git.sesse.net Git - vlc/blob - src/input/input_ext-dec.c

   1 /*****************************************************************************
   2  * input_ext-dec.c: services to the decoders
   3  *****************************************************************************
   4  * Copyright (C) 1998-2001 VideoLAN
   5  * $Id: input_ext-dec.c,v 1.41 2002/11/11 14:39:12 sam Exp $
   6  *
   7  * Authors: Christophe Massiot <massiot@via.ecp.fr>
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License as published by
  11  * the Free Software Foundation; either version 2 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  * GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with this program; if not, write to the Free Software
  21  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
  22  *****************************************************************************/
  23
  24 /*****************************************************************************
  25  * Preamble
  26  *****************************************************************************/
  27 #include <string.h>                                    /* memcpy(), memset() */
  28
  29 #include <vlc/vlc.h>
  30
  31 #include "stream_control.h"
  32 #include "input_ext-dec.h"
  33 #include "input_ext-intf.h"
  34 #include "input_ext-plugins.h"
  35
  36 /*****************************************************************************
  37  * InitBitstream: initialize a bit_stream_t structure and returns VLC_SUCCESS
  38  *                on success.
  39  *****************************************************************************/
  40 int InitBitstream( bit_stream_t * p_bit_stream, decoder_fifo_t * p_fifo,
  41                 void (* pf_bitstream_callback)( bit_stream_t *, vlc_bool_t ),
  42                 void * p_callback_arg )
  43 {
  44     /* Get the first pes packet */
  45     input_ExtractPES( p_fifo, &p_bit_stream->p_pes );
  46     if( !p_bit_stream->p_pes )
  47         return VLC_EGENERIC;
  48
  49     p_bit_stream->p_decoder_fifo = p_fifo;
  50     p_bit_stream->pf_bitstream_callback = pf_bitstream_callback;
  51     p_bit_stream->p_callback_arg = p_callback_arg;
  52
  53     p_bit_stream->p_data = p_bit_stream->p_pes->p_first;
  54     p_bit_stream->p_byte = p_bit_stream->p_data->p_payload_start;
  55     p_bit_stream->p_end  = p_bit_stream->p_data->p_payload_end;
  56     p_bit_stream->fifo.buffer = 0;
  57     p_bit_stream->fifo.i_available = 0;
  58     p_bit_stream->i_pts = p_bit_stream->p_pes->i_pts;
  59     p_bit_stream->i_dts = p_bit_stream->p_pes->i_dts;
  60     p_bit_stream->p_pts_validity = p_bit_stream->p_byte;
  61
  62     /* Call back the decoder. */
  63     if( p_bit_stream->pf_bitstream_callback != NULL )
  64     {
  65         p_bit_stream->pf_bitstream_callback( p_bit_stream, 1 );
  66     }
  67
  68     if( p_bit_stream->p_byte <= p_bit_stream->p_end - sizeof(WORD_TYPE) )
  69     {
  70         /* Get aligned on a word boundary.
  71          * NB : we _will_ get aligned, because we have at most
  72          * sizeof(WORD_TYPE) - 1 bytes to store, and at least
  73          * sizeof(WORD_TYPE) - 1 empty bytes in the bit buffer. */
  74         AlignWord( p_bit_stream );
  75     }
  76
  77     return VLC_SUCCESS;
  78 }
  79
  80 /*****************************************************************************
  81  * CloseBitstream: free the bitstream structure.
  82  *****************************************************************************/
  83 void CloseBitstream( bit_stream_t * p_bit_stream )
  84 {
  85     if( p_bit_stream->p_pes )
  86         input_DeletePES( p_bit_stream->p_decoder_fifo->p_packets_mgt,
  87                          p_bit_stream->p_pes );
  88 }
  89
  90 /*****************************************************************************
  91  * DecoderError : an error occured, use this function to empty the fifo
  92  *****************************************************************************/
  93 void DecoderError( decoder_fifo_t * p_fifo )
  94 {
  95     /* No need to take the lock, because input_ExtractPES already takes it
  96      * and also check for p_fifo->b_die */
  97
  98     /* Wait until a `die' order is sent */
  99     while( !p_fifo->b_die )
 100     {
 101         /* Trash all received PES packets */
 102         input_ExtractPES( p_fifo, NULL );
 103     }
 104 }
 105
 106 /*****************************************************************************
 107  * NextDataPacket: go to the data packet after *pp_data, return 1 if we
 108  * changed PES. This function can fail in case of end of stream, you can
 109  * check p_bit_stream->p_data or p_bit_stream->p_pes to know wether we did get
 110  * the next data packet.
 111  *****************************************************************************/
 112 static inline vlc_bool_t _NextDataPacket( decoder_fifo_t * p_fifo,
 113                                           bit_stream_t * p_bit_stream )
 114 {
 115     vlc_bool_t b_new_pes;
 116
 117     /* We are looking for the next data packet that contains real data,
 118      * and not just a PES header */
 119     do
 120     {
 121         /* We were reading the last data packet of this PES packet... It's
 122          * time to jump to the next PES packet */
 123         if( p_bit_stream->p_data->p_next == NULL )
 124         {
 125             /* The next packet could be found in the next PES packet */
 126             input_DeletePES( p_fifo->p_packets_mgt, p_bit_stream->p_pes );
 127             input_ExtractPES( p_fifo, &p_bit_stream->p_pes );
 128             if( !p_bit_stream->p_pes )
 129             {
 130                 /* Couldn't get the next PES, might be an eos */
 131                 p_bit_stream->p_data = NULL;
 132                 return 0;
 133             }
 134             p_bit_stream->p_data = p_bit_stream->p_pes->p_first;
 135             b_new_pes = 1;
 136         }
 137         else
 138         {
 139             /* Perhaps the next data packet of the current PES packet contains
 140              * real data (ie its payload's size is greater than 0). */
 141             p_bit_stream->p_data = p_bit_stream->p_data->p_next;
 142
 143             b_new_pes = 0;
 144         }
 145     } while ( p_bit_stream->p_data->p_payload_start ==
 146               p_bit_stream->p_data->p_payload_end );
 147
 148     return( b_new_pes );
 149 }
 150
 151 vlc_bool_t NextDataPacket( decoder_fifo_t * p_fifo,
 152                            bit_stream_t * p_bit_stream )
 153 {
 154     return( _NextDataPacket( p_fifo, p_bit_stream ) );
 155 }
 156
 157 /*****************************************************************************
 158  * BitstreamNextDataPacket: go to the next data packet, and update bitstream
 159  * context. This function can fail in case of eos!
 160  *****************************************************************************/
 161 static inline void _BitstreamNextDataPacket( bit_stream_t * p_bit_stream )
 162 {
 163     decoder_fifo_t *    p_fifo = p_bit_stream->p_decoder_fifo;
 164     vlc_bool_t          b_new_pes;
 165
 166     b_new_pes = _NextDataPacket( p_fifo, p_bit_stream );
 167     if( !p_bit_stream->p_pes ) return;
 168
 169     /* We've found a data packet which contains interesting data... */
 170     p_bit_stream->p_byte = p_bit_stream->p_data->p_payload_start;
 171     p_bit_stream->p_end  = p_bit_stream->p_data->p_payload_end;
 172
 173     /* Call back the decoder. */
 174     if( p_bit_stream->pf_bitstream_callback != NULL )
 175     {
 176         p_bit_stream->pf_bitstream_callback( p_bit_stream, b_new_pes );
 177     }
 178
 179     /* Discontinuity management. */
 180     if( p_bit_stream->p_data->b_discard_payload )
 181     {
 182         p_bit_stream->i_pts = p_bit_stream->i_dts = 0;
 183     }
 184
 185     /* Retrieve the PTS. */
 186     if( b_new_pes && p_bit_stream->p_pes->i_pts )
 187     {
 188         p_bit_stream->i_pts = p_bit_stream->p_pes->i_pts;
 189         p_bit_stream->i_dts = p_bit_stream->p_pes->i_dts;
 190         p_bit_stream->p_pts_validity = p_bit_stream->p_byte;
 191     }
 192 }
 193
 194 void BitstreamNextDataPacket( bit_stream_t * p_bit_stream )
 195 {
 196     _BitstreamNextDataPacket( p_bit_stream );
 197 }
 198
 199 /*****************************************************************************
 200  * UnalignedShowBits : places i_bits bits into the bit buffer, even when
 201  * not aligned on a word boundary
 202  *****************************************************************************/
 203 u32 UnalignedShowBits( bit_stream_t * p_bit_stream, unsigned int i_bits )
 204 {
 205     /* We just fill in the bit buffer. */
 206     while( p_bit_stream->fifo.i_available < i_bits )
 207     {
 208         if( p_bit_stream->p_byte < p_bit_stream->p_end )
 209         {
 210             p_bit_stream->fifo.buffer |= *(p_bit_stream->p_byte++)
 211                                             << (8 * sizeof(WORD_TYPE) - 8
 212                                             - p_bit_stream->fifo.i_available);
 213             p_bit_stream->fifo.i_available += 8;
 214         }
 215         else
 216         {
 217             _BitstreamNextDataPacket( p_bit_stream );
 218
 219             if( (ptrdiff_t)p_bit_stream->p_byte & (sizeof(WORD_TYPE) - 1) )
 220             {
 221                 /* We are not aligned anymore. */
 222                 if( ((ptrdiff_t)p_bit_stream->p_byte
 223                                     & (sizeof(WORD_TYPE) - 1)) * 8
 224                         < p_bit_stream->fifo.i_available )
 225                 {
 226                     /* We are not aligned, and won't be. Copy the first word
 227                      * of the packet in a temporary buffer, and we'll see
 228                      * later. */
 229                     int     i;
 230
 231                     /* sizeof(WORD_TYPE) - number of bytes to trash
 232                      * from the last payload */
 233                     int     j;
 234
 235                     p_bit_stream->i_showbits_buffer = 0;
 236
 237                     for( j = i = 0 ; i < sizeof(WORD_TYPE) ; i++ )
 238                     {
 239                         if( p_bit_stream->p_byte >= p_bit_stream->p_end )
 240                         {
 241                             j = i;
 242                             _BitstreamNextDataPacket( p_bit_stream );
 243                         }
 244                         ((byte_t *)&p_bit_stream->i_showbits_buffer)[i] =
 245                             * p_bit_stream->p_byte;
 246                         p_bit_stream->p_byte++;
 247                     }
 248
 249                     /* This is kind of kludgy. */
 250                     p_bit_stream->p_data->p_payload_start +=
 251                                                          sizeof(WORD_TYPE) - j;
 252                     p_bit_stream->p_byte =
 253                         (byte_t *)&p_bit_stream->i_showbits_buffer;
 254                     p_bit_stream->p_end =
 255                         (byte_t *)&p_bit_stream->i_showbits_buffer
 256                             + sizeof(WORD_TYPE);
 257                     p_bit_stream->showbits_data.p_next = p_bit_stream->p_data;
 258                     p_bit_stream->p_data = &p_bit_stream->showbits_data;
 259                 }
 260                 else
 261                 {
 262                     /* We are not aligned, but we can be. */
 263                     AlignWord( p_bit_stream );
 264                 }
 265             }
 266
 267             /* We have 32 bits ready for reading, it will be enough. */
 268             break;
 269         }
 270     }
 271
 272     /* It shouldn't loop :-)) */
 273     return( ShowBits( p_bit_stream, i_bits ) );
 274 }
 275
 276 /*****************************************************************************
 277  * UnalignedGetBits : returns i_bits bits from the bit stream and removes
 278  * them from the buffer, even when the bit stream is not aligned on a word
 279  * boundary
 280  *****************************************************************************/
 281 u32 UnalignedGetBits( bit_stream_t * p_bit_stream, unsigned int i_bits )
 282 {
 283     u32         i_result;
 284
 285     i_result = p_bit_stream->fifo.buffer
 286                     >> (8 * sizeof(WORD_TYPE) - i_bits);
 287     i_bits = -p_bit_stream->fifo.i_available;
 288
 289     /* Gather missing bytes. */
 290     while( i_bits >= 8 )
 291     {
 292         if( p_bit_stream->p_byte < p_bit_stream->p_end )
 293         {
 294             i_result |= *(p_bit_stream->p_byte++) << (i_bits - 8);
 295             i_bits -= 8;
 296         }
 297         else
 298         {
 299             _BitstreamNextDataPacket( p_bit_stream );
 300             i_result |= *(p_bit_stream->p_byte++) << (i_bits - 8);
 301             i_bits -= 8;
 302         }
 303     }
 304
 305     /* Gather missing bits. */
 306     if( i_bits > 0 )
 307     {
 308         unsigned int    i_tmp = 8 - i_bits;
 309
 310         if( p_bit_stream->p_byte < p_bit_stream->p_end )
 311         {
 312             i_result |= *p_bit_stream->p_byte >> i_tmp;
 313             p_bit_stream->fifo.buffer = *(p_bit_stream->p_byte++)
 314                  << ( sizeof(WORD_TYPE) * 8 - i_tmp );
 315             p_bit_stream->fifo.i_available = i_tmp;
 316         }
 317         else
 318         {
 319             _BitstreamNextDataPacket( p_bit_stream );
 320             i_result |= *p_bit_stream->p_byte >> i_tmp;
 321             p_bit_stream->fifo.buffer = *(p_bit_stream->p_byte++)
 322                  << ( sizeof(WORD_TYPE) * 8 - i_tmp );
 323             p_bit_stream->fifo.i_available = i_tmp;
 324         }
 325     }
 326     else
 327     {
 328         p_bit_stream->fifo.i_available = 0;
 329         p_bit_stream->fifo.buffer = 0;
 330     }
 331
 332     if( p_bit_stream->p_byte <= p_bit_stream->p_end - sizeof(WORD_TYPE) )
 333     {
 334         /* Get aligned on a word boundary. Otherwise it is safer
 335          * to do it the next time.
 336          * NB : we _will_ get aligned, because we have at most
 337          * sizeof(WORD_TYPE) - 1 bytes to store, and at least
 338          * sizeof(WORD_TYPE) - 1 empty bytes in the bit buffer. */
 339         AlignWord( p_bit_stream );
 340     }
 341
 342     return( i_result );
 343 }
 344
 345 /*****************************************************************************
 346  * UnalignedRemoveBits : removes i_bits (== -i_available) from the bit
 347  * buffer, even when the bit stream is not aligned on a word boundary
 348  *****************************************************************************/
 349 void UnalignedRemoveBits( bit_stream_t * p_bit_stream )
 350 {
 351     /* First remove all unnecessary bytes. */
 352     while( p_bit_stream->fifo.i_available <= -8 )
 353     {
 354         if( p_bit_stream->p_byte < p_bit_stream->p_end )
 355         {
 356             p_bit_stream->p_byte++;
 357             p_bit_stream->fifo.i_available += 8;
 358         }
 359         else
 360         {
 361             _BitstreamNextDataPacket( p_bit_stream );
 362             p_bit_stream->p_byte++;
 363             p_bit_stream->fifo.i_available += 8;
 364         }
 365     }
 366
 367     /* Remove unnecessary bits. */
 368     if( p_bit_stream->fifo.i_available < 0 )
 369     {
 370         if( p_bit_stream->p_byte < p_bit_stream->p_end )
 371         {
 372             p_bit_stream->fifo.buffer = *(p_bit_stream->p_byte++)
 373                  << ( sizeof(WORD_TYPE) * 8 - 8
 374                          - p_bit_stream->fifo.i_available );
 375             p_bit_stream->fifo.i_available += 8;
 376         }
 377         else
 378         {
 379             _BitstreamNextDataPacket( p_bit_stream );
 380             p_bit_stream->fifo.buffer = *(p_bit_stream->p_byte++)
 381                  << ( sizeof(WORD_TYPE) * 8 - 8
 382                          - p_bit_stream->fifo.i_available );
 383             p_bit_stream->fifo.i_available += 8;
 384         }
 385     }
 386     else
 387     {
 388         p_bit_stream->fifo.buffer = 0;
 389     }
 390
 391     if( p_bit_stream->p_byte <= p_bit_stream->p_end - sizeof(WORD_TYPE) )
 392     {
 393         /* Get aligned on a word boundary. Otherwise it is safer
 394          * to do it the next time.
 395          * NB : we _will_ get aligned, because we have at most
 396          * sizeof(WORD_TYPE) - 1 bytes to store, and at least
 397          * sizeof(WORD_TYPE) - 1 empty bytes in the bit buffer. */
 398         AlignWord( p_bit_stream );
 399     }
 400 }
 401
 402 /*****************************************************************************
 403  * CurrentPTS: returns the current PTS and DTS
 404  *****************************************************************************/
 405 void CurrentPTS( bit_stream_t * p_bit_stream, mtime_t * pi_pts,
 406                  mtime_t * pi_dts )
 407 {
 408     /* Check if the current PTS is already valid (ie. if the first byte
 409      * of the packet has already been used in the decoder). */
 410     ptrdiff_t p_diff = p_bit_stream->p_pts_validity - p_bit_stream->p_byte;
 411     if( p_diff < 0 || p_diff > 4 /* We are far away so it is valid */
 412          || (p_diff * 8) >= p_bit_stream->fifo.i_available
 413             /* We have buffered less bytes than actually read */ )
 414     {
 415         *pi_pts = p_bit_stream->i_pts;
 416         if( pi_dts != NULL ) *pi_dts = p_bit_stream->i_dts;
 417         p_bit_stream->i_pts = 0;
 418         p_bit_stream->i_dts = 0;
 419     }
 420     else
 421     {
 422         *pi_pts = 0;
 423         if( pi_dts != NULL) *pi_dts = 0;
 424     }
 425 }
 426
 427 /*****************************************************************************
 428  * NextPTS: returns the PTS and DTS for the next starting byte
 429  *****************************************************************************/
 430 void NextPTS( bit_stream_t * p_bit_stream, mtime_t * pi_pts,
 431               mtime_t * pi_dts )
 432 {
 433     /* Check if the current PTS is already valid (ie. if the first byte
 434      * of the packet has already been used in the decoder). */
 435     ptrdiff_t p_diff = p_bit_stream->p_pts_validity - p_bit_stream->p_byte - 1;
 436     if( p_diff < 0 || p_diff > 4 /* We are far away so it is valid */
 437          || (p_diff * 8) >= p_bit_stream->fifo.i_available
 438             /* We have buffered less bytes than actually read */ )
 439     {
 440         *pi_pts = p_bit_stream->i_pts;
 441         if( pi_dts != NULL ) *pi_dts = p_bit_stream->i_dts;
 442         p_bit_stream->i_pts = 0;
 443         p_bit_stream->i_dts = 0;
 444     }
 445     else
 446     {
 447         *pi_pts = 0;
 448         if( pi_dts != NULL) *pi_dts = 0;
 449     }
 450 }