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: a52.c,v 1.34 2004/02/25 17:48:52 fenrir Exp $
   6  *
   7  * Authors: Stéphane Borel <stef@via.ecp.fr>
   8  *          Christophe Massiot <massiot@via.ecp.fr>
   9  *          Gildas Bazin <gbazin@netcourrier.com>
  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
  94     add_submodule();
  95     set_description( _("A/52 audio packetizer") );
  96     set_capability( "packetizer", 10 );
  97     set_callbacks( OpenPacketizer, CloseDecoder );
  98 vlc_module_end();
  99
 100 /*****************************************************************************
 101  * OpenDecoder: probe the decoder and return score
 102  *****************************************************************************/
 103 static int OpenDecoder( vlc_object_t *p_this )
 104 {
 105     decoder_t *p_dec = (decoder_t*)p_this;
 106     decoder_sys_t *p_sys;
 107
 108     if( p_dec->fmt_in.i_codec != VLC_FOURCC('a','5','2',' ')
 109           && p_dec->fmt_in.i_codec != VLC_FOURCC('a','5','2','b') )
 110     {
 111         return VLC_EGENERIC;
 112     }
 113
 114     /* Allocate the memory needed to store the decoder's structure */
 115     if( ( p_dec->p_sys = p_sys =
 116           (decoder_sys_t *)malloc(sizeof(decoder_sys_t)) ) == NULL )
 117     {
 118         msg_Err( p_dec, "out of memory" );
 119         return VLC_EGENERIC;
 120     }
 121
 122     /* Misc init */
 123     p_sys->b_packetizer = VLC_FALSE;
 124     p_sys->i_state = STATE_NOSYNC;
 125     aout_DateSet( &p_sys->end_date, 0 );
 126
 127     p_sys->bytestream = block_BytestreamInit( p_dec );
 128
 129     /* Set output properties */
 130     p_dec->fmt_out.i_cat = AUDIO_ES;
 131     p_dec->fmt_out.i_codec = VLC_FOURCC('a','5','2',' ');
 132
 133     /* Set callback */
 134     p_dec->pf_decode_audio = (aout_buffer_t *(*)(decoder_t *, block_t **))
 135         DecodeBlock;
 136     p_dec->pf_packetize    = (block_t *(*)(decoder_t *, block_t **))
 137         DecodeBlock;
 138
 139     return VLC_SUCCESS;
 140 }
 141
 142 static int OpenPacketizer( vlc_object_t *p_this )
 143 {
 144     decoder_t *p_dec = (decoder_t*)p_this;
 145
 146     int i_ret = OpenDecoder( p_this );
 147
 148     if( i_ret == VLC_SUCCESS ) p_dec->p_sys->b_packetizer = VLC_TRUE;
 149
 150     return i_ret;
 151 }
 152
 153 /****************************************************************************
 154  * DecodeBlock: the whole thing
 155  ****************************************************************************
 156  * This function is called just after the thread is launched.
 157  ****************************************************************************/
 158 static void *DecodeBlock( decoder_t *p_dec, block_t **pp_block )
 159 {
 160     decoder_sys_t *p_sys = p_dec->p_sys;
 161     uint8_t p_header[A52_HEADER_SIZE];
 162     uint8_t *p_buf;
 163     void *p_out_buffer;
 164
 165     if( !pp_block || !*pp_block ) return NULL;
 166
 167     if( !aout_DateGet( &p_sys->end_date ) && !(*pp_block)->i_pts )
 168     {
 169         /* We've just started the stream, wait for the first PTS. */
 170         block_Release( *pp_block );
 171         return NULL;
 172     }
 173
 174     if( (*pp_block)->i_flags&BLOCK_FLAG_DISCONTINUITY )
 175     {
 176         p_sys->i_state = STATE_NOSYNC;
 177     }
 178
 179     block_BytestreamPush( &p_sys->bytestream, *pp_block );
 180
 181     while( 1 )
 182     {
 183         switch( p_sys->i_state )
 184         {
 185         case STATE_NOSYNC:
 186             while( block_PeekBytes( &p_sys->bytestream, p_header, 2 )
 187                    == VLC_SUCCESS )
 188             {
 189                 if( p_header[0] == 0x0b && p_header[1] == 0x77 )
 190                 {
 191                     p_sys->i_state = STATE_SYNC;
 192                     break;
 193                 }
 194                 block_SkipByte( &p_sys->bytestream );
 195             }
 196             if( p_sys->i_state != STATE_SYNC )
 197             {
 198                 block_BytestreamFlush( &p_sys->bytestream );
 199
 200                 /* Need more data */
 201                 return NULL;
 202             }
 203
 204         case STATE_SYNC:
 205             /* New frame, set the Presentation Time Stamp */
 206             p_sys->i_pts = p_sys->bytestream.p_block->i_pts;
 207             if( p_sys->i_pts != 0 &&
 208                 p_sys->i_pts != aout_DateGet( &p_sys->end_date ) )
 209             {
 210                 aout_DateSet( &p_sys->end_date, p_sys->i_pts );
 211             }
 212             p_sys->i_state = STATE_HEADER;
 213
 214         case STATE_HEADER:
 215             /* Get A/52 frame header (A52_HEADER_SIZE bytes) */
 216             if( block_PeekBytes( &p_sys->bytestream, p_header,
 217                                  A52_HEADER_SIZE ) != VLC_SUCCESS )
 218             {
 219                 /* Need more data */
 220                 return NULL;
 221             }
 222
 223             /* Check if frame is valid and get frame info */
 224             p_sys->i_frame_size = SyncInfo( p_header,
 225                                             &p_sys->i_channels,
 226                                             &p_sys->i_channels_conf,
 227                                             &p_sys->i_rate,
 228                                             &p_sys->i_bit_rate );
 229             if( !p_sys->i_frame_size )
 230             {
 231                 msg_Dbg( p_dec, "emulated sync word" );
 232                 block_SkipByte( &p_sys->bytestream );
 233                 p_sys->i_state = STATE_NOSYNC;
 234                 break;
 235             }
 236             p_sys->i_state = STATE_NEXT_SYNC;
 237
 238         case STATE_NEXT_SYNC:
 239             /* TODO: If pp_block == NULL, flush the buffer without checking the
 240              * next sync word */
 241
 242             /* Check if next expected frame contains the sync word */
 243             if( block_PeekOffsetBytes( &p_sys->bytestream,
 244                                        p_sys->i_frame_size, p_header, 2 )
 245                 != VLC_SUCCESS )
 246             {
 247                 /* Need more data */
 248                 return NULL;
 249             }
 250
 251             if( p_sys->b_packetizer &&
 252                 p_header[0] == 0 && p_header[1] == 0 )
 253             {
 254                 /* A52 wav files and audio CD's use stuffing */
 255                 p_sys->i_state = STATE_GET_DATA;
 256                 break;
 257             }
 258
 259             if( p_header[0] != 0x0b || p_header[1] != 0x77 )
 260             {
 261                 msg_Dbg( p_dec, "emulated sync word "
 262                          "(no sync on following frame)" );
 263                 p_sys->i_state = STATE_NOSYNC;
 264                 block_SkipByte( &p_sys->bytestream );
 265                 break;
 266             }
 267             p_sys->i_state = STATE_SEND_DATA;
 268             break;
 269
 270         case STATE_GET_DATA:
 271             /* Make sure we have enough data.
 272              * (Not useful if we went through NEXT_SYNC) */
 273             if( block_WaitBytes( &p_sys->bytestream,
 274                                  p_sys->i_frame_size ) != VLC_SUCCESS )
 275             {
 276                 /* Need more data */
 277                 return NULL;
 278             }
 279             p_sys->i_state = STATE_SEND_DATA;
 280
 281         case STATE_SEND_DATA:
 282             if( !(p_buf = GetOutBuffer( p_dec, &p_out_buffer )) )
 283             {
 284                 //p_dec->b_error = VLC_TRUE;
 285                 return NULL;
 286             }
 287
 288             /* Copy the whole frame into the buffer. When we reach this point
 289              * we already know we have enough data available. */
 290             block_GetBytes( &p_sys->bytestream, p_buf, p_sys->i_frame_size );
 291
 292             /* Make sure we don't reuse the same pts twice */
 293             if( p_sys->i_pts == p_sys->bytestream.p_block->i_pts )
 294                 p_sys->i_pts = p_sys->bytestream.p_block->i_pts = 0;
 295
 296             /* So p_block doesn't get re-added several times */
 297             *pp_block = block_BytestreamPop( &p_sys->bytestream );
 298
 299             p_sys->i_state = STATE_NOSYNC;
 300
 301             return p_out_buffer;
 302         }
 303     }
 304
 305     return NULL;
 306 }
 307
 308 /*****************************************************************************
 309  * CloseDecoder: clean up the decoder
 310  *****************************************************************************/
 311 static void CloseDecoder( vlc_object_t *p_this )
 312 {
 313     decoder_t *p_dec = (decoder_t*)p_this;
 314     decoder_sys_t *p_sys = p_dec->p_sys;
 315
 316     block_BytestreamRelease( &p_sys->bytestream );
 317
 318     free( p_sys );
 319 }
 320
 321 /*****************************************************************************
 322  * GetOutBuffer:
 323  *****************************************************************************/
 324 static uint8_t *GetOutBuffer( decoder_t *p_dec, void **pp_out_buffer )
 325 {
 326     decoder_sys_t *p_sys = p_dec->p_sys;
 327     uint8_t *p_buf;
 328
 329     if( p_dec->fmt_out.audio.i_rate != p_sys->i_rate )
 330     {
 331         msg_Info( p_dec, "A/52 channels:%d samplerate:%d bitrate:%d",
 332                   p_sys->i_channels, p_sys->i_rate, p_sys->i_bit_rate );
 333
 334         aout_DateInit( &p_sys->end_date, p_sys->i_rate );
 335         aout_DateSet( &p_sys->end_date, p_sys->i_pts );
 336     }
 337
 338     p_dec->fmt_out.audio.i_rate     = p_sys->i_rate;
 339     p_dec->fmt_out.audio.i_channels = p_sys->i_channels;
 340     p_dec->fmt_out.audio.i_bytes_per_frame = p_sys->i_frame_size;
 341     p_dec->fmt_out.audio.i_frame_length = A52_FRAME_NB;
 342
 343     p_dec->fmt_out.audio.i_original_channels = p_sys->i_channels_conf;
 344     p_dec->fmt_out.audio.i_physical_channels =
 345         p_sys->i_channels_conf & AOUT_CHAN_PHYSMASK;
 346
 347     p_dec->fmt_out.i_bitrate = p_sys->i_bit_rate;
 348
 349     if( p_sys->b_packetizer )
 350     {
 351         block_t *p_sout_buffer = GetSoutBuffer( p_dec );
 352         p_buf = p_sout_buffer ? p_sout_buffer->p_buffer : NULL;
 353         *pp_out_buffer = p_sout_buffer;
 354     }
 355     else
 356     {
 357         aout_buffer_t *p_aout_buffer = GetAoutBuffer( p_dec );
 358         p_buf = p_aout_buffer ? p_aout_buffer->p_buffer : NULL;
 359         *pp_out_buffer = p_aout_buffer;
 360     }
 361
 362     return p_buf;
 363 }
 364
 365 /*****************************************************************************
 366  * GetAoutBuffer:
 367  *****************************************************************************/
 368 static aout_buffer_t *GetAoutBuffer( decoder_t *p_dec )
 369 {
 370     decoder_sys_t *p_sys = p_dec->p_sys;
 371     aout_buffer_t *p_buf;
 372
 373     p_buf = p_dec->pf_aout_buffer_new( p_dec, A52_FRAME_NB  );
 374     if( p_buf == NULL ) return NULL;
 375
 376     p_buf->start_date = aout_DateGet( &p_sys->end_date );
 377     p_buf->end_date = aout_DateIncrement( &p_sys->end_date, A52_FRAME_NB );
 378
 379     return p_buf;
 380 }
 381
 382 /*****************************************************************************
 383  * GetSoutBuffer:
 384  *****************************************************************************/
 385 static block_t *GetSoutBuffer( decoder_t *p_dec )
 386 {
 387     decoder_sys_t *p_sys = p_dec->p_sys;
 388     block_t *p_block;
 389
 390     p_block = block_New( p_dec, p_sys->i_frame_size );
 391     if( p_block == NULL ) return NULL;
 392
 393     p_block->i_pts = p_block->i_dts = aout_DateGet( &p_sys->end_date );
 394
 395     p_block->i_length = aout_DateIncrement( &p_sys->end_date, A52_FRAME_NB ) -
 396         p_block->i_pts;
 397
 398     return p_block;
 399 }
 400
 401 /*****************************************************************************
 402  * SyncInfo: parse A/52 sync info
 403  *****************************************************************************
 404  * This code is borrowed from liba52 by Aaron Holtzman & Michel Lespinasse,
 405  * since we don't want to oblige S/PDIF people to use liba52 just to get
 406  * their SyncInfo...
 407  *****************************************************************************/
 408 static int SyncInfo( const byte_t * p_buf,
 409                      int * pi_channels, int * pi_channels_conf,
 410                      int * pi_sample_rate, int * pi_bit_rate )
 411 {
 412     static const uint8_t halfrate[12] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3 };
 413     static const int rate[] = { 32,  40,  48,  56,  64,  80,  96, 112,
 414                                 128, 160, 192, 224, 256, 320, 384, 448,
 415                                 512, 576, 640 };
 416     static const uint8_t lfeon[8] = { 0x10, 0x10, 0x04, 0x04,
 417                                       0x04, 0x01, 0x04, 0x01 };
 418     int frmsizecod;
 419     int bitrate;
 420     int half;
 421     int acmod;
 422
 423     if ((p_buf[0] != 0x0b) || (p_buf[1] != 0x77))        /* syncword */
 424         return 0;
 425
 426     if (p_buf[5] >= 0x60)                /* bsid >= 12 */
 427         return 0;
 428     half = halfrate[p_buf[5] >> 3];
 429
 430     /* acmod, dsurmod and lfeon */
 431     acmod = p_buf[6] >> 5;
 432     if ( (p_buf[6] & 0xf8) == 0x50 )
 433     {
 434         /* Dolby surround = stereo + Dolby */
 435         *pi_channels = 2;
 436         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 437                             | AOUT_CHAN_DOLBYSTEREO;
 438     }
 439     else switch ( acmod )
 440     {
 441     case 0x0:
 442         /* Dual-mono = stereo + dual-mono */
 443         *pi_channels = 2;
 444         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 445                             | AOUT_CHAN_DUALMONO;
 446         break;
 447     case 0x1:
 448         /* Mono */
 449         *pi_channels = 1;
 450         *pi_channels_conf = AOUT_CHAN_CENTER;
 451         break;
 452     case 0x2:
 453         /* Stereo */
 454         *pi_channels = 2;
 455         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT;
 456         break;
 457     case 0x3:
 458         /* 3F */
 459         *pi_channels = 3;
 460         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 461                             | AOUT_CHAN_CENTER;
 462         break;
 463     case 0x4:
 464         /* 2F1R */
 465         *pi_channels = 3;
 466         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 467                             | AOUT_CHAN_REARCENTER;
 468         break;
 469     case 0x5:
 470         /* 3F1R */
 471         *pi_channels = 4;
 472         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER
 473                             | AOUT_CHAN_REARCENTER;
 474         break;
 475     case 0x6:
 476         /* 2F2R */
 477         *pi_channels = 4;
 478         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 479                             | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT;
 480         break;
 481     case 0x7:
 482         /* 3F2R */
 483         *pi_channels = 5;
 484         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER
 485                             | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT;
 486         break;
 487     default:
 488         return 0;
 489     }
 490
 491     if ( p_buf[6] & lfeon[acmod] )
 492     {
 493         (*pi_channels)++;
 494         *pi_channels_conf |= AOUT_CHAN_LFE;
 495     }
 496
 497     frmsizecod = p_buf[4] & 63;
 498     if (frmsizecod >= 38)
 499         return 0;
 500     bitrate = rate [frmsizecod >> 1];
 501     *pi_bit_rate = (bitrate * 1000) >> half;
 502
 503     switch (p_buf[4] & 0xc0) {
 504     case 0:
 505         *pi_sample_rate = 48000 >> half;
 506         return 4 * bitrate;
 507     case 0x40:
 508         *pi_sample_rate = 44100 >> half;
 509         return 2 * (320 * bitrate / 147 + (frmsizecod & 1));
 510     case 0x80:
 511         *pi_sample_rate = 32000 >> half;
 512         return 6 * bitrate;
 513     default:
 514         return 0;
 515     }
 516 }