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