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 1.31 2003/11/22 23:39:14 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)->b_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_header[0] != 0x0b || p_header[1] != 0x77 )
 252             {
 253                 msg_Dbg( p_dec, "emulated sync word "
 254                          "(no sync on following frame)" );
 255                 p_sys->i_state = STATE_NOSYNC;
 256                 block_SkipByte( &p_sys->bytestream );
 257                 break;
 258             }
 259             p_sys->i_state = STATE_SEND_DATA;
 260             break;
 261
 262         case STATE_GET_DATA:
 263             /* Make sure we have enough data.
 264              * (Not useful if we went through NEXT_SYNC) */
 265             if( block_WaitBytes( &p_sys->bytestream,
 266                                  p_sys->i_frame_size ) != VLC_SUCCESS )
 267             {
 268                 /* Need more data */
 269                 return NULL;
 270             }
 271             p_sys->i_state = STATE_SEND_DATA;
 272
 273         case STATE_SEND_DATA:
 274             if( !(p_buf = GetOutBuffer( p_dec, &p_out_buffer )) )
 275             {
 276                 //p_dec->b_error = VLC_TRUE;
 277                 return NULL;
 278             }
 279
 280             /* Copy the whole frame into the buffer. When we reach this point
 281              * we already know we have enough data available. */
 282             block_GetBytes( &p_sys->bytestream, p_buf, p_sys->i_frame_size );
 283
 284             /* Make sure we don't reuse the same pts twice */
 285             if( p_sys->i_pts == p_sys->bytestream.p_block->i_pts )
 286                 p_sys->i_pts = p_sys->bytestream.p_block->i_pts = 0;
 287
 288             /* So p_block doesn't get re-added several times */
 289             *pp_block = block_BytestreamPop( &p_sys->bytestream );
 290
 291             p_sys->i_state = STATE_NOSYNC;
 292
 293             return p_out_buffer;
 294         }
 295     }
 296
 297     return NULL;
 298 }
 299
 300 /*****************************************************************************
 301  * CloseDecoder: clean up the decoder
 302  *****************************************************************************/
 303 static void CloseDecoder( vlc_object_t *p_this )
 304 {
 305     decoder_t *p_dec = (decoder_t*)p_this;
 306     decoder_sys_t *p_sys = p_dec->p_sys;
 307
 308     block_BytestreamRelease( &p_sys->bytestream );
 309
 310     free( p_sys );
 311 }
 312
 313 /*****************************************************************************
 314  * GetOutBuffer:
 315  *****************************************************************************/
 316 static uint8_t *GetOutBuffer( decoder_t *p_dec, void **pp_out_buffer )
 317 {
 318     decoder_sys_t *p_sys = p_dec->p_sys;
 319     uint8_t *p_buf;
 320
 321     if( p_dec->fmt_out.audio.i_rate != p_sys->i_rate )
 322     {
 323         msg_Info( p_dec, "A/52 channels:%d samplerate:%d bitrate:%d",
 324                   p_sys->i_channels, p_sys->i_rate, p_sys->i_bit_rate );
 325
 326         aout_DateInit( &p_sys->end_date, p_sys->i_rate );
 327         aout_DateSet( &p_sys->end_date, p_sys->i_pts );
 328     }
 329
 330     p_dec->fmt_out.audio.i_rate     = p_sys->i_rate;
 331     p_dec->fmt_out.audio.i_channels = p_sys->i_channels;
 332     p_dec->fmt_out.audio.i_bytes_per_frame = p_sys->i_frame_size;
 333     p_dec->fmt_out.audio.i_frame_length = A52_FRAME_NB;
 334
 335     p_dec->fmt_out.audio.i_original_channels = p_sys->i_channels_conf;
 336     p_dec->fmt_out.audio.i_physical_channels =
 337         p_sys->i_channels_conf & AOUT_CHAN_PHYSMASK;
 338
 339     p_dec->fmt_out.i_bitrate = p_sys->i_bit_rate;
 340
 341     if( p_sys->b_packetizer )
 342     {
 343         block_t *p_sout_buffer = GetSoutBuffer( p_dec );
 344         p_buf = p_sout_buffer ? p_sout_buffer->p_buffer : NULL;
 345         *pp_out_buffer = p_sout_buffer;
 346     }
 347     else
 348     {
 349         aout_buffer_t *p_aout_buffer = GetAoutBuffer( p_dec );
 350         p_buf = p_aout_buffer ? p_aout_buffer->p_buffer : NULL;
 351         *pp_out_buffer = p_aout_buffer;
 352     }
 353
 354     return p_buf;
 355 }
 356
 357 /*****************************************************************************
 358  * GetAoutBuffer:
 359  *****************************************************************************/
 360 static aout_buffer_t *GetAoutBuffer( decoder_t *p_dec )
 361 {
 362     decoder_sys_t *p_sys = p_dec->p_sys;
 363     aout_buffer_t *p_buf;
 364
 365     p_buf = p_dec->pf_aout_buffer_new( p_dec, A52_FRAME_NB  );
 366     if( p_buf == NULL ) return NULL;
 367
 368     p_buf->start_date = aout_DateGet( &p_sys->end_date );
 369     p_buf->end_date = aout_DateIncrement( &p_sys->end_date, A52_FRAME_NB );
 370
 371     return p_buf;
 372 }
 373
 374 /*****************************************************************************
 375  * GetSoutBuffer:
 376  *****************************************************************************/
 377 static block_t *GetSoutBuffer( decoder_t *p_dec )
 378 {
 379     decoder_sys_t *p_sys = p_dec->p_sys;
 380     block_t *p_block;
 381
 382     p_block = block_New( p_dec, p_sys->i_frame_size );
 383     if( p_block == NULL ) return NULL;
 384
 385     p_block->i_pts = p_block->i_dts = aout_DateGet( &p_sys->end_date );
 386
 387     p_block->i_length = aout_DateIncrement( &p_sys->end_date, A52_FRAME_NB ) -
 388         p_block->i_pts;
 389
 390     return p_block;
 391 }
 392
 393 /*****************************************************************************
 394  * SyncInfo: parse A/52 sync info
 395  *****************************************************************************
 396  * This code is borrowed from liba52 by Aaron Holtzman & Michel Lespinasse,
 397  * since we don't want to oblige S/PDIF people to use liba52 just to get
 398  * their SyncInfo...
 399  *****************************************************************************/
 400 static int SyncInfo( const byte_t * p_buf,
 401                      int * pi_channels, int * pi_channels_conf,
 402                      int * pi_sample_rate, int * pi_bit_rate )
 403 {
 404     static const uint8_t halfrate[12] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3 };
 405     static const int rate[] = { 32,  40,  48,  56,  64,  80,  96, 112,
 406                                 128, 160, 192, 224, 256, 320, 384, 448,
 407                                 512, 576, 640 };
 408     static const uint8_t lfeon[8] = { 0x10, 0x10, 0x04, 0x04,
 409                                       0x04, 0x01, 0x04, 0x01 };
 410     int frmsizecod;
 411     int bitrate;
 412     int half;
 413     int acmod;
 414
 415     if ((p_buf[0] != 0x0b) || (p_buf[1] != 0x77))        /* syncword */
 416         return 0;
 417
 418     if (p_buf[5] >= 0x60)                /* bsid >= 12 */
 419         return 0;
 420     half = halfrate[p_buf[5] >> 3];
 421
 422     /* acmod, dsurmod and lfeon */
 423     acmod = p_buf[6] >> 5;
 424     if ( (p_buf[6] & 0xf8) == 0x50 )
 425     {
 426         /* Dolby surround = stereo + Dolby */
 427         *pi_channels = 2;
 428         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 429                             | AOUT_CHAN_DOLBYSTEREO;
 430     }
 431     else switch ( acmod )
 432     {
 433     case 0x0:
 434         /* Dual-mono = stereo + dual-mono */
 435         *pi_channels = 2;
 436         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 437                             | AOUT_CHAN_DUALMONO;
 438         break;
 439     case 0x1:
 440         /* Mono */
 441         *pi_channels = 1;
 442         *pi_channels_conf = AOUT_CHAN_CENTER;
 443         break;
 444     case 0x2:
 445         /* Stereo */
 446         *pi_channels = 2;
 447         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT;
 448         break;
 449     case 0x3:
 450         /* 3F */
 451         *pi_channels = 3;
 452         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 453                             | AOUT_CHAN_CENTER;
 454         break;
 455     case 0x4:
 456         /* 2F1R */
 457         *pi_channels = 3;
 458         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 459                             | AOUT_CHAN_REARCENTER;
 460         break;
 461     case 0x5:
 462         /* 3F1R */
 463         *pi_channels = 4;
 464         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER
 465                             | AOUT_CHAN_REARCENTER;
 466         break;
 467     case 0x6:
 468         /* 2F2R */
 469         *pi_channels = 4;
 470         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
 471                             | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT;
 472         break;
 473     case 0x7:
 474         /* 3F2R */
 475         *pi_channels = 5;
 476         *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_CENTER
 477                             | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT;
 478         break;
 479     default:
 480         return 0;
 481     }
 482
 483     if ( p_buf[6] & lfeon[acmod] )
 484     {
 485         (*pi_channels)++;
 486         *pi_channels_conf |= AOUT_CHAN_LFE;
 487     }
 488
 489     frmsizecod = p_buf[4] & 63;
 490     if (frmsizecod >= 38)
 491         return 0;
 492     bitrate = rate [frmsizecod >> 1];
 493     *pi_bit_rate = (bitrate * 1000) >> half;
 494
 495     switch (p_buf[4] & 0xc0) {
 496     case 0:
 497         *pi_sample_rate = 48000 >> half;
 498         return 4 * bitrate;
 499     case 0x40:
 500         *pi_sample_rate = 44100 >> half;
 501         return 2 * (320 * bitrate / 147 + (frmsizecod & 1));
 502     case 0x80:
 503         *pi_sample_rate = 32000 >> half;
 504         return 6 * bitrate;
 505     default:
 506         return 0;
 507     }
 508 }