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 the VideoLAN team
   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., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  24  *****************************************************************************/
  25
  26 /*****************************************************************************
  27  * Preamble
  28  *****************************************************************************/
  29 #include <vlc/vlc.h>
  30 #include <vlc_codec.h>
  31 #include <vlc_aout.h>
  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 *, unsigned int *, unsigned int *,
  81                             unsigned int *, int * );
  82
  83 static uint8_t       *GetOutBuffer ( decoder_t *, void ** );
  84 static aout_buffer_t *GetAoutBuffer( decoder_t * );
  85 static block_t       *GetSoutBuffer( decoder_t * );
  86
  87 /*****************************************************************************
  88  * Module descriptor
  89  *****************************************************************************/
  90 vlc_module_begin();
  91     set_description( _("A/52 parser") );
  92     set_capability( "decoder", 100 );
  93     set_callbacks( OpenDecoder, CloseDecoder );
  94     set_category( CAT_INPUT );
  95     set_subcategory( SUBCAT_INPUT_ACODEC );
  96
  97     add_submodule();
  98     set_description( _("A/52 audio packetizer") );
  99     set_capability( "packetizer", 10 );
 100     set_callbacks( OpenPacketizer, CloseDecoder );
 101 vlc_module_end();
 102
 103 /*****************************************************************************
 104  * OpenDecoder: probe the decoder and return score
 105  *****************************************************************************/
 106 static int OpenDecoder( vlc_object_t *p_this )
 107 {
 108     decoder_t *p_dec = (decoder_t*)p_this;
 109     decoder_sys_t *p_sys;
 110
 111     if( p_dec->fmt_in.i_codec != VLC_FOURCC('a','5','2',' ')
 112           && p_dec->fmt_in.i_codec != VLC_FOURCC('a','5','2','b') )
 113     {
 114         return VLC_EGENERIC;
 115     }
 116
 117     /* Allocate the memory needed to store the decoder's structure */
 118     if( ( p_dec->p_sys = p_sys =
 119           (decoder_sys_t *)malloc(sizeof(decoder_sys_t)) ) == NULL )
 120     {
 121         msg_Err( p_dec, "out of memory" );
 122         return VLC_EGENERIC;
 123     }
 124
 125     /* Misc init */
 126     p_sys->b_packetizer = VLC_FALSE;
 127     p_sys->i_state = STATE_NOSYNC;
 128     aout_DateSet( &p_sys->end_date, 0 );
 129
 130     p_sys->bytestream = block_BytestreamInit( p_dec );
 131
 132     /* Set output properties */
 133     p_dec->fmt_out.i_cat = AUDIO_ES;
 134     p_dec->fmt_out.i_codec = VLC_FOURCC('a','5','2',' ');
 135     p_dec->fmt_out.audio.i_rate = 0; /* So end_date gets initialized */
 136
 137     /* Set callback */
 138     p_dec->pf_decode_audio = (aout_buffer_t *(*)(decoder_t *, block_t **))
 139         DecodeBlock;
 140     p_dec->pf_packetize    = (block_t *(*)(decoder_t *, block_t **))
 141         DecodeBlock;
 142
 143     return VLC_SUCCESS;
 144 }
 145
 146 static int OpenPacketizer( vlc_object_t *p_this )
 147 {
 148     decoder_t *p_dec = (decoder_t*)p_this;
 149
 150     int i_ret = OpenDecoder( p_this );
 151
 152     if( i_ret == VLC_SUCCESS ) p_dec->p_sys->b_packetizer = VLC_TRUE;
 153
 154     return i_ret;
 155 }
 156
 157 /****************************************************************************
 158  * DecodeBlock: the whole thing
 159  ****************************************************************************
 160  * This function is called just after the thread is launched.
 161  ****************************************************************************/
 162 static void *DecodeBlock( decoder_t *p_dec, block_t **pp_block )
 163 {
 164     decoder_sys_t *p_sys = p_dec->p_sys;
 165     uint8_t p_header[A52_HEADER_SIZE];
 166     uint8_t *p_buf;
 167     void *p_out_buffer;
 168
 169     if( !pp_block || !*pp_block ) return NULL;
 170
 171     if( (*pp_block)->i_flags&(BLOCK_FLAG_DISCONTINUITY|BLOCK_FLAG_CORRUPTED) )
 172     {
 173         if( (*pp_block)->i_flags&BLOCK_FLAG_CORRUPTED )
 174         {
 175             p_sys->i_state = STATE_NOSYNC;
 176             block_BytestreamFlush( &p_sys->bytestream );
 177         }
 178 //        aout_DateSet( &p_sys->end_date, 0 );
 179         block_Release( *pp_block );
 180         return NULL;
 181     }
 182
 183     if( !aout_DateGet( &p_sys->end_date ) && !(*pp_block)->i_pts )
 184     {
 185         /* We've just started the stream, wait for the first PTS. */
 186         block_Release( *pp_block );
 187         return NULL;
 188     }
 189
 190     block_BytestreamPush( &p_sys->bytestream, *pp_block );
 191
 192     while( 1 )
 193     {
 194         switch( p_sys->i_state )
 195         {
 196         case STATE_NOSYNC:
 197             while( block_PeekBytes( &p_sys->bytestream, p_header, 2 )
 198                    == VLC_SUCCESS )
 199             {
 200                 if( p_header[0] == 0x0b && p_header[1] == 0x77 )
 201                 {
 202                     p_sys->i_state = STATE_SYNC;
 203                     break;
 204                 }
 205                 block_SkipByte( &p_sys->bytestream );
 206             }
 207             if( p_sys->i_state != STATE_SYNC )
 208             {
 209                 block_BytestreamFlush( &p_sys->bytestream );
 210
 211                 /* Need more data */
 212                 return NULL;
 213             }
 214
 215         case STATE_SYNC:
 216             /* New frame, set the Presentation Time Stamp */
 217             p_sys->i_pts = p_sys->bytestream.p_block->i_pts;
 218             if( p_sys->i_pts != 0 &&
 219                 p_sys->i_pts != aout_DateGet( &p_sys->end_date ) )
 220             {
 221                 aout_DateSet( &p_sys->end_date, p_sys->i_pts );
 222             }
 223             p_sys->i_state = STATE_HEADER;
 224
 225         case STATE_HEADER:
 226             /* Get A/52 frame header (A52_HEADER_SIZE bytes) */
 227             if( block_PeekBytes( &p_sys->bytestream, p_header,
 228                                  A52_HEADER_SIZE ) != VLC_SUCCESS )
 229             {
 230                 /* Need more data */
 231                 return NULL;
 232             }
 233
 234             /* Check if frame is valid and get frame info */
 235             p_sys->i_frame_size = SyncInfo( p_header,
 236                                             &p_sys->i_channels,
 237                                             &p_sys->i_channels_conf,
 238                                             &p_sys->i_rate,
 239                                             &p_sys->i_bit_rate );
 240             if( !p_sys->i_frame_size )
 241             {
 242                 msg_Dbg( p_dec, "emulated sync word" );
 243                 block_SkipByte( &p_sys->bytestream );
 244                 p_sys->i_state = STATE_NOSYNC;
 245                 break;
 246             }
 247             p_sys->i_state = STATE_NEXT_SYNC;
 248
 249         case STATE_NEXT_SYNC:
 250             /* TODO: If pp_block == NULL, flush the buffer without checking the
 251              * next sync word */
 252
 253             /* Check if next expected frame contains the sync word */
 254             if( block_PeekOffsetBytes( &p_sys->bytestream,
 255                                        p_sys->i_frame_size, p_header, 2 )
 256                 != VLC_SUCCESS )
 257             {
 258                 /* Need more data */
 259                 return NULL;
 260             }
 261
 262             if( p_sys->b_packetizer &&
 263                 p_header[0] == 0 && p_header[1] == 0 )
 264             {
 265                 /* A52 wav files and audio CD's use stuffing */
 266                 p_sys->i_state = STATE_GET_DATA;
 267                 break;
 268             }
 269
 270             if( p_header[0] != 0x0b || p_header[1] != 0x77 )
 271             {
 272                 msg_Dbg( p_dec, "emulated sync word "
 273                          "(no sync on following frame)" );
 274                 p_sys->i_state = STATE_NOSYNC;
 275                 block_SkipByte( &p_sys->bytestream );
 276                 break;
 277             }
 278             p_sys->i_state = STATE_SEND_DATA;
 279             break;
 280
 281         case STATE_GET_DATA:
 282             /* Make sure we have enough data.
 283              * (Not useful if we went through NEXT_SYNC) */
 284             if( block_WaitBytes( &p_sys->bytestream,
 285                                  p_sys->i_frame_size ) != VLC_SUCCESS )
 286             {
 287                 /* Need more data */
 288                 return NULL;
 289             }
 290             p_sys->i_state = STATE_SEND_DATA;
 291
 292         case STATE_SEND_DATA:
 293             if( !(p_buf = GetOutBuffer( p_dec, &p_out_buffer )) )
 294             {
 295                 //p_dec->b_error = VLC_TRUE;
 296                 return NULL;
 297             }
 298
 299             /* Copy the whole frame into the buffer. When we reach this point
 300              * we already know we have enough data available. */
 301             block_GetBytes( &p_sys->bytestream, p_buf, p_sys->i_frame_size );
 302
 303             /* Make sure we don't reuse the same pts twice */
 304             if( p_sys->i_pts == p_sys->bytestream.p_block->i_pts )
 305                 p_sys->i_pts = p_sys->bytestream.p_block->i_pts = 0;
 306
 307             /* So p_block doesn't get re-added several times */
 308             *pp_block = block_BytestreamPop( &p_sys->bytestream );
 309
 310             p_sys->i_state = STATE_NOSYNC;
 311
 312             return p_out_buffer;
 313         }
 314     }
 315
 316     return NULL;
 317 }
 318
 319 /*****************************************************************************
 320  * CloseDecoder: clean up the decoder
 321  *****************************************************************************/
 322 static void CloseDecoder( vlc_object_t *p_this )
 323 {
 324     decoder_t *p_dec = (decoder_t*)p_this;
 325     decoder_sys_t *p_sys = p_dec->p_sys;
 326
 327     block_BytestreamRelease( &p_sys->bytestream );
 328
 329     free( p_sys );
 330 }
 331
 332 /*****************************************************************************
 333  * GetOutBuffer:
 334  *****************************************************************************/
 335 static uint8_t *GetOutBuffer( decoder_t *p_dec, void **pp_out_buffer )
 336 {
 337     decoder_sys_t *p_sys = p_dec->p_sys;
 338     uint8_t *p_buf;
 339
 340     if( p_dec->fmt_out.audio.i_rate != p_sys->i_rate )
 341     {
 342         msg_Info( p_dec, "A/52 channels:%d samplerate:%d bitrate:%d",
 343                   p_sys->i_channels, p_sys->i_rate, p_sys->i_bit_rate );
 344
 345         aout_DateInit( &p_sys->end_date, p_sys->i_rate );
 346         aout_DateSet( &p_sys->end_date, p_sys->i_pts );
 347     }
 348
 349     p_dec->fmt_out.audio.i_rate     = p_sys->i_rate;
 350     p_dec->fmt_out.audio.i_channels = p_sys->i_channels;
 351     p_dec->fmt_out.audio.i_bytes_per_frame = p_sys->i_frame_size;
 352     p_dec->fmt_out.audio.i_frame_length = A52_FRAME_NB;
 353
 354     p_dec->fmt_out.audio.i_original_channels = p_sys->i_channels_conf;
 355     p_dec->fmt_out.audio.i_physical_channels =
 356         p_sys->i_channels_conf & AOUT_CHAN_PHYSMASK;
 357
 358     p_dec->fmt_out.i_bitrate = p_sys->i_bit_rate;
 359
 360     if( p_sys->b_packetizer )
 361     {
 362         block_t *p_sout_buffer = GetSoutBuffer( p_dec );
 363         p_buf = p_sout_buffer ? p_sout_buffer->p_buffer : NULL;
 364         *pp_out_buffer = p_sout_buffer;
 365     }
 366     else
 367     {
 368         aout_buffer_t *p_aout_buffer = GetAoutBuffer( p_dec );
 369         p_buf = p_aout_buffer ? p_aout_buffer->p_buffer : NULL;
 370         *pp_out_buffer = p_aout_buffer;
 371     }
 372
 373     return p_buf;
 374 }
 375
 376 /*****************************************************************************
 377  * GetAoutBuffer:
 378  *****************************************************************************/
 379 static aout_buffer_t *GetAoutBuffer( decoder_t *p_dec )
 380 {
 381     decoder_sys_t *p_sys = p_dec->p_sys;
 382     aout_buffer_t *p_buf;
 383
 384     p_buf = p_dec->pf_aout_buffer_new( p_dec, A52_FRAME_NB  );
 385     if( p_buf == NULL ) return NULL;
 386
 387     p_buf->start_date = aout_DateGet( &p_sys->end_date );
 388     p_buf->end_date = aout_DateIncrement( &p_sys->end_date, A52_FRAME_NB );
 389
 390     return p_buf;
 391 }
 392
 393 /*****************************************************************************
 394  * GetSoutBuffer:
 395  *****************************************************************************/
 396 static block_t *GetSoutBuffer( decoder_t *p_dec )
 397 {
 398     decoder_sys_t *p_sys = p_dec->p_sys;
 399     block_t *p_block;
 400
 401     p_block = block_New( p_dec, p_sys->i_frame_size );
 402     if( p_block == NULL ) return NULL;
 403
 404     p_block->i_pts = p_block->i_dts = aout_DateGet( &p_sys->end_date );
 405
 406     p_block->i_length = aout_DateIncrement( &p_sys->end_date, A52_FRAME_NB ) -
 407         p_block->i_pts;
 408
 409     return p_block;
 410 }
 411
 412 /*****************************************************************************
 413  * SyncInfo: parse A/52 sync info
 414  *****************************************************************************
 415  * This code is borrowed from liba52 by Aaron Holtzman & Michel Lespinasse,
 416  * since we don't want to oblige S/PDIF people to use liba52 just to get
 417  * their SyncInfo...
 418  *****************************************************************************/
 419 static int SyncInfo( const byte_t * p_buf,
 420                      unsigned int * pi_channels,
 421                      unsigned int * pi_channels_conf,
 422                      unsigned int * pi_sample_rate, int * pi_bit_rate )
 423 {
 424     static const uint8_t halfrate[12] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3 };
 425     static const int rate[] = { 32,  40,  48,  56,  64,  80,  96, 112,
 426                                 128, 160, 192, 224, 256, 320, 384, 448,
 427                                 512, 576, 640 };
 428     static const uint8_t lfeon[8] = { 0x10, 0x10, 0x04, 0x04,
 429                                       0x04, 0x01, 0x04, 0x01 };
 430     int frmsizecod;
 431     int bitrate;
 432     int half;
 433     int acmod;
 434
 435     if ((p_buf[0] != 0x0b) || (p_buf[1] != 0x77))        /* syncword */
 436         return 0;
 437
 438     if (p_buf[5] >= 0x60)                /* bsid >= 12 */
 439         return 0;
 440     half = halfrate[p_buf[5] >> 3];
 441
 442     /* acmod, dsurmod and lfeon */
 443     acmod = p_buf[6] >> 5;
 444     if ( (p_buf[6] & 0xf8) == 0x50 )
 445     {
 446         /* Dolby surround = stereo + Dolby */
 447         *pi_channels = 2;
 448         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 449                             | AOUT_CHAN_DOLBYSTEREO;
 450     }
 451     else switch ( acmod )
 452     {
 453     case 0x0:
 454         /* Dual-mono = stereo + dual-mono */
 455         *pi_channels = 2;
 456         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 457                             | AOUT_CHAN_DUALMONO;
 458         break;
 459     case 0x1:
 460         /* Mono */
 461         *pi_channels = 1;
 462         *pi_channels_conf = AOUT_CHAN_CENTER;
 463         break;
 464     case 0x2:
 465         /* Stereo */
 466         *pi_channels = 2;
 467         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT;
 468         break;
 469     case 0x3:
 470         /* 3F */
 471         *pi_channels = 3;
 472         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 473                             | AOUT_CHAN_CENTER;
 474         break;
 475     case 0x4:
 476         /* 2F1R */
 477         *pi_channels = 3;
 478         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 479                             | AOUT_CHAN_REARCENTER;
 480         break;
 481     case 0x5:
 482         /* 3F1R */
 483         *pi_channels = 4;
 484         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER
 485                             | AOUT_CHAN_REARCENTER;
 486         break;
 487     case 0x6:
 488         /* 2F2R */
 489         *pi_channels = 4;
 490         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 491                             | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT;
 492         break;
 493     case 0x7:
 494         /* 3F2R */
 495         *pi_channels = 5;
 496         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER
 497                             | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT;
 498         break;
 499     default:
 500         return 0;
 501     }
 502
 503     if ( p_buf[6] & lfeon[acmod] )
 504     {
 505         (*pi_channels)++;
 506         *pi_channels_conf |= AOUT_CHAN_LFE;
 507     }
 508
 509     frmsizecod = p_buf[4] & 63;
 510     if (frmsizecod >= 38)
 511         return 0;
 512     bitrate = rate [frmsizecod >> 1];
 513     *pi_bit_rate = (bitrate * 1000) >> half;
 514
 515     switch (p_buf[4] & 0xc0) {
 516     case 0:
 517         *pi_sample_rate = 48000 >> half;
 518         return 4 * bitrate;
 519     case 0x40:
 520         *pi_sample_rate = 44100 >> half;
 521         return 2 * (320 * bitrate / 147 + (frmsizecod & 1));
 522     case 0x80:
 523         *pi_sample_rate = 32000 >> half;
 524         return 6 * bitrate;
 525     default:
 526         return 0;
 527     }
 528 }