 500     frmsizecod = p_buf[4] & 63;
 501     if (frmsizecod >= 38)
 502         return 0;
 503     bitrate = rate [frmsizecod >> 1];
 504     *pi_bit_rate = (bitrate * 1000) >> half;
 505
 506     switch (p_buf[4] & 0xc0) {
 507     case 0:
 508         *pi_sample_rate = 48000 >> half;
 509         return 4 * bitrate;
 510     case 0x40:
 511         *pi_sample_rate = 44100 >> half;
 512         return 2 * (320 * bitrate / 147 + (frmsizecod & 1));
 513     case 0x80:
 514         *pi_sample_rate = 32000 >> half;
 515         return 6 * bitrate;
 516     default:
 517         return 0;
 518     }
 519 }