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., 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 *, 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( !aout_DateGet( &p_sys->end_date ) && !(*pp_block)->i_pts )
 172     {
 173         /* We've just started the stream, wait for the first PTS. */
 174         block_Release( *pp_block );
 175         return NULL;
 176     }
 177
 178     if( (*pp_block)->i_flags&(BLOCK_FLAG_DISCONTINUITY|BLOCK_FLAG_CORRUPTED) )
 179     {
 180         p_sys->i_state = STATE_NOSYNC;
 181     }
 182
 183     block_BytestreamPush( &p_sys->bytestream, *pp_block );
 184
 185     while( 1 )
 186     {
 187         switch( p_sys->i_state )
 188         {
 189         case STATE_NOSYNC:
 190             while( block_PeekBytes( &p_sys->bytestream, p_header, 2 )
 191                    == VLC_SUCCESS )
 192             {
 193                 if( p_header[0] == 0x0b && p_header[1] == 0x77 )
 194                 {
 195                     p_sys->i_state = STATE_SYNC;
 196                     break;
 197                 }
 198                 block_SkipByte( &p_sys->bytestream );
 199             }
 200             if( p_sys->i_state != STATE_SYNC )
 201             {
 202                 block_BytestreamFlush( &p_sys->bytestream );
 203
 204                 /* Need more data */
 205                 return NULL;
 206             }
 207
 208         case STATE_SYNC:
 209             /* New frame, set the Presentation Time Stamp */
 210             p_sys->i_pts = p_sys->bytestream.p_block->i_pts;
 211             if( p_sys->i_pts != 0 &&
 212                 p_sys->i_pts != aout_DateGet( &p_sys->end_date ) )
 213             {
 214                 aout_DateSet( &p_sys->end_date, p_sys->i_pts );
 215             }
 216             p_sys->i_state = STATE_HEADER;
 217
 218         case STATE_HEADER:
 219             /* Get A/52 frame header (A52_HEADER_SIZE bytes) */
 220             if( block_PeekBytes( &p_sys->bytestream, p_header,
 221                                  A52_HEADER_SIZE ) != VLC_SUCCESS )
 222             {
 223                 /* Need more data */
 224                 return NULL;
 225             }
 226
 227             /* Check if frame is valid and get frame info */
 228             p_sys->i_frame_size = SyncInfo( p_header,
 229                                             &p_sys->i_channels,
 230                                             &p_sys->i_channels_conf,
 231                                             &p_sys->i_rate,
 232                                             &p_sys->i_bit_rate );
 233             if( !p_sys->i_frame_size )
 234             {
 235                 msg_Dbg( p_dec, "emulated sync word" );
 236                 block_SkipByte( &p_sys->bytestream );
 237                 p_sys->i_state = STATE_NOSYNC;
 238                 break;
 239             }
 240             p_sys->i_state = STATE_NEXT_SYNC;
 241
 242         case STATE_NEXT_SYNC:
 243             /* TODO: If pp_block == NULL, flush the buffer without checking the
 244              * next sync word */
 245
 246             /* Check if next expected frame contains the sync word */
 247             if( block_PeekOffsetBytes( &p_sys->bytestream,
 248                                        p_sys->i_frame_size, p_header, 2 )
 249                 != VLC_SUCCESS )
 250             {
 251                 /* Need more data */
 252                 return NULL;
 253             }
 254
 255             if( p_sys->b_packetizer &&
 256                 p_header[0] == 0 && p_header[1] == 0 )
 257             {
 258                 /* A52 wav files and audio CD's use stuffing */
 259                 p_sys->i_state = STATE_GET_DATA;
 260                 break;
 261             }
 262
 263             if( p_header[0] != 0x0b || p_header[1] != 0x77 )
 264             {
 265                 msg_Dbg( p_dec, "emulated sync word "
 266                          "(no sync on following frame)" );
 267                 p_sys->i_state = STATE_NOSYNC;
 268                 block_SkipByte( &p_sys->bytestream );
 269                 break;
 270             }
 271             p_sys->i_state = STATE_SEND_DATA;
 272             break;
 273
 274         case STATE_GET_DATA:
 275             /* Make sure we have enough data.
 276              * (Not useful if we went through NEXT_SYNC) */
 277             if( block_WaitBytes( &p_sys->bytestream,
 278                                  p_sys->i_frame_size ) != VLC_SUCCESS )
 279             {
 280                 /* Need more data */
 281                 return NULL;
 282             }
 283             p_sys->i_state = STATE_SEND_DATA;
 284
 285         case STATE_SEND_DATA:
 286             if( !(p_buf = GetOutBuffer( p_dec, &p_out_buffer )) )
 287             {
 288                 //p_dec->b_error = VLC_TRUE;
 289                 return NULL;
 290             }
 291
 292             /* Copy the whole frame into the buffer. When we reach this point
 293              * we already know we have enough data available. */
 294             block_GetBytes( &p_sys->bytestream, p_buf, p_sys->i_frame_size );
 295
 296             /* Make sure we don't reuse the same pts twice */
 297             if( p_sys->i_pts == p_sys->bytestream.p_block->i_pts )
 298                 p_sys->i_pts = p_sys->bytestream.p_block->i_pts = 0;
 299
 300             /* So p_block doesn't get re-added several times */
 301             *pp_block = block_BytestreamPop( &p_sys->bytestream );
 302
 303             p_sys->i_state = STATE_NOSYNC;
 304
 305             return p_out_buffer;
 306         }
 307     }
 308
 309     return NULL;
 310 }
 311
 312 /*****************************************************************************
 313  * CloseDecoder: clean up the decoder
 314  *****************************************************************************/
 315 static void CloseDecoder( vlc_object_t *p_this )
 316 {
 317     decoder_t *p_dec = (decoder_t*)p_this;
 318     decoder_sys_t *p_sys = p_dec->p_sys;
 319
 320     block_BytestreamRelease( &p_sys->bytestream );
 321
 322     free( p_sys );
 323 }
 324
 325 /*****************************************************************************
 326  * GetOutBuffer:
 327  *****************************************************************************/
 328 static uint8_t *GetOutBuffer( decoder_t *p_dec, void **pp_out_buffer )
 329 {
 330     decoder_sys_t *p_sys = p_dec->p_sys;
 331     uint8_t *p_buf;
 332
 333     if( p_dec->fmt_out.audio.i_rate != p_sys->i_rate )
 334     {
 335         msg_Info( p_dec, "A/52 channels:%d samplerate:%d bitrate:%d",
 336                   p_sys->i_channels, p_sys->i_rate, p_sys->i_bit_rate );
 337
 338         aout_DateInit( &p_sys->end_date, p_sys->i_rate );
 339         aout_DateSet( &p_sys->end_date, p_sys->i_pts );
 340     }
 341
 342     p_dec->fmt_out.audio.i_rate     = p_sys->i_rate;
 343     p_dec->fmt_out.audio.i_channels = p_sys->i_channels;
 344     p_dec->fmt_out.audio.i_bytes_per_frame = p_sys->i_frame_size;
 345     p_dec->fmt_out.audio.i_frame_length = A52_FRAME_NB;
 346
 347     p_dec->fmt_out.audio.i_original_channels = p_sys->i_channels_conf;
 348     p_dec->fmt_out.audio.i_physical_channels =
 349         p_sys->i_channels_conf & AOUT_CHAN_PHYSMASK;
 350
 351     p_dec->fmt_out.i_bitrate = p_sys->i_bit_rate;
 352
 353     if( p_sys->b_packetizer )
 354     {
 355         block_t *p_sout_buffer = GetSoutBuffer( p_dec );
 356         p_buf = p_sout_buffer ? p_sout_buffer->p_buffer : NULL;
 357         *pp_out_buffer = p_sout_buffer;
 358     }
 359     else
 360     {
 361         aout_buffer_t *p_aout_buffer = GetAoutBuffer( p_dec );
 362         p_buf = p_aout_buffer ? p_aout_buffer->p_buffer : NULL;
 363         *pp_out_buffer = p_aout_buffer;
 364     }
 365
 366     return p_buf;
 367 }
 368
 369 /*****************************************************************************
 370  * GetAoutBuffer:
 371  *****************************************************************************/
 372 static aout_buffer_t *GetAoutBuffer( decoder_t *p_dec )
 373 {
 374     decoder_sys_t *p_sys = p_dec->p_sys;
 375     aout_buffer_t *p_buf;
 376
 377     p_buf = p_dec->pf_aout_buffer_new( p_dec, A52_FRAME_NB  );
 378     if( p_buf == NULL ) return NULL;
 379
 380     p_buf->start_date = aout_DateGet( &p_sys->end_date );
 381     p_buf->end_date = aout_DateIncrement( &p_sys->end_date, A52_FRAME_NB );
 382
 383     return p_buf;
 384 }
 385
 386 /*****************************************************************************
 387  * GetSoutBuffer:
 388  *****************************************************************************/
 389 static block_t *GetSoutBuffer( decoder_t *p_dec )
 390 {
 391     decoder_sys_t *p_sys = p_dec->p_sys;
 392     block_t *p_block;
 393
 394     p_block = block_New( p_dec, p_sys->i_frame_size );
 395     if( p_block == NULL ) return NULL;
 396
 397     p_block->i_pts = p_block->i_dts = aout_DateGet( &p_sys->end_date );
 398
 399     p_block->i_length = aout_DateIncrement( &p_sys->end_date, A52_FRAME_NB ) -
 400         p_block->i_pts;
 401
 402     return p_block;
 403 }
 404
 405 /*****************************************************************************
 406  * SyncInfo: parse A/52 sync info
 407  *****************************************************************************
 408  * This code is borrowed from liba52 by Aaron Holtzman & Michel Lespinasse,
 409  * since we don't want to oblige S/PDIF people to use liba52 just to get
 410  * their SyncInfo...
 411  *****************************************************************************/
 412 static int SyncInfo( const byte_t * p_buf,
 413                      unsigned int * pi_channels,
 414                      unsigned int * pi_channels_conf,
 415                      unsigned int * pi_sample_rate, int * pi_bit_rate )
 416 {
 417     static const uint8_t halfrate[12] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3 };
 418     static const int rate[] = { 32,  40,  48,  56,  64,  80,  96, 112,
 419                                 128, 160, 192, 224, 256, 320, 384, 448,
 420                                 512, 576, 640 };
 421     static const uint8_t lfeon[8] = { 0x10, 0x10, 0x04, 0x04,
 422                                       0x04, 0x01, 0x04, 0x01 };
 423     int frmsizecod;
 424     int bitrate;
 425     int half;
 426     int acmod;
 427
 428     if ((p_buf[0] != 0x0b) || (p_buf[1] != 0x77))        /* syncword */
 429         return 0;
 430
 431     if (p_buf[5] >= 0x60)                /* bsid >= 12 */
 432         return 0;
 433     half = halfrate[p_buf[5] >> 3];
 434
 435     /* acmod, dsurmod and lfeon */
 436     acmod = p_buf[6] >> 5;
 437     if ( (p_buf[6] & 0xf8) == 0x50 )
 438     {
 439         /* Dolby surround = stereo + Dolby */
 440         *pi_channels = 2;
 441         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 442                             | AOUT_CHAN_DOLBYSTEREO;
 443     }
 444     else switch ( acmod )
 445     {
 446     case 0x0:
 447         /* Dual-mono = stereo + dual-mono */
 448         *pi_channels = 2;
 449         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 450                             | AOUT_CHAN_DUALMONO;
 451         break;
 452     case 0x1:
 453         /* Mono */
 454         *pi_channels = 1;
 455         *pi_channels_conf = AOUT_CHAN_CENTER;
 456         break;
 457     case 0x2:
 458         /* Stereo */
 459         *pi_channels = 2;
 460         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT;
 461         break;
 462     case 0x3:
 463         /* 3F */
 464         *pi_channels = 3;
 465         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 466                             | AOUT_CHAN_CENTER;
 467         break;
 468     case 0x4:
 469         /* 2F1R */
 470         *pi_channels = 3;
 471         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 472                             | AOUT_CHAN_REARCENTER;
 473         break;
 474     case 0x5:
 475         /* 3F1R */
 476         *pi_channels = 4;
 477         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER
 478                             | AOUT_CHAN_REARCENTER;
 479         break;
 480     case 0x6:
 481         /* 2F2R */
 482         *pi_channels = 4;
 483         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 484                             | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT;
 485         break;
 486     case 0x7:
 487         /* 3F2R */
 488         *pi_channels = 5;
 489         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER
 490                             | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT;
 491         break;
 492     default:
 493         return 0;
 494     }
 495
 496     if ( p_buf[6] & lfeon[acmod] )
 497     {
 498         (*pi_channels)++;
 499         *pi_channels_conf |= AOUT_CHAN_LFE;
 500     }
 501
 502     frmsizecod = p_buf[4] & 63;
 503     if (frmsizecod >= 38)
 504         return 0;
 505     bitrate = rate [frmsizecod >> 1];
 506     *pi_bit_rate = (bitrate * 1000) >> half;
 507
 508     switch (p_buf[4] & 0xc0) {
 509     case 0:
 510         *pi_sample_rate = 48000 >> half;
 511         return 4 * bitrate;
 512     case 0x40:
 513         *pi_sample_rate = 44100 >> half;
 514         return 2 * (320 * bitrate / 147 + (frmsizecod & 1));
 515     case 0x80:
 516         *pi_sample_rate = 32000 >> half;
 517         return 6 * bitrate;
 518     default:
 519         return 0;
 520     }
 521 }