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, 1999, 2000 VideoLAN
   5  * $Id: input_ext-dec.c,v 1.18 2001/08/22 17:21:45 massiot 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 "config.h"
  33 #include "common.h"
  34 #include "threads.h"
  35 #include "mtime.h"
  36
  37 #include "intf_msg.h"
  38
  39 #include "stream_control.h"
  40 #include "input_ext-dec.h"
  41 #include "input_ext-intf.h"
  42 #include "input_ext-plugins.h"
  43
  44 /*****************************************************************************
  45  * InitBitstream: initialize a bit_stream_t structure
  46  *****************************************************************************/
  47 void InitBitstream( bit_stream_t * p_bit_stream, decoder_fifo_t * p_fifo,
  48                     void (* pf_bitstream_callback)( struct bit_stream_s *,
  49                                                     boolean_t ),
  50                     void * p_callback_arg )
  51 {
  52     p_bit_stream->p_decoder_fifo = p_fifo;
  53     p_bit_stream->pf_next_data_packet = NextDataPacket;
  54     p_bit_stream->pf_bitstream_callback = pf_bitstream_callback;
  55     p_bit_stream->p_callback_arg = p_callback_arg;
  56
  57     /* Get the first data packet. */
  58     vlc_mutex_lock( &p_fifo->data_lock );
  59     while ( DECODER_FIFO_ISEMPTY( *p_fifo ) )
  60     {
  61         if ( p_fifo->b_die )
  62         {
  63             vlc_mutex_unlock( &p_fifo->data_lock );
  64             return;
  65         }
  66         vlc_cond_wait( &p_fifo->data_wait, &p_fifo->data_lock );
  67     }
  68     p_bit_stream->p_data = DECODER_FIFO_START( *p_fifo )->p_first;
  69     p_bit_stream->p_byte = p_bit_stream->p_data->p_payload_start;
  70     p_bit_stream->p_end  = p_bit_stream->p_data->p_payload_end;
  71     p_bit_stream->fifo.buffer = 0;
  72     p_bit_stream->fifo.i_available = 0;
  73     vlc_mutex_unlock( &p_fifo->data_lock );
  74
  75     /* Call back the decoder. */
  76     if( p_bit_stream->pf_bitstream_callback != NULL )
  77     {
  78         p_bit_stream->pf_bitstream_callback( p_bit_stream, 1 );
  79     }
  80
  81     if( p_bit_stream->p_byte <= p_bit_stream->p_end - sizeof(WORD_TYPE) )
  82     {
  83         /* Get aligned on a word boundary.
  84          * NB : we _will_ get aligned, because we have at most
  85          * sizeof(WORD_TYPE) - 1 bytes to store, and at least
  86          * sizeof(WORD_TYPE) - 1 empty bytes in the bit buffer. */
  87         AlignWord( p_bit_stream );
  88     }
  89 }
  90
  91 /*****************************************************************************
  92  * NextDataPacket: go to the next data packet
  93  *****************************************************************************/
  94 void NextDataPacket( bit_stream_t * p_bit_stream )
  95 {
  96     decoder_fifo_t *    p_fifo = p_bit_stream->p_decoder_fifo;
  97     boolean_t           b_new_pes;
  98
  99     /* We are looking for the next data packet that contains real data,
 100      * and not just a PES header */
 101     do
 102     {
 103         /* We were reading the last data packet of this PES packet... It's
 104          * time to jump to the next PES packet */
 105         if( p_bit_stream->p_data->p_next == NULL )
 106         {
 107             /* We are going to read/write the start and end indexes of the
 108              * decoder fifo and to use the fifo's conditional variable,
 109              * that's why we need to take the lock before. */
 110             vlc_mutex_lock( &p_fifo->data_lock );
 111
 112             /* Free the previous PES packet. */
 113             p_fifo->pf_delete_pes( p_fifo->p_packets_mgt,
 114                                    DECODER_FIFO_START( *p_fifo ) );
 115             DECODER_FIFO_INCSTART( *p_fifo );
 116
 117             if( DECODER_FIFO_ISEMPTY( *p_fifo ) )
 118             {
 119                 /* Wait for the input to tell us when we receive a packet. */
 120                 vlc_cond_wait( &p_fifo->data_wait, &p_fifo->data_lock );
 121             }
 122
 123             /* The next byte could be found in the next PES packet */
 124             p_bit_stream->p_data = DECODER_FIFO_START( *p_fifo )->p_first;
 125
 126             vlc_mutex_unlock( &p_fifo->data_lock );
 127
 128             b_new_pes = 1;
 129         }
 130         else
 131         {
 132             /* Perhaps the next data packet of the current PES packet contains
 133              * real data (ie its payload's size is greater than 0). */
 134             p_bit_stream->p_data = p_bit_stream->p_data->p_next;
 135
 136             b_new_pes = 0;
 137         }
 138     } while ( p_bit_stream->p_data->p_payload_start
 139                == p_bit_stream->p_data->p_payload_end );
 140
 141     /* We've found a data packet which contains interesting data... */
 142     p_bit_stream->p_byte = p_bit_stream->p_data->p_payload_start;
 143     p_bit_stream->p_end  = p_bit_stream->p_data->p_payload_end;
 144
 145     /* Call back the decoder. */
 146     if( p_bit_stream->pf_bitstream_callback != NULL )
 147     {
 148         p_bit_stream->pf_bitstream_callback( p_bit_stream, b_new_pes );
 149     }
 150 }
 151
 152 /*****************************************************************************
 153  * UnalignedShowBits : places i_bits bits into the bit buffer, even when
 154  * not aligned on a word boundary
 155  *****************************************************************************/
 156 void UnalignedShowBits( bit_stream_t * p_bit_stream, unsigned int i_bits )
 157 {
 158     /* We just fill in the bit buffer. */
 159     while( p_bit_stream->fifo.i_available < i_bits )
 160     {
 161         if( p_bit_stream->p_byte < p_bit_stream->p_end )
 162         {
 163             p_bit_stream->fifo.buffer |= *(p_bit_stream->p_byte++)
 164                                             << (8 * sizeof(WORD_TYPE) - 8
 165                                             - p_bit_stream->fifo.i_available);
 166             p_bit_stream->fifo.i_available += 8;
 167         }
 168         else
 169         {
 170             p_bit_stream->pf_next_data_packet( p_bit_stream );
 171
 172             if( (ptrdiff_t)p_bit_stream->p_byte & (sizeof(WORD_TYPE) - 1) )
 173             {
 174                 /* We are not aligned anymore. */
 175                 if( ((ptrdiff_t)p_bit_stream->p_byte
 176                                     & (sizeof(WORD_TYPE) - 1)) * 8
 177                         < p_bit_stream->fifo.i_available )
 178                 {
 179                     /* We are not aligned, and won't be. Copy the first word
 180                      * of the packet in a temporary buffer, and we'll see
 181                      * later. */
 182                     int     i;
 183
 184                     /* sizeof(WORD_TYPE) - number of bytes to trash
 185                      * from the last payload */
 186                     int     j;
 187
 188                     p_bit_stream->i_showbits_buffer = 0;
 189
 190                     for( j = i = 0 ; i < sizeof(WORD_TYPE) ; i++ )
 191                     {
 192                         if( p_bit_stream->p_byte >= p_bit_stream->p_end )
 193                         {
 194                             j = i;
 195                             p_bit_stream->pf_next_data_packet( p_bit_stream );
 196                         }
 197                         ((byte_t *)&p_bit_stream->i_showbits_buffer)[i] =
 198                             * p_bit_stream->p_byte;
 199                         p_bit_stream->p_byte++;
 200                     }
 201
 202                     /* This is kind of kludgy. */
 203                     p_bit_stream->p_data->p_payload_start +=
 204                                                          sizeof(WORD_TYPE) - j;
 205                     p_bit_stream->p_byte =
 206                         (byte_t *)&p_bit_stream->i_showbits_buffer;
 207                     p_bit_stream->p_end =
 208                         (byte_t *)&p_bit_stream->i_showbits_buffer
 209                             + sizeof(WORD_TYPE);
 210                     p_bit_stream->showbits_data.p_next = p_bit_stream->p_data;
 211                     p_bit_stream->p_data = &p_bit_stream->showbits_data;
 212                 }
 213                 else
 214                 {
 215                     /* We are not aligned, but we can be. */
 216                     AlignWord( p_bit_stream );
 217                 }
 218             }
 219         }
 220     }
 221 }
 222
 223 /*****************************************************************************
 224  * UnalignedGetBits : returns i_bits bits from the bit stream and removes
 225  * them from the buffer, even when the bit stream is not aligned on a word
 226  * boundary
 227  *****************************************************************************/
 228 u32 UnalignedGetBits( bit_stream_t * p_bit_stream, unsigned int i_bits )
 229 {
 230     u32         i_result;
 231
 232     i_result = p_bit_stream->fifo.buffer
 233                     >> (8 * sizeof(WORD_TYPE) - i_bits);
 234     i_bits = -p_bit_stream->fifo.i_available;
 235
 236     /* Gather missing bytes. */
 237     while( i_bits >= 8 )
 238     {
 239         if( p_bit_stream->p_byte < p_bit_stream->p_end )
 240         {
 241             i_result |= *(p_bit_stream->p_byte++) << (i_bits - 8);
 242             i_bits -= 8;
 243         }
 244         else
 245         {
 246             p_bit_stream->pf_next_data_packet( p_bit_stream );
 247             i_result |= *(p_bit_stream->p_byte++) << (i_bits - 8);
 248             i_bits -= 8;
 249         }
 250     }
 251
 252     /* Gather missing bits. */
 253     if( i_bits > 0 )
 254     {
 255         unsigned int    i_tmp = 8 - i_bits;
 256
 257         if( p_bit_stream->p_byte < p_bit_stream->p_end )
 258         {
 259             i_result |= *p_bit_stream->p_byte >> i_tmp;
 260             p_bit_stream->fifo.buffer = *(p_bit_stream->p_byte++)
 261                  << ( sizeof(WORD_TYPE) * 8 - i_tmp );
 262             p_bit_stream->fifo.i_available = i_tmp;
 263         }
 264         else
 265         {
 266             p_bit_stream->pf_next_data_packet( p_bit_stream );
 267             i_result |= *p_bit_stream->p_byte >> i_tmp;
 268             p_bit_stream->fifo.buffer = *(p_bit_stream->p_byte++)
 269                  << ( sizeof(WORD_TYPE) * 8 - i_tmp );
 270             p_bit_stream->fifo.i_available = i_tmp;
 271         }
 272     }
 273     else
 274     {
 275         p_bit_stream->fifo.i_available = 0;
 276         p_bit_stream->fifo.buffer = 0;
 277     }
 278
 279     if( p_bit_stream->p_byte <= p_bit_stream->p_end - sizeof(WORD_TYPE) )
 280     {
 281         /* Get aligned on a word boundary. Otherwise it is safer
 282          * to do it the next time.
 283          * NB : we _will_ get aligned, because we have at most
 284          * sizeof(WORD_TYPE) - 1 bytes to store, and at least
 285          * sizeof(WORD_TYPE) - 1 empty bytes in the bit buffer. */
 286         AlignWord( p_bit_stream );
 287     }
 288
 289     return( i_result );
 290 }
 291
 292 /*****************************************************************************
 293  * UnalignedRemoveBits : removes i_bits (== -i_available) from the bit
 294  * buffer, even when the bit stream is not aligned on a word boundary
 295  *****************************************************************************/
 296 void UnalignedRemoveBits( bit_stream_t * p_bit_stream )
 297 {
 298     /* First remove all unnecessary bytes. */
 299     while( p_bit_stream->fifo.i_available <= -8 )
 300     {
 301         if( p_bit_stream->p_byte < p_bit_stream->p_end )
 302         {
 303             p_bit_stream->p_byte++;
 304             p_bit_stream->fifo.i_available += 8;
 305         }
 306         else
 307         {
 308             p_bit_stream->pf_next_data_packet( p_bit_stream );
 309             p_bit_stream->p_byte++;
 310             p_bit_stream->fifo.i_available += 8;
 311         }
 312     }
 313
 314     /* Remove unnecessary bits. */
 315     if( p_bit_stream->fifo.i_available < 0 )
 316     {
 317         if( p_bit_stream->p_byte < p_bit_stream->p_end )
 318         {
 319             p_bit_stream->fifo.buffer = *(p_bit_stream->p_byte++)
 320                  << ( sizeof(WORD_TYPE) * 8 - 8
 321                          - p_bit_stream->fifo.i_available );
 322             p_bit_stream->fifo.i_available += 8;
 323         }
 324         else
 325         {
 326             p_bit_stream->pf_next_data_packet( p_bit_stream );
 327             p_bit_stream->fifo.buffer = *(p_bit_stream->p_byte++)
 328                  << ( sizeof(WORD_TYPE) * 8 - 8
 329                          - p_bit_stream->fifo.i_available );
 330             p_bit_stream->fifo.i_available += 8;
 331         }
 332     }
 333     else
 334     {
 335         p_bit_stream->fifo.buffer = 0;
 336     }
 337
 338     if( p_bit_stream->p_byte <= p_bit_stream->p_end - sizeof(WORD_TYPE) )
 339     {
 340         /* Get aligned on a word boundary. Otherwise it is safer
 341          * to do it the next time.
 342          * NB : we _will_ get aligned, because we have at most
 343          * sizeof(WORD_TYPE) - 1 bytes to store, and at least
 344          * sizeof(WORD_TYPE) - 1 empty bytes in the bit buffer. */
 345         AlignWord( p_bit_stream );
 346     }
 347 }
 348