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 1.22 2001/12/09 17:01:37 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 "defs.h"
  28
  29 #include <string.h>                                    /* memcpy(), memset() */
  30 #include <sys/types.h>                                              /* off_t */
  31
  32 #include "common.h"
  33 #include "intf_msg.h"
  34 #include "threads.h"
  35 #include "mtime.h"
  36
  37 #include "stream_control.h"
  38 #include "input_ext-dec.h"
  39 #include "input_ext-intf.h"
  40 #include "input_ext-plugins.h"
  41
  42 /*****************************************************************************
  43  * InitBitstream: initialize a bit_stream_t structure
  44  *****************************************************************************/
  45 void InitBitstream( bit_stream_t * p_bit_stream, decoder_fifo_t * p_fifo,
  46                     void (* pf_bitstream_callback)( struct bit_stream_s *,
  47                                                     boolean_t ),
  48                     void * p_callback_arg )
  49 {
  50     p_bit_stream->p_decoder_fifo = p_fifo;
  51     p_bit_stream->pf_next_data_packet = NextDataPacket;
  52     p_bit_stream->pf_bitstream_callback = pf_bitstream_callback;
  53     p_bit_stream->p_callback_arg = p_callback_arg;
  54
  55     /* Get the first data packet. */
  56     vlc_mutex_lock( &p_fifo->data_lock );
  57     while ( DECODER_FIFO_ISEMPTY( *p_fifo ) )
  58     {
  59         if ( p_fifo->b_die )
  60         {
  61             vlc_mutex_unlock( &p_fifo->data_lock );
  62             return;
  63         }
  64         vlc_cond_wait( &p_fifo->data_wait, &p_fifo->data_lock );
  65     }
  66     p_bit_stream->p_data = DECODER_FIFO_START( *p_fifo )->p_first;
  67     p_bit_stream->p_byte = p_bit_stream->p_data->p_payload_start;
  68     p_bit_stream->p_end  = p_bit_stream->p_data->p_payload_end;
  69     p_bit_stream->fifo.buffer = 0;
  70     p_bit_stream->fifo.i_available = 0;
  71     vlc_mutex_unlock( &p_fifo->data_lock );
  72
  73     /* Call back the decoder. */
  74     if( p_bit_stream->pf_bitstream_callback != NULL )
  75     {
  76         p_bit_stream->pf_bitstream_callback( p_bit_stream, 1 );
  77     }
  78
  79     if( p_bit_stream->p_byte <= p_bit_stream->p_end - sizeof(WORD_TYPE) )
  80     {
  81         /* Get aligned on a word boundary.
  82          * NB : we _will_ get aligned, because we have at most
  83          * sizeof(WORD_TYPE) - 1 bytes to store, and at least
  84          * sizeof(WORD_TYPE) - 1 empty bytes in the bit buffer. */
  85         AlignWord( p_bit_stream );
  86     }
  87 }
  88
  89 /*****************************************************************************
  90  * NextDataPacket: go to the next data packet
  91  *****************************************************************************/
  92 void NextDataPacket( bit_stream_t * p_bit_stream )
  93 {
  94     decoder_fifo_t *    p_fifo = p_bit_stream->p_decoder_fifo;
  95     boolean_t           b_new_pes;
  96
  97     /* We are looking for the next data packet that contains real data,
  98      * and not just a PES header */
  99     do
 100     {
 101         /* We were reading the last data packet of this PES packet... It's
 102          * time to jump to the next PES packet */
 103         if( p_bit_stream->p_data->p_next == NULL )
 104         {
 105             /* We are going to read/write the start and end indexes of the
 106              * decoder fifo and to use the fifo's conditional variable,
 107              * that's why we need to take the lock before. */
 108             vlc_mutex_lock( &p_fifo->data_lock );
 109
 110             /* Free the previous PES packet. */
 111             p_fifo->pf_delete_pes( p_fifo->p_packets_mgt,
 112                                    DECODER_FIFO_START( *p_fifo ) );
 113             DECODER_FIFO_INCSTART( *p_fifo );
 114
 115             if( DECODER_FIFO_ISEMPTY( *p_fifo ) )
 116             {
 117                 /* Wait for the input to tell us when we receive a packet. */
 118                 vlc_cond_wait( &p_fifo->data_wait, &p_fifo->data_lock );
 119             }
 120
 121             /* The next byte could be found in the next PES packet */
 122             p_bit_stream->p_data = DECODER_FIFO_START( *p_fifo )->p_first;
 123
 124             vlc_mutex_unlock( &p_fifo->data_lock );
 125
 126             b_new_pes = 1;
 127         }
 128         else
 129         {
 130             /* Perhaps the next data packet of the current PES packet contains
 131              * real data (ie its payload's size is greater than 0). */
 132             p_bit_stream->p_data = p_bit_stream->p_data->p_next;
 133
 134             b_new_pes = 0;
 135         }
 136     } while ( p_bit_stream->p_data->p_payload_start
 137                == p_bit_stream->p_data->p_payload_end );
 138
 139     /* We've found a data packet which contains interesting data... */
 140     p_bit_stream->p_byte = p_bit_stream->p_data->p_payload_start;
 141     p_bit_stream->p_end  = p_bit_stream->p_data->p_payload_end;
 142
 143     /* Call back the decoder. */
 144     if( p_bit_stream->pf_bitstream_callback != NULL )
 145     {
 146         p_bit_stream->pf_bitstream_callback( p_bit_stream, b_new_pes );
 147     }
 148 }
 149
 150 /*****************************************************************************
 151  * UnalignedShowBits : places i_bits bits into the bit buffer, even when
 152  * not aligned on a word boundary
 153  *****************************************************************************/
 154 u32 UnalignedShowBits( bit_stream_t * p_bit_stream, unsigned int i_bits )
 155 {
 156     /* We just fill in the bit buffer. */
 157     while( p_bit_stream->fifo.i_available < i_bits )
 158     {
 159         if( p_bit_stream->p_byte < p_bit_stream->p_end )
 160         {
 161             p_bit_stream->fifo.buffer |= *(p_bit_stream->p_byte++)
 162                                             << (8 * sizeof(WORD_TYPE) - 8
 163                                             - p_bit_stream->fifo.i_available);
 164             p_bit_stream->fifo.i_available += 8;
 165         }
 166         else
 167         {
 168             p_bit_stream->pf_next_data_packet( p_bit_stream );
 169
 170             if( (ptrdiff_t)p_bit_stream->p_byte & (sizeof(WORD_TYPE) - 1) )
 171             {
 172                 /* We are not aligned anymore. */
 173                 if( ((ptrdiff_t)p_bit_stream->p_byte
 174                                     & (sizeof(WORD_TYPE) - 1)) * 8
 175                         < p_bit_stream->fifo.i_available )
 176                 {
 177                     /* We are not aligned, and won't be. Copy the first word
 178                      * of the packet in a temporary buffer, and we'll see
 179                      * later. */
 180                     int     i;
 181
 182                     /* sizeof(WORD_TYPE) - number of bytes to trash
 183                      * from the last payload */
 184                     int     j;
 185
 186                     p_bit_stream->i_showbits_buffer = 0;
 187
 188                     for( j = i = 0 ; i < sizeof(WORD_TYPE) ; i++ )
 189                     {
 190                         if( p_bit_stream->p_byte >= p_bit_stream->p_end )
 191                         {
 192                             j = i;
 193                             p_bit_stream->pf_next_data_packet( p_bit_stream );
 194                         }
 195                         ((byte_t *)&p_bit_stream->i_showbits_buffer)[i] =
 196                             * p_bit_stream->p_byte;
 197                         p_bit_stream->p_byte++;
 198                     }
 199
 200                     /* This is kind of kludgy. */
 201                     p_bit_stream->p_data->p_payload_start +=
 202                                                          sizeof(WORD_TYPE) - j;
 203                     p_bit_stream->p_byte =
 204                         (byte_t *)&p_bit_stream->i_showbits_buffer;
 205                     p_bit_stream->p_end =
 206                         (byte_t *)&p_bit_stream->i_showbits_buffer
 207                             + sizeof(WORD_TYPE);
 208                     p_bit_stream->showbits_data.p_next = p_bit_stream->p_data;
 209                     p_bit_stream->p_data = &p_bit_stream->showbits_data;
 210                 }
 211                 else
 212                 {
 213                     /* We are not aligned, but we can be. */
 214                     AlignWord( p_bit_stream );
 215                 }
 216             }
 217
 218             /* We have 32 bits ready for reading, it will be enough. */
 219             break;
 220         }
 221     }
 222
 223     /* It shouldn't loop :-)) */
 224     return( ShowBits( p_bit_stream, i_bits ) );
 225 }
 226
 227 /*****************************************************************************
 228  * UnalignedGetBits : returns i_bits bits from the bit stream and removes
 229  * them from the buffer, even when the bit stream is not aligned on a word
 230  * boundary
 231  *****************************************************************************/
 232 u32 UnalignedGetBits( bit_stream_t * p_bit_stream, unsigned int i_bits )
 233 {
 234     u32         i_result;
 235
 236     i_result = p_bit_stream->fifo.buffer
 237                     >> (8 * sizeof(WORD_TYPE) - i_bits);
 238     i_bits = -p_bit_stream->fifo.i_available;
 239
 240     /* Gather missing bytes. */
 241     while( i_bits >= 8 )
 242     {
 243         if( p_bit_stream->p_byte < p_bit_stream->p_end )
 244         {
 245             i_result |= *(p_bit_stream->p_byte++) << (i_bits - 8);
 246             i_bits -= 8;
 247         }
 248         else
 249         {
 250             p_bit_stream->pf_next_data_packet( p_bit_stream );
 251             i_result |= *(p_bit_stream->p_byte++) << (i_bits - 8);
 252             i_bits -= 8;
 253         }
 254     }
 255
 256     /* Gather missing bits. */
 257     if( i_bits > 0 )
 258     {
 259         unsigned int    i_tmp = 8 - i_bits;
 260
 261         if( p_bit_stream->p_byte < p_bit_stream->p_end )
 262         {
 263             i_result |= *p_bit_stream->p_byte >> i_tmp;
 264             p_bit_stream->fifo.buffer = *(p_bit_stream->p_byte++)
 265                  << ( sizeof(WORD_TYPE) * 8 - i_tmp );
 266             p_bit_stream->fifo.i_available = i_tmp;
 267         }
 268         else
 269         {
 270             p_bit_stream->pf_next_data_packet( p_bit_stream );
 271             i_result |= *p_bit_stream->p_byte >> i_tmp;
 272             p_bit_stream->fifo.buffer = *(p_bit_stream->p_byte++)
 273                  << ( sizeof(WORD_TYPE) * 8 - i_tmp );
 274             p_bit_stream->fifo.i_available = i_tmp;
 275         }
 276     }
 277     else
 278     {
 279         p_bit_stream->fifo.i_available = 0;
 280         p_bit_stream->fifo.buffer = 0;
 281     }
 282
 283     if( p_bit_stream->p_byte <= p_bit_stream->p_end - sizeof(WORD_TYPE) )
 284     {
 285         /* Get aligned on a word boundary. Otherwise it is safer
 286          * to do it the next time.
 287          * NB : we _will_ get aligned, because we have at most
 288          * sizeof(WORD_TYPE) - 1 bytes to store, and at least
 289          * sizeof(WORD_TYPE) - 1 empty bytes in the bit buffer. */
 290         AlignWord( p_bit_stream );
 291     }
 292
 293     return( i_result );
 294 }
 295
 296 /*****************************************************************************
 297  * UnalignedRemoveBits : removes i_bits (== -i_available) from the bit
 298  * buffer, even when the bit stream is not aligned on a word boundary
 299  *****************************************************************************/
 300 void UnalignedRemoveBits( bit_stream_t * p_bit_stream )
 301 {
 302     /* First remove all unnecessary bytes. */
 303     while( p_bit_stream->fifo.i_available <= -8 )
 304     {
 305         if( p_bit_stream->p_byte < p_bit_stream->p_end )
 306         {
 307             p_bit_stream->p_byte++;
 308             p_bit_stream->fifo.i_available += 8;
 309         }
 310         else
 311         {
 312             p_bit_stream->pf_next_data_packet( p_bit_stream );
 313             p_bit_stream->p_byte++;
 314             p_bit_stream->fifo.i_available += 8;
 315         }
 316     }
 317
 318     /* Remove unnecessary bits. */
 319     if( p_bit_stream->fifo.i_available < 0 )
 320     {
 321         if( p_bit_stream->p_byte < p_bit_stream->p_end )
 322         {
 323             p_bit_stream->fifo.buffer = *(p_bit_stream->p_byte++)
 324                  << ( sizeof(WORD_TYPE) * 8 - 8
 325                          - p_bit_stream->fifo.i_available );
 326             p_bit_stream->fifo.i_available += 8;
 327         }
 328         else
 329         {
 330             p_bit_stream->pf_next_data_packet( p_bit_stream );
 331             p_bit_stream->fifo.buffer = *(p_bit_stream->p_byte++)
 332                  << ( sizeof(WORD_TYPE) * 8 - 8
 333                          - p_bit_stream->fifo.i_available );
 334             p_bit_stream->fifo.i_available += 8;
 335         }
 336     }
 337     else
 338     {
 339         p_bit_stream->fifo.buffer = 0;
 340     }
 341
 342     if( p_bit_stream->p_byte <= p_bit_stream->p_end - sizeof(WORD_TYPE) )
 343     {
 344         /* Get aligned on a word boundary. Otherwise it is safer
 345          * to do it the next time.
 346          * NB : we _will_ get aligned, because we have at most
 347          * sizeof(WORD_TYPE) - 1 bytes to store, and at least
 348          * sizeof(WORD_TYPE) - 1 empty bytes in the bit buffer. */
 349         AlignWord( p_bit_stream );
 350     }
 351 }
 352